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<div class="moz-cite-prefix">Another source, the one I used to
compile the AM propagation spread sheets is the BBC publication by
H E Farrow Long & Medium Wave Propagation (1958). This gives
an insight into ground conductivity and signal strength
measurement. There are free copies available online, however, if
anyone needs a copy I can email a decent set of scanned pages,
it's about 5 Mbyte in total.<br>
<br>
Tony Bailey<br>
<br>
On 20/12/15 16:36, Two Lochs Radio wrote:<br>
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<div>Appreciated, though there must be some comfort in the fact
that the design has been 'standard issue' for a century, and is
used by many of the most powerful AM transmitters such as
Drotiwich. You might also find BS1386 of some interest.</div>
<div> </div>
<div>The most critical aspects seem to be as you'd expect getting
a good earth place below the capacity hat, and getting a high
quality tuning coil with very low resistance and able to handle
the relatively high voltages involved (but for a transmitter of
a 100W or so that's not so tough). </div>
<div> </div>
<div>The client needs 'expectations management', I guess. If you
find the theoretical antenna design would in all
likliehood cut the client's electricity bill to a quarter, he
might be willing to accept a little uncertainty in the exact
radiation performance! If you could take the antenna efficiency
up from 8% to say 30-40%, there's a very big saving in runnings
costs to be had.</div>
<div> </div>
<div>Alex</div>
<div> </div>
<div> </div>
<blockquote>
<div>----- Original Message ----- </div>
<div><b>From:</b> <a moz-do-not-send="true"
title="transplanfm@hotmail.com"
href="mailto:transplanfm@hotmail.com">Ian Hickling</a> </div>
<div><b>To:</b> <a moz-do-not-send="true"
title="cma-l@mailman.commedia.org.uk"
href="mailto:cma-l@mailman.commedia.org.uk">The Community
Media Association Discussion List</a> </div>
<div><b>Sent:</b> Sunday, December 20, 2015 1:24 PM</div>
<div><b>Subject:</b> [cma-l] AM v FM</div>
<div><br>
</div>
<div dir="ltr">I appreciate all the advice and input - thank
you.<br>
I have the huge advantage of having worked in an engineering
laboratory that built VHF and UHF antennas and range-tested
them so I am very fortunate to have an inbuilt comprehension
of how they look and perform.<br>
Nowhere in all that worthy information is there evidence of
energy propagation patterns - actually measured in the field
as opposed to calculated or computer modelled.<br>
Most important - the difference between success and failure.<br>
I can't guarantee to a Client how well an AM (MF) antenna will
perform as I can with FM (VHF) - and that worries me.<br>
<br>
<div>
<div><b>Ian Hickling</b><br>
</div>
Partner<br>
<br>
<a moz-do-not-send="true" href="http://www.transplanuk.com/"
target="_blank"><img moz-do-not-send="true" alt=""></a>
<div><i>Office: 01635 578435 (7am-11pm UK time)</i></div>
<div><i>Carphone: 07530 980115 (only responds when driving)</i></div>
<div><i>6 Horn Street, Compton, NEWBURY, RG20 6QS</i></div>
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Local Reports at <a class="moz-txt-link-freetext" href="http://www.ravensound.pilgrimsound.co.uk">http://www.ravensound.pilgrimsound.co.uk</a></pre>
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