In article ,
David Combs wrote:

No, it doesn't. AM BC band broadcast antennas are not a full
wavelength, and the aren't resonant at the transmit frequency.


Please say more about that. Thanks!


They all
use use L/C networks to make the tower work at the allocated frequency.

What, some kind of impedance matching?

Yup. It's an impedance match / transformation arrangement, which
matches the impedance of the antenna (often far off resonance in these
cases) to the impedance of the transmission line.

Although the antenna by itself is not resonant, the antenna + matching
circuit is.

Some ATU are as large as the AM transmitter when the tower is difficult
to configure.

ATU -- what's that?

Antenna Tuning Unit. A big impedance L/C impedance matcher.

PS: And if you feel like writing a bunch, give us all a tutorial!

If you're really interested in this topic, may I suggest looking
through Laport's classic text from the 1950s, "Radio Antenna
Engineering"? Lots of information, and some very nice photos of long-
and medium-wave antenna setups (military and commercial).

Although original copies are few and far between (and rather
expensive) these days, the book's copyright expired a few years ago
and it reverted to the public domain. I scanned it, and you can
download a copy at no charge.

http://snulbug.mtview.ca.us/books/Ra...naEngineering/
http://www.lulu.com/shop/edmund-lapo...-17560294.html

If you decide you want a printed copy,

http://www.lulu.com/shop/edmund-lapo...ct-188778.html

Lulu sells it for the cost of printing and shipping... I set the
"author's commission" to zero, so they don't charge a royalty or take
a percentage of it.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!