Thursday, July 28, 2011

Simple Antennas for the Hawaii Amateur Radio Operator, part 6

Here are a few more unusual and somewhat offbeat antennas I've used with varying degrees of success.  All of these "creations" work to the extent that you will get some contacts.  I've lived in a few challenging places where amateur radio antennas were never part of the landlord's world view.  Although my current qth is quite nice, it is still restricted to a small lot shared by 3 other modest rental homes and is approximately 20' away from utility poles.  With all of the salt air and moisture found on Hawaii Island, you can imagine the corona discharge problems I face several times a year.  To be fair, the Hawaii Electric Light Company does its best to keep the transmissions lines inspected and cleaned.  On an island with about 4,000 square miles, line maintenance is a major headache for the telephone, cable, and power companies.

In my antenna book for 2002, I found a stop-gap antenna that served me well while the backyard was being torn up for a new septic tank and water lines.  In place of a normal radial field for the trusty 40-meter vertical, I attached one line of the 450-ohm twin lead to the antenna and the other to my qth's metal roof.  The roof was bonded together.  After I scraped off a bare spot and attached the other lead, I fired up the old Swan 100-MX (20 watts or so).  With the help of my trusty Drake MN-4 ATU, I was able to get a decent match on all bands between 40 and 10 meters.  Nothing spectacular, but the substitute ground plane seemed to work.  I was able to make my infrequent appearance on the daily 40-meter interisland net with reports ranging from 56 to 58 on ssb.  Once the backyard work was done, I restored a normal ground system and painted over the roof area used for the antenna connection.  I'm not sure how efficient this antenna system was, but it did allow me to get on the air.

Recently, I've tried out a system used by many recreational vehicle owners.  I had an old mag mount with a 20-meter "Ham Stick" in the garage.  While the Odyssey van was parked on the lawn for a car wash I never did complete, I placed the mag-mounted "Ham Stick" on the van's roof, attached four, 16.5 ' radials to the antenna mount, and ran some RG-8 into the qth, and began a fun afternoon.  This primitive system worked well and I made several decent (57) ssb contacts to the U.S. mainland.  SWR was fairly low across the band (1.7 to 1).  With the ATU in line, I was able to improve the swr a bit.  Again, nothing fancy, but the lashup did work.  Once I figure out how to mount a permanent antenna on the van, I can use that system as a backup to the rig in the house.

The weekend lies ahead and that means some operating time.  Aloha es 73 de KH6JRM.