Monday, June 6, 2016

Simple Ham Radio Antennas--2 Meter Loop Antenna. Post #798.


If you're having difficulty viewing this video, please insert this title link into your browser search box: https://www.youtube.com/watch?v=ZEzSlUqPEWw.  Sometimes, a mistake can turn out to be something interesting and useful.  In this video from KB3TQO, an experimental 70 cm loop antenna was enlarged by accident and turned into a nice, wide banded loop antenna for 2 meters.  As some readers have pointed out, the antenna may be wide banded because of the ferrite balun used in the antenna.  At VHF frequencies, this balun will serve as a dummy load, leaving only a few watts or less to become a usable signal.  The antenna would be more efficient if the 4:1 balun was made from coaxial cable. However, the antenna tunes nicely, presents a good load to the transceiver, and does get contacts on the 2 meter band. Part of the fun of amateur radio is designing antennas such as this, even if there are significant losses in the design.  We learn from our mistakes. With a few minor changes, this antenna will be a winner.

When I was a novice licensee in 1977, my first HF contact on 40 meters (7.125 MHz) was made using a Heathkit Dummy Load.  I was testing my HW-101 and was trying to adjust the drive and plate current by transmitting CW into the dummy load, not expecting anything unusual.   Lo and behold, a ham a few miles away answered my shaky "CQ" and gave me a 549 report!  I was quite surprised by all of this. I managed to carry on a very slow conversation for 10 minutes or so and got a chuckle from the other ham when I told him my antenna was a dummy load.  One never knows where your signal will go, even if you use a dummy load just to tune up.  So, congratulations to KB3TQO for daring to experiment and having some fun.  His antenna works, despite the ferrite balun.

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