RadioBanter - View Single Post

November 17th 03, 08:49 AM

On 16 Nov 2003 23:42:38 GMT, (WP20032) wrote:

My question was directed at a theoretically RF tight container. In such a
case, how effective would the reradiator be....20 dB down....40 dB, etc. I am
not sure how this would be calculated in the relatively near field, with
reflections.

TIA
Wayne

Hi Wayne,

Resonant cavities are RF tight containers, and they exhibit less than
1dB to several many. The lower values are a function of low loss
(very large resonators), the higher values are a function of either
high loss or poor coupling. No doubt when you have folks residing
within the "cavity" loss becomes an issue - and then add coupling loss
to boot. This says nothing as to the state if the cavity is resonant
or not.

If the radiating antenna is within less than a wavelength of the
pickup, you don't stand much chance of coming out with less than 3dB
loss. You may as well count on at least 20dB loss.

A low power, half duplex, cross band repeater would probably remove
all the presumptions and actually work. One half residing within a
shield would also cut down on annoying hits on a shared frequency.

73's
Richard Clark, KB7QHC