Anybody selling these for 2.4ghz?

Yes:

http://www.readymaderc.com/store/ind...roducts_id=396

I also sell them individually. See my blog for details.

-Alex

What is the difference between having four wires and three? in gain?

Very little difference in gain. I find the cloverleaf is a better TX antenna. Some here prefer the skew-planar wheel.

-Alex

http://www.lindenir.com/2.html
This kind of antenna could also be interesting for the receivers... hemispherical circularly polarized antenna, developed by genetic algorithms, probably patented.

...

Originally Posted by Mictronics

Here is another picture:


Some more informations about the math behind:
http://www.hindawi.com/journals/ijap/2008/197849/

Even with polar coordinates for modeling. Let's warm up 4NEC2 ...]

Been there, done that!

(not easy to build and it did not work well at all)

OMM

Originally Posted by IBCrazy

Those look good, Matt. Flux core won't hurt the antenna at all. However I must warn you, once you fly the cloverleaf/SPW combination, that Vee/patch will forever remain in a box

-Alex

hi alex
i am new to FPV and still trying out the range and video quality of my 900mhz 200mW stock whip RX TX from hobbyking
this SP antenna will/should be my next mod to the system
did i understand clearly by the quote above u mean that the range of the SP system will be approximately the same as with a Vee Vtx and patch Vrx but with much better video quality ?

Originally Posted by QiW

hi alex
i am new to FPV and still trying out the range and video quality of my 900mhz 200mW stock whip RX TX from hobbyking
this SP antenna will/should be my next mod to the system
did i understand clearly by the quote above u mean that the range of the SP system will be approximately the same as with a Vee Vtx and patch Vrx but with much better video quality ?

Sort of...

Theoretically range is 40% less, but that is almost NEVER realized. Most will get 2-3X the range out of a CP system as they do a linear system due to multipath problems regarding linear polarization. OMM got 2km on 10 mw on his Quadcopter! So did Marc Antonio on his airplane.

-Alex

Originally Posted by Old Man Mike

Been there, done that!

(not easy to build and it did not work well at all)

OMM

Thanks, for that, Mike. I almost tried it

Linear polarization is only good for the stationary TX and RX (like wifi) and also used primarily because antennas are cheaper.

Circular is always used for non-stationary TX or RX in the professional applications (like satellite communication).

RC electronics just doesn't seem to use it, probably due to costs and size. I am glad someone is exploring this now. It could also be theoretically possible to have video tx on the 2.4ghz and use 2.4ghz radio (like FASST), both with opposing circular polarizations. Someone should try it.

Originally Posted by IBCrazy

Sort of...

Theoretically range is 40% less, but that is almost NEVER realized. Most will get 2-3X the range out of a CP system as they do a linear system due to multipath problems regarding linear polarization. OMM got 2km on 10 mw on his Quadcopter! So did Marc Antonio on his airplane.

-Alex

thanks for the reply
i am using futaba fasst for my RC
so in theory a 200mW 900mhz system with SP antennas should be adequate for my standard RC range (i hope) .. i don't intend to go beyond 2km for now

I would suggest a cloverleaf on the TX and a skew-planar wheel on the RX. I have found this to be the best combination. On paper the skew-planar wheel on both ends is better. In practice, I find the cloverleaf to be better on the TX.

-Alex

I've been looking, but can't seem to find any discussion about the SMB connectors - where to get them, and what to use to crimp coax on one. Does one use the same ones for soldering an antenna directly as well as for crimping coax? I am sure its somewhere - could someone direct me to this info?

Originally Posted by IBCrazy

I would suggest a cloverleaf on the TX and a skew-planar wheel on the RX. I have found this to be the best combination. On paper the skew-planar wheel on both ends is better. In practice, I find the cloverleaf to be better on the TX.

-Alex

great .. thanks again
the type/thickness of wire used should not be an issue right ? as long a it holds up against the wind and does not deform so easily