Re:LF: Cardioid RX antenna for LF...

["manginbenoit.pro" <manginbenoit.pro@laposte.net>]

GE Stefan and all,

Try and see Jean-Pierre / F1AFJ 's page, he built and modeled a 2-turn K9AY, the one he uses for his grabber.

Nothing to say about performance, it seems. Judge it by the summer T/A captures... Plus, (I did not test it) his QSD RX es MMIC preamp seems to work VY FB.

I tried a 2-turn K9AY for 160, but it is definetely too long, there is too much wire. 0,2 lambdas seems to be a maximum. Voltage levels are correct but directionnal properties degrade seriously.

Nevermind on 137, we will never reach a quarter-wave long RX antenna !!!

Maybe a 2-turn Flag should be tested ? Does anybody use MMANA ? I can try and model one using this software.

I don't use EZNEC at all.

de F8GRY/Ben




> > Message du 13/05/12 19:12
> > De : "Stefan Schäfer" 
> > A : rsgb_lf_group@blacksheep.org
> > Copie à : 
> > Objet : LF: Cardioid RX antenna for LF...
> >
> > Hello Group,
> > 
> > I've just started to play a bit in EZNEC, trying to simulate a receive 
> > loop antenna for the new YV7MAE grabber. 
> > http://dl.dropbox.com/u/74746618/LF/YV7MAE_LF_Grabber.html ... still 
> > using a wire receive antenna with excellent results but now a 
> > directional antenna is needed.
> > 
> > So i modelled a loop with a possible shape and a ground connection. Then 
> > i added a R on the far end of the source. The results of the elevation 
> > and 3D plot are surprising good. Maybe i have done a mistake in 
> > modelling? Optimal performance was obtained at R = 8 kOhm. This resulted 
> > in the best F/B and beamwidth... Results of ZENEC are here: 
> > http://dl.dropbox.com/u/19882028/LF/Cardioid%20for%20LF.png
> > 
> > Any ideas, experiance or advice?
> > 
> > I guess a preamp is needed when such a antenna is used. The typical 1:9 
> > un-un does not look useful for me...
> > 
> > 73, Stefan/DK7FC
> > 
> >