[TheList] Aerials

Thu Feb 8 19:26:45 AEDT 2018

http://www.csgnetwork.com/antennaevcalc.html

Use this to calculate the optimum length at 1/4 wave.

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.

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.

On 8/02/2018 9:14 p.m., Grant Carroll wrote:
>
> Dear all,
>
> 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.
>
> 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!
>
> But I’m sure there is someone on here who can tell me the perfect 
> length and the reason for it.
>
> Cheers and thanks for your help.
>
> Grunter1.
>
>
>
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