Tuesday, July 26, 2011

Simple Antennas for the Hawaii Amateur Radio Operator, part 5

One of the things I've enjoyed most about being an amateur or ham operator in Hawaii is the fairly consistent good weather for building and erecting home-brew antennas.  Other than our rainy season (November to March, generally), antenna experiments can be done in an unhurried fashion.  Since I'm not the most mechanically inclined operator, I need all the time I can get to make something that works.  In the 37 years since I was a novice class ham, I've built a large number of skyhooks that were just plain awful and a few others that were gems--largely because they worked despite my "cut and trim" approach to the art of antennas.  Over the past 3 decades, a combination of study and gradually increasing technical skills have enabled me to erect a number of antennas that not only look presentable, but also do a decent job of launching rf into the "ether".  While most of my antenna projects have been modest because of space restrictions, I've managed to make simple loops, verticals, and dipoles that give me hours of pleasure.

Occasionally, I run across a few antenna designs that can best be termed "unusual" or even bizarre.  When I pulled out my antenna notebook for 1997, I discovered an intriguing design by K3MT called "Grasswire Antenna:  another approach to hidden rf antennas."  The antenna first appeared in an April 1997 internet post.  Basically, K3MT end-fed an 85' piece of #12 gauge insulated wire through a trifilar balun wound on a T-200-2 core.  He laid the wire on the grass and attached a counterpoise wire (he also used an 8' ground stake as an alternative to the counterpoise).  He ran some coax to his shack and voila!  He had a wire that seemed to work fairly well.  His article contained a number of graphs which seemingly demonstrated how well the antenna worked.  His attached log showed a string of 559 to 599 reports from many stations.  He also designed a "grass" off-center fed dipole for those that prefer a G5RV or dipole configuration.  Whatever the limitations of this antenna might have been, it was a winner from the stealth point of view...out of sight, out of mind for nosey neighbors and HOAs.  K3MT said he could just roll up the antenna when he was done.

With all that in mind, I made a "quick and dirty" 20-meter dipole, fed it with RG-8 coax, laid the contraption on the front lawn, and attached the "ground warmer" to the Drake MN-4 ATU.  I actually made a few 20-meter contacts on Saturday afternoon.  Nothing fantastic (539 to 559), but I did make a few qsos.  Of course, I did a lot better when I attached the dipole as an inverted "vee" to my 33' pvc mast.  I don't know if this sort of antenna would be useful to those of  you facing severe operating restrictions.  You may want to experiment with this idea.  Who knows?  This antenna could give you an alternative to not operating at all.

Now that the news shift is over for the day, it's time to head home for a few hours of operating time.  Have a good day and get on the air.  Aloha es 73 KH6JRM.