Alex,

Solder a quarter wave length of wire to the center conductor of the coax
with a loop at the end of the wire to attach your line to raise it. A
quarter of a wavelength from the wire end of the coax, coil enough of
the coax to form an RF choke. (I think the ARRL Antenna Handbook has the
information you need about how many turns and what diameter to make the
coil.) Seal the end of the coax to keep out moisture. Then hoist the
antenna up and you have a coaxial sleeve antenna.

73,
Bob AD3K

Alex wrote:
Has anyone tried building a 1/2 wave coaxial sleeve antenna for 40m? I have
a large tree with a branch at 70' and i thought i'd pull the antenna up with
a rope. Should i make the sleeve out of copper pipe? A 1/2 wave vertical
would be a nice antenna for 40m and i thought a coaxial sleeve antenna would
give me a great feed impedance. Any thoughts? The coax are 100' of RG8.



--
Robert L. Spooner
Registered Professional Engineer
Associate Research Engineer
Intelligent Control Systems Department

Applied Research Laboratory Phone: (814) 863-4120
The Pennsylvania State University FAX: (814) 863-7841
P. O. Box 30
State College, PA 16804-0030