I found, on average, that moving the antennae out off the edge and above of the building (just a couple of metres) at the corners improved the signals at VLF/137 the most -
As ever I used a coaxial cable (havenet figured out the fiber optic solution yet) back which was bonded to the building rebar/earthing before it entered inside -
Unfortunatley for me in this Oklahoma and my home in Alaska constructed "stick built" wooden property I dont have concrete and rebar reinforcement, except on the footings, so nothing except true earth to bond to. My building is virtually transparent to a load of frequencies and we dont keep the noise within the interior of the building :-(( - My previous QTH in China and Singapore did have the rebar/concrete construction and it knocked off 40dB or so of common mode noise...
Laurence KL 1 X/ BY3A etc
> To: [email protected]
> Date: Thu, 13 May 2010 19:27:07 +0000
> From: [email protected]
> Subject: Re: VLF: Outdoor test for different places for active E-field antennas for VLF
>
> Hello Stefan,
>
> Many thanks for sharing your findings.
> I have done similar tests at 137 kHz and 400 kHz.
> In a nutshell, it did not pay off to raise the antenna 6 meter ( total
> height 12 meter) above the semi flat roof of my house, compared to 5 metre
> high in the garden as the signal to noise ratio did not improve.
>
> Unfortunately, I did not monitor the Russian Alpha signals at the time.
> I did find a 15 dB lower signal level at 11.906 kHz at my city location
> compared to a a free field location, though.
> Both antennas were at the same height.
>
> I have a few chestnut trees 20 metre away which are full with new leaves
> and blossom.
> At 400 kHz they have a screening effect of 1.5 to 2 dB!
>
> Maybe you can check the signal to noise issue again when you have a real
> signal for comparison, to make sure that your assumptions are valid.
>
> Enjoy your weekend!
>
> 73,
> Roelof, pa0rdt
>
The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with Hotmail. Get busy.
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