Here is the 'T" antenna I referred to. It is totally plastic.

http://www.happywanderer.net.au/page...9&parent2id=24

If link doesnt work the website is www.happywanderer.net.au and the image
is on first screen. The totally plastic covered yagi I saw was somewhere in
ebay. I,ll see if I can find it again.
Regards
John



"John" wrote in message
. au...
Whilst trying to source a "digital" TV antenna I came across some with all
external surfaces plastic. One was a small yagi with all external surfaces
plastic, hopefully with metal elements embedded. Another a "T" shape made
out of plastic conduit with elements inside conduit.
My question is how do they work?. If they are detecting electrical fields
how does increasing source impedance by 100,s of megohms improve things?.
Capacitive coupling, I suppose at the frequencies involved there would be
some.
If it works as well as all metal why doesn,t every one use it and stop
corrosion?
Hope this is not too off topic.
Many thanks
John