5.8GHz Helical Antenna

[Biffa]

Having failed to make a neat and tidy Skew Planar I thought I would leave them alone for a while until I can work out a usable jig thingy to hold everything in place (props to Gav as his are a work of art), I thought I would turn my attention to making a Helical.

Very easy to do and in total cost no more than £4 to make I have to say I am very impressed with the results.

Compared to the Fat Shark SpiroNet antenna on my goggles the difference is immediately noticeable (still using a SpiroNet on the VTX) there is virtually no drop out/static at all and the picture ';feels'; more solid.

I took the SpiroNets out to just over .5 of a K before I lost faith and had to turn back, I can tell after just one flight with the Helical that I will be able to go significantly further, so I will be making sure my RTH works correctly and see what sort of distance I can cover.

[Britishguy]

excellent biffa, i was looking at those and the patch antennas

what dbi do you think that is?

[Biffa]

what dbi do you think that is?

I have no idea

[Britishguy]

lol, well aslong as it works ;D

[powerlord]

And you get the added benefit of looking like a dalek

Sent from my HTC One using Tapatalk

[mutley2]

Nice un, just make sure you don';t turn your head too much because they have a much smalller beam width (more turns = higher gain = smaller beam width)

[Gav]

Top job mate. 

[nub]

nice1 biffa, i was watching some videos the other week about making your own helical antenna';s thought about giving it a go myself but never followed it through.

aye just mind try keep in line when your further out due to the gain pattern of the antenna, i was thinking about building a ground station and using some sort of antenna tracking.

hmmm wonder how wide the pattern is in real kind of terms, like at the tip of the pattern your talking what 20 degrees, what would that be in say meters?

[Biffa]

Cheers guys.

Interestingly flying out to about 400 meters I didn';t notice any signal drop off when turning my head from one side to the other. I shall experiment a little further and see exactly how much the directional aspect comes into play.

Problem yesterday was that I flew from just outside my door and the only direction I can go any distance not over residential they have started landscaping and the lakes are in at about 500m and beyond that the land is pretty water logged. Not ideal to be experimenting over as I don';t have any welly boots

Even if I just used the Helical for pretty localised flying the signal quality is miles ahead of the SpiroNet on the goggles.

[nub]

interesting think i might have to order some stuff today

[Biffa]

Decided to knock up a v2 of my Helical antenna

Having the v1 stuck to the goggles was, for obvious reasons, pretty impractical so I bodged this together in some spare time this morning.

Now just need the wind to die down to test - stupid Mother Nature...

[flybywire]

Excellent fettlin'; Biffa.  Would you mind just jotting down a few tech specs pls?  Such as dia/length of coil etc also is the back plate size critical?  I guess it is.
One more thing, I did manage to get some SMA plugs (for FAt Shark/Immersion stuff) or whatever they';re called a while ago, but seemed to be expensive for what they are?
Do you have a link(s) to suppliers please?
Actual fact, a short build log/instruction manual would be magnificent, and please don';t leave ';simple'; stuff out, I';m simple myself.

Many thanks

Andy
P.S I do Have a Spironet circular patch antenna, which seems to work well, but does indeed have a very narrow ';beam'; width.  I would like to try it on my ';Attitudes';, but they have the SMA socket at a queer angle, unlike your Dominators.  I would need a short ';flex'; cable to be able to align it pointing forward.

[Biffa]

Howdy Andy, I kind of followed this series of build videos and used his template for my v1 and slightly modified it to fit the right angle board mount SMA on the reflector plate for the v2.

How to build a 5.8 GHz 4 Turn Helical Part 1

How to build a 5.8 GHz 4 Turn Helical Part 2

How to build a 5.8 GHz 4 Turn Helical Part 3

4-Turn Helical Prebuild

I picked up the SMA connectors off Ebay here:

http://www.ebay.co.uk/itm/190693704891?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

http://www.ebay.co.uk/itm/180655922237?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Of course you can find them in the UK, but at a little more expense.

For the Helical itself I have just used some 1.8mm twin and earth cable I had kicking about in the shed.

The reflector is copper clad PCB board again from Ebay just cut with a hacksaw and rounded with the Dremel:

http://www.ebay.co.uk/itm/360732664403

The thing the Helical is wrapped around is part of an Epipen I just dismantled and cut down to suit. I think when I can be bothered I will buy some 5/8 dowel, but again I like making use of things to hand to keep costs down.

[flybywire]

THanks Steve.
Useful links.  Yes, I remeber seeing the US links for sma suppliers, but needed them quickly so paid stupid premium (rip-off) prices from UK seller.

I';ll go pester the design tech  at the school I work at, he was regailing the virtues of our laser cutter & 3D printers during the fire alarm assembly today!

Andy

[Balders]

If anyone wants some 30cm sma pigtails (one end straight one end right angled) in a hurry drop me a pm. I have a few at home.

[nub]

Biffa is that 10AWG wire your using, if it is where did it u get it from, some where online?

cheers.

[Biffa]

Biffa is that 10AWG wire your using, if it is where did it u get it from, some where online?

cheers.

It';s 1.5mm twin and earth from Wicks that I had kicking around in the shed. Think that';s about 16AWG

[nub]

ah right cheers.

[dirtyharry]

I did a  very similar ariel to this type a while back and got some good results , also used that type of connector biffa used (great minds think alike and all that) . theres a link below. Just print it 1:1 scale , stick it on your fiberglass/plastic/plywood and cut it out. A 4 turn gives a good 60 degree beam. You don';t have to bother with the "transformer" bit in the instructions it only made a difference to my 3 turn one.

Dimensions are based on the average frequency from a 200mw boscam setup +1.5mm household twin n earth , Coil should have an inside diameter of 15.8mm , I used a car wheel brace with some gafa tape around it to get the right dimension to rap around ( 15.4mm and it bounces out to 15.8) .
My pdf design is here
http://www.mediafire.com/download/qroegnz0hfqaf46/4+turn+helical+base+how+to.PDF

Coil former ( copied from flitetest) , needs wrapped round the 15.4mm tube
http://forum.flitetest.com/attachment.php?attachmentid=4762&d=1338984925

Original details of how to make the coil are here :-
http://flitetest.com/articles/How_to_build_a_5_8GHz_Helical_Antenna

[Biffa]

A new product from HK, not sure if it';s worth the money though

My home made ones cost about a £5...

http://www.hobbyking.com/hobbyking/store/__51626__Axial_Mode_Helical_RHCP_Antenna_5_8GHz_Circular_Wireless_SMA_.html

[Hands0n]

Ouch! £58 for that?  On slow boat from China these can be had for not more than £7.

I';m currently building one myself with a 3D printed support and base, requiring only a PCB/copper plate, SMA connectors/pigtail and a bit of spare twin and earth wire.

This is it today, the coil has been built using the wire forming tool (the long blue tube), and mounted into the coil support. The copper/PCB needs to be cut into a circle that will mount in the slot at the base of the coil support, and the two half circle base plates complete the protection.  It is simply glued together when assembled.

Total cost? Probably around the £5 mark for the bits I cannot make/scrounge ::)

[attach=1]

[teslahed]

Here';s my first attempt with the same 3d printed bits;



I need to source some copper clad PCB for the reflector next, but other than that i have the other parts i will need to finish this. Hopefully i';ll get it done by the middle of next week.

[Hands0n]

You';ll be ahead of me Chris - I got the board today, cut it out and fitted, but waiting on the SMA pigtail from China.

Looking forward to seeing these work.

[teslahed]

If you';ve got any spare copper clad board i can swap you an SMA pigtail for a bit!

I';d have to solder it up but i can do that tomorrow and get it posted first class monday for you if you like.

[Hands0n]

Ooh, that';d be awfully decent of you. PM me your postal address and I';ll pop a board in the post to you and let you know where to send the pigtail to. 

Do you want the full board or just a bit large enough to cut to shape?

[Biffa]

That looks really nice Chris

[Hands0n]

After the experience of cutting out and shaping the PCB reflector I could really do with someone with a CNC who could cut more to order ::)

[Biffa]

You could probably get a hole saw to match the size.

[Hands0n]

Good idea. I';ll see if I can find one the correct size

Sent from my Nexus 5 using Tapatalk

[Biffa]

I know on Ebay you can get a set for about £5 that goes up to 64mm which according to the build I follow is the right size for 5.8.