Topband: Grounded half square/half loop detuning

[Petr Ourednik]

Hi all,

as I received just one reply from all of You it seems to be nightmare to
detune
properly this antenna isn't it?

Even antenna's gurus are silent...? :)

I will be glad to get any ideas as I tried a lot but my rx ant is
useless still.

73 - Petr, OK1RP
 

On Thu, 04 Mar 2010 19:01:42 +0100, "Petr Ourednik" <indians at xsmail.com>
said:
> Hello folks,
> 
> I am sorry to bother all of You but according to discussion about the 
> detuning the antennas I have also question.
> All the discussion has been made about the detuning the verticals if I
> remember.
> 
> I am using the big grounded half square (or maybe to say > half loop)
> with 
> vertical sections 25m/20m and horizontal section 78m. The system is
> grounded
> with the wire going under surface back to the feed point where I have LC
> network to
> match on 160/80/40m. (switched remotely by relays)
> On both sides I have also radial system. 4x25m on the feed point (25m
> vertical) side 
> (I know > not so many) and 10x16m on the other side of the antenna.
> 
> The nightmare I have with this nice antenna is that I have no space to
> put receiving
> antenna far away from this loop so my rotary Delta is no more then
> 10-15m away. In fact in 
> the middle of the loop which makes the strange coupling between them and
> the performance
> of the receiving antenna is completely destroyed. (...I guess)
> 
> I tried to detune the TX antenna by switching the relays to another LC
> (80/40m when
> I operated 160m etc.) with no effect, also I tried to disconnect the
> coax from the TX
> when I tried to receive on Delta with no effect.
> 
> So simply how can I detune this big monster loop or better to say how to
> ensure that 
> receiving antenna works well and the problem is really with coupling to
> TX ant please?
> 
> Any feedback or help is appreciated.
> 
> 73 - Petr, OK1RP
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