"Tom Horne" wrote in message
news:Md4Zi.36$WN2.29@trnddc08...
Is it possible to ask questions here without triggering an arcane debate
about competing views of theory. I'm about to find out. I asked earlier
in another thread what measuring instruments I would need to have the use
of in order to compare the effective radiated power of different antennas.
As near as I can tell there was no answer.

I built a collinear J pole using copper tubing. I'd like to know if it is
more or less effective at radiating whatever works to the stations I'd
like to be able to talk to under conditions of emergency operation then
say a collinear ground plane or any other omni directional antenna.


There is no exect answer to the question. If you are only transmitting to
one fixed station , the better types of antennas can be determined. If
transmitting to several differant stations, there is usually no one antenna
that will be the best.

Several times I and some of the local hams have been together and had mobile
rigs with the same mounts and differant antennas. Swapping antennas from
car to car, the results were differant depending on where the distance
stations are. Sometimes the 1/4 wave would be beter and on the same mount a
5/8 or longer colinear would be beter on other stations. While we could not
use it on the same mount, one ham had a 40 meter antenna on the bumper of
his car and it had a beter receive signal on one repeater than the antennas
cut for 2 meters we tried on the same car.

It is not so much as the effective radiatred power, but having both stations
in the same lobe of the power. Antennas do not really give any gain to the
signal, they just redirect the ammount you have to a differant direction.
Just as a beam will have lots of gain, if it is not pointed at or near the
desired station, they will not be heard.