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Increase the range on your 2.4 Ghz radio

Old 04-26-2008, 08:42 PM
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aviatordave
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Default Increase the range on your 2.4 Ghz radio

I thought this was interesting so I will share. I'm just passing the info along as I have not tried it yet but plan to. A guy at RCG gave it a whirl and rough estimates are 50-60% increase in range.

Here is the thread

and here is the template

A 9dbi gain can be achieved. Maybe some antenna gurus can comment on this.

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Old 04-26-2008, 10:40 PM
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fr4nk1yn
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I just took a look I WOULD'NT try it. It turns the antennae directional. Good as long as your in the cone but once outside of it your signal is going to drop off. It's concetrating the signal in one direction mostly.
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Old 04-27-2008, 02:14 AM
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Gnascher
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This is terriffic for WiFi ... I use it in my own house and get a 40dB gain between my wireless router on the 2nd floor, and my living room in the opposite corner of the house. It's not a "perfect" parabola amplifier, but it's "good enough" to see a significant boost if you get it aimed just right.

But fr4nk1yn is correct, there is no magic here. You only are getting a boost by "directionalizing" your signal ... for a wifi system, that means all the signal that was just shooting out into my yard is now getting reflected down to my living room. For Wifi, that's a good thing ... more signal for me to use, and less for my neighbors to freeload on.

On an airplane, this would result in a stronger signal on a relatively narrower beam at the expense of a WEAKER signal anywhere that isn't directly in this beam. This is bad, since your airplane will no doubt spend most of its time nowhere near the hotter signal beam.

Don't do this. Even the DX6 has been effectively user tested (not marketing hype) at nearly a mile with direct line of site. You'll likely never need range any greater than that, since it's your eyesight that's going to fail you before your radio does!
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Old 04-27-2008, 02:32 AM
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rea59
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Gnascher is correct! This is just section of a parabolic reflector. Typically the focal point (tx antenna) Will be located 1/4 wavelength from the reflector. This will cause the radiated energy to be focused out in a beam. These are better used on the receiving end as then it's focusing the received energy on the antenna.

Last edited by rea59; 04-27-2008 at 02:18 PM.
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Old 04-27-2008, 02:34 AM
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Also little or no gain on the Tx side but a huge increase on the received energy.
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Old 04-27-2008, 04:49 AM
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Interesting, there is alot I didnt know. but trying at home on my wifi is a cool thought.
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Old 04-27-2008, 04:23 PM
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This type antenna mod is discussed quite well in one of RC Cam's pages. Good for WIFI, not very practical for RC use, in fact could cause many problems over the basic setup. If interesed in more detail, Google "patch antenna"/
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Old 04-27-2008, 05:14 PM
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Those guys are using patch antennae too.
I've seen two references in that thread now of lockups when turned away from the plane but they still like it.
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Old 04-27-2008, 10:24 PM
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Eric_N57105
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Originally Posted by rea59 View Post
Gnascher is correct! This is just section of a parabolic reflector. Typically the focal point (tx antenna) Will be located 1/4 wavelength from the reflector. This will cause the radiated energy to be focused out in a beam. These are better used on the receiving end as then it's focusing the received energy on the antenna.
How would you keep such a directional antenna on an aircraft pointing at the TX antenna? It doesn't make any sense to put it at the receiver in this case.

If you use it on the TX, all you have to do is keep the antenna pointed directly at the aircraft. This is something we trained ourselves NOT to do before as there was a cone of silence off the end of the vertical antennas we use. But with a parabolic, it would be necessary and easy to keep it pointed at the aircraft.

Propagation wise, it makes absolutely no difference if the gain is at the TX antenna or the RX antenna. You still get the same overall system gain.

If you try it on a WiFi network with more than one PC, you have to put the antennas on the PC end, not the router end. Then point the PC antennas at the router which still uses the omnidirectional vertical it came with. Again, signalwise, it doesn't make any difference in gain, but because of directionality, it does.

I'm going to try it on my wifi tonight also. Why do it at all? Because it's cool and something to do. Why not?

Eric
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Old 04-28-2008, 12:17 AM
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rea59
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Originally Posted by Eric_N57105 View Post
How would you keep such a directional antenna on an aircraft pointing at the TX antenna? It doesn't make any sense to put it at the receiver in this case.

If you use it on the TX, all you have to do is keep the antenna pointed directly at the aircraft. This is something we trained ourselves NOT to do before as there was a cone of silence off the end of the vertical antennas we use. But with a parabolic, it would be necessary and easy to keep it pointed at the aircraft.
My point exactly!!

Originally Posted by Eric_N57105 View Post
Propagation wise, it makes absolutely no difference if the gain is at the TX antenna or the RX antenna. You still get the same overall system gain.
Eric
You could look at it this way, however remember in basic physics you can't get something for nothing. The power out of the transmitter remains fixed. Adding the parabolic will focus that power but not increase it. When used on a receiving antenna (or if you prefer the receiving side of a system) the energy already out there (from the TX) is then focused on the Rx antenna showing a gain of the received signal strength. No new energy is created it just allows a Rx to gather weaker signals at a usable level.

As already stated this is only useful on "fixed" antennas in systems where the location of the transmitted source is known and also fixed. (wifi/home satellite systems). These are also great for weather radars where both the Tx and Rx antennas are one in the same.

In our RC planes these are possibly the worst thing you could use.
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Old 04-28-2008, 06:15 AM
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I guess I don't understand why the need to increase the range. My 2.4 radios will reach much further than I can see anyway.
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Old 04-28-2008, 06:26 AM
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That came from the FPV forum. I'd imagine they're flying beyond visual sight(?).
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Old 04-28-2008, 02:12 PM
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Originally Posted by fr4nk1yn View Post
That came from the FPV forum. I'd imagine they're flying beyond visual sight(?).
yep, pretty much. I wouldnt say most fly out of sight, but high or far enough way that makes it hard to distinguish what the plane is doing. Fly by video is my next goal in this hobby.
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