[CM] fm again

plutek-infinity plutek at infinity.net
Tue, 20 Nov 2007 20:49:25 -0500 (EST)

>From: Juan I Reyes <juanig@ccrma.Stanford.EDU>

>Looking at these really nice pictures (priceless as Dave points out),
>and out of curiosity, I can't resist to post this silly question:
>For an FM transmitter what it is the minimum length of the antenna for
>broadcasting at a frequency around 100MHz. ?

"Fundamentals of Radio" (Jordan, Nelson, Osterbrock, Pumphrey, Smeby, and Everitt - Prentice-Hall, New York: 1944) states that the velocity of electromagnetic waves is 300,000,000 m/s and that transmission of radio waves requires an antenna at least of the order of one-quarter wavelength, and most commonly one-half wavelength.

given all that, i guess the wavelength would be 3m, the minimum antenna length would be 0.75m, and the most common antenna length would be 1.5m. of course, i may be wildly off on this, since i have no experience in the field -- just happen to own that very interesting book.

see http://peterlutek.com/temp/antenna.jpg for a scan of the cogent bit of the book. (i'll be removing the scan in a day or two)