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<a class="moz-txt-link-freetext" href="http://www.csgnetwork.com/antennaevcalc.html">http://www.csgnetwork.com/antennaevcalc.html</a><br>
<br>
Use this to calculate the optimum length at 1/4 wave.<br>
<br>
This will be MORE than accurate enough for receive only because when
you use an antenna for transmitting, you check the SWR at low power
first so you don't blow the final's when at full power.<br>
<br>
The reason an antenna needs to be the correct length is because its
a fraction of the transmitted (or received) wavelength, be it 1/4,
1/2 or even 5/8th. A simple example is FM 98mhz, the full wavelength
of the signal is a little over 3M, if you cut a 1/4 wave antenna for
your receiver to 750mm, you are pretty much on the money. <br>
<br>
<div class="moz-cite-prefix">On 8/02/2018 9:14 p.m., Grant Carroll
wrote:<br>
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<blockquote
cite="mid:1857516731.972139.1518077668786@webmail.xtra.co.nz"
type="cite">
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<p>Dear all,<br>
</p>
<p>This may seem a stupid question to some of you but I think it
needs to be asked - what is the optimum length for an aerial
for a scanner receiving VHF communications i.e. the ESA and
ESB bands.</p>
<p>Obviously, it needs to be longer than a UHF aerial but what
is the ideal length. I�ve used aerials of various lengths on
my scanners and with VHF I find the longer the aerial the
worse the reception after about two metres - in other words
bigger is not better!</p>
<p>But I�m sure there is someone on here who can tell me the
perfect length and the reason for it.</p>
<p>Cheers and thanks for your help.</p>
<p>Grunter1.</p>
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