Increase antenna range of 2.4 Ghz

[Andy K]

I ordered a RC helicopter. 2.4 GHz

The specs says it has a 120 ft. range.

It is reported that the range can be extended by lengthening the antenna.

The antenna length is 3.25 cm long.

Would increasing it's length to 6.5 cm increase the range ?

Do I need to solder the same diameter copper wire to it ?

Thanks.

I found this.

What do you think ?

The length of the antenna on a typical 2.4GHz receiver is 28.8 to 32 mm long, most are about 28.8 mm. The antenna is that length of bare line often at the end of a longer coaxial cable to move the antenna farther out from the receiver. Yes, the length of this is somewhat critical and can greatly vary the distance that the signal can be reliably received. To long can be just as bad as to short unless you can accurately make sure it is some odd multiple of an electrical quarter wavelength; i.e. 3/4, 5/4, 7/4 etc. Note that electrical wavelength can be different than a simple measurement as it depends on the velocity factor of any coax or other line involved.

[amdx]

Look around, you will find a fellow that has a yagi mounted to his
hat. No, no, I meant look around on google!
The yagi is driven by his transmitter, as long as he looks at his flying
machine the antenna is pointed in the right direction.
The yagi gives him 10 or 12 db gain.
Better have good eyes, I once got an airplane so high, I lost it.
Luckily a drive around the neighborhood and we found it crashed in the
street a good 1/2 mile away.

Mikek

[Jan Panteltje]

On a sunny day (Sat, 17 Jan 2015 10:57:40 -0800 (PST)) it happened Andy K
<andrewke...@gmail.com> wrote in
<7d427407-00b1-4651...@googlegroups.com>:

>I ordered a RC helicopter. 2.4 GHz
>
>The specs says it has a 120 ft. range.
>
>It is reported that the range can be extended by lengthening the antenna.
>
>The antenna length is 3.25 cm long.
>
>Would increasing it's length to 6.5 cm increase the range ?
>
>Do I need to solder the same diameter copper wire to it ?
>
>Thanks.
>
>I found this.
>
>What do you think ?

You can go directional by buying a 10 $ or so yagi on ebay:
http://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=2.4+GHz+yagi&_sacat=0

[Andy K]

I will consider the yagi.

But first I want to extend the built in antenna and see how it works.

I have a lambda antenna. A length of 8.3 cm should greatly increase the range.

Will post my results.

Andy

[Phil Allison]

Andy K wrote:

> I ordered a RC helicopter. 2.4 GHz
>
> The specs says it has a 120 ft. range.
>
> It is reported that the range can be extended by lengthening the antenna.
>
> The antenna length is 3.25 cm long.
>
> Would increasing it's length to 6.5 cm increase the range ?
>
> Do I need to solder the same diameter copper wire to it ?
>

** FFS - try it and find out.

>
> I found this.
>
> What do you think ?
>
> The length of the antenna on a typical 2.4GHz receiver is 28.8 to 32 mm long, most are about 28.8 mm. The antenna is that length of bare line often at the end of a longer coaxial cable to move the antenna farther out from the receiver. Yes, the length of this is somewhat critical and can greatly vary the distance that the signal can be reliably received. To long can be just as bad as to short unless you can accurately make sure it is some odd multiple of an electrical quarter wavelength; i.e. 3/4, 5/4, 7/4 etc.

** Not totally wrong.

Note that electrical wavelength can be different than a simple measurement as it depends on the velocity factor of any coax or other line involved.

** Utter bollocks.

A 1/4 wave antenna has an omnidirectional pattern in the horizontal plane - essential for a heli. Increasing the length creates more problems than it solves as the impedance no longer matches the line and load.

The only way to significantly increase range is at the transmitter end by using a directional antenna like a Yagi. 10dB gain is easily achieved so more than double the range.

BUT you will need to point the thing directly at the model to get that increase.


.... Phil

[Clifford Heath]

Andy: You cannot just extend the wire and improve the range. The antenna
must resonate at the desired frequency, and changing the length will
change the resonance.

By combining the signal in-phase from multiple resonant elements (which
includes un-connected elements that increase the signal strength on
connected elements, as in a Yagi) you can increase the received power.

The trouble is that the multiple elements interfere with the local field
and hence with each other, so they will create a directional pattern -
stronger in some directions and weaker in others. In the case of a fixed
TV antenna where the direction to the transmitter is known, that's fine,
as long as you aim it right. If you go for a Yagi with large gain,
there'll be large nulls either side of the direction it's pointing. That
means that if you're flying at maximum range, and you fly into the null,
or point the antenna away a little, you lose signal. The higher the
gain, the narrower the central lobe.

You know those vertical rectangular antennae used for mobile phone cell
towers? They might have a horizontal spread of 45 degrees, but the
vertical spread is only 1.5 degrees... and that's perfect for mobile
phone use.

Summary: There's no free lunch. If you want gain, it has to be
directional. So if you can't point the antennae in the right direction,
you can't use a high gain antenna.

Clifford Heath.

[Alie...@gmail.com]

On Sunday, January 18, 2015 at 1:29:42 AM UTC-8, Clifford Heath wrote:
> On 18/01/15 10:34, Andy K wrote:
> > On Saturday, January 17, 2015 at 1:59:15 PM UTC-6, Jan Panteltje wrote:
> >> You can go directional by buying a 10 $ or so yagi on ebay:
> >> http://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=2.4+GHz+yagi&_sacat=0
> > I will consider the yagi.
> > But first I want to extend the built in antenna and see how it works.
> > I have a lambda antenna. A length of 8.3 cm should greatly increase the
> > range.
>
> Andy: You cannot just extend the wire and improve the range. The antenna
> must resonate at the desired frequency, and changing the length will
> change the resonance.

Meaning you're wasting power feeding a mismatched antenna.

> By combining the signal in-phase from multiple resonant elements (which
> includes un-connected elements that increase the signal strength on
> connected elements, as in a Yagi) you can increase the received power.
>
> The trouble is that the multiple elements interfere with the local field
> and hence with each other, so they will create a directional pattern -
> stronger in some directions and weaker in others. In the case of a fixed
> TV antenna where the direction to the transmitter is known, that's fine,
> as long as you aim it right. If you go for a Yagi with large gain,
> there'll be large nulls either side of the direction it's pointing. That
> means that if you're flying at maximum range, and you fly into the null,
> or point the antenna away a little, you lose signal. The higher the
> gain, the narrower the central lobe.

IOW the transmitted signal is "squeezed" into a beam instead of being spread equally in all directions (simplified).

> You know those vertical rectangular antennae used for mobile phone cell
> towers? They might have a horizontal spread of 45 degrees, but the
> vertical spread is only 1.5 degrees... and that's perfect for mobile
> phone use.
>
> Summary: There's no free lunch. If you want gain, it has to be
> directional. So if you can't point the antennae in the right direction,
> you can't use a high gain antenna.

Best response so far.

The OP specifically wants more range. There's another obvious solution, but there are FCC limits on transmitted RF:

http://www.afar.net/tutorials/fcc-rules

What's the EIRP of the OP's XMTR? Is it fixed frequency or frequency-hopping? Does he have a Ham license?


Mark L. Fergerson

[Phil Allison]

Clifford Heath wrote:

>
> Summary: There's no free lunch. If you want gain, it has to be
> directional. So if you can't point the antennae in the right direction,
> you can't use a high gain antenna.

** A vertical array of dipoles generates gain with an omnidirectional pattern in the horizontal plane. Commonly known as a "collinear" antenna.Very common in broadcasting and two way radio applications.

http://en.wikipedia.org/wiki/Collinear_antenna_array

Here is page that shows how to make you own collinear on 2.4GHz.

http://www.nodomainname.co.uk/Omnicolinear/2-4collinear.htm

Not really practical for a heli which needs an antenna that is compact and genuinely omnidirectional.


.... Phil

[DecadentLinuxUserNumeroUno]

On Sun, 18 Jan 2015 09:58:41 -0800, nu...@bid.nes wrote:

snip

> The OP specifically wants more range. There's another obvious
> solution, but there are FCC limits on transmitted RF:
>
> http://www.afar.net/tutorials/fcc-rules
>
> What's the EIRP of the OP's XMTR? Is it fixed frequency or
> frequency-hopping? Does he have a Ham license?
>
>
> Mark L. Fergerson

An RC controller used to be sub gigahertz FM carrier devices.

The 2.5 GHz job almost MUST be a hopper so that others can also be
present in the same area, and nobody has to go out and buy crystals, like
in the way back era.

This is in the wifi spectrum.

https://www.flickr.com/photos/48373875@N06/13790579683/

Note that that image is two segments of the full spectrum declaration,
which I cut and then pasted next to each other.

Here is the full sheet in high resolution glory, and the UK and
Australian versions are there as well.

<http://tinyurl.com/ootmesp>

[mpm]

On Sunday, January 18, 2015 at 4:29:42 AM UTC-5, Clifford Heath wrote:
> You know those vertical rectangular antennae used for mobile phone cell
> towers? They might have a horizontal spread of 45 degrees, but the
> vertical spread is only 1.5 degrees... and that's perfect for mobile
> phone use.

More like 88-deg H, and 6-deg V.
And cross-pol, too.

In reply to Phil A's statement, you can also extend range by upping the transmit power, but of course, there are regulatory constraints to such efforts. In fact, there are likely to be regulatory contraints on using Yagi's too, unless (at least in the US) the device was authorized pursuant to FCC OET (part 2, etc..) to use directional antennas.

[mpm]

On Sunday, January 18, 2015 at 6:00:44 PM UTC-5, Phil Allison wrote:
> Clifford Heath wrote:
>
> >
> > Summary: There's no free lunch. If you want gain, it has to be
> > directional. So if you can't point the antennae in the right direction,
> > you can't use a high gain antenna.
>
> ** A vertical array of dipoles generates gain with an omnidirectional pattern in the horizontal plane. Commonly known as a "collinear" antenna.Very common in broadcasting and two way radio applications.

Agreed, but you need to think three-dimentionally.
Even a collinear antenna can be "pointed" in a direction.

Also: Note to Clifford... :)
antenna = radio
antennae = insect

I'm sure I'll get grief from the other side of the pond for that one...
Of course, they should call it "aerial" anyway.

[Phil Allison]

DecadentLinuxUserNumeroUno wrote:


> An RC controller used to be sub gigahertz FM carrier devices.
>

** Yep - on 27Mhz, 72Mhz and 75Mhz bands in the USA.

27, 29 and 36 and 40 MHz bands in Australia.

Both AM and FM modulation are used, in the AM case it is 100% depth, PPM and in the FM case it is narrow band FSK mimicking the pulses of PPM.

The number of pulses per fame corresponds with the number of channels that can be independently controlled - max is about 9. Frames are repeated at a 50Hz rate.

Output power from the transmitter is about 1 watt, transmit antennas are mostly 1/8 wave and receive antennas often much less than that depending on whether the model is a car, boat, plane or heli.

Digital transmission on 2.4GHz is still a bit novel.


.... Phil

[DecadentLinuxUserNumeroUno]

On Mon, 19 Jan 2015 00:24:40 +0000, DecadentLinuxUserNumeroUno wrote:


> Here is the full sheet in high resolution glory, and the UK and
> Australian versions are there as well.

snip and replace with NEWER, direct from the source...

http://www.ntia.doc.gov/page/2011/united-states-frequency-allocation-
chartp>

[mpm]

On Sunday, January 18, 2015 at 10:26:45 PM UTC-5, Phil Allison wrote:
> DecadentLinuxUserNumeroUno wrote:
>
>
> > An RC controller used to be sub gigahertz FM carrier devices.
> >
> ** Yep - on 27Mhz, 72Mhz and 75Mhz bands in the USA.

72 MHz would have been "interesting" 30 years ago.
Sandwiched near TV-4, and that band was used a lot by paging companies for radio remotes in simulcast systems. Back in the day that band was probably fairly congested.

And 27 MHz would have been Citizens Band (CB), if I recall correctly.

Just thinking out loud on the O.P.'s question...
I wonder if adding a little receive preamp on the R/C vehicle would be the best way to increase its range (as opposed to trying something on the transmit side)?

[mike]

A few decades ago, I bought a radio-controlled model airplane.
Later found out why it was so cheap.
There was a pager on the exact frequency.

[Phil Allison]

mpm wrote:

> >
> > > An RC controller used to be sub gigahertz FM carrier devices.
> > >
> > ** Yep - on 27Mhz, 72Mhz and 75Mhz bands in the USA.
>
>

> And 27 MHz would have been Citizens Band (CB),

** 5 spots were allocated to RC models.

26.995, 27.045, 27.095, 27.145 & 27.195

You will not find them on a standard 27MHz CB radio.

Folk regularly used them with competition RC cars and boats.

Bit iffy with planes.


... Phil

[John S]

...Or unless you have a ham license and operate 2390-2450 MHz.

[Jan Panteltje]

On a sunny day (Mon, 19 Jan 2015 05:07:58 -0600) it happened John S
<Sop...@invalid.org> wrote in <m9ioh6$ols$1...@dont-email.me>:

>...Or unless you have a ham license and operate 2390-2450 MHz.

2400-2450 MHz is only satellite traffic for hams over here.
Is a drone a satellite? Needs to go higher and faster ;-)

But moon bounce should be OK.
:-)

[Clifford Heath]

On 19/01/15 14:10, mpm wrote:
> Also: Note to Clifford... :)
> antenna = radio
> antennae = insect
> I'm sure I'll get grief from the other side of the pond for that one...

I'm in Australia. We swing both ways on that one.
<http://grammarist.com/usage/antennae-antennas/>

[Clifford Heath]

On 19/01/15 10:00, Phil Allison wrote:
> Clifford Heath wrote:
>> Summary: There's no free lunch. If you want gain, it has to be
>> directional. So if you can't point the antennae in the right direction,
>> you can't use a high gain antenna.
> ** A vertical array of dipoles generates gain with an omnidirectional pattern in the horizontal plane. Commonly known as a "collinear" antenna.Very common in broadcasting and two way radio applications.

Still directional, of course, favouring horizontal radiation over vertical.

What are the spacing and phasing requirements for the dipoles?