antenna ground planes

"abripl" wrote in message
oups.com...
A "conventional com antenna" could mean anything ...

Come on Jim. Most of us understood it to mean a regular 1/4 wave that
is used for metal airplanes with their "ground plane". You are
technically too correct sometimes.

"Come on" my ass. I answer these questions on a daily basis and you have
absolutely no idea what sorts of permutations and combinations can arise ...
and what people mean by "regular" and "normal" and what it means to give
wrong advice. I like to think that when I answer a question it is because
I've got a pretty good handle on the situation and can give something that
is technically and structurally defensible. If you want to hipshoot
answers, then hipshoot the results. So far I haven't given any bad advice
when I've been given the whole scenario. That's 35 years of antenna advice.
For free, you will note, and I'll be damned if I will give advice without
knowing for sure the parameters.


There are all sorts of conventions addapted from coloqua. For example
"conventionaly" you know who Americans are. But America is a continent
and not a country.

First of all, that is "colloquia" (sp), which is not a word but a
*******ization (not an "addapted" misspelling either) of "colloquial" which
IS a word. America is not a continent, not even "conventionaly" which is
also spelled wrong. North America is a continent. South America is a
continent. Evidently you've never had to teach or make up exams where
people have to be correct to get the right answer.

Jim

"raptor" wrote in message
...

I wonder about something else. How long would a "full wave" antenna
have to be for aviation comm radios? I've got some old walkie talkies
that have those very long pull out antenna's, they must be 5 or 6
feet. Are those full wave?

The lenght of the antenna is proportional to the frequency used. Your
'walkie talkies' are most likely 27MHz CB type. A full wavelength would be
11 metres, which is a bit long to handle ;-)

On your plane, the comm frequencies are from 118MHz to 136MHz. The
wavelength in the middle of that range is about 2.35 metre. You can probably
hide a full wave antenna for that frequency in a fuselage but there's other
considerations like impedance and radiation pattern that influence the
decision. I'm sure Jim will be able to tell you the nitty gritty details, I
would have to look it up..

Rob

118 to 137. Full wave antenna isn't going to buy you squat. Quarter wave
is about as good as it gets.

Jim



"Rob Turk" wrote in message
news:cCDaf.416$zc1.177@amstwist00...
"raptor" wrote in message
...

On your plane, the comm frequencies are from 118MHz to 136MHz.