"JosephKK" wrote in message
news
On Sun, 25 Jan 2009 14:27:33 -0800 (PST), wrote:
snip
You might be surprised just how much level you can
get from a tuned small loop on the low bands.
As an example, that 16 inch loop provides more
signal than the whip on a car. I once tried it with a
delco radio in my truck. I hooked the loop up to it,
and it was as hot as a firecracker vs the standard
whip.
The catch is the system is very high Q, and requires
constant tuning of the cap as you change frequency.
That bites you when you use resonant loops. Of course non-resonant
loops don't have nearly the effective performance. Initial
selectivity to reduce the noise bandwidth before amplification or
mixing is why it is so common.
I recall medium-size table radios having a loop antenna in/on the back
cover. I don't know whether there was also a ferrite rod inside.