View Single Post
  #14  
Old June 14th 08, 02:46 PM posted to rec.aviation.soaring
Tim Mara
external usenet poster
 
Posts: 375
Default Transponder antenna - blade vs stub monopole

wrong! A ground plane should have a radius of at least 1/4 wavelength of the
antenna's operating frequency, a 23" antenna ground plane then would be
about right for a VHF airband communication antenna (118-136 mhz) and in
gliders this is seldom possible so use what you can get..
Transponder antenna ground planes are typically recommended to be 6"
diameter.
These are ideal....but not always possible so use what you can, too large
isn't a problem but performance can degrade from the ideal as it becomes
smaller.
tim
Please visit the Wings & Wheels website at www.wingsandwheels.com

"Alan" wrote in message
...
In article

brianDG303 writes:
Is there a downside to mounting on a ground plane inside the fuselage
of a non-carbon glass glider?


Since the ground plane should extend at least 23 inches in each
direction around the antenna, it is probably hard to get that inside
the glider.

One that extends front and back but is more limited to the sides
(perhaps wrapping around inside) probably would work, but would be
a bit reduced from a full ground plane.

Alan