Source for RG174 and BALUN

In reply to F5VGL:

Dear Jaakko,

Many thanks for your nice work !

When I read G6WRW’spot and antenna description Yahoo | Mail, Weather, Search, Politics, News, Finance, Sports & Videos , I saw that my antenna was working in NVIS mode, not a bad thing for SOTA in EU.

Best 73 and good luck for next “Crêt de la Neige” trip…

Alain F6ENO

RG174 coax ordered from SYCOM. 40p/m, £1.75 for correct (small diameter cable) BNCs.

Thanks for replies. Got hold a nice circuit to homebrew a balun too, looking forward to lightweight HF!!

73 Colin

In reply to F6ENO:

Hi Alain,

Of course the model I showed was some kind of approximation to the case without balun or common mode choke on the feed line. With the balun you can expect better dipole symmetry, since it introduces high impedance to the current flowing into the coax.

One more observation from this model was that the antenna gain was reduced by about 3 dB, because the coax was conducting part of the RF current close to the lossy ground. To summarize you should use balun if you want to have ideal NVIS antenna with maximum antenna gain straight up. Otherwise it is not so important.

73, Jaakko OH7BF/F5VGL

In reply to F5VGL:
HI Jaakko,

Do you use “4nec” or “Mmana” soft for the simulation ?
I find that both are not very easy to use… hi !

73 Alain

In reply to F6ENO:

Hi Alain,

EZNEC by W7EL

http://www.eznec.com/

73, Jaakko OH7BF/F5VGL