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Message-ID: <3.0.1.16.20011031113528.30c72ac0@mail.cc.kuleuven.ac.be>
Date: Wed, 31 Oct 2001 11:35:28
To: rsgb_lf_group@blacksheep.org
From: "Rik Strobbe" <rik.strobbe@fys.kuleuven.ac.be>
Subject: Re: LF: <Tech> More on Antenna Loss
In-reply-to: <E15ybmy-0006lX-00@gemini.herts.ac.uk>
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Hello Jim & group,

>G3NYK (6m high, 30m long inv. L): Rloss = 4733/f^0.86 (for points 
>below 600kHz only)
>
>M0BMU(8m high, 40m long inv. L): Rloss = 1550/f^0.75
>
>ZL2CA(Don't know, but must be quite big!): Rloss = 142/f^0.50

While doing research for my LF antenna webpage I came across a formula the
gave the pentration depth of an E-field in the soil as :

                   D = 509/(S^0.5*F^0.5) 
where D = depth in m, S = soil conductiviy in S/m and F = frequency in Hz

Assuming the the ground loss is proportional to the distance 'traveled'
through the soil the results of Bob (ZL2CA) seemed really a textbook case
compared to the measurements of Jim (MBMU) and Alan (G3NYK), so I wonder if
the 2 last do suffer more from additional losses (buildings and greenery
close to the antenna) compared to Bob ?

BTW : The emperical equations are a bit dependent on the frequency range
you take. For Jim's measurements I get R = 1555*F^-0.75 for the whole range
but then I took only the points between 100 and 300 kHz (to have the same
range as Bob) and got R = 1830*F^-0.79.

73, Rik  ON7YD