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Mar 29, 2011, 06:25 AM
Engineer for Christ
IBCrazy's Avatar
Quote:
Originally Posted by Hugeone
At theta = 0, this antenna might be provocative for some...

-Hugo
I never even considered the angle. however if I adjust the element lengths about 3% I can go from a dual polarized antenna with very little if any rejection, to circularly polarized with over 15db rejection!

When I designed the above, I was manipulating a 3/2 wave turnstile using reactive vectors to correct phasing issues. Turns out I got a 100 OHM CP antenna. Use a 75 ohm 1/4 wave stub and... 50 ohms!

-Alex
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Mar 29, 2011, 11:27 PM
Registered User
yzguy's Avatar
I saw someone ask this, but did not see the answer...

if I want to make one of these for 5.8, and I want to try to solder the ground legs directly to a connector, should the legs be the specified length from the center of the connector? or from the outside edge? (at these small sizes, that distance is likely significant )
Mar 30, 2011, 03:38 AM
Registered FPVer :)
markus123456's Avatar
Quote:
Originally Posted by yzguy
I saw someone ask this, but did not see the answer...

if I want to make one of these for 5.8, and I want to try to solder the ground legs directly to a connector, should the legs be the specified length from the center of the connector? or from the outside edge? (at these small sizes, that distance is likely significant )
I assume the modells etc. were made with an ideal situation in mind, alas the legs starting at the center. So IMHO you should compensate for the diameter.
I'm too interested to hear Alexs take on this.

Markus
Mar 30, 2011, 01:08 PM
Engineer for Christ
IBCrazy's Avatar
Quote:
Originally Posted by yzguy
I saw someone ask this, but did not see the answer...

if I want to make one of these for 5.8, and I want to try to solder the ground legs directly to a connector, should the legs be the specified length from the center of the connector? or from the outside edge? (at these small sizes, that distance is likely significant )
It doesn't matter. It is the over all length of the loop that is critical. So long as all of your legs are the correct length, where they terminate is almost irrelevant. The reason is that once the signal hits the plug, it is completed. Thus is doesn't really matter how wide it is so long as it is a little more than 1 full wavelength.

-Alex
Mar 30, 2011, 02:32 PM
Registered User
yzguy's Avatar
I will make 3 individual loops, and terminate each ground leg at the outside edge of the connector, so the leg length is correct. (I'll make a temporary jig to hold it all in place)
Mar 30, 2011, 03:25 PM
Pat K
Quote:
Originally Posted by IBCrazy
It doesn't matter. It is the over all length of the loop that is critical. So long as all of your legs are the correct length, where they terminate is almost irrelevant. The reason is that once the signal hits the plug, it is completed. Thus is doesn't really matter how wide it is so long as it is a little more than 1 full wavelength.

-Alex
Do we need to account for the length that is "enclosed" in the soldering joint? I guess it is not contributing to the radiating length. Is it correct to increase the length of each loop by 2mm as 1mm per side looks "stuck" in the soldering joint?
Pat
Mar 30, 2011, 09:58 PM
Engineer for Christ
IBCrazy's Avatar
Quote:
Originally Posted by Papat
Do we need to account for the length that is "enclosed" in the soldering joint? I guess it is not contributing to the radiating length. Is it correct to increase the length of each loop by 2mm as 1mm per side looks "stuck" in the soldering joint?
Pat
No, that really isn't necessary either. I believe you are over thinking this. Just cut and bend your wire per the equations. I think you will find it works very well.

-Alex
Mar 31, 2011, 02:47 AM
Pat K
Quote:
Originally Posted by IBCrazy
No, that really isn't necessary either. I believe you are over thinking this. Just cut and bend your wire per the equations. I think you will find it works very well.

-Alex
Thks Alex, I've sticked to your length recommendations for my first set of antennas: 1 cloverleaf for the Tx and one Skew Planar for the Rx as you advised. Will do my first FPV flight on saturday, if weather permits. My first flight will probably be quite disturbed by my monitor "black screen of death..." as it seems to be quite sensitive even at very short range. However, I made a test at home with my plasma screen and it never cuts the communication even walking around the house from ground floor to 2nd floor despite having many floors and walls to cross. Seems to be good sign.
Pat
Mar 31, 2011, 03:44 AM
Registered User
Quote:
Originally Posted by Papat
Thks Alex, I've sticked to your length recommendations for my first set of antennas: 1 cloverleaf for the Tx and one Skew Planar for the Rx as you advised. Will do my first FPV flight on saturday, if weather permits. My first flight will probably be quite disturbed by my monitor "black screen of death..." as it seems to be quite sensitive even at very short range. However, I made a test at home with my plasma screen and it never cuts the communication even walking around the house from ground floor to 2nd floor despite having many floors and walls to cross. Seems to be good sign.
Pat
hi where are the designs for the skew planar? i thought one clover for the tx and one for the rx was the way to go?

thanks

Josh
Mar 31, 2011, 04:33 AM
Pat K
Quote:
Originally Posted by Joshbb
hi where are the designs for the skew planar? i thought one clover for the tx and one for the rx was the way to go?

thanks

Josh
Here it is. I recall Alex advised a skew planar at the Rx in some threads even if a cloverleaf is very good as well.
Pat
Mar 31, 2011, 05:11 AM
Registered User
Quote:
Originally Posted by Papat
Here it is. I recall Alex advised a skew planar at the Rx in some threads even if a cloverleaf is very good as well.
Pat
thanks, for that, sort of a 4 leaf clover should be fun for me with my 5.8ghz
Mar 31, 2011, 06:49 AM
Engineer for Christ
IBCrazy's Avatar
After building many of these for various people around the world, I find the 5.8GHz units the easiest to build. I bottom feed them to make it easier.

I find the cloverleaf is half as difficult as the skew-planar wheel.

-Alex
Mar 31, 2011, 09:24 AM
Registered User
Quote:
Originally Posted by IBCrazy
After building many of these for various people around the world, I find the 5.8GHz units the easiest to build. I bottom feed them to make it easier.

I find the cloverleaf is half as difficult as the skew-planar wheel.

-Alex
I got a set of CL from Alex for my 5.8Ghz and they are great. I have ground tested it, very good range. I hope to have a flight this Sun.

Thanks Alex.

JeffY
Mar 31, 2011, 03:09 PM
Registered User
Quote:
Originally Posted by BlueAngel2000
Nosaari, i think you have to say, that you only fly with a 25mw Airwave 5,8GHz transmitter.
I get about 100m with standard whips, with these 25mw Airwave.
1000m with standard whips on the 200mW Set from Foxtech.

I will try soon the CL and SPW with 25mW and 200mW.
Even tho I do not even get near 100m with my 5.8 rubber duck whips... But I would rather say its a problem of my receiver than the antennas so I will now stop spamming this thread about problems with my receiver


Quote:
Originally Posted by Hugeone
nosaari,

Your coax does not seem to have a Teflon center, it may have melted and short.

-Hugo
After hearing so many success storys especially with the 5.8 clovers I guess something like this must have happened (and a crappy receiver in my fatshark goggles I will try to get new and better coax cable and plugs and resolder my two antennas and hopefully get the results these great antennas deserve!

Thanks again to alex for the great tutorial, even tho my antennas do not (yet) perform good, I sure had fun making them
Last edited by nosaari; Mar 31, 2011 at 03:10 PM. Reason: Someone stole my first quote!
Mar 31, 2011, 08:49 PM
Engineer for Christ
IBCrazy's Avatar
Sadly, I have found that some RX's are just not compatible with the cloverleaf. The Lawmate 1.2GHz is one of them. You might have another. It's time for you to build a 3 turn helical. Use the Hecker transformer to match it. Use a wooden dowel as the former. This will make for incredible performance.

-Alex


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