Friday, July 27, 2012

Simple Antennas for Amateur Radio Operators--a continuing series.

KH6JRM's Amateur Radio Blog

Post #175

A "long wire" antenna

One of the joys of being an amateur radio operator is the creation of antennas.  Since I live on a restricted lot surrounded by neighbors and high power distribution lines from the local utility, I have to be creative if I want to get on the air.  Like many of you, I've had to live with compromise antennas most of my amateur "career".  Sometimes, opportunities come along that just beg for experimentation. 

Such was the case today, when several of my neighbors mentioned they would be visiting relatives for several days.  Since my teaching assignments won't begin until 01 August (or later, if you are a substitute teacher such as I), I offered to keep on eye on their homes until they returned.

Goody!  There are several 30 to 50-foot trees in back of my house on my neighbor's property that just call out for antenna use.  Oh, well, that must be my imagination.  Anyway, I decided to string up a full-wave 40-meter "long wire" through the trees and tie off the end on a fence post about 100-feet from my qth.  So, using a big slingshot, some fishing line, and a 6-ounce fishing sinker, I launched this skyhook through the trees and tied off the end on the distant post.  Using the top of a spare 32-foot fiberglass pole as the first support, the antenna was run out about 100-feet throught the trees, with about 35-feet running off at a 45-degree angle as a counterpoise.  I attached about 40-feet of 450-ohm twin lead to the top of the fiberglass pole, with one wire soldered to the 100-foot of wire and the other lead soldered to the 35-foot counterpoise.  The antenna resembles a lazy inverted "L".

The twin lead goes into a 4:1 W9INN balun.  Twenty feet of RG-6 (with suitable connectors) goes to the Drake MN-4.  Three feet of RG-6 attached the tuner to the Swan 100-MX.  The antenna can be tuned from 40 to 10 meters without upsetting the old Drake or the venerable Swan.  I also have an 8-foot copper ground rod outside of the shack which is attached to two 33-foot counterpoise wires running around the property.  The antenna works fairly well, especially since the longer portion of the wire is pointed NNE--that puts most of my signal into the Pacific Northwest of the U.S. mainland.  Reports on cw run between 569 and 589 with 20 watts from the Swan 100-MX.  After Sunday, I'll have to take the antenna down.  The neighbors are due back on Monday.  In the meantime, I'm having fun.  Once Monday arrives, I'll return to the inverted "vee" and my two loop antennas.  The antenna was fairly cheap, since I used wire and connectors I already had in storage.  Besides, with all the rain our area has been receiving, I needed to take advantage of whatever sun was available.  Antenna erection day (today) was most pleasant--mostly sunny.  I probably shouldn't say much, because I see some evening showers coming towards the Hamakua coast.  Such is life.   Enjoy what you can.

Have a good, productive weekend.

Aloha es 73 de KH6JRM--BK29jx15