My newest 3 & 1/4 turn 2510mhz cnc cut Helical antenna.

[Kondor-FPV]

I am very pleased to show this antenna. It's arguably the lightest 2.4 ghz helical ever made. It's cnc cut out of 1.7mm vetronite (fiberglass pcb material without copper).
Its diameter was calculated for a center frequency of 2510, turn pitch angle is 13.43°.
The reflector is .4mm Fr4 with copper on both sides, and I installed a female sma in the back, soldering it well to the reflector. The antenna weighs only 34 grams. That's got to be the lightest helical antenna on 2.4 ever made.

This baby came out fine on the first try, I am amazed really. I just soldered the wave trap match where I thought it would go and put it on the Daiwa swr meter.
I had channel 5 lawmate selected (2370mhz), and it showed 1.5:1 ( I thought this could be good or bad), So I switched to channel 8 (2510mhz) and swr dropped to 1.2:1 , 2490mhz, is 1.25:1 and 2450 is 1.35:1 .
This means the SWR can still be lowered. I will lightly paint it all white and that should shift the frequency down by roughly 3% (that's what happens on my Pinwheels).
I think I can squeeze a 1.1:1 if I am lucky.

That's very good for a first cut prototype.

[Derrick]

Looks great... I'm in the market for a 5.8ghz version

[Kondor-FPV]

Looks great... I'm in the market for a 5.8ghz version

I think I shipped this to Colorado but it ain't no 3 turn

[Derrick]

I think I shipped this to Colorado but it ain't no 3 turn

Hmmm... I don't think I gave you my address.

[Kondor-FPV]

Thanks guys. It must be some other fpv flyer in your area than

But yes, a 3 1/4 turn will have around 6dbi, maybe 7 at these frequencies. 90° beam aperture at 3db. It's kinda like flying with a 8db patch, just better. The axial ratio of a 3 turn is way better than a 8-12 turn cannon, efficiency is also WAYY better (simulation shows 80% but I'll be happy with 70%).

I can easily scale down my 5.8ghz 8 turn antenna if you want one.

Edit: the long extension at the reflector has two holes spaced 32mm to screw onto my MFD tracker, so it's an integrated mounting bracket

[SENTRY]

Kondor you showoff

[FPVdude]

Looks a lot better than my duct tape and cardboard version...
question: why the weird extension on the reflector? is that good? It looks cool..

[Superevan]

Who woulda though designer antennas would ever be a thing. Nice work kondor!

[volto]

Very cool, Kondor.

[IBCrazy]

Keep playing with the wave trap bend it up and down or sliding it around and it will converge where you want it. It just takes some playing with it to get it to perfection sometimes.

You make a very good point about the fficiency. Helicals aren't very efficient. The nice thing is they maintain circularity really well.

One note I have been researching on the helical is the ARRL antenna book states that "the best helical ever simulated has an efficiency of 60%". While I found this to be true with the traditional parallel strip match they present as well as the gamma match, the Wave trap and tapered microstrip tend to do better. That said, build a Crosshair antenna and see how you like it. A 2.4GHz with a 4"X4" reflector has 8dbi gain and an even better axial ratio than your helical (.97 for the crosshair) and it is 98% efficient. If you can build or cut a better brace than the 4-bolt method I am using in my production models, I will be very happy to buy formers from you

-Alex