Monday, June 25, 2012

Simple Antennas for Amateur Radio Operators--a continuing series


The July 2012 issue of "QST" contains an interesting antenna article by Jeffery Brone, WB2JNA.  The article entitled "A Dipole Doesn't Have to be Straight--There's always a way to put some kind of antenna into service" runs from page 36 to page 37.  Brone's idea may give you another way to get on the air despite severe space restrictions.

Simply put, Brone ran approximately 35 feet of light gauge wire (#22 or #24 AWG) to  a balcony of his third floor apartment and ran another 35 feet around the apartment, "tacked up along the ceiling and corners, resulting in a full size dipole for 40 meters."  He fed the antenna through a MFJ manual tuner with  3 feet of homemade laddder line (2 inch spacing between the wires)  "and it loads up on all bands--40 through 10 meters."  Running low power (15 watts cw), Brone has been able to work Chagos Island, Africa, and South America.

Brone says common sense applies when you use this homebrew antenna--avoid folding the wire back on itself and use low power to minimize RFI and exposure to RF.  Brone concludes his excellent article with what he calls the "10 rules of stealth/apartment/restricted antennas":
"Something for an antenna is better than nothing."
"More wire is usually better than less, unless the antenna is only meant for one band."
"Balanced (center fed dipole or vertical) is better than unbalanced (end fed wire), all other things being equal."
"All other things are seldom equal.  Try different arrangements.  Read up on the subject."
"Get a tuner.  A low priced manual one is okay.  You'll want it for some bands and will appreciate the flexibility it gives you."
"Get a dummy load, too."
"Keep the power low for safety and less RFI."
"CW and digital modes produce more contacts than SSB."
"Listen, listen, listen."
"Put up the best antenna you can manage, then get on the air and have fun!"

Indoor antennas do work if you allow for their limitations.  When I first became a Novice operator back in 1977, my first antenna was a 70-foot loop tacked to the ceiling of the teacher's cottage my wife and I shared in Honokaa.  Fed with 300-ohm twin lead and hooked to a balun and a Drake MN-4, the homebrew loop did a good job on 40 and 15 meters.  I still have the old Drake MN-4, so I guess the tuner survived my initial efforts at antenna design.

Now, I have an inverted vee, an "upper and outer" vertical with counterpoise, and an under-the-house 40 meter loop.  My small backyard can just accommodate the vertical and the vee.  I suppose I'm luckier than many who face CC&Rs, HOAs, and no backyard space.  Give this bent dipole of WB2JNA's a try--it could open an entire new frontier for you.

Aloha es 73 de KH6JRM--BK29jx15