RF Shorts for July 12, 2013

The 'Perfect Antenna'? 

Ira Wiesenfield, P.E., and Roger Blouch, a writer at Urgent Communications, wrote "Here's the perfect antenna" on Urgentcomm.com this week. The antenna being described is for HF but the claims reminded me of the papers and debates over the “Cross-Field” antenna at past IEEE BTS Symposiums.

The articles states, “If you designed a perfect antenna, it would be an isotropic radiator with no nulls; it also would be able to work on multiple bands and have a wide bandwidth, so that antenna changes would be unnecessary as you change channels or bands. It would be compact in size (4-feet tall x 4-feet long x 1-foot wide) and not disturbed by metal or structures in close proximity to the antenna. Additionally, it would have a natural immunity to noise and other manmade interference. In other words, you would have the EH antenna manufactured by Madison, Miss.-based Alpha Cognetics.”

With that praise, it isn't surprising the authors were hired by Ted Hart, the inventor of the antenna, to evaluate it. The results look good, but I'd be interest in a critical review of the theory behind this compact antenna.

More information is available on the Alpha Cognetics web site. The price is $6,995 for a 3.5-8.0 MHz auto-tune roof mount antenna. A portable version for the same frequency range is $7,995. In the article Wisenfield and Blouch note that once you consider the cost of towers for support and installation for other HF antennas for the same frequency range the price is competitive.

I'd be interested in knowing if the same techniques could be used effectively to improve VHF reception in hand-held devices!

Doug Lung

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.