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Cheap Detector for Ambient 5G Signals
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Kevin Foster
Nov 17, 2016, 10:57:13 PM11/17/16
to
When 5G comes along, I probably won't be able to afford the cost of a
professional EMF meter.
Does anyone have any suggestions how I could make a kind of "sniffer"
that would display ambient field intensity on an LED bargraph, or even
just a audible output with changing pitch?
The range of interest is 25 to 50GHz (millimeter wave) such as would be
emitted from small cell antennae, etc.
The meter can be pocket size and have as many wire antenna as necessary
to cover this bandwidth.
Kevin Foster
professional EMF meter.
Does anyone have any suggestions how I could make a kind of "sniffer"
that would display ambient field intensity on an LED bargraph, or even
just a audible output with changing pitch?
The range of interest is 25 to 50GHz (millimeter wave) such as would be
emitted from small cell antennae, etc.
The meter can be pocket size and have as many wire antenna as necessary
to cover this bandwidth.
Kevin Foster
John Larkin
Nov 17, 2016, 11:15:40 PM11/17/16
to
past 40 GHz.
Yes, here it is:
http://www.linear.com/product/LTC5596
That would be cool, but it will need some good antenna design.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
Kevin Foster
Nov 18, 2016, 1:47:46 AM11/18/16
to
fractal antenna, plus a few diodes, RF transistors and a VCO driven speaker.
Am I dreaming?
Kevin Foster
Spehro Pefhany
Nov 18, 2016, 8:13:18 AM11/18/16
to
--sp
--
Best regards,
Spehro Pefhany
Amazon link for AoE 3rd Edition: http://tinyurl.com/ntrpwu8
John Larkin
Nov 18, 2016, 12:38:31 PM11/18/16
to
On Fri, 18 Nov 2016 17:47:38 +1100, Kevin Foster
If you mean to amplify the RF pre-detection, past 40 GHz, that would
be very difficult. There are some MMIC amps that work out there, but
they are expensive and still need careful handling.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
be very difficult. There are some MMIC amps that work out there, but
they are expensive and still need careful handling.
--
John Larkin Highland Technology, Inc
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
krw
Nov 18, 2016, 1:06:41 PM11/18/16
to
I see all sorts of ridiculously expensive EVM boards out there. Boards
that they give to larger companies, by the trunk loads.
Phil Hobbs
Nov 18, 2016, 2:04:33 PM11/18/16
to
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
Tim Wescott
Nov 18, 2016, 2:37:13 PM11/18/16
to
antenna, said diode, a cap and a voltage detector to "see" signals right
under the tower.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
I'm looking for work -- see my website!
John Larkin
Nov 18, 2016, 4:35:33 PM11/18/16
to
If the LO was an impulse generator, picket fence in the frequency
domain, it would be interesting. It's a sampler. That could be very
simple.
John Larkin
Nov 18, 2016, 4:39:29 PM11/18/16
to
Distributors are often the best route for them.
But eval boards seem to be designed by the lowest-end junor engineers.
And they have so many jumper options that they don't help much.
--
John Larkin Highland Technology, Inc
Jeff Liebermann
Nov 18, 2016, 5:21:31 PM11/18/16
to
On Fri, 18 Nov 2016 17:47:38 +1100, Kevin Foster
<kfo...@internode.com> wrote:
>> http://www.linear.com/product/LTC5596
Nice chip but needs some broadband gain to produce useful output.
>That is an excellent chip. But I was hoping for something more like a
>fractal antenna, plus a few diodes, RF transistors and a VCO driven speaker.
Fractal antennas might be useful if you want the largest gain in the
smallest package, but are otherwise no better then conventional
antennas.
Speaker? 5G is all about high speed data. If you want to actually
talk to someone, it's a VoIP channel or service on top of the 5G data.
If you managed to demodulate the data, all you'll hear out of speaker
is hissing noise.
>Am I dreaming?
Nope. Some of my checkered background is in direction finders. I've
spent some time working with mechanical rotating antenna DF systems,
which work quite nicely. Some of my old rants on Doppler DF. There
is a note on the bottom of the first link which explains why I like
rotating antenna direction finders:
<http://www.qsl.net/n9zia/doppler_notes1.txt>
<http://www.qsl.net/n9zia/doppler_notes2.txt
When you say "ambient", I'll assume that it's just trying to detect
the source and location of the a 5G emitter, whether base station or
handset, without attempting to decode any data. That's done with a
directional antenna, with minimum side lobes, an RF bandpass filter
for tuning, some gain, an RF detector, and some means of displaying
the results.
At 26.5-40GHz (Ka band), that should to be possible using a Ka band
TVRO (TV receive only) downconverter. Thanks to DBS (direct broadcast
satellite) service, Ka band antennas and equipment is becoming more
common. Your antenna will probably be a TVRO dish. The front end
will be a Ka band LNB with the IF (intermediate frequency) output in
the traditional 950-2140Mhz range. That's much easier to amplify and
detect, and would not require a 40GHz detector.
<http://www.norsat.com/solutions/microwave-products/lnb-ka-band/>
For a PPI (plan position indicator) to obtain a relative bearing,
spinning the antenna with a synchronous motor and displaying the
results on a computah screen should be the most useful method. Aiming
the dish by hand and drawing lines on a map works but is tedious and
slow. With a PPI display, you can distinguish between the direct path
from the source of the 5G signal, from the false bearings produced by
reflections.
You also mentioned "cheap". It can be done cheaply if you build it
something like a microwave oven leakage detector. The antenna can be
a simple horn antenna hung on some WR-28 waveguide with a diode
detector and some kind of 30GHz bandpass filter to keep out the junk.
You'll need to get fairly close to the 4G antenna main lobe, which
might be a problem if it's located on top of a tall tower. Long range
may also be a problem because of atmospheric absorption by water vapor
at the 20GHz end of the Ka band.
<http://www.rfcafe.com/references/electrical/images/atm_absorption.gif>
Incidentally, if you do build such a device, and want to export it,
you will run into ITAR limitations. Just about anything that reeks of
direction finding is considered defense related.
Yawn... Back to billing, bookkeeping, and office untrashing.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
<kfo...@internode.com> wrote:
>> http://www.linear.com/product/LTC5596
Nice chip but needs some broadband gain to produce useful output.
>That is an excellent chip. But I was hoping for something more like a
>fractal antenna, plus a few diodes, RF transistors and a VCO driven speaker.
smallest package, but are otherwise no better then conventional
antennas.
Speaker? 5G is all about high speed data. If you want to actually
talk to someone, it's a VoIP channel or service on top of the 5G data.
If you managed to demodulate the data, all you'll hear out of speaker
is hissing noise.
>Am I dreaming?
Nope. Some of my checkered background is in direction finders. I've
spent some time working with mechanical rotating antenna DF systems,
which work quite nicely. Some of my old rants on Doppler DF. There
is a note on the bottom of the first link which explains why I like
rotating antenna direction finders:
<http://www.qsl.net/n9zia/doppler_notes1.txt>
<http://www.qsl.net/n9zia/doppler_notes2.txt
When you say "ambient", I'll assume that it's just trying to detect
the source and location of the a 5G emitter, whether base station or
handset, without attempting to decode any data. That's done with a
directional antenna, with minimum side lobes, an RF bandpass filter
for tuning, some gain, an RF detector, and some means of displaying
the results.
At 26.5-40GHz (Ka band), that should to be possible using a Ka band
TVRO (TV receive only) downconverter. Thanks to DBS (direct broadcast
satellite) service, Ka band antennas and equipment is becoming more
common. Your antenna will probably be a TVRO dish. The front end
will be a Ka band LNB with the IF (intermediate frequency) output in
the traditional 950-2140Mhz range. That's much easier to amplify and
detect, and would not require a 40GHz detector.
<http://www.norsat.com/solutions/microwave-products/lnb-ka-band/>
For a PPI (plan position indicator) to obtain a relative bearing,
spinning the antenna with a synchronous motor and displaying the
results on a computah screen should be the most useful method. Aiming
the dish by hand and drawing lines on a map works but is tedious and
slow. With a PPI display, you can distinguish between the direct path
from the source of the 5G signal, from the false bearings produced by
reflections.
You also mentioned "cheap". It can be done cheaply if you build it
something like a microwave oven leakage detector. The antenna can be
a simple horn antenna hung on some WR-28 waveguide with a diode
detector and some kind of 30GHz bandpass filter to keep out the junk.
You'll need to get fairly close to the 4G antenna main lobe, which
might be a problem if it's located on top of a tall tower. Long range
may also be a problem because of atmospheric absorption by water vapor
at the 20GHz end of the Ka band.
<http://www.rfcafe.com/references/electrical/images/atm_absorption.gif>
Incidentally, if you do build such a device, and want to export it,
you will run into ITAR limitations. Just about anything that reeks of
direction finding is considered defense related.
Yawn... Back to billing, bookkeeping, and office untrashing.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
krw
Nov 18, 2016, 10:47:16 PM11/18/16
to
On Fri, 18 Nov 2016 13:39:17 -0800, John Larkin
We don't go to distributors for information. Purchasing buys some
components via distributors, mainly because some manufacturers don't
want to go direct. The disties are just useless middlemen.
pretty good. Sometimes we get one that's so complicated that it takes
a PC program (and USB) to operate it. Those tend to smoke a lot.
What pisses me off is when the FAE tells me to build like the EVM.
Well, if that was all that was on my board, it would make life easy.
components via distributors, mainly because some manufacturers don't
want to go direct. The disties are just useless middlemen.
>
>But eval boards seem to be designed by the lowest-end junor engineers.
>And they have so many jumper options that they don't help much.
That must depend on the manufacturer. The one's I've used seem to be
>But eval boards seem to be designed by the lowest-end junor engineers.
>And they have so many jumper options that they don't help much.
pretty good. Sometimes we get one that's so complicated that it takes
a PC program (and USB) to operate it. Those tend to smoke a lot.
What pisses me off is when the FAE tells me to build like the EVM.
Well, if that was all that was on my board, it would make life easy.
John Larkin
Nov 18, 2016, 11:04:33 PM11/18/16
to
send you to a forum. A distributor's application engineer is often the
only path to real support. All the Xilinx help we've got lately is
from Avnet, not from Xilinx. TI, ditto.
>>
>>But eval boards seem to be designed by the lowest-end junor engineers.
>>And they have so many jumper options that they don't help much.
>
>That must depend on the manufacturer. The one's I've used seem to be
>pretty good. Sometimes we get one that's so complicated that it takes
>a PC program (and USB) to operate it. Those tend to smoke a lot.
>
>What pisses me off is when the FAE tells me to build like the EVM.
>Well, if that was all that was on my board, it would make life easy.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
John Larkin Highland Technology, Inc
krw
Nov 18, 2016, 11:19:43 PM11/18/16
to
On Fri, 18 Nov 2016 20:04:26 -0800, John Larkin
I don't have that problem. The TI FAE took me out to lunch yesterday
and the Atmel/Microchip FAEs had the pleasure Tuesday. ;-) I
generally get two invites a week[*] (three this week but likely none
next).
[*]Either they bring food in for a "lunch and learn" or take us out.
One FAE told us that if he takes us out, the company pays for his
lunch, too. Otherwise, he has to pay for it himself. :-)
and the Atmel/Microchip FAEs had the pleasure Tuesday. ;-) I
generally get two invites a week[*] (three this week but likely none
next).
[*]Either they bring food in for a "lunch and learn" or take us out.
One FAE told us that if he takes us out, the company pays for his
lunch, too. Otherwise, he has to pay for it himself. :-)
upsid...@downunder.com
Nov 19, 2016, 2:07:29 PM11/19/16
to
On Fri, 18 Nov 2016 14:21:19 -0800, Jeff Liebermann <je...@cruzio.com>
wrote:
>When you say "ambient", I'll assume that it's just trying to detect
>the source and location of the a 5G emitter, whether base station or
>handset, without attempting to decode any data. That's done with a
>directional antenna, with minimum side lobes, an RF bandpass filter
>for tuning, some gain, an RF detector, and some means of displaying
>the results.
Most cellular systems rely on reflections, not on LOS (line-of-sight)
propagation, Thus, there is not much point of using directional
antennas, you should use an omnidirectional (isotropic) antenna to
capture the total RF power available in the air volume ("ambient").
A Ka band LNB coupled to more or less omnidirectional antenna feeding
a microwave leakage detector might be the simplest approach.
I do not know, how 5G systems are actually going to be implemented,
but the nasty problem with microwave dipoles is that the capture area
is proportional to the wavelength squared and hence also received
power is proportional to the wavelength squared, hence things are
quite nasty at 28 - 39 GHz.
One way to avoid this kind of problems is to use phased arrays or MIMO
(Multiple input, multiple output) systems.
But apparently the OP is just interested in the total "ambient" power
for a signal strength meter, so no MIMO processing needed.
wrote:
>When you say "ambient", I'll assume that it's just trying to detect
>the source and location of the a 5G emitter, whether base station or
>handset, without attempting to decode any data. That's done with a
>directional antenna, with minimum side lobes, an RF bandpass filter
>for tuning, some gain, an RF detector, and some means of displaying
>the results.
propagation, Thus, there is not much point of using directional
antennas, you should use an omnidirectional (isotropic) antenna to
capture the total RF power available in the air volume ("ambient").
A Ka band LNB coupled to more or less omnidirectional antenna feeding
a microwave leakage detector might be the simplest approach.
I do not know, how 5G systems are actually going to be implemented,
but the nasty problem with microwave dipoles is that the capture area
is proportional to the wavelength squared and hence also received
power is proportional to the wavelength squared, hence things are
quite nasty at 28 - 39 GHz.
One way to avoid this kind of problems is to use phased arrays or MIMO
(Multiple input, multiple output) systems.
But apparently the OP is just interested in the total "ambient" power
for a signal strength meter, so no MIMO processing needed.
Kevin Foster
Nov 19, 2016, 2:47:57 PM11/19/16
to
On 20/11/16 06:07, upsid...@downunder.com wrote:
> On Fri, 18 Nov 2016 14:21:19 -0800, Jeff Liebermann <je...@cruzio.com>
> wrote:
>
>> When you say "ambient", I'll assume that it's just trying to detect
>> the source and location of the a 5G emitter, whether base station or
>> handset, without attempting to decode any data. That's done with a
>> directional antenna, with minimum side lobes, an RF bandpass filter
>> for tuning, some gain, an RF detector, and some means of displaying
>> the results.
>
> Most cellular systems rely on reflections, not on LOS (line-of-sight)
> propagation, Thus, there is not much point of using directional
> antennas, you should use an omnidirectional (isotropic) antenna to
> capture the total RF power available in the air volume ("ambient").
>
> A Ka band LNB coupled to more or less omnidirectional antenna feeding
> a microwave leakage detector might be the simplest approach.
>
Not being an experienced RF constructor, that is exactly the type of
> On Fri, 18 Nov 2016 14:21:19 -0800, Jeff Liebermann <je...@cruzio.com>
> wrote:
>
>> When you say "ambient", I'll assume that it's just trying to detect
>> the source and location of the a 5G emitter, whether base station or
>> handset, without attempting to decode any data. That's done with a
>> directional antenna, with minimum side lobes, an RF bandpass filter
>> for tuning, some gain, an RF detector, and some means of displaying
>> the results.
>
> Most cellular systems rely on reflections, not on LOS (line-of-sight)
> propagation, Thus, there is not much point of using directional
> antennas, you should use an omnidirectional (isotropic) antenna to
> capture the total RF power available in the air volume ("ambient").
>
> A Ka band LNB coupled to more or less omnidirectional antenna feeding
> a microwave leakage detector might be the simplest approach.
>
solution I was looking for.
However, standard microwave detectors are calibrated for 2.45GHz. How
would it read in the Ka band?
Given that the device needs to be portable, can you point me to a
suitable antenna? Cold I just mount the LNB in a stainless steel salad bowl?
Remember, this is just a "sniffer" not a calibrated lab grade instrument.
Kevin Foster
Kevin Foster
Nov 19, 2016, 3:01:01 PM11/19/16
to
from the LNB is within the approx. 2GHz frequency range of a standard
microwave detector.
Here is what appears to be a standard LNB on eBay.
http://www.ebay.com.au/itm/Inverto-Twin-KA-Band-LNB-KA-SAT-Saorsat-Ready-Eutelsat-9E-HD-Compatible-/261079564181?_trksid=p2141725.m3641.l6368
But according to the specs it appears to be limited to 19.7-20.2GHz. Is
this typical, or are wide band versions available, e.g. covering the
full 25-40GHz Ka range?
If not, how easy would it be to modify an commercial LNB to do this?
Kevin Foster
upsid...@downunder.com
Nov 19, 2016, 3:04:41 PM11/19/16
to
On Sun, 20 Nov 2016 06:47:47 +1100, Kevin Foster
<kfo...@internode.com> wrote:
>On 20/11/16 06:07, upsid...@downunder.com wrote:
>> On Fri, 18 Nov 2016 14:21:19 -0800, Jeff Liebermann <je...@cruzio.com>
>> wrote:
>>
>>> When you say "ambient", I'll assume that it's just trying to detect
>>> the source and location of the a 5G emitter, whether base station or
>>> handset, without attempting to decode any data. That's done with a
>>> directional antenna, with minimum side lobes, an RF bandpass filter
>>> for tuning, some gain, an RF detector, and some means of displaying
>>> the results.
>>
>> Most cellular systems rely on reflections, not on LOS (line-of-sight)
>> propagation, Thus, there is not much point of using directional
>> antennas, you should use an omnidirectional (isotropic) antenna to
>> capture the total RF power available in the air volume ("ambient").
>>
>> A Ka band LNB coupled to more or less omnidirectional antenna feeding
>> a microwave leakage detector might be the simplest approach.
>>
>
>Not being an experienced RF constructor, that is exactly the type of
>solution I was looking for.
>
>However, standard microwave detectors are calibrated for 2.45GHz. How
>would it read in the Ka band?
The LNB converts the Ka band signal to something line 950 .. 2xxx MHz.
<kfo...@internode.com> wrote:
>On 20/11/16 06:07, upsid...@downunder.com wrote:
>> On Fri, 18 Nov 2016 14:21:19 -0800, Jeff Liebermann <je...@cruzio.com>
>> wrote:
>>
>>> When you say "ambient", I'll assume that it's just trying to detect
>>> the source and location of the a 5G emitter, whether base station or
>>> handset, without attempting to decode any data. That's done with a
>>> directional antenna, with minimum side lobes, an RF bandpass filter
>>> for tuning, some gain, an RF detector, and some means of displaying
>>> the results.
>>
>> Most cellular systems rely on reflections, not on LOS (line-of-sight)
>> propagation, Thus, there is not much point of using directional
>> antennas, you should use an omnidirectional (isotropic) antenna to
>> capture the total RF power available in the air volume ("ambient").
>>
>> A Ka band LNB coupled to more or less omnidirectional antenna feeding
>> a microwave leakage detector might be the simplest approach.
>>
>
>Not being an experienced RF constructor, that is exactly the type of
>solution I was looking for.
>
>However, standard microwave detectors are calibrated for 2.45GHz. How
>would it read in the Ka band?
A typical sniffer is usually not that selective, so it should react to
2xxx MHz signals.
>Given that the device needs to be portable, can you point me to a
>suitable antenna? Cold I just mount the LNB in a stainless steel salad bowl?
sufficient or some other means to connect into the waveguide.
upsid...@downunder.com
Nov 20, 2016, 2:48:18 AM11/20/16
to
On Sun, 20 Nov 2016 07:00:53 +1100, Kevin Foster
There are several services allocated into the Ka band, such as
satellite TV and now the proposed 5G allocation (three segments in the
Ka band). That device you found is intended for the satellite segment
only. Why would those support the full Ka band when 99.99 % of users
would not benefit from it ?
> Is
>this typical, or are wide band versions available, e.g. covering the
>full 25-40GHz Ka range?
If the LNB output is somewhere between 1-2 GHz, you would need the
ability to switch the LNB local oscillator (LO) in 1 GHz steps,
requiring 15 different LO frequencies. If they are still using
dielectric DRO oscillators in LNBs, you would need to manually
exchange the DRO element for each 1 GHz wide sub band or have 25
separate DROs and switch on one electrically.
The other issue is the front selectivity, which would kill most
signals above 25 GHz. If it is just a waveguide input without input
filter, this may work, since the desired frequency is above design
frequency. For frequencies well below designed frequency, those
frequencies would be cut off totally due to waveguide effects.
>If not, how easy would it be to modify an commercial LNB to do this?
Who knows, some might be easy, some impossible.
Anyway, to do such modifications, you need good test equipment and a
lot microwave building skills.
>
>Kevin Foster
satellite TV and now the proposed 5G allocation (three segments in the
Ka band). That device you found is intended for the satellite segment
only. Why would those support the full Ka band when 99.99 % of users
would not benefit from it ?
> Is
>this typical, or are wide band versions available, e.g. covering the
>full 25-40GHz Ka range?
ability to switch the LNB local oscillator (LO) in 1 GHz steps,
requiring 15 different LO frequencies. If they are still using
dielectric DRO oscillators in LNBs, you would need to manually
exchange the DRO element for each 1 GHz wide sub band or have 25
separate DROs and switch on one electrically.
The other issue is the front selectivity, which would kill most
signals above 25 GHz. If it is just a waveguide input without input
filter, this may work, since the desired frequency is above design
frequency. For frequencies well below designed frequency, those
frequencies would be cut off totally due to waveguide effects.
>If not, how easy would it be to modify an commercial LNB to do this?
Anyway, to do such modifications, you need good test equipment and a
lot microwave building skills.
>
>Kevin Foster
Kevin Foster
Nov 20, 2016, 6:24:58 AM11/20/16
to
walk-around monitor for unquantified field intensity.
Maybe once 5G is rolled out some suitable sub-assemblies will emerge.
How about a SMA connected horn and x10 frequency prescaler for an
existing digital EMF meter such as this?
https://www.amazon.com/Cornet-ED85EXS-Cellular-Radiation-Detector/dp/B00S15WGI0
Kevin Foster
Jeff Liebermann
Nov 20, 2016, 1:18:24 PM11/20/16
to
On Sat, 19 Nov 2016 21:07:35 +0200, upsid...@downunder.com wrote:
>On Fri, 18 Nov 2016 14:21:19 -0800, Jeff Liebermann <je...@cruzio.com>
>wrote:
>
>>When you say "ambient", I'll assume that it's just trying to detect
>>the source and location of the a 5G emitter, whether base station or
>>handset, without attempting to decode any data. That's done with a
>>directional antenna, with minimum side lobes, an RF bandpass filter
>>for tuning, some gain, an RF detector, and some means of displaying
>>the results.
>Most cellular systems rely on reflections, not on LOS (line-of-sight)
>propagation,
At this time LTE can use reflections in the form of MIMO to boost data
>On Fri, 18 Nov 2016 14:21:19 -0800, Jeff Liebermann <je...@cruzio.com>
>wrote:
>
>>When you say "ambient", I'll assume that it's just trying to detect
>>the source and location of the a 5G emitter, whether base station or
>>handset, without attempting to decode any data. That's done with a
>>directional antenna, with minimum side lobes, an RF bandpass filter
>>for tuning, some gain, an RF detector, and some means of displaying
>>the results.
>Most cellular systems rely on reflections, not on LOS (line-of-sight)
>propagation,
performance. It's not a requirement for communications. Since all
the MIMO streams are on the same frequency, an RF detector will show
the signal coming from two or more sources (one per antenna). However,
since the MIMO antennas are all on the same tower or panel, a crude
detector will show it coming from a single source (i.e. the top of the
tower or panel).
>Thus, there is not much point of using directional
>antennas, you should use an omnidirectional (isotropic) antenna to
>capture the total RF power available in the air volume ("ambient").
antenna. What 5G promises is beam steering. This takes a high gain
steerable (phased) antenna array, and points it at a specific user for
the short period of time that the data needs to be sent. The rest of
the time, when nothing is being sent, the antenna beam points to other
users. What this means is that if nobody is using the cell site,
there's little or no RF being emitted, so there's nothing to detect.
Another problem is automatic power control. The cell site transmit
power is automagically adjusted for the lowest possible power that
produces a minimum acceptable SNR (signal to noise ratio) at the
receiving end. Handsets that are close to the tower get very little
RF sent in their direction. Distant stations probably get maximum
power. The variable signal levels can make detection a problem if
there isn't enough signal to work with.
There are omnidirectional, or rather something like isotropic
receivers available for lower frequencies. They're called exposure
meters, some of which work to 30GHz and higher:
<http://www.narda-sts.us/products_main.php>
Because of the lack of antenna and RF gain, they are not very
sensitive and have limited range.
>A Ka band LNB coupled to more or less omnidirectional antenna feeding
>a microwave leakage detector might be the simplest approach.
of gain needed to act as a "detector". The LNB is circular polarized,
which will detect both linear (vertical or horizontal) polarizations.
However, I do find articles proposing circular polarization for 5G
cellular, which may cause difficulties if here is a polarization
mismatch.
>I do not know, how 5G systems are actually going to be implemented,
>but the nasty problem with microwave dipoles is that the capture area
>is proportional to the wavelength squared and hence also received
>power is proportional to the wavelength squared, hence things are
>quite nasty at 28 - 39 GHz.
5mm long in free space, and probably 1.5mm long on a ceramic
substrate.
>One way to avoid this kind of problems is to use phased arrays or MIMO
>(Multiple input, multiple output) systems.
require a fairly large number of dipoles or patches to work. They
make plenty of sense on top of a fixed tower or building that doesn't
move. They make less sense on a detector that can be aimed in any
direction and would not require a directional scanning antenna to
function. Methinks a very conventional horn or dish antenna will be
just fine for a simple detector.
On the borderline is a phased array on a smartphone or tablet. There's
barely enough room for such an antenna, but it would work to keep the
handset antenna pointed at the cell tower, or the strongest
reflection. However, most of the proposals I've seen have the handset
festooned with multiple antennas and switch between antennas for the
best signal with no attempt to do beam steering.
MIMO is utilizing reflections to provide additional bandwidth. It
does nothing for increasing signal strength. Details if you want
them.
>But apparently the OP is just interested in the total "ambient" power
>for a signal strength meter, so no MIMO processing needed.
The OP didn't bother describing how the detector is to be used. My
guess(tm) is a gun like affair, with a small panel, dish, or horn
antenna on the front. Or maybe something like a Geiger counter with a
cable connected antenna and front end. Or maybe a panel antenna with
a black box stuck on the back. My idea would be a mechanically
scanning horn antenna with a PPI (plan position indicator) display.
Note that even a small dish at 30GHz is going to have a rather narrow
-3dB beamwidth.
<http://www.satsig.net/pointing/antenna-beamwidth-calculator.htm>
A 0.5 meter dish, at 30GHz, will have a whopping 42dBi gain, but with
a 0.67 degree beamwidth, will be VERY difficult to aim. If you've
ever tried to align a DBS TV satellite dish, you'll understand the
problem. Less gain and a wider beamwidth might be better.
Jeff Liebermann
Nov 20, 2016, 1:54:20 PM11/20/16
to
On Sun, 20 Nov 2016 07:00:53 +1100, Kevin Foster
<kfo...@internode.com> wrote:
>Thanks for your detailed response. I now understand that the _output_
>from the LNB is within the approx. 2GHz frequency range of a standard
>microwave detector.
Not 2GHz, but more like 1GHz bandwidth as 950 - 1950MHz.
<kfo...@internode.com> wrote:
>Thanks for your detailed response. I now understand that the _output_
>from the LNB is within the approx. 2GHz frequency range of a standard
>microwave detector.
Some will do 950 - 2150MHz. Some detail:
<http://www.satsig.net/lnb/explanation-description-lnb.htma>
>Here is what appears to be a standard LNB on eBay.
>http://www.ebay.com.au/itm/Inverto-Twin-KA-Band-LNB-KA-SAT-Saorsat-Ready-Eutelsat-9E-HD-Compatible-/261079564181?_trksid=p2141725.m3641.l6368
>But according to the specs it appears to be limited to 19.7-20.2GHz. Is
>this typical, or are wide band versions available, e.g. covering the
>full 25-40GHz Ka range?
>
>If not, how easy would it be to modify an commercial LNB to do this?
butchered 3.7 to 4.2Ghz C band LNB's and moved them to 2.4GHz mostly
by adding chip caps and tiny pieces of copper tape. I also helped a
friend do much the same moving a 12GHz Ku band LNB down to 10GHz (X
band) for a ham radio link. Also, some tweaks on 2.5GHz MMDS antennas
and transverters down to 2.4GHz.
All of these required a substantial amount of microwave test
equipment. At 10GHz and below, these are commonly available. At
higher frequencies, they are less common, very expensive, and very
easy to blow up. Also, experience in microwave structures and
techniques are very helpful.
What I expect to happen is someone, with experience, knowledge, and a
pile of test equipment, starts out by modifying some common device
like the Ka band LBN you found on eBay. If successful, they throw
together a web page, and soon everyone else with similar ideas
performs the "mods" and usually improves on them.
Here's a Ka band LNB dissected and moved from 22 to 24GHz for ham
radio use:
<http://www.m0dts.co.uk/index.php?tag=24GHz&item=98>
I would speculate that the Ka band LNBs are much like the Ku band LNBs
that I've dissected. There's very little in the way of front end
filtering. What filtering is present is in the form of a strip line
filter on the PCB. There are many geometries available. Something
like one of these:
<https://www.google.com/search?q=strip+line+bandpass+filter&tbm=isch>
To move it up in frequency, a Dremel tool to remove shrink the pads is
usually sufficient. The bad news is that you will need a 30GHz sweep
generator and pile of test equipment. The rest is moving the LO
(local oscillator) frequency. That can be a DRO (dielectric resonator
oscillator) or a more stable and less noisy PLL (phase lock loop). I'm
not sure what's involved until I dissect a Ka band LNB, but I expect
more of the same Dremel tool trimming.
Jeff Liebermann
Nov 20, 2016, 2:22:45 PM11/20/16
to
versions of such things all over the internet. Search the RF paranoia
web sites for specifics.
I must confess that I've designed a few of these. Here's a free idea
if you want to pursue it. It's a brick with several LED's. Each LED
represents a cellular band or rather parts of a cellular band. Inside
the brick are a collection of cavity bandpass filters, each tuned to
one of the cellular bands. Each filter input has a PCB or ceramic
antenna for the lower frequencies, and a slot antenna for the higher
frequencies. At the output of each filter is a simple diode detector.
After the detectors are analog comparators that indicate that there's
RF present on that band, which lights up the associated LEDs. The
basic idea is that you wave this brick at a cell tower, and it will
tell you which bands are active on the tower. Today, cheap spectrum
analyzers can all this and more, so it's obsolete except for the
possibility of doing it cheap.
>Maybe once 5G is rolled out some suitable sub-assemblies will emerge.
order to generate a schematic. It's difficult to modify such things
without knowing how it works.
>How about a SMA connected horn and x10 frequency prescaler for an
>existing digital EMF meter such as this?
>https://www.amazon.com/Cornet-ED85EXS-Cellular-Radiation-Detector/dp/B00S15WGI0
<https://www.microwaves101.com/encyclopedias/microwave-connectors>
No prescaler. A downconverter (mixer) from 30Ghz down to a frequency
that the Cornet device can see will work. Building a 30GHz tunable
local oscillator will be the tricky part. Again, you should be able
to move a Ka band LNB to 30GHz, and use the Cornet device (or any
spectrum analyzer) to "see" the signals.
Another possible is a 24Ghz microwave radar gun. I have a really old
Kustom Signals 24GHz gun that works nicely for measuring speed. The
front end is a Gunnplexer (circulator/oscillator/mixer). Skim through
the photos of gunnplexers:
<https://www.google.com/search?q=gunnplexer&tbm=isch>
An Introduction to 24 GHz
<http://www.kwarc.org/10ghz/24g.html>
See the section on 24Ghz components.
John Larkin
Nov 20, 2016, 2:58:47 PM11/20/16
to
territory?
When I worked in New Orleans, we were practically the only OEM in
Louisiana. The TI guys would fly in from Texas to wine and dine us. I
was considering using a $7 National part in a new system, so TI quoted
us 90 cents.
In San Francisco, our company is relatively small fry. And the big
semi companies are backing off on actual support for everyone. It
wouldn't be so bad if the data sheets were better.
I am designing in one ADC, the ADC10080. It has an internal bandgap
reference that is connected through a resistor to a pin, so you can
override it with an external reference. What is the value of that
resistor? The data sheet doesn't say, and the support people can't
find out.
srober...@gmail.com
Nov 20, 2016, 3:06:35 PM11/20/16
to
K&S rectangular hobby tubing has been used as waveguide by Hams at 47 Ghz to build sub-harmonic mixers. It helps if you silver plate it to lower the loss from skin depth issues. The largest size rectangular tubing that K&S sells should be a ways below cutoff at the frequencies proposed for 5G.
The SBMS microwave ham radio boasts a file called 47ghzmxr2.pdf that is worth a look.
A friend of mine got 138 Ghz working using very small diodes soldered to the end of UT-141 coax with conical horns made of brass sheet. He used subharmonic conversion as well. However he had a 23 Ghz spectrum analyser as a detector and a tunable microwave source at 22 ghz as the excitation. He achieved 30 cm range.
It's do-able, but you need a local oscillator to bias the diode into conduction.
Steve
The SBMS microwave ham radio boasts a file called 47ghzmxr2.pdf that is worth a look.
A friend of mine got 138 Ghz working using very small diodes soldered to the end of UT-141 coax with conical horns made of brass sheet. He used subharmonic conversion as well. However he had a 23 Ghz spectrum analyser as a detector and a tunable microwave source at 22 ghz as the excitation. He achieved 30 cm range.
It's do-able, but you need a local oscillator to bias the diode into conduction.
Steve
krw
Nov 20, 2016, 5:59:09 PM11/20/16
to
On Sun, 20 Nov 2016 11:58:39 -0800, John Larkin
Me? I don't buy anything. They give me samples. ;-)
The company buys enough that we have one dedicated analog FAE (who
moved locally and works out of his house) and something like a third
of digital/processor FAE. They just added another analog FAE to the
territory (we probably get 1/3 of his time), so business is good. I
don't know if the sales guy is dedicated to us but it wouldn't
surprise me.
As far as Atmel/Microchip goes, I was an early promoter of their ARM
processors and have standardized on them for my piece of the business.
My designs also use tons of Microchip opamps.
Of course they aren't the only ones that come through, though I'm a
hard sell for LTC (too expensive) and Maxim (you gotta be kidding).
and several of the TI groups in here selling us stuff. There is a lot
of overlap.
Five years ago, I worked at a small company that used TI DSPs and some
power stuff. Our volumes were fairly small (a few thousand units a
year) but we still got some service from TI. Most of it was through a
disty but TI used to fly bigwigs through, mostly because we found some
really nasty bugs and they kept trying to placate us (maybe they were
afraid of getting their ass sued). The part never worked and AFAIK,
the problem was never fixed. I know as long as I was there, the
bubblegum would break loose every once in a while and customers would
get pissed. Again. I knew how to fix it but was never allowed to
spend any time on a real fix, just more patches. It would have meant
a board spin, and worse, some BSP changes.
The company buys enough that we have one dedicated analog FAE (who
moved locally and works out of his house) and something like a third
of digital/processor FAE. They just added another analog FAE to the
territory (we probably get 1/3 of his time), so business is good. I
don't know if the sales guy is dedicated to us but it wouldn't
surprise me.
As far as Atmel/Microchip goes, I was an early promoter of their ARM
processors and have standardized on them for my piece of the business.
My designs also use tons of Microchip opamps.
Of course they aren't the only ones that come through, though I'm a
hard sell for LTC (too expensive) and Maxim (you gotta be kidding).
>
>When I worked in New Orleans, we were practically the only OEM in
>Louisiana. The TI guys would fly in from Texas to wine and dine us. I
>was considering using a $7 National part in a new system, so TI quoted
>us 90 cents.
I wonder if they'll still do that. ;-) We do get both the National
>When I worked in New Orleans, we were practically the only OEM in
>Louisiana. The TI guys would fly in from Texas to wine and dine us. I
>was considering using a $7 National part in a new system, so TI quoted
>us 90 cents.
and several of the TI groups in here selling us stuff. There is a lot
of overlap.
Five years ago, I worked at a small company that used TI DSPs and some
power stuff. Our volumes were fairly small (a few thousand units a
year) but we still got some service from TI. Most of it was through a
disty but TI used to fly bigwigs through, mostly because we found some
really nasty bugs and they kept trying to placate us (maybe they were
afraid of getting their ass sued). The part never worked and AFAIK,
the problem was never fixed. I know as long as I was there, the
bubblegum would break loose every once in a while and customers would
get pissed. Again. I knew how to fix it but was never allowed to
spend any time on a real fix, just more patches. It would have meant
a board spin, and worse, some BSP changes.
>
>In San Francisco, our company is relatively small fry. And the big
>semi companies are backing off on actual support for everyone. It
>wouldn't be so bad if the data sheets were better.
>
>I am designing in one ADC, the ADC10080. It has an internal bandgap
>reference that is connected through a resistor to a pin, so you can
>override it with an external reference. What is the value of that
>resistor? The data sheet doesn't say, and the support people can't
>find out.
So you can't burn up the bandgap?
>In San Francisco, our company is relatively small fry. And the big
>semi companies are backing off on actual support for everyone. It
>wouldn't be so bad if the data sheets were better.
>
>I am designing in one ADC, the ADC10080. It has an internal bandgap
>reference that is connected through a resistor to a pin, so you can
>override it with an external reference. What is the value of that
>resistor? The data sheet doesn't say, and the support people can't
>find out.
John Larkin
Nov 20, 2016, 8:20:13 PM11/20/16
to
might even have access to the chip designers. The little companies get
bad data sheets and forums, or support people who can only read us the
data sheets.
>
>As far as Atmel/Microchip goes, I was an early promoter of their ARM
>processors and have standardized on them for my piece of the business.
>My designs also use tons of Microchip opamps.
>
>Of course they aren't the only ones that come through, though I'm a
>hard sell for LTC (too expensive) and Maxim (you gotta be kidding).
They are probably eager to hear my ideas for goofy\\\\\ brilliant new
products.
resistor from a 0..+3V DAC into that pin to tweak the gain. Or maybe I
need opamps and stuff. The data sheet does say "do not load this pin"
so I need a circuit that will drive it without loading it.
krw
Nov 20, 2016, 9:07:48 PM11/20/16
to
On Sun, 20 Nov 2016 17:20:05 -0800, John Larkin
Sure, and they're always asking us what features we want on the chips,
too. The "Lunch-N-Learns" are mostly for their product managers to
show us their new (and planned) toys to get feedback on our needs. Of
course they can't afford this for 1K sorts of Digikey customers.
That's why LTC has such good tools. They can compete in the low
volume, though high margin space because they have great support
through their tools, rather than expensive people. It'll be
interesting to see how this integrates in with ADI's business model.
parts but it's in some pretty specialized applications. Maxim even
has its adherents but they burned me with a part about five years ago.
I had prototypes built and running when they cancelled the part. The
first words had said to by boss was "I told you so".
Diving it sounds a lot like "loading" it, just to something other than
0V.
too. The "Lunch-N-Learns" are mostly for their product managers to
show us their new (and planned) toys to get feedback on our needs. Of
course they can't afford this for 1K sorts of Digikey customers.
That's why LTC has such good tools. They can compete in the low
volume, though high margin space because they have great support
through their tools, rather than expensive people. It'll be
interesting to see how this integrates in with ADI's business model.
>>
>>As far as Atmel/Microchip goes, I was an early promoter of their ARM
>>processors and have standardized on them for my piece of the business.
>>My designs also use tons of Microchip opamps.
>>
>>Of course they aren't the only ones that come through, though I'm a
>>hard sell for LTC (too expensive) and Maxim (you gotta be kidding).
>
>Interestingly, LTC sends factory people to see us about once a year.
>They are probably eager to hear my ideas for goofy\\\\\ brilliant new
>products.
LTC is around frequently and there are designers who use some of their
>>As far as Atmel/Microchip goes, I was an early promoter of their ARM
>>processors and have standardized on them for my piece of the business.
>>My designs also use tons of Microchip opamps.
>>
>>Of course they aren't the only ones that come through, though I'm a
>>hard sell for LTC (too expensive) and Maxim (you gotta be kidding).
>
>Interestingly, LTC sends factory people to see us about once a year.
>They are probably eager to hear my ideas for goofy\\\\\ brilliant new
>products.
parts but it's in some pretty specialized applications. Maxim even
has its adherents but they burned me with a part about five years ago.
I had prototypes built and running when they cancelled the part. The
first words had said to by boss was "I told you so".
0V.
Spehro Pefhany
Nov 20, 2016, 9:54:02 PM11/20/16
to
On Sun, 20 Nov 2016 17:20:05 -0800, the renowned John Larkin
<jjla...@highlandtechnology.com> wrote:
>
>Sure, but what's the resistor value? I'd like to run one external
>resistor from a 0..+3V DAC into that pin to tweak the gain. Or maybe I
>need opamps and stuff. The data sheet does say "do not load this pin"
>so I need a circuit that will drive it without loading it.
>
I'm sure you know you can just get the free (to you) $199 eval board
<jjla...@highlandtechnology.com> wrote:
>
>Sure, but what's the resistor value? I'd like to run one external
>resistor from a 0..+3V DAC into that pin to tweak the gain. Or maybe I
>need opamps and stuff. The data sheet does say "do not load this pin"
>so I need a circuit that will drive it without loading it.
>
and measure it.. but it might vary a lot from chip to chip .
Spehro Pefhany
Nov 20, 2016, 10:14:59 PM11/20/16
to
On Sun, 20 Nov 2016 21:53:58 -0500, Spehro Pefhany
<spef...@interlogDOTyou.knowwhat> wrote:
>On Sun, 20 Nov 2016 17:20:05 -0800, the renowned John Larkin
><jjla...@highlandtechnology.com> wrote:
>
>>
>>Sure, but what's the resistor value? I'd like to run one external
>>resistor from a 0..+3V DAC into that pin to tweak the gain. Or maybe I
>>need opamps and stuff. The data sheet does say "do not load this pin"
>>so I need a circuit that will drive it without loading it.
>>
>
>I'm sure you know you can just get the free (to you) $199 eval board
>and measure it.. but it might vary a lot from chip to chip .
>
>--sp
P.S. I'm designing in a TI AFE chip - it has an internal clock for the
<spef...@interlogDOTyou.knowwhat> wrote:
>On Sun, 20 Nov 2016 17:20:05 -0800, the renowned John Larkin
><jjla...@highlandtechnology.com> wrote:
>
>>
>>Sure, but what's the resistor value? I'd like to run one external
>>resistor from a 0..+3V DAC into that pin to tweak the gain. Or maybe I
>>need opamps and stuff. The data sheet does say "do not load this pin"
>>so I need a circuit that will drive it without loading it.
>>
>
>I'm sure you know you can just get the free (to you) $199 eval board
>and measure it.. but it might vary a lot from chip to chip .
>
>--sp
auto zero or external clock, which can be a crystal or a digital
input. if you use the digital input, nowhere does it say what to do
with the other pin from the crystal oscillator.
Upon request, they say I can either leave it open or ground it, which
seems.. odd. I guess it's an input connected by a few M to some
internal node that would have been the crystal drive, but would like
to see what's actually on the other side of the wire bonds.
krw
Nov 20, 2016, 10:20:06 PM11/20/16
to
On Sun, 20 Nov 2016 22:14:56 -0500, Spehro Pefhany
oscillator output open. It often can't be used for anything useful,
either.
<spef...@interlogDOTyou.knowwhat> wrote:
>On Sun, 20 Nov 2016 21:53:58 -0500, Spehro Pefhany
><spef...@interlogDOTyou.knowwhat> wrote:
>
>>On Sun, 20 Nov 2016 17:20:05 -0800, the renowned John Larkin
>><jjla...@highlandtechnology.com> wrote:
>>
>>>
>>>Sure, but what's the resistor value? I'd like to run one external
>>>resistor from a 0..+3V DAC into that pin to tweak the gain. Or maybe I
>>>need opamps and stuff. The data sheet does say "do not load this pin"
>>>so I need a circuit that will drive it without loading it.
>>>
>>
>>I'm sure you know you can just get the free (to you) $199 eval board
>>and measure it.. but it might vary a lot from chip to chip .
>>
>>--sp
>
>P.S. I'm designing in a TI AFE chip - it has an internal clock for the
>auto zero or external clock, which can be a crystal or a digital
>input. if you use the digital input, nowhere does it say what to do
>with the other pin from the crystal oscillator.
>
>Upon request, they say I can either leave it open or ground it, which
>seems.. odd. I guess it's an input connected by a few M to some
>internal node that would have been the crystal drive, but would like
>to see what's actually on the other side of the wire bonds.
I haven't seen any that require anything other than to leave the
>On Sun, 20 Nov 2016 21:53:58 -0500, Spehro Pefhany
><spef...@interlogDOTyou.knowwhat> wrote:
>
>>On Sun, 20 Nov 2016 17:20:05 -0800, the renowned John Larkin
>><jjla...@highlandtechnology.com> wrote:
>>
>>>
>>>Sure, but what's the resistor value? I'd like to run one external
>>>resistor from a 0..+3V DAC into that pin to tweak the gain. Or maybe I
>>>need opamps and stuff. The data sheet does say "do not load this pin"
>>>so I need a circuit that will drive it without loading it.
>>>
>>
>>I'm sure you know you can just get the free (to you) $199 eval board
>>and measure it.. but it might vary a lot from chip to chip .
>>
>>--sp
>
>P.S. I'm designing in a TI AFE chip - it has an internal clock for the
>auto zero or external clock, which can be a crystal or a digital
>input. if you use the digital input, nowhere does it say what to do
>with the other pin from the crystal oscillator.
>
>Upon request, they say I can either leave it open or ground it, which
>seems.. odd. I guess it's an input connected by a few M to some
>internal node that would have been the crystal drive, but would like
>to see what's actually on the other side of the wire bonds.
oscillator output open. It often can't be used for anything useful,
either.
Spehro Pefhany
Nov 20, 2016, 10:35:10 PM11/20/16
to
The pin is listed as an input *only* on the datasheet, which is why I
was concerned. The other pin- the crystal drive (clock output) can be
configured as an input using an internal register and that is where
you feed the clock signal in.
The input must have a weakpullup or maybe they leave the Pierce
oscillator bias resistor in place, who knows?
John Larkin
Nov 20, 2016, 11:22:19 PM11/20/16
to
On Sun, 20 Nov 2016 22:14:56 -0500, Spehro Pefhany
That situation sounds like the standard weak-inverter semi-reliable
crystal oscillator. The unused pin is the inverter output, and you
drive the input.
Grounding it is a little weird.
Chip schematics (dream on!) or at least block diagrams sure help.
crystal oscillator. The unused pin is the inverter output, and you
drive the input.
Grounding it is a little weird.
Chip schematics (dream on!) or at least block diagrams sure help.
John Larkin
Nov 20, 2016, 11:23:49 PM11/20/16
to
On Sun, 20 Nov 2016 22:35:07 -0500, Spehro Pefhany
The guy who wrote the data sheet probably doesn't understand it
either.
either.
Jeff Liebermann
Nov 21, 2016, 12:16:20 AM11/21/16
to
On Sun, 20 Nov 2016 12:06:27 -0800 (PST), srober...@gmail.com
wrote:
>K&S rectangular hobby tubing has been used as waveguide by Hams
>at 47 Ghz to build sub-harmonic mixers. It helps if you silver
>plate it to lower the loss from skin depth issues. The largest
>size rectangular tubing that K&S sells should be a ways
>below cutoff at the frequencies proposed for 5G.
My guess(tm) is that WR28 would be the most common for 5G frequencies:
<http://www.rfcafe.com/references/electrical/waveguide-chart.htm>
0.280 x 0.140 inches. Yeah, that's tiny. I've been doing silver
plating and using electroless silver at home for quite a while.
<http://www.finishing.com/faqs/silverathome.shtml>
However most everything I've done is at lower frequencies (L,C,X bands
and wi-fi).
>The SBMS microwave ham radio boasts a file called 47ghzmxr2.pdf
>that is worth a look.
<http://www.ham-radio.com/sbms/sd/47ghzmxr2.pdf>
<http://www.ham-radio.com/sbms/sd/47ghzndx.htm>
Looks like he uses round tubing for waveguide instead of tubular.
Looks nice, but I would feel better if there were some photos of the
actual mixer and some numerical test results. Hmmm... dated 2003.
>A friend of mine got 138 Ghz working using very small diodes
>soldered to the end of UT-141 coax with conical horns made of
>brass sheet. He used subharmonic conversion as well. However
>he had a 23 Ghz spectrum analyser as a detector and a tunable
>microwave source at 22 ghz as the excitation. He achieved 30 cm range.
Nicely done. I couldn't do that with my pile of antique pile of test
equipment. My HP141T/HP8555a spectrum analyzer will go to 18GHz.
<http://802.11junk.com/jeffl/pics/home/slides/test-equip-mess.html>
If I purchase the external mixers, it will go to 43GHz.
<http://www.ebay.com/itm/322255706936>
<http://www.qsl.net/g8bke/HPMIX.htm>
(Notice the burnout limit = 1 milliwatt). Actually, I do have some
suitable mixers, but the diodes are all fried. Yet another project.
My highest frequency source goes to only 4GHz, which rather limits
what I can do. 138GHz is currently out of my range.
>It's do-able, but you need a local oscillator to bias the diode
>into conduction.
Yep. That's the problem with upconverters and downconverters. One
needs to have a local oscillator source to feed the mixer.
wrote:
>K&S rectangular hobby tubing has been used as waveguide by Hams
>at 47 Ghz to build sub-harmonic mixers. It helps if you silver
>plate it to lower the loss from skin depth issues. The largest
>size rectangular tubing that K&S sells should be a ways
>below cutoff at the frequencies proposed for 5G.
<http://www.rfcafe.com/references/electrical/waveguide-chart.htm>
0.280 x 0.140 inches. Yeah, that's tiny. I've been doing silver
plating and using electroless silver at home for quite a while.
<http://www.finishing.com/faqs/silverathome.shtml>
However most everything I've done is at lower frequencies (L,C,X bands
and wi-fi).
>The SBMS microwave ham radio boasts a file called 47ghzmxr2.pdf
>that is worth a look.
<http://www.ham-radio.com/sbms/sd/47ghzndx.htm>
Looks like he uses round tubing for waveguide instead of tubular.
Looks nice, but I would feel better if there were some photos of the
actual mixer and some numerical test results. Hmmm... dated 2003.
>A friend of mine got 138 Ghz working using very small diodes
>soldered to the end of UT-141 coax with conical horns made of
>brass sheet. He used subharmonic conversion as well. However
>he had a 23 Ghz spectrum analyser as a detector and a tunable
>microwave source at 22 ghz as the excitation. He achieved 30 cm range.
equipment. My HP141T/HP8555a spectrum analyzer will go to 18GHz.
<http://802.11junk.com/jeffl/pics/home/slides/test-equip-mess.html>
If I purchase the external mixers, it will go to 43GHz.
<http://www.ebay.com/itm/322255706936>
<http://www.qsl.net/g8bke/HPMIX.htm>
(Notice the burnout limit = 1 milliwatt). Actually, I do have some
suitable mixers, but the diodes are all fried. Yet another project.
My highest frequency source goes to only 4GHz, which rather limits
what I can do. 138GHz is currently out of my range.
>It's do-able, but you need a local oscillator to bias the diode
>into conduction.
needs to have a local oscillator source to feed the mixer.
upsid...@downunder.com
Nov 21, 2016, 2:33:57 AM11/21/16
to
On Sun, 20 Nov 2016 11:22:40 -0800, Jeff Liebermann <je...@cruzio.com>
wrote:
>On Sun, 20 Nov 2016 22:24:50 +1100, Kevin Foster
><kfo...@internode.com> wrote:
>
>>Thanks. I am beginning to see the complexities. I was hoping for a cheap
>>walk-around monitor for unquantified field intensity.
>
>In other words, an RF dosimeter or radiation detector. There are
>versions of such things all over the internet. Search the RF paranoia
>web sites for specifics.
With such applications put the local oscillator in the middle of the
band of interest and feed it to simple mixer which folds the upper and
lower bands to the same baseband frequency. Feed the mixer output to a
broadband 0 - 2.5 GHz signal indicator. This will cover 5 GHz
(Flo+/-2.5 GHz) of the band. Folding the upper and lower bands
doesn't hurt, since we are only interested in total RF power.
To generate 28 GHz LO signal use some oscillator (e.g. DRO) in 9-10
GHz range, overdrive it in a MMIC stage and filter out the 3rd
harmonic to feed the mixer
wrote:
>On Sun, 20 Nov 2016 22:24:50 +1100, Kevin Foster
><kfo...@internode.com> wrote:
>
>>Thanks. I am beginning to see the complexities. I was hoping for a cheap
>>walk-around monitor for unquantified field intensity.
>
>In other words, an RF dosimeter or radiation detector. There are
>versions of such things all over the internet. Search the RF paranoia
>web sites for specifics.
band of interest and feed it to simple mixer which folds the upper and
lower bands to the same baseband frequency. Feed the mixer output to a
broadband 0 - 2.5 GHz signal indicator. This will cover 5 GHz
(Flo+/-2.5 GHz) of the band. Folding the upper and lower bands
doesn't hurt, since we are only interested in total RF power.
To generate 28 GHz LO signal use some oscillator (e.g. DRO) in 9-10
GHz range, overdrive it in a MMIC stage and filter out the 3rd
harmonic to feed the mixer
Jeff Liebermann
Nov 21, 2016, 12:01:35 PM11/21/16
to
the 30GHz frequency, but the IF amp and detector can be quite crude.
I've done something like that using a cheap satellite TV signal meter:
<http://www.ebay.com/itm/112211347132>
Apply 12VDC to the output port through a 75 ohm load resistor to power
the meter. The input port goes to the mixer. Inside the meter is a
rather crude MMIC 950-1950MHz amplifier and detector to drive the
meter. Most of the gain is at the 950MHz end.
If you feel link playing, put a cellular yagi antenna on the input
port of the meter and use it to find cell sites operating in the
850-950MHz region. I was doing that for a while until I build
something better. It doesn't work too well at PCS frequencies
1900MHz.
The problem with such schemes is that it's difficult to tell what the
detector is hearing. It could be some other service on adjacent
frequencies. For example, it could be responding to 24GHz speed trap
radar. With a simple mixer, minimizing the LO radiation out the
antenna might be a problem. Besides, the OP wanted "cheap" which to
me means a horn antenna, RF bandpass filter, diode detector, and DC
amplifier. In other words, a 30GHz field strength meter.
upsid...@downunder.com
Nov 21, 2016, 3:43:32 PM11/21/16
to
On Mon, 21 Nov 2016 09:01:30 -0800, Jeff Liebermann <je...@cruzio.com>
but the noise figure would be quite bad, but who cares, if you are
only interested in the envelope power.
>I've done something like that using a cheap satellite TV signal meter:
><http://www.ebay.com/itm/112211347132>
>Apply 12VDC to the output port through a 75 ohm load resistor to power
>the meter. The input port goes to the mixer. Inside the meter is a
>rather crude MMIC 950-1950MHz amplifier and detector to drive the
>meter. Most of the gain is at the 950MHz end.
>
>If you feel link playing, put a cellular yagi antenna on the input
>port of the meter and use it to find cell sites operating in the
>850-950MHz region. I was doing that for a while until I build
>something better. It doesn't work too well at PCS frequencies
>1900MHz.
One should remember that microwave cellular communications doesn't
benefit from line of sight point to point communications. You are
fully dependent on in-room reflections as i the IR remote case.
>The problem with such schemes is that it's difficult to tell what the
>detector is hearing. It could be some other service on adjacent
>frequencies.
Today, these are speed radars and satellite services. In the future,
there are other services too.
> For example, it could be responding to 24GHz speed trap
>radar. With a simple mixer, minimizing the LO radiation out the
>antenna might be a problem. Besides, the OP wanted "cheap" which to
>me means a horn antenna,
A horn might have too much "gain" or directivity for usable
measurements.
>RF bandpass filter, diode detector, and DC
>amplifier. In other words, a 30GHz field strength meter.
Waveguide filters on the RF as well as on the LO ports will keep most
of the low frequency (below 20 GHz) crud away, while any post mixer
filtering will keep away any interference far away from the LO.
wrote:
>On Mon, 21 Nov 2016 09:33:58 +0200, upsid...@downunder.com wrote:
>
>>On Sun, 20 Nov 2016 11:22:40 -0800, Jeff Liebermann <je...@cruzio.com>
>>wrote:
>>
>>>On Sun, 20 Nov 2016 22:24:50 +1100, Kevin Foster
>>><kfo...@internode.com> wrote:
>>>
>>>>Thanks. I am beginning to see the complexities. I was hoping for a cheap
>>>>walk-around monitor for unquantified field intensity.
>>>
>>>In other words, an RF dosimeter or radiation detector. There are
>>>versions of such things all over the internet. Search the RF paranoia
>>>web sites for specifics.
>
>>With such applications put the local oscillator in the middle of the
>>band of interest and feed it to simple mixer which folds the upper and
>>lower bands to the same baseband frequency. Feed the mixer output to a
>>broadband 0 - 2.5 GHz signal indicator. This will cover 5 GHz
>>(Flo+/-2.5 GHz) of the band. Folding the upper and lower bands
>>doesn't hurt, since we are only interested in total RF power.
>>
>>To generate 28 GHz LO signal use some oscillator (e.g. DRO) in 9-10
>>GHz range, overdrive it in a MMIC stage and filter out the 3rd
>>harmonic to feed the mixer
>
>Yep, that would work. The LO and mixer are a bit complicated due to
>the 30GHz frequency, but the IF amp and detector can be quite crude.
The classical 1N21 mixer diode might be usable at those frequencies,
>On Mon, 21 Nov 2016 09:33:58 +0200, upsid...@downunder.com wrote:
>
>>On Sun, 20 Nov 2016 11:22:40 -0800, Jeff Liebermann <je...@cruzio.com>
>>wrote:
>>
>>>On Sun, 20 Nov 2016 22:24:50 +1100, Kevin Foster
>>><kfo...@internode.com> wrote:
>>>
>>>>Thanks. I am beginning to see the complexities. I was hoping for a cheap
>>>>walk-around monitor for unquantified field intensity.
>>>
>>>In other words, an RF dosimeter or radiation detector. There are
>>>versions of such things all over the internet. Search the RF paranoia
>>>web sites for specifics.
>
>>With such applications put the local oscillator in the middle of the
>>band of interest and feed it to simple mixer which folds the upper and
>>lower bands to the same baseband frequency. Feed the mixer output to a
>>broadband 0 - 2.5 GHz signal indicator. This will cover 5 GHz
>>(Flo+/-2.5 GHz) of the band. Folding the upper and lower bands
>>doesn't hurt, since we are only interested in total RF power.
>>
>>To generate 28 GHz LO signal use some oscillator (e.g. DRO) in 9-10
>>GHz range, overdrive it in a MMIC stage and filter out the 3rd
>>harmonic to feed the mixer
>
>Yep, that would work. The LO and mixer are a bit complicated due to
>the 30GHz frequency, but the IF amp and detector can be quite crude.
but the noise figure would be quite bad, but who cares, if you are
only interested in the envelope power.
>I've done something like that using a cheap satellite TV signal meter:
><http://www.ebay.com/itm/112211347132>
>Apply 12VDC to the output port through a 75 ohm load resistor to power
>the meter. The input port goes to the mixer. Inside the meter is a
>rather crude MMIC 950-1950MHz amplifier and detector to drive the
>meter. Most of the gain is at the 950MHz end.
>
>If you feel link playing, put a cellular yagi antenna on the input
>port of the meter and use it to find cell sites operating in the
>850-950MHz region. I was doing that for a while until I build
>something better. It doesn't work too well at PCS frequencies
>1900MHz.
benefit from line of sight point to point communications. You are
fully dependent on in-room reflections as i the IR remote case.
>The problem with such schemes is that it's difficult to tell what the
>detector is hearing. It could be some other service on adjacent
>frequencies.
there are other services too.
> For example, it could be responding to 24GHz speed trap
>radar. With a simple mixer, minimizing the LO radiation out the
>antenna might be a problem. Besides, the OP wanted "cheap" which to
>me means a horn antenna,
measurements.
>RF bandpass filter, diode detector, and DC
>amplifier. In other words, a 30GHz field strength meter.
of the low frequency (below 20 GHz) crud away, while any post mixer
filtering will keep away any interference far away from the LO.
srober...@gmail.com
Nov 21, 2016, 5:21:31 PM11/21/16
to
Older US KA band radar detectors with the stepped ridge waveguide horn are quite broadband, especially the ones that have fixed 11 Ghz LOs. In the near field, a few meters of range, they should quite fine for this. The ones that try to identify the band or emitter by sweeping the LO and IF may not be good candidates for this task.
Ebay is full of the things, but the trick is identifying the internal topology.
There is a class of older radar detectors with little input filtering that will sound off just fine in this band. Sadly they are the ones that were easily detected with counter detector devices in some states... Thus they were only on the market a few years, maybe five.
Steve
Ebay is full of the things, but the trick is identifying the internal topology.
There is a class of older radar detectors with little input filtering that will sound off just fine in this band. Sadly they are the ones that were easily detected with counter detector devices in some states... Thus they were only on the market a few years, maybe five.
Steve
Robert Baer
Nov 21, 2016, 9:43:34 PM11/21/16
to
Jeff Liebermann wrote:
> On Mon, 21 Nov 2016 09:33:58 +0200, upsid...@downunder.com wrote:
>
>> On Sun, 20 Nov 2016 11:22:40 -0800, Jeff Liebermann<je...@cruzio.com>
>> wrote:
>>
>>> On Sun, 20 Nov 2016 22:24:50 +1100, Kevin Foster
>>> <kfo...@internode.com> wrote:
>>>
>>>> Thanks. I am beginning to see the complexities. I was hoping for a cheap
>>>> walk-around monitor for unquantified field intensity.
>>>
>>> In other words, an RF dosimeter or radiation detector. There are
>>> versions of such things all over the internet. Search the RF paranoia
>>> web sites for specifics.
>
>> With such applications put the local oscillator in the middle of the
>> band of interest and feed it to simple mixer which folds the upper and
>> lower bands to the same baseband frequency. Feed the mixer output to a
>> broadband 0 - 2.5 GHz signal indicator. This will cover 5 GHz
>> (Flo+/-2.5 GHz) of the band. Folding the upper and lower bands
>> doesn't hurt, since we are only interested in total RF power.
>>
>> To generate 28 GHz LO signal use some oscillator (e.g. DRO) in 9-10
>> GHz range, overdrive it in a MMIC stage and filter out the 3rd
>> harmonic to feed the mixer
>
> Yep, that would work. The LO and mixer are a bit complicated due to
> the 30GHz frequency, but the IF amp and detector can be quite crude.
> I've done something like that using a cheap satellite TV signal meter:
> <http://www.ebay.com/itm/112211347132>
* Bait and switch?
> On Mon, 21 Nov 2016 09:33:58 +0200, upsid...@downunder.com wrote:
>
>> On Sun, 20 Nov 2016 11:22:40 -0800, Jeff Liebermann<je...@cruzio.com>
>> wrote:
>>
>>> On Sun, 20 Nov 2016 22:24:50 +1100, Kevin Foster
>>> <kfo...@internode.com> wrote:
>>>
>>>> Thanks. I am beginning to see the complexities. I was hoping for a cheap
>>>> walk-around monitor for unquantified field intensity.
>>>
>>> In other words, an RF dosimeter or radiation detector. There are
>>> versions of such things all over the internet. Search the RF paranoia
>>> web sites for specifics.
>
>> With such applications put the local oscillator in the middle of the
>> band of interest and feed it to simple mixer which folds the upper and
>> lower bands to the same baseband frequency. Feed the mixer output to a
>> broadband 0 - 2.5 GHz signal indicator. This will cover 5 GHz
>> (Flo+/-2.5 GHz) of the band. Folding the upper and lower bands
>> doesn't hurt, since we are only interested in total RF power.
>>
>> To generate 28 GHz LO signal use some oscillator (e.g. DRO) in 9-10
>> GHz range, overdrive it in a MMIC stage and filter out the 3rd
>> harmonic to feed the mixer
>
> Yep, that would work. The LO and mixer are a bit complicated due to
> the 30GHz frequency, but the IF amp and detector can be quite crude.
> I've done something like that using a cheap satellite TV signal meter:
> <http://www.ebay.com/itm/112211347132>
"Item is out of stock"
So how do i get some?
Jeff Liebermann
Nov 21, 2016, 11:19:02 PM11/21/16
to
On Mon, 21 Nov 2016 18:43:31 -0800, Robert Baer
<rober...@localnet.com> wrote:
>Jeff Liebermann wrote:
>> I've done something like that using a cheap satellite TV signal meter:
>> <http://www.ebay.com/itm/112211347132>
>* Bait and switch?
> "Item is out of stock"
> So how do i get some?
They're all over eBay and Amazon in a few configurations. Search for
"satellite meter" or "satellite finder".
<http://www.ebay.com/sch/i.html?_nkw=satellite+finder>
<http://www.ebay.com/sch/i.html?_nkw=satellite+meter>
I guess a warning might be useful. I've own about 10 of these meters.
They're quite useful, quite cheap, but not really quality instruments.
The interior construction and solder are abysmal. This looks like
some of the better meters:
<http://goughlui.com/2015/02/05/repair-teardown-unbranded-sf-95-analog-satlink-ws-6903-digital-satellite-finder/>
Some meters were unstable and would go into oscillation for no obvious
reason. Others are seriously lacking in gain. One was dead on
arrival but fixed by resoldering a few ugly connections. When I need
one to aim a dish, I usually grab 4 or more meters just in case one
fails. I had one installation where 3 out 4 sat finders didn't work
quite right. I can also testify that dropping a satellite finder onto
concrete from about 20ft will cause it to self-disassemble. Caveat
Emptor.
<rober...@localnet.com> wrote:
>Jeff Liebermann wrote:
>> I've done something like that using a cheap satellite TV signal meter:
>> <http://www.ebay.com/itm/112211347132>
>* Bait and switch?
> "Item is out of stock"
> So how do i get some?
"satellite meter" or "satellite finder".
<http://www.ebay.com/sch/i.html?_nkw=satellite+finder>
<http://www.ebay.com/sch/i.html?_nkw=satellite+meter>
I guess a warning might be useful. I've own about 10 of these meters.
They're quite useful, quite cheap, but not really quality instruments.
The interior construction and solder are abysmal. This looks like
some of the better meters:
<http://goughlui.com/2015/02/05/repair-teardown-unbranded-sf-95-analog-satlink-ws-6903-digital-satellite-finder/>
Some meters were unstable and would go into oscillation for no obvious
reason. Others are seriously lacking in gain. One was dead on
arrival but fixed by resoldering a few ugly connections. When I need
one to aim a dish, I usually grab 4 or more meters just in case one
fails. I had one installation where 3 out 4 sat finders didn't work
quite right. I can also testify that dropping a satellite finder onto
concrete from about 20ft will cause it to self-disassemble. Caveat
Emptor.
Jeff Liebermann
Nov 21, 2016, 11:51:01 PM11/21/16
to
On Mon, 21 Nov 2016 22:43:32 +0200, upsid...@downunder.com wrote:
>The classical 1N21 mixer diode might be usable at those frequencies,
>but the noise figure would be quite bad, but who cares, if you are
>only interested in the envelope power.
No way. At 30GHz, the cat whisker inside the 1N21 or 1N23 diode makes
>The classical 1N21 mixer diode might be usable at those frequencies,
>but the noise figure would be quite bad, but who cares, if you are
>only interested in the envelope power.
a dandy inductor.
<http://www.ganssle.com/tem/images/tem257-rectifier.jpg>
At 30GHz lead length is critical and must be minimized. Microwave
diodes come in much much much smaller packages.
>One should remember that microwave cellular communications doesn't
>benefit from line of sight point to point communications. You are
>fully dependent on in-room reflections as i the IR remote case.
found that wireless routers spend most of their working lives at
802.11g speeds and modes, without the benefit of 802.11n MIMO
features. The only time 802.11n speeds are achieved is when I either
force the router to use them by disabling 802.11b/g, or when I have a
nearly ideal situation that includes both a direct line of sight an a
highly reflective environment.
802.11ac did it right. I can force an 802.11ac router to only use
802.11ac and it will slow all the way down to a 6.5Mbit/sec rate. No
need to switch to 802.11a rates. Anyway, 802.11ac acted the same as
802.11n on 2.4GHz. Anything that increases the BER (bit error rate)
will cause it to slow down, switch modes, drop out of 802.11n MIMO,
and only use the direct path.
>> For example, it could be responding to 24GHz speed trap
>>radar. With a simple mixer, minimizing the LO radiation out the
>>antenna might be a problem. Besides, the OP wanted "cheap" which to
>>me means a horn antenna,
>
>A horn might have too much "gain" or directivity for usable
>measurements.
Rectangular WR28 waveguide would be 0.14 x 0.28 in (3.5 x 7.0 mm) and
is a 2:1 rectangle. My guess(tm) a 3 x 6 cm horn would be about
right. Plugging into a handy horn antenna guestimator:
<http://www.rfwireless-world.com/calculators/Horn-Antenna-Calculator.html>
I get:
Gain = 22.6dBi
Beamwidth vertical = 17 degrees
Beamwidth horizontal = 11.7
No problem. That should work quite nicely and is much better than a
dish, which ended up with a too narrow beamwidth of less than 1
degree. Construction of a horn is also much easier.
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