Monday, July 9, 2012

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

KH6JRM's Amateur Radio Blog
Post 165


One of the creative things amateur radio operators can do these days is to build simple, effect wire antennas.  Although most commercial antennas are well made and perform well, there is nothing quite like building your own antenna and working DX on a shoestring budget.  So, let's begin with my favorite band--20 meters.

After I took down my temporary "long wire" antenna this morning, it was time to rebuild a 20-meter antenna that had seen better days.  As mentioned in post 164, rodents and other unnamed creatures chewed on my feed lines and elements, creating an ugly mess.  Fortunately, I still had a homebrew 33-foot mast made from 2-inch pvc pipe which could be pressed into service.  I attached 16 1/2 feet of AWG 22 wire to one half of the mast and another 16 1/2 feet of wire to the bottom of the mast.  At the midway point of the mast, I attached and soldered 40-feet of 450-ohm ladder line.  The line ran into a 4:1 balun.  A short length of RG-6 coax with suitable connectors ran to the Drake MN-4 ATU.  A 3-foot patch cord made from RG-6 ran into the Swan 100-MX.  I tested the homebrew vertical dipole on 20, 15, and 10 meters.  The antenna caused no problems with the Drake MN-4 or the Swan-100 MX transceiver.  I also tried the vertical dipole on 40 meters just to see if it would load.  Results on 40 meters were mediocre, but I could load the antenna on this band if I had to.

The vertical dipole had several advantages, including the elimination of a radial system, which has been a problem in my small backyard.  I can also swivel the mast down to ground level quickly without tangling radial wires in the mast.  The antenna performs well, blends in with the environment, and can be safely stowed when it is not in use.

I still have the 40-meter inverted vee which performs well on 40 through 10 meters.  My backyard is getting populated by several masts and various lengths of wire.  I may have to remove some of the structures to keep the visual impact low and to keep lawn mowers out of trouble.

I'm doing as much maintenance and antenna repair as I can before school begins on 01 August.  After that date, it's back to my "regular" job as a substitute teacher.  My xyl and I get called frequently to teach, so I'm not fully retired--yet.  One must keep busy to prevent the brain from "rusting".

Have an excellent, productive day!

Aloha es 73 de KH6JRM--BK29jx15