Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss
Ferrite rod antennas in AM broadcast receivers
1,186 views
Skip to first unread message
George
Sep 2, 2012, 8:35:35 PM9/2/12
to
I have been trying to find info on designing ferrite rod antennas into AM broadcast receivers. Googling so far has just produced general loop antenna principles and characteristics of the rod material itself.
Does a ferrite rod antenna have to be tuned to resonance when changing frequencies with the 0.5 - 1.6 MHz band? Or can decent performance be realized across the band without re-tuning? Are there gain vs. frequency curves available for given ferrite rod antenna designs?
And I'd like to understand the antenna's phase (delay) performance across the AM band for a given design.
I'd appreciate if someone can point me to this info.
Thanks.
Does a ferrite rod antenna have to be tuned to resonance when changing frequencies with the 0.5 - 1.6 MHz band? Or can decent performance be realized across the band without re-tuning? Are there gain vs. frequency curves available for given ferrite rod antenna designs?
And I'd like to understand the antenna's phase (delay) performance across the AM band for a given design.
I'd appreciate if someone can point me to this info.
Thanks.
Phil Allison
Sep 2, 2012, 8:53:59 PM9/2/12
to
"George"
I have been trying to find info on designing ferrite rod antennas into AM
broadcast receivers. Googling so far has just produced general loop antenna
principles and characteristics of the rod material itself.
> Does a ferrite rod antenna have to be tuned to resonance when changing
> frequencies with the 0.5 - 1.6 MHz band?
Pre-selection of the antenna signal is crucial to getting good results with
the AM broadcast band, otherwise the receiver will suffer badly from cross
modulation effects and images of the IF frequency.
> Or can decent performance be realized across the band without re-tuning?
>Are there gain vs. frequency curves available for given ferrite rod antenna
>designs?
and directionality.
> And I'd like to understand the antenna's phase (delay) performance across
> the AM band for a given design.
... Phil
George
Sep 3, 2012, 12:44:12 AM9/3/12
to
[OP here]
To clarify my questions:
I'm building an AM broadcast receiver to be used in a non-standard application. It will use an existing wideband COTS software defined radio product that does not provide tuning information to the ferrite antenna. So I'd like to be able to get enough antenna gain across the broadcast band from the antenna to avoid having to tune the antenna to resonance on each frequency. But space limitations dictate use of a ferrite.
This non-standard application DOES require knowledge of the antenna delay vs. frequency.
To clarify my questions:
I'm building an AM broadcast receiver to be used in a non-standard application. It will use an existing wideband COTS software defined radio product that does not provide tuning information to the ferrite antenna. So I'd like to be able to get enough antenna gain across the broadcast band from the antenna to avoid having to tune the antenna to resonance on each frequency. But space limitations dictate use of a ferrite.
This non-standard application DOES require knowledge of the antenna delay vs. frequency.
Winston
Sep 3, 2012, 1:00:33 AM9/3/12
to
you could use to resonate your loopstick using
a voltage variable capacitor?
http://en.wikipedia.org/wiki/Varicap
--Winston
Tim Williams
Sep 3, 2012, 2:18:12 AM9/3/12
to
A tuned antenna is important in a superhet, where with an IF of 455kHz, an
LO frequency of 1005kHz could pull in two channels, 550 and 1460kHz. But
since your detector is different, this doesn't need to matter.
So you need a Q of about 1. Size the L and C accordingly. That's the
best you can do, and of course your antenna gain will be terrible (far
below isotropic).
Could you define "antenna delay", and quantify how it must be known?
In general, a radio has absolutely no phase reference, and because
bandwidth is generally narrow (e.g., 10kHz out of a >1MHz band), a radio
is very insensitive to relatively sharp changes in phase vs. frequency
(even if that phase shift lands in the middle of the channel)*. Is this a
diversity application of some sort?
* Obvious exception: analog TV, which is notably sensitive to multipath.
One could argue, because this signal is wideband, and more time- than
frequency-domain oriented, it doesn't count.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
"George" <geo...@thefiftysports.com> wrote in message
news:b2f8f837-5eac-4b7e...@googlegroups.com...
LO frequency of 1005kHz could pull in two channels, 550 and 1460kHz. But
since your detector is different, this doesn't need to matter.
So you need a Q of about 1. Size the L and C accordingly. That's the
best you can do, and of course your antenna gain will be terrible (far
below isotropic).
Could you define "antenna delay", and quantify how it must be known?
In general, a radio has absolutely no phase reference, and because
bandwidth is generally narrow (e.g., 10kHz out of a >1MHz band), a radio
is very insensitive to relatively sharp changes in phase vs. frequency
(even if that phase shift lands in the middle of the channel)*. Is this a
diversity application of some sort?
* Obvious exception: analog TV, which is notably sensitive to multipath.
One could argue, because this signal is wideband, and more time- than
frequency-domain oriented, it doesn't count.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
"George" <geo...@thefiftysports.com> wrote in message
news:b2f8f837-5eac-4b7e...@googlegroups.com...
Jeff Liebermann
Sep 3, 2012, 2:18:17 AM9/3/12
to
On Sun, 2 Sep 2012 17:35:35 -0700 (PDT), George
<geo...@thefiftysports.com> wrote:
>I have been trying to find info on designing ferrite rod
>antennas into AM broadcast receivers. Googling so far
>has just produced general loop antenna principles and
>characteristics of the rod material itself.
Google for "loopstick".
<geo...@thefiftysports.com> wrote:
>I have been trying to find info on designing ferrite rod
>antennas into AM broadcast receivers. Googling so far
>has just produced general loop antenna principles and
>characteristics of the rod material itself.
>Does a ferrite rod antenna have to be tuned to resonance
>when changing frequencies with the 0.5 - 1.6 MHz band?
>Or can decent performance be realized across the band
>without re-tuning?
Bandwidth, Small, Gain... pick any two. (from Roy Lewallan W7EL).
What the loopstick does dramatically shrink the size of the BCB
antenna so that it can be crammed into a small AM portable radio. This
is what the coils looked like before ferrite loopsticks became
popular:
<http://1.bp.blogspot.com/-oU_qtG02Tak/T7BOxG3C2xI/AAAAAAAAACg/l44F3TUQU6Q/s1600/RA-10.jpg>
The price of small size is narrow bandwidth. Quite a bit of effort
goes into raising the Q (thus narrowing the bandwidth) of the
loopstick by using Litz wire instead of ordinary copper wire. The
antenna gain remains about the same. Typical Q is 200-1000 or a
bandwidth of a few KHz which isn't really suitable for a broadband SDR
front end. If you want a broadband input filter and antenna, then
forget about using a ferrite loopstick and build an air loop.
Something like this:
<http://www.radiomuseum.org/forum/philco_loop_replaces_aerial.html>
>Are there gain vs. frequency curves available for given ferrite rod antenna designs?
gain of the antenna isn't really important. More antenna gain means
just hearing more noise. The signal to noise ratio remains constant.
Antenna directivity is important, but you don't have much control with
a small loopstick.
>And I'd like to understand the antenna's phase (delay) performance across the AM band for a given design.
SDR digitizer front end, the phase shift (group delay) at the
bandwidth edges is going to be rather horrible. Specifically, it's
going to look exactly like the phase shift through a single tuned LC
circuit.
<http://www.angelfire.com/electronic2/index1/loopstick.html>
<http://en.wikipedia.org/wiki/Loop_antenna#AM_broadcast_receiver_loop_antennas>
--
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
Phil Allison
Sep 3, 2012, 3:55:26 AM9/3/12
to
"George is a TROLL "
[OP here]
To clarify my questions:
I'm building an AM broadcast receiver to be used in a non-standard
application.
You are obviously yet ANOTHER idiotic code scribbler wasting our time.
It will use an existing wideband COTS software defined radio product that
does not provide tuning information to the ferrite antenna. So I'd like to
be able to get enough antenna gain across the broadcast band from the
antenna to avoid having to tune the antenna to resonance on each frequency.
But space limitations dictate use of a ferrite.
Your ideas are totally stupid.
This non-standard application DOES require knowledge of the antenna delay
vs. frequency.
... Phil
Jan Panteltje
Sep 3, 2012, 3:56:48 AM9/3/12
to
On a sunny day (Sun, 2 Sep 2012 17:35:35 -0700 (PDT)) it happened George
<geo...@thefiftysports.com> wrote in
<3459d769-ae23-475d...@googlegroups.com>:
>I have been trying to find info on designing ferrite rod antennas into AM b=
>roadcast receivers. Googling so far has just produced general loop antenna=
Its just a magnetic pickup for the eM field.
And because of that very directional sensitive.
Most are black....
<geo...@thefiftysports.com> wrote in
<3459d769-ae23-475d...@googlegroups.com>:
>I have been trying to find info on designing ferrite rod antennas into AM b=
>roadcast receivers. Googling so far has just produced general loop antenna=
> principles and characteristics of the rod material itself.
>
>Does a ferrite rod antenna have to be tuned to resonance when changing freq=
>
>uencies with the 0.5 - 1.6 MHz band?
Yes
Its just a magnetic pickup for the eM field.
And because of that very directional sensitive.
Most are black....
John Larkin
Sep 3, 2012, 12:34:53 PM9/3/12
to
Gain is cheap nowadays, and AM reception is generally dominated by
external noise, not receiver noise figure. A good opamp or jfet will
get you below 1 nV/rootHz noise, so resonant gain isn't necessary. If
delay matters, it's better to not resonate the antenna.
An untuned loop, or an untuned ferrite rod, would work, far below
self-resonance. A few-turn loop would act like an almost ideal H-field
probe, and its gain and delay behavior are calculable.
What are you trying to do? Do you expect to have a lot of signal? Is
the transmitter nearby?
--
John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
George
Sep 3, 2012, 8:48:39 PM9/3/12
to
On Monday, September 3, 2012 9:34:46 AM UTC-7, John Larkin wrote:
> On Sun, 2 Sep 2012 21:44:12 -0700 (PDT), George
>
>
>
> On Sun, 2 Sep 2012 21:44:12 -0700 (PDT), George
>
>
>
> >[OP here]
>
> >
>
> >To clarify my questions:
>
> >
>
> >I'm building an AM broadcast receiver to be used in a non-standard application. It will use an existing wideband COTS software defined radio product that does not provide tuning information to the ferrite antenna. So I'd like to be able to get enough antenna gain across the broadcast band from the antenna to avoid having to tune the antenna to resonance on each frequency. But space limitations dictate use of a ferrite.
>
> >
>
> >This non-standard application DOES require knowledge of the antenna delay vs. frequency.
>
>
>
> There's nothing fundamentally wrong with using an untuned antenna.
>
> Gain is cheap nowadays, and AM reception is generally dominated by
>
> external noise, not receiver noise figure. A good opamp or jfet will
>
> get you below 1 nV/rootHz noise, so resonant gain isn't necessary. If
>
> delay matters, it's better to not resonate the antenna.
>
>
>
> An untuned loop, or an untuned ferrite rod, would work, far below
>
> self-resonance. A few-turn loop would act like an almost ideal H-field
>
> probe, and its gain and delay behavior are calculable.
>
>
>
> What are you trying to do? Do you expect to have a lot of signal? Is
>
> the transmitter nearby?
You may be right about going with an untuned antenna. It's worth a try. If a high-gain amp in lieu of a tuned stick will give me the receive gain of a traditional ferrite, that's all I need. And it avoids phase non-linearity issues which my app is very sensitive to. Besides, I'm sampling the whole AM broadcast band at once and can't tolerate a narrow-band front end due to the high-Q ferrite antenna.
>
> >
>
> >To clarify my questions:
>
> >
>
> >I'm building an AM broadcast receiver to be used in a non-standard application. It will use an existing wideband COTS software defined radio product that does not provide tuning information to the ferrite antenna. So I'd like to be able to get enough antenna gain across the broadcast band from the antenna to avoid having to tune the antenna to resonance on each frequency. But space limitations dictate use of a ferrite.
>
> >
>
> >This non-standard application DOES require knowledge of the antenna delay vs. frequency.
>
>
>
> There's nothing fundamentally wrong with using an untuned antenna.
>
> Gain is cheap nowadays, and AM reception is generally dominated by
>
> external noise, not receiver noise figure. A good opamp or jfet will
>
> get you below 1 nV/rootHz noise, so resonant gain isn't necessary. If
>
> delay matters, it's better to not resonate the antenna.
>
>
>
> An untuned loop, or an untuned ferrite rod, would work, far below
>
> self-resonance. A few-turn loop would act like an almost ideal H-field
>
> probe, and its gain and delay behavior are calculable.
>
>
>
> What are you trying to do? Do you expect to have a lot of signal? Is
>
> the transmitter nearby?
Two concerns:
1. The Websites I have seen talk highly about the performance that is achievable with high-mu ferrite over ordinary loops in the same board space. Makes me wonder if I can get to that antenna gain without ferrite, even with a good amplifier. That amplifier is going to have its own problems like 3IM overload, etc. I understand the high environmental noise argument.
2. The ferrite loop would have reduced the near-field impulse noise E-field pickup which now may become a problem.
Well, all I can do is to try it.
Phil Hobbs
Sep 3, 2012, 8:55:22 PM9/3/12
to
vs bandwidth. See e.g.
http://highfrequencyelectronics.com/Archives/Feb07/HFE0207_tutorial.pdf
There's a bibliography at
http://www.home.earthlink.net/~christrask/magloop.html .
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
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
Jamie
Sep 3, 2012, 9:08:59 PM9/3/12
to
if you're sampling the whole AM band at once. Agc in the IF stage works
good because it only acts on the selected pass freq.
I suppose if you are doing this a with a high res DSP you could pull
out the weak ones with DFT's.
Jamie
Phil Allison
Sep 3, 2012, 9:11:19 PM9/3/12
to
"George is a TROLL "
You may be right about going with an untuned antenna. It's worth a try.
If a high-gain amp in lieu of a tuned stick will give me the receive gain of
a traditional ferrite, that's all I need.
And it avoids phase non-linearity issues which my app is very sensitive to.
Besides, I'm sampling the whole AM broadcast band at once and can't tolerate
a narrow-band front end due to the high-Q ferrite antenna.
He won't answer, so you KNOW it is 100% stupid.
.... Phil
josephkk
Sep 4, 2012, 11:32:23 PM9/4/12
to
antenna.
Well maybe, but with a Q of no more than 1/2. The biggest problem after
that is amplify a bit first then filter down to AM band or filter first
then amplify?
In either case the filter design will be at least 6th order to be useful
and that gets you into possibly ugly phase/frequency/delay issues. And
very likely difficult implementation problems. Inverse Chebychev or
Bessel may be possible choices.
After that most of the tough stuff is done, just an serious 16-bit, 10
MS/s digitizer, and analytical software (oops maybe i spoke too soon,
sounds like medium sized FPGA).
?-)
George
Sep 12, 2012, 5:26:41 PM9/12/12
to
On Monday, September 3, 2012 9:34:46 AM UTC-7, John Larkin wrote:
> On Sun, 2 Sep 2012 21:44:12 -0700 (PDT), George
>
> <geo...@thefiftysports.com> wrote:
>
>
>
> >[OP here]
>
> >
>
> >To clarify my questions:
>
> >
>
> >I'm building an AM broadcast receiver to be used in a non-standard application. It will use an existing wideband COTS software defined radio product that does not provide tuning information to the ferrite antenna. So I'd like to be able to get enough antenna gain across the broadcast band from the antenna to avoid having to tune the antenna to resonance on each frequency. But space limitations dictate use of a ferrite.
>
> >
>
> >This non-standard application DOES require knowledge of the antenna delay vs. frequency.
>
>
>
> There's nothing fundamentally wrong with using an untuned antenna.
>
> Gain is cheap nowadays, and AM reception is generally dominated by
>
> external noise, not receiver noise figure. A good opamp or jfet will
>
> get you below 1 nV/rootHz noise, so resonant gain isn't necessary. If
>
> delay matters, it's better to not resonate the antenna.
>
>
>
> An untuned loop, or an untuned ferrite rod, would work, far below
>
> self-resonance. A few-turn loop would act like an almost ideal H-field
>
> probe, and its gain and delay behavior are calculable.
>
>
>
> What are you trying to do? Do you expect to have a lot of signal? Is
>
> the transmitter nearby?
>
>
>
>
>
> --
>
>
>
> John Larkin Highland Technology Inc
>
> www.highlandtechnology.com jlarkin at highlandtechnology dot com
>
>
Agree an un-tuned loop or rod followed by an amp is the way we should go. Any suggestions on who to contact for engineering services in order to sub-contract the design?
>
> <geo...@thefiftysports.com> wrote:
>
>
>
> >[OP here]
>
> >
>
> >To clarify my questions:
>
> >
>
> >I'm building an AM broadcast receiver to be used in a non-standard application. It will use an existing wideband COTS software defined radio product that does not provide tuning information to the ferrite antenna. So I'd like to be able to get enough antenna gain across the broadcast band from the antenna to avoid having to tune the antenna to resonance on each frequency. But space limitations dictate use of a ferrite.
>
> >
>
> >This non-standard application DOES require knowledge of the antenna delay vs. frequency.
>
>
>
> There's nothing fundamentally wrong with using an untuned antenna.
>
> Gain is cheap nowadays, and AM reception is generally dominated by
>
> external noise, not receiver noise figure. A good opamp or jfet will
>
> get you below 1 nV/rootHz noise, so resonant gain isn't necessary. If
>
> delay matters, it's better to not resonate the antenna.
>
>
>
> An untuned loop, or an untuned ferrite rod, would work, far below
>
> self-resonance. A few-turn loop would act like an almost ideal H-field
>
> probe, and its gain and delay behavior are calculable.
>
>
>
> What are you trying to do? Do you expect to have a lot of signal? Is
>
> the transmitter nearby?
>
>
>
>
>
> --
>
>
>
> John Larkin Highland Technology Inc
>
> www.highlandtechnology.com jlarkin at highlandtechnology dot com
>
>
You asked about signal levels. The signals are ordinary AM broadcast carriers which should be plenty strong for our needs. And yes, external noise predominates in this application.
George
Phil Allison
Sep 12, 2012, 6:55:51 PM9/12/12
to
"George = IDIOT "
>
Agree an un-tuned loop or rod followed by an amp is the way we should go.
Any suggestions on who to contact for engineering services in order to
sub-contract the design?
** Try the tooth fairy.
Agree an un-tuned loop or rod followed by an amp is the way we should go.
Any suggestions on who to contact for engineering services in order to
sub-contract the design?
You asked about signal levels. The signals are ordinary AM broadcast
carriers which should be plenty strong for our needs.
And yes, external noise predominates in this application.
Cos it is all your mad idea.
John Larkin
Sep 12, 2012, 7:05:33 PM9/12/12
to
On Wed, 12 Sep 2012 14:26:41 -0700 (PDT), George
http://brucesherrydesigns.com/
does research and design for us now and then, when we can't get around
to potentially interesting stuff ourselves. You might ask him if he's
interested.
>
>You asked about signal levels. The signals are ordinary AM broadcast carriers which should be plenty strong for our needs. And yes, external noise predominates in this application.
You should be able to look up typical AM field strengths in cities,
and calculate the H-field, and see how much signal you'd get from a
given loop. Or measure it.
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
<geo...@thefiftysports.com> wrote:
>On Monday, September 3, 2012 9:34:46 AM UTC-7, John Larkin wrote:
>> On Sun, 2 Sep 2012 21:44:12 -0700 (PDT), George
>>
>> <geo...@thefiftysports.com> wrote:
>>
>>
>>
>> >[OP here]
>>
>> >
>>
>> >To clarify my questions:
>>
>> >
>>
>> >I'm building an AM broadcast receiver to be used in a non-standard application. It will use an existing wideband COTS software defined radio product that does not provide tuning information to the ferrite antenna. So I'd like to be able to get enough antenna gain across the broadcast band from the antenna to avoid having to tune the antenna to resonance on each frequency. But space limitations dictate use of a ferrite.
>>
>> >
>>
>> >This non-standard application DOES require knowledge of the antenna delay vs. frequency.
>>
>>
>>
>> There's nothing fundamentally wrong with using an untuned antenna.
>>
>> Gain is cheap nowadays, and AM reception is generally dominated by
>>
>> external noise, not receiver noise figure. A good opamp or jfet will
>>
>> get you below 1 nV/rootHz noise, so resonant gain isn't necessary. If
>>
>> delay matters, it's better to not resonate the antenna.
>>
>>
>>
>> An untuned loop, or an untuned ferrite rod, would work, far below
>>
>> self-resonance. A few-turn loop would act like an almost ideal H-field
>>
>> probe, and its gain and delay behavior are calculable.
>>
>>
>>
>> What are you trying to do? Do you expect to have a lot of signal? Is
>>
>> the transmitter nearby?
>>
>>
>>
>>
>>
>> --
>>
>>
>>
>> John Larkin Highland Technology Inc
>>
>> www.highlandtechnology.com jlarkin at highlandtechnology dot com
>>
>>
>Agree an un-tuned loop or rod followed by an amp is the way we should go. Any suggestions on who to contact for engineering services in order to sub-contract the design?
Bruce...
>On Monday, September 3, 2012 9:34:46 AM UTC-7, John Larkin wrote:
>> On Sun, 2 Sep 2012 21:44:12 -0700 (PDT), George
>>
>> <geo...@thefiftysports.com> wrote:
>>
>>
>>
>> >[OP here]
>>
>> >
>>
>> >To clarify my questions:
>>
>> >
>>
>> >I'm building an AM broadcast receiver to be used in a non-standard application. It will use an existing wideband COTS software defined radio product that does not provide tuning information to the ferrite antenna. So I'd like to be able to get enough antenna gain across the broadcast band from the antenna to avoid having to tune the antenna to resonance on each frequency. But space limitations dictate use of a ferrite.
>>
>> >
>>
>> >This non-standard application DOES require knowledge of the antenna delay vs. frequency.
>>
>>
>>
>> There's nothing fundamentally wrong with using an untuned antenna.
>>
>> Gain is cheap nowadays, and AM reception is generally dominated by
>>
>> external noise, not receiver noise figure. A good opamp or jfet will
>>
>> get you below 1 nV/rootHz noise, so resonant gain isn't necessary. If
>>
>> delay matters, it's better to not resonate the antenna.
>>
>>
>>
>> An untuned loop, or an untuned ferrite rod, would work, far below
>>
>> self-resonance. A few-turn loop would act like an almost ideal H-field
>>
>> probe, and its gain and delay behavior are calculable.
>>
>>
>>
>> What are you trying to do? Do you expect to have a lot of signal? Is
>>
>> the transmitter nearby?
>>
>>
>>
>>
>>
>> --
>>
>>
>>
>> John Larkin Highland Technology Inc
>>
>> www.highlandtechnology.com jlarkin at highlandtechnology dot com
>>
>>
>Agree an un-tuned loop or rod followed by an amp is the way we should go. Any suggestions on who to contact for engineering services in order to sub-contract the design?
http://brucesherrydesigns.com/
does research and design for us now and then, when we can't get around
to potentially interesting stuff ourselves. You might ask him if he's
interested.
>
>You asked about signal levels. The signals are ordinary AM broadcast carriers which should be plenty strong for our needs. And yes, external noise predominates in this application.
and calculate the H-field, and see how much signal you'd get from a
given loop. Or measure it.
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
John Larkin
Sep 12, 2012, 7:21:11 PM9/12/12
to
On Thu, 13 Sep 2012 08:55:51 +1000, "Phil Allison" <phi...@tpg.com.au>
wrote:
What's wrong with an untuned loop? Old tube AM radios had loop
antennas, pretty small ones. Q couldn't have been very high, or else
they wouldn't have tracked the LO.
Longwire antennas, untuned, make gobs of signal into an old
Hallicrafters receiver. A foot is all you need to pick up AM in a
city, and that's an e-field probe with a ghastly impedance mismatch.
--
John Larkin Highland Technology, Inc
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
wrote:
antennas, pretty small ones. Q couldn't have been very high, or else
they wouldn't have tracked the LO.
Longwire antennas, untuned, make gobs of signal into an old
Hallicrafters receiver. A foot is all you need to pick up AM in a
city, and that's an e-field probe with a ghastly impedance mismatch.
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Photonics and fiberoptic TTL data links
Phil Allison
Sep 12, 2012, 7:30:21 PM9/12/12
to
"John Larkin"
"Phil Allison"
>>
>>"George = IDIOT "
>>>
>>Agree an un-tuned loop or rod followed by an amp is the way we should go.
>>Any suggestions on who to contact for engineering services in order to
>>sub-contract the design?
>>
>>
>>** Try the tooth fairy.
>>
>>You asked about signal levels. The signals are ordinary AM broadcast
>>carriers which should be plenty strong for our needs.
>>
>>** Horse poo.
>>
>>
>>And yes, external noise predominates in this application.
>>
>>
>>** No, insanity does.
>>
>> Cos it is all your mad idea.
>>
>>
>
> What's wrong with an untuned loop? Old tube AM radios had loop
> antennas, pretty small ones. Q couldn't have been very high, or else
> they wouldn't have tracked the LO.
** They were NOTHING like what the mad OP is on about.
>>"George = IDIOT "
>>>
>>Agree an un-tuned loop or rod followed by an amp is the way we should go.
>>Any suggestions on who to contact for engineering services in order to
>>sub-contract the design?
>>
>>
>>** Try the tooth fairy.
>>
>>You asked about signal levels. The signals are ordinary AM broadcast
>>carriers which should be plenty strong for our needs.
>>
>>** Horse poo.
>>
>>
>>And yes, external noise predominates in this application.
>>
>>
>>** No, insanity does.
>>
>> Cos it is all your mad idea.
>>
>>
>
> What's wrong with an untuned loop? Old tube AM radios had loop
> antennas, pretty small ones. Q couldn't have been very high, or else
> they wouldn't have tracked the LO.
> Longwire antennas, untuned, make gobs of signal into an old
> Hallicrafters receiver. A foot is all you need to pick up AM in a
> city,
Fuck knows what the colossal idiot is really trying to do - radio location
maybe.
Can't you tell a TROLL when you see one ?
( Rhetorical question .. )
Hint:
They ignore all questions and criticisms and only pick the one reply that
seems to back their fuckwit, secret idea up.
... Phil
upsid...@downunder.com
Sep 12, 2012, 8:14:37 PM9/12/12
to
While I have not seen the original message from the OP, there are some
issues.
1.) A small (relative to the wavelength) loop antenna will have a very
low radiation resistance (in milliohms), well smaller than the 50/75
ohm input impedance assumed by most receivers.
2.) The atmospheric noise level at VLF/LF/MF bands is extremely high,
so good results can be obtained with very poor antennas (such as
loopsticks with gains in the -30 .. -40 dB range).
Tuned loopsticks work quite OK due to the impedance transformation
between the resonant LC and the pick up coil.
Trying to use untuned (ferrite) loops at VLF/LF/MF would require some
very low input amplifier stages (such as hefty common base stages) to
actually take advantage of the current available in the loop.
issues.
1.) A small (relative to the wavelength) loop antenna will have a very
low radiation resistance (in milliohms), well smaller than the 50/75
ohm input impedance assumed by most receivers.
2.) The atmospheric noise level at VLF/LF/MF bands is extremely high,
so good results can be obtained with very poor antennas (such as
loopsticks with gains in the -30 .. -40 dB range).
Tuned loopsticks work quite OK due to the impedance transformation
between the resonant LC and the pick up coil.
Trying to use untuned (ferrite) loops at VLF/LF/MF would require some
very low input amplifier stages (such as hefty common base stages) to
actually take advantage of the current available in the loop.
josephkk
Sep 12, 2012, 10:21:38 PM9/12/12
to
On Wed, 12 Sep 2012 16:21:11 -0700, John Larkin
<jla...@highlandtechnology.com> wrote:
>On Thu, 13 Sep 2012 08:55:51 +1000, "Phil Allison" <phi...@tpg.com.au>
>wrote:
>
>>
>>"George = IDIOT "
>>>
>>Agree an un-tuned loop or rod followed by an amp is the way we should go.
>>Any suggestions on who to contact for engineering services in order to
>>sub-contract the design?
>>
>>
>>** Try the tooth fairy.
>>
>>You asked about signal levels. The signals are ordinary AM broadcast
>>carriers which should be plenty strong for our needs.
>>
>>** Horse poo.
>>
>>
>>And yes, external noise predominates in this application.
>>
>>
>>** No, insanity does.
>>
>> Cos it is all your mad idea.
>>
>>
>
>What's wrong with an untuned loop? Old tube AM radios had loop
>antennas, pretty small ones. Q couldn't have been very high, or else
>they wouldn't have tracked the LO.
Better than you might think, it is the dominant property in image
<jla...@highlandtechnology.com> wrote:
>On Thu, 13 Sep 2012 08:55:51 +1000, "Phil Allison" <phi...@tpg.com.au>
>wrote:
>
>>
>>"George = IDIOT "
>>>
>>Agree an un-tuned loop or rod followed by an amp is the way we should go.
>>Any suggestions on who to contact for engineering services in order to
>>sub-contract the design?
>>
>>
>>** Try the tooth fairy.
>>
>>You asked about signal levels. The signals are ordinary AM broadcast
>>carriers which should be plenty strong for our needs.
>>
>>** Horse poo.
>>
>>
>>And yes, external noise predominates in this application.
>>
>>
>>** No, insanity does.
>>
>> Cos it is all your mad idea.
>>
>>
>
>What's wrong with an untuned loop? Old tube AM radios had loop
>antennas, pretty small ones. Q couldn't have been very high, or else
>they wouldn't have tracked the LO.
rejection. Resonated with another section of the variable capacitor that
generated LO. Q of maybe 50 most likely, more than that would hurt RX
bandwidth.
>
>Longwire antennas, untuned, make gobs of signal into an old
>Hallicrafters receiver. A foot is all you need to pick up AM in a
>city, and that's an e-field probe with a ghastly impedance mismatch.
A Hallicrafters is a bit better than an average AM receiver.
>Longwire antennas, untuned, make gobs of signal into an old
>Hallicrafters receiver. A foot is all you need to pick up AM in a
>city, and that's an e-field probe with a ghastly impedance mismatch.
?-)
John Larkin
Sep 12, 2012, 11:40:53 PM9/12/12
to
I took a banana lead, plugged it into both sides of a dual Pomona bnc
adapter, and ran that into our spectrum analyzer. That made a single
turn loop about a foot in diameter, basically an untuned H-field
probe. The whole AM band was picket-fenced with lines, and the bigger
ones were around -70 dBm, roughly 70 microvolts RMS. Noise floor maybe
20 dB below the better peaks. Adding a second, longer lead and
wrapping a few turns got me to -60, about 200 uV. Tons of signal.
Using the 3' banana lead as a single-wire antenna, basically an
E-field probe, I got similar amplitudes but a much higher noise floor.
That was into 50 ohms, a terrible mismatch to a short antenna.
--
John Larkin Highland Technology Inc
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Photonics and fiberoptic TTL data links
Phil Allison
Sep 12, 2012, 11:51:31 PM9/12/12
to
"John Larkin"
> I took a banana lead, plugged it into both sides of a dual Pomona bnc
> adapter, and ran that into our spectrum analyzer. That made a single
> turn loop about a foot in diameter, basically an untuned H-field
> probe.
samples the whole AM band at once and does some kind of magic trick.
I would say he was " off with the fairies" but that is a big insult to
fairies.
... Phil
John Larkin
Sep 12, 2012, 11:57:02 PM9/12/12
to
On Thu, 13 Sep 2012 13:51:31 +1000, "Phil Allison" <phi...@tpg.com.au>
wrote:
>
loop, some gain, and an ADC could easily capture the AM band for
digital signal processing.
wrote:
>
>"John Larkin"
>
>> I took a banana lead, plugged it into both sides of a dual Pomona bnc
>> adapter, and ran that into our spectrum analyzer. That made a single
>> turn loop about a foot in diameter, basically an untuned H-field
>> probe.
>
>
>** The OP is crapping on about a device that fits in the palm of the hand,
>samples the whole AM band at once and does some kind of magic trick.
I don't know what the magic trick is, but a small several-turn untuned
>
>> I took a banana lead, plugged it into both sides of a dual Pomona bnc
>> adapter, and ran that into our spectrum analyzer. That made a single
>> turn loop about a foot in diameter, basically an untuned H-field
>> probe.
>
>
>** The OP is crapping on about a device that fits in the palm of the hand,
>samples the whole AM band at once and does some kind of magic trick.
loop, some gain, and an ADC could easily capture the AM band for
digital signal processing.
Phil Allison
Sep 13, 2012, 12:01:37 AM9/13/12
to
"John Larkin"
"Phil Allison"<
>>
>>"John Larkin"
>>
>>> I took a banana lead, plugged it into both sides of a dual Pomona bnc
>>> adapter, and ran that into our spectrum analyzer. That made a single
>>> turn loop about a foot in diameter, basically an untuned H-field
>>> probe.
>>
>>
>>** The OP is crapping on about a device that fits in the palm of the hand,
>>samples the whole AM band at once and does some kind of magic trick.
>>
>>"John Larkin"
>>
>>> I took a banana lead, plugged it into both sides of a dual Pomona bnc
>>> adapter, and ran that into our spectrum analyzer. That made a single
>>> turn loop about a foot in diameter, basically an untuned H-field
>>> probe.
>>
>>
>>** The OP is crapping on about a device that fits in the palm of the hand,
>>samples the whole AM band at once and does some kind of magic trick.
>>
>>I would say he was " off with the fairies" but that is a big insult to
>>fairies.
>
>
>>fairies.
>
>
> I don't know what the magic trick is, but a small several-turn untuned
> loop, some gain, and an ADC could easily capture the AM band for
> digital signal processing.
** You are merely crapping on about your own, false imaginations.
> loop, some gain, and an ADC could easily capture the AM band for
> digital signal processing.
The one thing you are uniquely expert on.
Yawwnnnnnnnnnnnnnnnnnn.....................
... Phil
John Larkin
Sep 13, 2012, 12:03:15 AM9/13/12
to
On Thu, 13 Sep 2012 14:01:37 +1000, "Phil Allison" <phi...@tpg.com.au>
wrote:
>
Oh, go fix another broken guitar amp or something.
wrote:
>
George
Sep 13, 2012, 12:30:29 AM9/13/12
to
On Wednesday, September 12, 2012 8:56:57 PM UTC-7, John Larkin wrote:
> On Thu, 13 Sep 2012 13:51:31 +1000, "Phil Allison" <phi...@tpg.com.au>
>
> wrote:
>
>
>
> >
>
> >"John Larkin"
>
> >
>
> >> I took a banana lead, plugged it into both sides of a dual Pomona bnc
>
> >> adapter, and ran that into our spectrum analyzer. That made a single
>
> >> turn loop about a foot in diameter, basically an untuned H-field
>
> >> probe.
>
> >
>
> >
>
> >** The OP is crapping on about a device that fits in the palm of the hand,
>
> >samples the whole AM band at once and does some kind of magic trick.
>
>
>
> I don't know what the magic trick is, but a small several-turn untuned
>
> loop, some gain, and an ADC could easily capture the AM band for
>
> digital signal processing.
>
>
>
Sounds right. Our spec an measurements agree (in the ballpark) with predicted receive signal level of -80 dBm using a -35 dBi antenna receiving a 1 kW transmitter at 100 km distance.
> On Thu, 13 Sep 2012 13:51:31 +1000, "Phil Allison" <phi...@tpg.com.au>
>
> wrote:
>
>
>
> >
>
> >"John Larkin"
>
> >
>
> >> I took a banana lead, plugged it into both sides of a dual Pomona bnc
>
> >> adapter, and ran that into our spectrum analyzer. That made a single
>
> >> turn loop about a foot in diameter, basically an untuned H-field
>
> >> probe.
>
> >
>
> >
>
> >** The OP is crapping on about a device that fits in the palm of the hand,
>
> >samples the whole AM band at once and does some kind of magic trick.
>
>
>
> I don't know what the magic trick is, but a small several-turn untuned
>
> loop, some gain, and an ADC could easily capture the AM band for
>
> digital signal processing.
>
>
>
k...@att.bizzzzzzzzzzzz
Sep 13, 2012, 9:52:55 AM9/13/12
to
On Wed, 12 Sep 2012 20:57:02 -0700, John Larkin
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>On Thu, 13 Sep 2012 13:51:31 +1000, "Phil Allison" <phi...@tpg.com.au>
>wrote:
>
>>
>>"John Larkin"
>>
>>> I took a banana lead, plugged it into both sides of a dual Pomona bnc
>>> adapter, and ran that into our spectrum analyzer. That made a single
>>> turn loop about a foot in diameter, basically an untuned H-field
>>> probe.
>>
>>
>>** The OP is crapping on about a device that fits in the palm of the hand,
>>samples the whole AM band at once and does some kind of magic trick.
>
>I don't know what the magic trick is, but a small several-turn untuned
>loop, some gain, and an ADC could easily capture the AM band for
>digital signal processing.
This is done (software defined radio) but I think the problem with it is
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>On Thu, 13 Sep 2012 13:51:31 +1000, "Phil Allison" <phi...@tpg.com.au>
>wrote:
>
>>
>>"John Larkin"
>>
>>> I took a banana lead, plugged it into both sides of a dual Pomona bnc
>>> adapter, and ran that into our spectrum analyzer. That made a single
>>> turn loop about a foot in diameter, basically an untuned H-field
>>> probe.
>>
>>
>>** The OP is crapping on about a device that fits in the palm of the hand,
>>samples the whole AM band at once and does some kind of magic trick.
>
>I don't know what the magic trick is, but a small several-turn untuned
>loop, some gain, and an ADC could easily capture the AM band for
>digital signal processing.
overloading the receiver with a strong signal. It's sorta the same problem
that FFT based spectrum analyzers have.
John Larkin
Sep 13, 2012, 10:07:19 AM9/13/12
to
MHz or something. Noise dithering is no problem... noise is free here.
So the dynamic range should be pretty good, and sub-LSB signals should
be useful. A little front-end gain switching wouldn't hurt.
You could also software phase-lock to each carrier. We were thinking
about doing that in another situation where we had to do I-Q sort of
processing. Our idea was to make a PLL using a DDS as the virtual VCO,
all digitally in an FPGA. Lotsa code but not much hardware.
k...@att.bizzzzzzzzzzzz
Sep 13, 2012, 10:59:00 AM9/13/12
to
On Thu, 13 Sep 2012 07:07:19 -0700, John Larkin
the AM band.
>You could also software phase-lock to each carrier. We were thinking
>about doing that in another situation where we had to do I-Q sort of
>processing. Our idea was to make a PLL using a DDS as the virtual VCO,
>all digitally in an FPGA. Lotsa code but not much hardware.
FPGAs are *way* too expensive for anything on AM. ;-)
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>On Thu, 13 Sep 2012 09:52:55 -0400, "k...@att.bizzzzzzzzzzzz"
><k...@att.bizzzzzzzzzzzz> wrote:
>
>>On Wed, 12 Sep 2012 20:57:02 -0700, John Larkin
>><jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>>
>>>On Thu, 13 Sep 2012 13:51:31 +1000, "Phil Allison" <phi...@tpg.com.au>
>>>wrote:
>>>
>>>>
>>>>"John Larkin"
>>>>
>>>>> I took a banana lead, plugged it into both sides of a dual Pomona bnc
>>>>> adapter, and ran that into our spectrum analyzer. That made a single
>>>>> turn loop about a foot in diameter, basically an untuned H-field
>>>>> probe.
>>>>
>>>>
>>>>** The OP is crapping on about a device that fits in the palm of the hand,
>>>>samples the whole AM band at once and does some kind of magic trick.
>>>
>>>I don't know what the magic trick is, but a small several-turn untuned
>>>loop, some gain, and an ADC could easily capture the AM band for
>>>digital signal processing.
>>
>>This is done (software defined radio) but I think the problem with it is
>>overloading the receiver with a strong signal. It's sorta the same problem
>>that FFT based spectrum analyzers have.
>>
>
>In the AM band, you could oversample like crazy, say 12 bits at 100
>MHz or something. Noise dithering is no problem... noise is free here.
>So the dynamic range should be pretty good, and sub-LSB signals should
>be useful. A little front-end gain switching wouldn't hurt.
But once the front end is saturated, you're dead. There's TOO MUCH noise in
>On Thu, 13 Sep 2012 09:52:55 -0400, "k...@att.bizzzzzzzzzzzz"
><k...@att.bizzzzzzzzzzzz> wrote:
>
>>On Wed, 12 Sep 2012 20:57:02 -0700, John Larkin
>><jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>>
>>>On Thu, 13 Sep 2012 13:51:31 +1000, "Phil Allison" <phi...@tpg.com.au>
>>>wrote:
>>>
>>>>
>>>>"John Larkin"
>>>>
>>>>> I took a banana lead, plugged it into both sides of a dual Pomona bnc
>>>>> adapter, and ran that into our spectrum analyzer. That made a single
>>>>> turn loop about a foot in diameter, basically an untuned H-field
>>>>> probe.
>>>>
>>>>
>>>>** The OP is crapping on about a device that fits in the palm of the hand,
>>>>samples the whole AM band at once and does some kind of magic trick.
>>>
>>>I don't know what the magic trick is, but a small several-turn untuned
>>>loop, some gain, and an ADC could easily capture the AM band for
>>>digital signal processing.
>>
>>This is done (software defined radio) but I think the problem with it is
>>overloading the receiver with a strong signal. It's sorta the same problem
>>that FFT based spectrum analyzers have.
>>
>
>In the AM band, you could oversample like crazy, say 12 bits at 100
>MHz or something. Noise dithering is no problem... noise is free here.
>So the dynamic range should be pretty good, and sub-LSB signals should
>be useful. A little front-end gain switching wouldn't hurt.
the AM band.
>You could also software phase-lock to each carrier. We were thinking
>about doing that in another situation where we had to do I-Q sort of
>processing. Our idea was to make a PLL using a DDS as the virtual VCO,
>all digitally in an FPGA. Lotsa code but not much hardware.
upsid...@downunder.com
Sep 13, 2012, 11:29:53 AM9/13/12
to
On Thu, 13 Sep 2012 10:59:00 -0400, "k...@att.bizzzzzzzzzzzz"
If you have plenty of power to burn (i.e. _not_ battery powered), use
sufficient collector/drain current, say 1 A, use push-pull, use
negative feedback to linearize and the front end is not going to be
the problem, the problem starts with the ADC.
sufficient collector/drain current, say 1 A, use push-pull, use
negative feedback to linearize and the front end is not going to be
the problem, the problem starts with the ADC.
John Larkin
Sep 13, 2012, 12:08:18 PM9/13/12
to
On Thu, 13 Sep 2012 10:59:00 -0400, "k...@att.bizzzzzzzzzzzz"
I don't think the OP is building a radio. It has something to do with
measuring the phases of the various carriers, maybe some geo-location
thing or something. Or something.
--
John Larkin Highland Technology, Inc
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
measuring the phases of the various carriers, maybe some geo-location
thing or something. Or something.
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Photonics and fiberoptic TTL data links
John Larkin
Sep 13, 2012, 12:50:00 PM9/13/12
to
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Photonics and fiberoptic TTL data links
k...@att.bizzzzzzzzzzzz
Sep 13, 2012, 1:20:21 PM9/13/12
to
Well, everything is the problem.
k...@att.bizzzzzzzzzzzz
Sep 13, 2012, 1:21:45 PM9/13/12
to
josephkk
Sep 14, 2012, 1:57:47 AM9/14/12
to
On Thu, 13 Sep 2012 09:08:18 -0700, John Larkin
<jla...@highlandtechnology.com> wrote:
>
>>>In the AM band, you could oversample like crazy, say 12 bits at 100
>>>MHz or something. Noise dithering is no problem... noise is free here.
>>>So the dynamic range should be pretty good, and sub-LSB signals should
>>>be useful. A little front-end gain switching wouldn't hurt.
>>
>>But once the front end is saturated, you're dead. There's TOO MUCH noise in
>>the AM band.
>>
>>>You could also software phase-lock to each carrier. We were thinking
>>>about doing that in another situation where we had to do I-Q sort of
>>>processing. Our idea was to make a PLL using a DDS as the virtual VCO,
>>>all digitally in an FPGA. Lotsa code but not much hardware.
>>
>>FPGAs are *way* too expensive for anything on AM. ;-)
>
>I don't think the OP is building a radio. It has something to do with
>measuring the phases of the various carriers, maybe some geo-location
>thing or something. Or something.
>
Any way you want to slice it, OP wants to do something with radio signals
<jla...@highlandtechnology.com> wrote:
>
>>>In the AM band, you could oversample like crazy, say 12 bits at 100
>>>MHz or something. Noise dithering is no problem... noise is free here.
>>>So the dynamic range should be pretty good, and sub-LSB signals should
>>>be useful. A little front-end gain switching wouldn't hurt.
>>
>>But once the front end is saturated, you're dead. There's TOO MUCH noise in
>>the AM band.
>>
>>>You could also software phase-lock to each carrier. We were thinking
>>>about doing that in another situation where we had to do I-Q sort of
>>>processing. Our idea was to make a PLL using a DDS as the virtual VCO,
>>>all digitally in an FPGA. Lotsa code but not much hardware.
>>
>>FPGAs are *way* too expensive for anything on AM. ;-)
>
>I don't think the OP is building a radio. It has something to do with
>measuring the phases of the various carriers, maybe some geo-location
>thing or something. Or something.
>
in the AM band. That implies a receiver of some kind.
?-)
amdx
Sep 14, 2012, 1:45:36 PM9/14/12
to
E4000 tuner.
The modules consist of
1. A switching unit with a VHF broadcast band filter
2. A 300 KHz to ~60MHz pre-amplifier of around 18dB gain
3. An HF to VHF converter DC to 60 MHz input up-converted to 125 to
185MHz output
4. A VHF 50MHz to ~2GHz pre-amplifier of up to 18dB gain
5. A PC power rail filter
6. A voltage regulator for an external unit
http://makearadio.com/visitors/nick-sdr2.php
Mikek
broadbandglob...@gmail.com
Sep 27, 2012, 10:13:00 PM9/27/12
to
On Monday, September 3, 2012 9:34:46 AM UTC-7, John Larkin wrote:
> On Sun, 2 Sep 2012 21:44:12 -0700 (PDT), George
>
> <geo...@thefiftysports.com> wrote:
>
>
>
> >[OP here]
>
> >
>
> >To clarify my questions:
>
> >
>
> >I'm building an AM broadcast receiver to be used in a non-standard application. It will use an existing wideband COTS software defined radio product that does not provide tuning information to the ferrite antenna. So I'd like to be able to get enough antenna gain across the broadcast band from the antenna to avoid having to tune the antenna to resonance on each frequency. But space limitations dictate use of a ferrite.
>
> >
>
> >This non-standard application DOES require knowledge of the antenna delay vs. frequency.
>
>
>
> There's nothing fundamentally wrong with using an untuned antenna.
>
> Gain is cheap nowadays, and AM reception is generally dominated by
>
> external noise, not receiver noise figure. A good opamp or jfet will
>
> get you below 1 nV/rootHz noise, so resonant gain isn't necessary. If
>
> delay matters, it's better to not resonate the antenna.
>
>
>
> An untuned loop, or an untuned ferrite rod, would work, far below
>
> self-resonance. A few-turn loop would act like an almost ideal H-field
>
> probe, and its gain and delay behavior are calculable.
>
>
>
> What are you trying to do? Do you expect to have a lot of signal? Is
>
> the transmitter nearby?
>
>
>
Long-delayed follow-up ... :o)
> <geo...@thefiftysports.com> wrote:
>
>
>
> >[OP here]
>
> >
>
> >To clarify my questions:
>
> >
>
> >I'm building an AM broadcast receiver to be used in a non-standard application. It will use an existing wideband COTS software defined radio product that does not provide tuning information to the ferrite antenna. So I'd like to be able to get enough antenna gain across the broadcast band from the antenna to avoid having to tune the antenna to resonance on each frequency. But space limitations dictate use of a ferrite.
>
> >
>
> >This non-standard application DOES require knowledge of the antenna delay vs. frequency.
>
>
>
> There's nothing fundamentally wrong with using an untuned antenna.
>
> Gain is cheap nowadays, and AM reception is generally dominated by
>
> external noise, not receiver noise figure. A good opamp or jfet will
>
> get you below 1 nV/rootHz noise, so resonant gain isn't necessary. If
>
> delay matters, it's better to not resonate the antenna.
>
>
>
> An untuned loop, or an untuned ferrite rod, would work, far below
>
> self-resonance. A few-turn loop would act like an almost ideal H-field
>
> probe, and its gain and delay behavior are calculable.
>
>
>
> What are you trying to do? Do you expect to have a lot of signal? Is
>
> the transmitter nearby?
>
>
>
You were right about using a mag loop followed by an amp to get broadcast band receive antenna performance equivalent to that to a ferrite stick but without the tuning requirement.
We contracted the design and will have a demo unit in a few weeks. Thanks.
John Larkin
Sep 28, 2012, 2:00:48 PM9/28/12
to
levels (microvolts) are you seeing?
iiiijjjj
Oct 1, 2012, 12:14:18 AM10/1/12
to
It has taken many person hours to answer this question. Since it is so simple the OP should just try it in the lab with an oscilloscope. Is that not the easy answer?
Phil Allison
Oct 1, 2012, 12:22:20 AM10/1/12
to
"iiiijjjj"
>
>
> It has taken many person hours to answer this question.
> Since it is so simple the OP should just try it in the lab
> with an oscilloscope. Is that not the easy answer?
>
** You have totally missed the central issue in the story.
>
> It has taken many person hours to answer this question.
> Since it is so simple the OP should just try it in the lab
> with an oscilloscope. Is that not the easy answer?
>
.... Phil
John Larkin
Oct 1, 2012, 12:39:55 AM10/1/12
to
On Sun, 30 Sep 2012 21:14:18 -0700 (PDT), iiiijjjj
<bitter...@yahoo.ie> wrote:
>It has taken many person hours to answer this question. Since it is so simple the OP should just try it in the lab with an oscilloscope. Is that not the easy answer?
Please explain how that measurement would be performed.
<bitter...@yahoo.ie> wrote:
>It has taken many person hours to answer this question. Since it is so simple the OP should just try it in the lab with an oscilloscope. Is that not the easy answer?
0 new messages