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Old Mar 11, 2014, 09:50 AM
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Oh, so if I screw it down and as long as it reads short on my meter from the reflector to the element it's ok then I don't have to use the solder method. I am assuming that the screw head on top of the reflector does not affect the signal at all.

Wow that is an even quicker way to do it because I have my reflector attached to a piece of wood so I'm just going to put a screw through the end of the shield (that has a big solder ball on the end now) and the reflector right into the wood back.

Thanks!!
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Old Mar 12, 2014, 10:46 AM
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Originally Posted by kurtrdoc View Post
I am assuming that the screw head on top of the reflector does not affect the signal at all.
None whatsoever. I think its already mentioned on the previous page RE: people attaching the reflector to their pan/tilt via screws through
the reflector
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Old Mar 12, 2014, 09:08 PM
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I was 99.9% sure that it would not affect the signal but thanks for clearing up the last .1%!!!!
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Old Mar 14, 2014, 09:14 PM
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Can I use aluminum foil for reflector ?
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Old Mar 15, 2014, 11:07 AM
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Originally Posted by CoolD View Post
Can I use aluminum foil for reflector ?
Sure - who can stop you from doing that?
Just... Soldering alu foil isn't easy task.
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Old Mar 15, 2014, 11:13 AM
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Sure - who can stop you from doing that?
Just... Soldering alu foil isn't easy task.
thanks, I've been reading and it seems i could use a wiremesh with holes smaller than 1/8th of the wave length or maybe its 1/16th.

i'll give it a shot with alu foil and if it works I might later upgrade to a metal sheet.

thanks to IBCrazy and this forum
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Old Mar 21, 2014, 06:30 PM
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Just how forgiving is this antenna design? You can probably fly more than a mile outside of the beam at nearly 3 miles safely. The flicker at 0:42 is my video diversity trying the other antenna (3dBi omni) very briefly

FPV - Flying outside directional beam (1 min 17 sec)
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Old Apr 10, 2014, 08:27 AM
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Quite a nice guide. Thank you IBcrazy for sharing this in such great detail. I am going to construct a biquad like this for my 1,2GHz lawmate video receiver at 1120 MHz.

While IBCrazy states that the reflector size is non critical

Quote:
Originally Posted by IBCrazy View Post
...
The reflector should be square cut with sides of your full wavelength measurement. The reflector size is not critical, so do not worry about being off by a small margin on its size. Since mine is made for 910 MHz, my element is 12 7/8 square
... this http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=27469 biquad antenna calculator (see attached fig.) suggests a length for each side of the reflector.

So I am wondering: Might 'matched' reflector further improve biquad performance?

Additionally the calculator yields a "Wire" diameter and length. Maybe this is supposed to address the spacer?
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Old Apr 10, 2014, 10:35 AM
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Originally Posted by Jack_LaLanne View Post
Quite a nice guide. Thank you IBcrazy for sharing this in such great detail. I am going to construct a biquad like this for my 1,2GHz lawmate video receiver at 1120 MHz.

While IBCrazy states that the reflector size is non critical



... this http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=27469 biquad antenna calculator (see attached fig.) suggests a length for each side of the reflector.

So I am wondering: Might 'matched' reflector further improve biquad performance?

Additionally the calculator yields a "Wire" diameter and length. Maybe this is supposed to address the spacer?
A matched reflector changes the F/B ratio, that's all. It will make a big difference when violating the Fresnel zone. At range it will make almost no difference.

-Alex
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Old Apr 10, 2014, 10:43 AM
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Originally Posted by IBCrazy View Post
A matched reflector changes the F/B ratio, that's all. It will make a big difference when violating the Fresnel zone. At range it will make almost no difference.

-Alex
Thank you. In that case I will go with whatever suitable looking PCB ebay will give me. Since I don't have the right tool, I believe cutting could be a hassle.

What do you think about those wire parameters in the mentioned calculator? It reminded me of a post about your blue beam antennas, where you explain the coax length used etc. I think I will use RG58 anyway since that is what I have, but still curious..

btw: my old 2,4 GHz biquad, where ground is not connected to the reflector. Tested with an 802.11g access point and with airwave awm650rx.

edit: obviously the wire parameter in the figure above refers to the material for the 'quad'.
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Old Yesterday, 01:53 PM
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I am wondering how the mentioned calculator went >2 mm on the wire that's quite heavy.

http://www.lecad.fs.uni-lj.si/~leon/other/wlan/biquad :

"Thinner wire means slightly more gain. But the main impact is in SWR. The best diameter is 2*0.0056 lambda. .."

Ok. I am going with

1.5 mm wire
100 mm * 250 mm reflector
RG58 coax
the coax' shielding instead of copper pipe as proposed

I will solder the shielding to the reflector and the quad
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Old Yesterday, 10:54 PM
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I wouldn't sweat this one too much. The truth is that you can mitigate most things by changing another parameter. For example, using a smaller wire results in higher SWR, but you can move the elements closer to the reflector and bring SWR back down.

-Alex
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Old Today, 06:56 AM
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Originally Posted by IBCrazy View Post
I wouldn't sweat this one too much. The truth is that you can mitigate most things by changing another parameter. For example, using a smaller wire results in higher SWR, but you can move the elements closer to the reflector and bring SWR back down.

-Alex
Thank you. At 1120 MHz which distance would you choose for 1 mm or 1.5 mm copper wires to account for an OK SWR ? I ordered 2 meters of both just in case 1.5 will be too stiff for decent quad formation.
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