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Can you help this reader improve his 2m base antenna?

Posted: 25 Jan 2018 11:29 AM PST
http://feedproxy.google.com/~r/kb6nu...m_medium=email


A reader writes:

I have that nifty 2 m J-Pole antenna made of ladder line. Its something
like 55 inches long. If I made a full-length 2 m antenna, how would that
change the propagation? With my setup, it wouldÂ*be easy to get another PVC
pipe and extend it upward to use as a support for a longerÂ*antenna.

I replied:

I’m not sure how it would change the propagation, but it would definitely
change the feedpoint impedance, and that’s something you DON’T WANT.
Remember that you want a “matched system,� i.e. a 50-ohm transmitter
output, a feedline with a characteristic impedance of 50 ohms, and an
antenna with an input impedance of 50 ohms.

To improve the performance on your current antenna, what you want to do is
to get it up higher. Remember that VHF/UHF radio is pretty much a
line-of-sight kind of thing. The higher up the antenna, the further your
signal will reach.

On the other hand, if you just want to play around with antennas, you might
want to try building a 2m collinear array. I’m not really an antenna
expert, but basically collinear array consists of two or more half-wave
dipoles, stacked end to end along a common axis. Many repeaters use
collinear arrays, and I’m kind of surprised that more hams don’t use them
at home. I guess it’s because for most repeater work, a J-pole works just
fine and is simpler to make.

Google “2m collinear antennas� and you’ll find a number of plans for
building one.

I did Google 2m collinear antenna and found a couple of likely prospects:

WB3AYW Wire Collinear for 2 Meters. This antenna is made with wire and some
PVC pipe for coil forms. It looks like it would inexpensive to make and
work well besides.

M0ZPH 2m ( 144MHz ) / 70cmÂ* (430 MHz) Coax Collinear. This antenna is a bit
more difficult to make, but not overly so, and it has the advantage of also
being usable on the 70 cm band.



Have any of you built a collinear antenna? If so, which plans did you use?
How did it work out for you?

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