5.8GHz 3 and 4 turn helicals.

[JT]

 I';ve been wanting to try out helicals for a while to get some longer range FPV, I';ve flown out to 1.5km on a set of Gavs skews quite happily, they probably would go a little bit further but I dare not try lol. Commercial helicals look either complete cheap rubbish or are pricey and tend to have many turns giving a much narrower beam, fine for long range(more turns=more gain) with a tracker but I wanted a wider beam so that I can wear the antenna on my goggles and do any tracking with my head but still get some more range (2-3km would be fine)
So over the last few days I';ve cobbled together the bits I need(cheers for the semi rigid pigtails Bazzerh  ) and knocked up a 3d printed design to make a 3 turn and a 4 turn helical ::)
The 3 turn should have a beam of around 62 degrees and the 4 turn about 10 degrees less than that. So far I have made up a 3 turn, the design needs a bit of tweaking which I will do before making the 4 turn one but should work just fine. So far I';ve only tried it in the house but it works well there lol, I need my glamorous assistant to come with me to do some range tests before flying with it

Here is the mk1 3 turn helical(it';s not as massive as it looks in the pics lol, the reflector plate on the back is 52mm wide)

[nub]

lovely colour

hope it works, i tried making my own a while ago but it didn';t work out to well, good luck.

[Yellow]

wow looks amazing, can';t wait to hear how it goes

[JT]

lovely colour

hope it works, i tried making my own a while ago but it didn';t work out to well, good luck.

Pretty isn';t it? 
It should work  I used mathematics and everything

wow looks amazing, can';t wait to hear how it goes

I';m keen to go try it but I have to look after the kids monday and tuesday afternoons/evenings so won';t get a chance until wednesday

[Ynot6]

for any one else wants to try these, IB crazys tutorials are exelent.

[bazzerh]

the camera angles make them look huge! notice you';ve got the wave trap installed, i dont know what it does but i think its important...

i';m going to make some this week and use them at weston park hopefully. found some printable stuff on thingiverse and my friend has done them for me.

im going to try having the coax in front of the reflector rather than drilling through it. same as ibcrazys versions i think. so basically laid on the reflector and soldered in place with the inner core popping straight out and linking onto the helical, should work well with a 90deg coax connector and goggles.

did start reading some posts about tuning them and stub lengths but it way over my head and equipment level so im just going to make one with the guides ive got and hope for the best 

[JT]

 lol, the gigantism happens when I use my phone to take close ups lol.
Yeah, I just designed to  what came out of a calculator. The one on thingiverse by ';Dave855'; (if that';s the one you downloaded)seems to have a narrower diameter coil than what comes out of the calculator?

[bazzerh]

there';s a lot of useless carp on thingiverse, i know that from the flip32 case i had printed and it wouldn';t fit a flip32 in a million years. i havent seen my printed parts yet but i';ll run a ruler over it when i do. i went with the set of files by dvogonen i think so dodged the dave855 bullet lol.

edit; just realised it was remixed from daves dodgy files. doh

back to the epoxied on dowel idea then

[JT]

 I';ll upload mine later Baz 

[bazzerh]

it might be a problem getting yours to fit my reflector discs which are 47mm diameter. i';ll go with what i';ve got for now and then look at remixing yours but for weston its going to be make and make do i think. just seen a video saying how wide the mhz range is with these so maybe a slight difference in coil sizes and spacings won';t hurt too much.

btw how do you tell the polarity? with helical pointing towards your eyes and starting at base, if you traced the coil with your finger what motion corresponds to RH polarity, clockwise or anti-cw?

[JT]

RH is like a normal thread  , my design has the advantage that it will take either right or left handed coils 

It also has a 52mm gap for the disc so your 47mm would happily glue in it 

[JT]

Thingiverse link 

http://www.thingiverse.com/thing:883293

[JT]

 Finally got round to sorting out the 4 turn, this ones in red to stop nub getting too excited 




Hope to get to test them both out in the next couple of days 

Here is the thingiverse link  http://www.thingiverse.com/thing:885142

I may make a few up and sell if they work well, I do have to wait for some leads from China though 

[JT]

 ';Flyinghippy'; came round to give me a hand with an initial test on these antennas, we took them to the beach as this is the clearest along the ground place we have. The two points we had were not a perfect line as it runs very close to a concrete sea wall at a couple of points but straight enough in that a LOS between antennas was just about there.
Now this was along the ground so not anything like as good as it would be in the air,it was also very humid and had just been raining, we were standing 2.2km apart, first just to try I used one of Gav';s skews, I had mostly snow with the glimpse of an image here and there (I';m sure it would have had a signal at this distance 100m or so up,I have flown 1500m with this antenna with no problems), next I tried my 3 turn helical.......Perfect picture!!!!!  the angle seems pretty good too,I could turn my head probably 35-40 degrees either way from straight and still see just fine, at 90 degrees the picture almost vanishes but at 180 the picture is more or less fine again!
Next was the 4 turn, again a spot on picture, it did take a bit more fiddling with as it wasn';t aimed high enough to start with but still pretty good although not as wide as the 3 turn angle.

To give you an idea of how good these worked I had my tx with me a 9x with DJT module and the RSSI showed 0% and I couldn';t move the servos of the plane we were using to transmit from, again I';m sure this would have worked if the plane was in the air 100m or so.
All in all I';m very happy with my antennas and will fly with one the next time the wind and rain lets us go!

[nub]

fek aye that seems to have worked out well eh, nice1 ::)

[Friskle]

Finally got round to sorting out the 4 turn, this ones in red to stop nub getting too excited 




Hope to get to test them both out in the next couple of days 

Here is the thingiverse link  http://www.thingiverse.com/thing:885142

I may make a few up and sell if they work well, I do have to wait for some leads from China though 

Would certainly consider a purchase JT :)

[Gav]

Top job mate!  Nice clean build - super duper results - perfecto!

skews antennae are great for a simple lightweight solution for fpv, but if you have the space in your flight case/ kit bag or whatever and don';t mind the larger size Darlek whisk on your noggin, then happy days!  Could prove especially useful for that extra bit of focused beam reception when 250 quad racing through bushes n trees.

   
cheers
Gav

[JT]

Top job mate!  Nice clean build - super duper results - perfecto!

skews antennae are great for a simple lightweight solution for fpv, but if you have the space in your flight case/ kit bag or whatever and don';t mind the larger size Darlek whisk on your noggin, then happy days!  Could prove especially useful for that extra but of focused beam reception when 250 quad racing through bushes n trees.

   
cheers
Gav

Cheers Gav   

Who wouldn';t like to look like a dalek???   I do wish I had bought the skyzone goggles with built in diversity now instead of attitudes as a skew to fly around myself and one of these to go off in one direction to a greater distance or penetration would be a perfect combination.

[deano]

If the price is right id be interested

[JT]

 Got round to having these tested, I';ve made a few small changes to the design to get the lowest part of the coil closer to the reflector at the base. I had one with and one without the wavetrap tested and the one without is better, I have been told elsewhere the wavetrap is not needed on 5.8ghz. The swr was 1.25 on the tweaked design which is pretty damn good ::)
I';ll be making a few for sale to see how they go