[Amps] 10dB and propagation

[Ian White G3SEK]

Yuri wrote:
>You guys might try to poke fun at this. But there are many factors 
>contributing to signal levels received at the other end. Antenna 
>pattern, local ground conditions, terrain and propagation conditions. 
>VHFers know about ducting on VHF between W6 and KH6, you drive up the 
>hill and you can find spot where your signal (few watts) will hit it 
>and you QSO with KH6. You go few hundred feet up or down and you lose it.
>
Sure, all of that is true... but it all goes strictly dB for dB. There 
is no support for tropo ducts behaving in a non-linear fashion.

Let's not confuse the variable *importance* of a dB under different 
circumstances (which is obviously true) with any suggestion that the 
propagation medium itself is non-linear.

A non-linear medium would have to mean that your signal was directly 
affecting the ionization density or the refractive index of the 
troposphere. As I already said, that's wishful thinking at amateur power 
levels.


-- 
73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek