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Hi all, I am ready to make another helical after making the last one about 5 years ago. I built the last one based on the Hacker web site and it worked quite well but in the end I reverted to using a 14db patch for long range work due in main to it's ease of use.

In the 5 years since the last effort I see many more designs on the web but they all differ in measurments and claims. I'm thinking of using 123mm of wire per turn at 30mm pitch.

Has anyone else done any testing of these ? Any first hand info would be great.

Thanks, Terry

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for what frequency ?

have you access to any kind of network analyzers ?

or even a SWR meter for the frequency band you use ?

if an antenna design is only a few mm away your result can be really poor.

I have access to all the measure equipment you can imagine,

I can frequency and gain sweep them.

and I live only a stamp away from you :-)

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for what frequency ?

You may have guessed from the measurments I quoted, 2450 :D

have you access to any kind of network analyzers ?

or even a SWR meter for the frequency band you use ?

analyzers no, tunable oscillator and swr bridge yes. I have no problem comparing aerials I just wanted input from you guys to narrow down the the amount of aerials I need to make. I thought in the year since I made mine that someone here may have done some testing, there seems to be lots more on the web !

I have access to all the measure equipment you can imagine,

I can frequency and gain sweep them.

and I live only a stamp away from you :-)

Thanks for your kind offer Thomas, if I get close to wanting to measure the difference between 2 almost identical aerial I will let you know ;)

Terry

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Great ! you will get far with antennas at good SWR readings,

first time I made a Goofprof Patch it was far off, really bad SWR,

so I changed it to be good at the right frequency and gained sevaral dB.

If I had not done that, my tests of it would have failed it !

please keep us updated, drawings, pictures, range test and compare with other know antenna types.

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OK, I did not get the response I hopped for when I asked for info so I guess nobody has made one.

I had a go myself with info off the net and a lot of testing, I could write a book on what I have done so far but I could do double if I had the time.

Here are some findings, I won't go into big detail !

They say that helicals are easy to make as they are not critical.

I would agree but I have found it is at the expense of high gain. No matter how hard I try I can't get a helical to out perform a 14dbi quad patch. My best is to match the 14dbi gain but with a little less beam width, although this is made up for by a more circular polarization. Notice I said 'more circular', it's not the same at all angles, just less critical.

To sum up I would say if you want more gain than the GPP and have a helper who can point your aerial then a helical is a practical design that you can make yourself.

Terry

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Well I was not going to get into a build type thread but seeing as you asked so nice :D

I started with 123mm of 2mm wire per turn at 30mm pitch and made a 30 turn helical but this was I estimate 12dbi +/- 1dbi gain.

I ended up with 135mm of 2mm wire per turn at 27mm pitch and only 20 turns giving me around 14dbi +/- 1dbi gain.

The only critical bit to adjust is the matching strip which is a 6mm wide brass strip connected as the first 1/4 turn. This strip is adjusted against the reflector using a wedge of balsa and glued when correct.

I used a 1/8 balsa sheet as the support for the helix for minimal effect.

Terry

post-2-1179847981_thumb.jpg

Edited by Terry

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Ohh, don't take any notice of the white marks on the reflector, they are just where I had a different helix glued before ;)

Terry

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Yes since Thomas asked so politely :lol: I just wish to top it off with a "Thank You Terry" for posting the pictures and progress on your Helical antenna! I too am interested on how you are making out with your project!

John ;)

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Thanks guys, it's so far only been tested on a fixed transmitter at about 200m distance. I then check the RSSI and swapped aerials to compare.

I would like to build one is a large tube that my helper could put on her shoulder like a rocket launcher :P

Terry

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Maybe Mark but I want to find some 4" or 5" to be sure it dose not effect the tunning, just not found what I want yet ;)

Terry

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