Friday, September 12, 2008

Finally Bested the Best

... with the best...


One of the many avenues to participating in Amateur radio is to build your own antennas.  This gets more interesting once you have a radio to work the lower frequencies (Anything less than 50MHz), but even in the 144MHz band, there is still a few different antenna designs to choose from.

Back in June when I was just getting started, the first antenna I tried building was a J Pole.  It consists of two parallel elements, one three times as long as the other.  I made it out of 1/2" copper tubing and the appropriate fittings (end caps, T junction, elbow).  When I finally finished it and fired it up, I got an SWR of 1.8.  The Standing Wave Ratio is a measurement of how much radio wave energy is actually radiated away from the radio versus simply reflected back to the radio, creating a standing wave.  The closer to 1 it is, the better.  (Anything below 2 is pretty good)

I then promply spent two months building antenna after antenna trying to at least match the performance of this.  Hasn't happened, until now.

I didn't even expect it to be that good.  I'm moving into my first apartment this week, and didn't think bring an eight foot piece of copper tubing was going to be the best arrangment.  Last month I just threw together a TV line J pole, not expecting much.  I didn't even bother plugging it into an SWR meter, and just threw it in my radio box.

This week I figured I should test it before I move 2 hours away from most of my junk boxes.  Taped it to the end of a piece of PVC pipe, plugged it into an SWR meter, and would you believe it?  1.3.  Dialed into a local repeater and it performed about as well as the full sized copper version.

What a kick that I finally topped my first antenna, and it was pretty much the same design.  J poles really do kick ass in the VHF arena.  The best thing about this antenna working is that I now have an antenna no bulkier than a coil of coax to take to my apartment and hang somehow (Buddy up with the guys who live above us? It'd only take one nail on the top of their balcony...)


On a side note: I asked my dad for some fishing line, and he said, "Sure, I used to have (literally) miles of it," and gave me the remnants of one of his 1000 yard spools of monofilament line.  19 years and he still keeps pulling stuff out of that garage that I don't expect.

No comments:

Post a Comment