[Amps] High SWR

[Ian White GM3SEK]

Gary Smith wrote:
> I have been told that a high swr on a yagi antenna reduces the front 
>to back ratio.  Any truth (facts?) to support this info?

None.

Improper installation can allow RF currents to flow on the outside of 
the feedline and/or the boom. This will change the radiation pattern, 
filling in nulls and possibly reducing the front/back radio.

RF currents on the outside of the feedline will also change the 
impedance at the antenna feedpoint, usually resulting in a higher VSWR.

Feedline radiation and high VSWR often occur together; but high VSWR 
does not *cause* feedline radiation.


-- 

73 from Ian GM3SEK         'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek