Helix antenna with lossy wire

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F4INX
Posts: 7
Joined: Tue 15 Dec 2020, 18:25

Helix antenna with lossy wire

Post by F4INX » Thu 24 Dec 2020, 02:40

Hello,

I'm trying to model an antenna similar to an helix with fine pitch with lossy wire. I use a script similar to the script in http://openems.de/index.php/Tutorial:_Helical_Antenna, using the function AddCurve. Unfortunately, this function does not seem to support losses in wire.

Could you please tell me how to include the losses of the wires ?

If the functionality is not native, is there a way to tweak the software to get this ?

Thanks a lot,

thorsten
Posts: 1438
Joined: Mon 27 Jun 2011, 12:26

Re: Helix antenna with lossy wire

Post by thorsten » Thu 24 Dec 2020, 10:35

AddCurve is only the primitive (shape). In this case a infinite thin metal wire. What you need to look at is the material definition for it.
Adding to this losses is not simple and I'm at the moment unsure if the conducting sheet material can handle curves. But you should give it a try...
Otherwise it will get very difficult to model a thin wire with losses,
At what frequencies are you operating? I usually find that metal losses are small compared to dielectric losses (which you do not have here?) and therefore in most case not really necessary to include. If you antenna is in the single digit GHz I would assume you will achieve good efficiency and you should not worry about it.

regards
Thorsten

F4INX
Posts: 7
Joined: Tue 15 Dec 2020, 18:25

Re: Helix antenna with lossy wire

Post by F4INX » Thu 31 Dec 2020, 11:50

Hi Thorsten,

Many thanks for your answer.
This was to model a small compact antenna around 3 (!) MHz for ham radio.
In my case, the wire losses are dominant because the wire is really long (approx 100 m of wire) and wound into a compact helix.
The dielectric losses would have been negligible not only due to the low frequency used but also because it was meant to be wound around an hollow PVC tube.

Anyway, I have changed my mind on the antenna I will use for my needs.

Regards,

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