On Nov 2, 7:30*pm, "Jim, K7JEB" wrote:
Kreco Antennas in Cresco, PA makes a line of
coaxial dipole basestation antennas that exhibit
a 50-ohm feedpoint impedance. *Here's the
website for their high-band basic model:

* *http://www.krecoantennas.com/hbcaxial.htm

They pull off this trick by, *I THINK*, shortening
the top element slightly and lengthening the skirt in
*just the right way* to achieve a match at a spot
frequency.

An interesting variant on the basic antenna is their
"shunt-fed" coaxial dipole that places the entire
antenna at DC ground for lightning protection. *Here's
the webpage for it:

*http://www.krecoantennas.com/shuntfed.htm

I've used their antennas in the past with excellent
results, but they are a bit pricey.

Jim, K7JEB

We have used these at work. The 50 ohm value is very "nominal".


http://www.krecoantennas.com/hbcaxial.htm

Jimmie