Aircraft antennas

Charlie: I recently installed a VHF com antenna on the tailboom frame of my
Baby Belle helo. It's dimensions are 16" X 12" Which are less than the
length of the antenna. I ran an antenna check using an MFJ 250 antenna
analyzer and the highest VSWR I got was 2.2. This was so much better than
the bent antenna that had been on the belly of the ship which did have a
large ground plane but had VSWR greater than 3 and in some cases as high as
5. One thing you can do is try out a prototype ground plane and then have a
Ham or someone with the right equipment do a check.

--
Stuart Fields
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478 ph
(760) 408-9747 publication cell
"ccwillwerth" wrote in message
...
Hi, I am about ready to cover my Cub type airframe, but need a place to
attach a com antenna. I was considering brazing a plate to the airframe
so that it would be just under the fabric. The antenna is the type that
has a ceramic insulator on the bottom of the antenna that insulates the
stainless steel antenna from the airframe. Does the antenna need a large
plate for a ground plane or will a small plate be sufficient? If a ground
plane is required, can the copper foil tape be used on the inside of the
fabric as the ground plane?

Charlie

Oops. The installed ground plane dimensions are 16"X12".
--
Kathy Fields
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478
(760) 408-9747 general and layout cell
(760) 608-1299 technical and advertising cell

www.vkss.com
www.experimentalhelo.com


"Stuart & Kathryn Fields" wrote in message
.. .
Charlie: I recently installed a VHF com antenna on the tailboom frame of
my
Baby Belle helo. It's dimensions are 16" X 12" Which are less than the
length of the antenna. I ran an antenna check using an MFJ 250 antenna
analyzer and the highest VSWR I got was 2.2. This was so much better than
the bent antenna that had been on the belly of the ship which did have a
large ground plane but had VSWR greater than 3 and in some cases as high
as
5. One thing you can do is try out a prototype ground plane and then have
a
Ham or someone with the right equipment do a check.

--
Stuart Fields
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478 ph
(760) 408-9747 publication cell
"ccwillwerth" wrote in message
...
Hi, I am about ready to cover my Cub type airframe, but need a place to
attach a com antenna. I was considering brazing a plate to the airframe
so that it would be just under the fabric. The antenna is the type that
has a ceramic insulator on the bottom of the antenna that insulates the
stainless steel antenna from the airframe. Does the antenna need a
large
plate for a ground plane or will a small plate be sufficient? If a
ground
plane is required, can the copper foil tape be used on the inside of the
fabric as the ground plane?

Charlie