tomerbr schrieb:

this was a qustion from my instractor in college



1/4 wavelength is resonant to spread most of the power into the air (or
even into vacuum). Any multiple length of 1/4 wavelength works as well.

Explainig *why* 1/4 wavelength is resonant is just another thingy....

You can use allmost any mechanical length. By adding a coil or a
capacitor you can make it resonant electrically.
Lengths under one full wavelength will provide a somewhat near ground
radiation diagram. Longer antennas are directional towards the antenna
tip. This is not that good for vertical antennas other you want your
signal going to mars.


There are some special constructions like cophased antennas or multiple
dipoles in one unit. These antennas provide some to much gain over
simple verticlas as the radiation diagram flattens the diagram of
radiated power down to earth so that less radiated power goes out to
space. These antenna constructions can have the length of 1 to 5 (or
even more) full wavelengths.

Please excuse my bad and very simple english.
Season greetings from Berlin/ Germany.