ELT Antenna

I dissagree with your specs. The calculator below can be found at
http://www.hamuniverse.com/jpole.html

I don't have the exact specs of a B-17s rudder, but My C-172 was taller than
5 ft

Enter The Operating Frequency
Freq MHz



A (Long section) dimension is: feet, inches, meters

B (Short section) dimension is: feet, inches, meters

C (Feed point) dimension is: feet, inches, meters

D (Spacing) dimension is: feet, inches, meters

Inside (spacing) dimensions are metal to metal measurements, NOT center to

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"Jim Weir" wrote in message
...
Did you really read what the guy had to say? Do you know that a j-pole at
121.5
is longer than a B-17's rudder assembly? Do you understand that you have
to
radiate equally efficiently at both the fundamental and second (NOT third)
harmonic?

Did you read that he has only a small amount of fiberglass in the tail,
and that
most of it is carbon fiber? Did you read that there is another com
antenna in
that same location?

I read it and concluded that they guy didn't have a chance in hell of
putting
his ELT antenna in the tailfeathers, but waited around to see if somebody
that
knew what they were talking about came up with a clever idea...I don't
claim to
have cornered the market on clever.

Do you understand that a j-pole does NOT have a built-in ground plane, but
is a
matched half wave radiator? Why do you limit the dipole to a 90 degree
angle?
If SWR is all you are concerned with, I can give you an antenna that is
good
from DC to 20 GHz.. It is called a 51 ohm resistor.

Jim (still waiting for clever) Weir



shared these priceless pearls of wisdom:

-A j-pole antenna has a built in ground plane and works very well. Just
-google on jpole or j-pole antenna. Or maybe a full wave loop if you
-have the area for one. A dipole also can be used with up to a 90 degree
-angle in the center. Just some ideas. Contact a local ham radio club. A
-dipole with a 90 degree angle is fairly omni-directional and easy to
-build.
-
-Have the antenna checked BEFORE testing for SWR with an MFJ antenna
-analyzer from a local ham club. The ARRL antenna handook for VHF is an
-excellent resource.
-
-I would definitely MAKE SURE the antenna cannot come loose. Use 50 ohm
-coax to feed if that is what impedence the radio expects.
-
-Rob


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com