4 axial mode helical antennas in array with common reflector

[jujun]

Hello,

I want to build an array of 4 axial mode helical antennas. Each antenna have an impedance near 140 ohm, how to match it to a 50 coax ?
I feel that there is a very easy way to do it (parallel feed), but I cannot find documents about it, even in the ARRL books.
Do you have more information about it ?


Thank you

J

[iMo]

https://slideplayer.com/slide/6987034/#

[jujun]

Thank you, they seems to use a simple power splitter.

I didnt explained well what I'am looking for. It's not really 4 distinct antennas, it's 4 helicals on one reflector.

So I dont think it will change a lot of things, but because of the size of the construction in 2.3 Ghz, it would be better to have something embded at the back of the reflector.

[iMo]

Here is a picture of a power splitter (mid of the page "Rear side of Quad antenna with power divider."

http://www.nitehawk.com/rasmit/ras_pics.html

[Howardlong]

The way I’ve done it in the last is to implement an integrated transformer on each antenna to match down to 50 ohms and then use a four way coaxial power splitter.

http://www.g6lvb.com/quadruple_helix.htm

You don’t say what frequency you’re working at, or if it’s wideband. You could indeed match at the characteristic impedance if you can fabricate the right feed, keeping in mind how you’d achieve that in a physical environment (i.e., is it outdoors?).

You could certianly transform the impedances up to 200 ohms in each fabricated feed, and then feed in parallel at a star point for example. Remember to keep mind the inherent losses of any method you use.