mr1956 wrote in
:

....

I have been reading the ARRL antenna book and while there is much
information, a lot of it is over my head. But one point I think a
chapter makes is that a 1/4 wave monopole will work better than a 1/2
wave using an artificial ground plane because of the way the voltage
peaks at the end of the antenna; or that is how it seems.

Your transmitter is designed for a particular load impedance, almost
certainly 50 ohms... check the specs.

The load presented to the transmitter terminals depends on the feed point
impedance of the antenna, and impedance transformation that may occur on
the coaxial feedline.

In the case you describe, the *antenna system* design was most unsuited
to a 50 ohm transmitter, hence the considerable loss predicted.

Your newer proposal for a quarter wave wire perpedicular to the rocket
body with the coax shield connected to the metallic rocket body is not
exactly 50 ohms, but probably close enough that antenna system efficiency
will be fairly good and the transmitter should deliver most of its rated
power.


Owen