Message-ID: <5BF41A1FC8F645BB9CD4349DD1155F3A@MJUPC>
From: "Mike Underhill" <mike@underhill.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <500EB973.8080005@iup.uni-heidelberg.de> <F4839781003A4ABDA02E5B6D4CCE9329@MJUPC> <500F0ADB.8050602@iup.uni-heidelberg.de>
In-Reply-To: <500F0ADB.8050602@iup.uni-heidelberg.de>
Date: Wed, 25 Jul 2012 00:32:16 +0100
MIME-Version: 1.0
Subject: Re: LF: Re: Pretests for the 630m band dipole
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Hello Stefan, and thanks for interesting reply.

But a few more comments before I go back to lurking. As yet I am not signed 
up to lurk also on the yahoo reflector.  Perhaps I will when a bit less busy 
and if persuaded  of the benefits of doing so.

> I want to try to get a antenna orientation beaming to G and PA, where the 
> most RX stations are present
My point is that you might have to orientate the antenna at right angles to 
what is normally expected if the loop mode is stronger than the dipole mode. 
It indeed may depend on ground conductivity?

> I will also try different heights above ground, starting from 0 to maybe 
> 2m or 5m AGL.
This will be very interesting.  Over dry ground  on 160m amd 80m I have 
found that differences with similar height differences to these are quite 
small, less than 6dB or so.  It is not until you approach the critical 
height that the height gain becomes very significant.

>> Occasionally broadcast signals in the 31m and 25m bands were found to be 
>> be stronger on the underground antenna than on the reference antenna.
> A stronger S/N or a stronger signal level?
The signals were definitely stronger but the noise level was usually a bit 
higher, perhaps by 6 to 10dB.

> BTW it is not at all easy to evaluate the differences of such different 
> antenna arrangements. I have never seen such a QSB on any band. Probably 
> it is the best to have a local RX station and do the tests on groundwave 
> distance. Probably the antenna radiates in a very high angle But the 
> difference (of the simulation) between 90 deg and 20 deg is just 5 dB 
> while the antenna gain is stated to be -5 dBi..
Good points. But it is measurements that confirm the veracity of simulations 
and never the other way round.

Looking forward to seeing your results.  And now back to lurking!

73 - Mike - G3LHZ
 .