Wednesday, June 20, 2012

Simple Antennas for the Amateur Radio Operator--a continuing series

AN "ALL-BAND" ANTENNA THAT REALLY WORKS

The best laid plans of man and beast often go astray.  Such was the case today, when planned antenna maintenance took a back seat to heavy showers and gusty winds rolling off the Pacific Ocean.  Along the Hamakua Coast, such occurances make travel a bit hazardous and any outdoor work a study in frustration.

So, with tools in hand, I returned to the ham shack for plan number 3.  Plan number 2 was doing some repairs and maintenance around the house.  Now that I'm semi-retired, I find there is sufficient time to keep the house orderly while pursuing a variety of amateur radio interests.  Once the housework was done, it was once again out to the shack for some general clean up and antenna research.

One of my favorite research tools is the "Antenna Wire Classics" published by ARRL.  I'm currently paging through volume two of this outstanding series.  What I was looking for was a simple, multi-band antenna that was easy to build and didn't cost much money.  OK, I'm cheap.  A retirement income doesn't permit me to indulge in my wildest antenna schemes.  Besides, the size of my rental house and lot is small, which requires  antennas of simple, functional design.  And since I'm a complete idiot when it comes to building complicated things, I'd rather settle for antennas that even a bumbler such as I can do.

On page 3-20 of volume two, I found an article by R. L. Cope, W8MOK, entitled "All-Band" Antenna.  The original article was published in the Hints and Kinks column of the December 1954 edition of "QST."

According to R. L., "the arrangement consists of dipoles, cut for each band and connected in parallel at the center.  although I have not checked standing-wave ratios, the results seem to indicate that it gets out as well as a bunch of individually-fed doublets.  If you haven't tried it, you're in for some surprises."  This amateur fed the arrangement with a random length  of 70-ohm coaxial cable.  I suspect RG-6 would work well (nominal impedance is around 72 ohms).  Since I have some of this cable in the shack and a good supply of 22-gauge wire in a storage box, the actual time required to get this antenna in the air should be minimal.  I might even build it as an inverted vee, if I can't find an extra 30-foot length of pvc pipe.

Some of you may recognize this antenna as the proverbial "fan dipole" which is often cited in various antenna forums.  Anyway, this simple design is worth a look.  Once the weather clears, I'll build a copy and see if results are as good as described.

Have a good day. 

Aloha es 73 de KH6JRM--BK29jx15