I have that nifty 2 m J-Pole antenna made of ladder line. It’s something like 55 inches long. If I made a full-length 2 m antenna, how would that change the propagation? With my setup, it would be easy to get another PVC pipe and extend it upward to use as a support for a longer 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 ) / 70cm (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?