Worked All Plymouth
About a week ago, Tom, KE8HUM, answered my CQ. He lives in Plymouth, MI, only 12 miles from me, according to QRZ.Com. He apologized, but I enjoy working guys no matter where they are. He’s a member of our club, a nice guy, and I have his QSL in my collection of QSL cards from stations whose call signs spell words.
About an hour and a half later, I was still down in the shack and worked Gary, K1YAN, Plymouth, MA. I joked with Gary that I was going for the “Worked All Plymouth” award, but, as it turns out, I have a long way to go. According to the Boston Globe, there are 30 cities in the U.S. alone with the name Plymouth.
Even so, if you live in one of those Plymouths, let me know, and maybe we can set up a sked.
Another coincidence
A couple of days ago, I happened upon VP5/AF3K down in the Turks and Caicos Islands. After a quick “TU 599” contact with him, I worked Bry, AF4K in Florida. Coincidences like that are always amusing.
Speaking of Bry, we worked a couple weeks ago as well. During that QSO, which was kind of tough due to poor conditions, he remarked, “You can’t buy propagation.”
DLM antenna
Another recent contact was Rob, K1DFT. As I often do, I called up his QRZ.Com page, where I found this sentence, ” Holds numerious patents world wide in antennas and antenna development and also invented the DLM Antenna technology.”
After our contact, I Googled “DLM antenna” and found a bunch of references to news articles in the 2004-2005 time frame,one even published by the IEEE. After reading a couple of the articles, it all came back to me. At the time, there were a lot of claims about this invention, which he claimed could reduce the size of the antenna by 70%, while maintaining, or even increasing, bandwidth.
Of course, as it turns out, the claims were too good to be true. While there certainly may be some value to this particular design, it’s not as revolutionary as some of the hype would lead you to believe.
This kind of thing seems to happen with some regularity. The latest being the spray-on antenna that was being touted six or seven years ago. The moral of the story is don’t believe everything you read, even in prestigious technical journals.
Dave New, N8SBE says
The DLM antenna article is apropos April 1.
Rob Vincent says
Dave, the DLM antenna is very real and works very well. If you or anyone else use a remote keyless entry to a Ford you are using a DLM antenna. About 10 million have been sold to Ford Motor Company
_Jim says
Uhhh … you fell into the common trap, Dan. Reading a bunch of tripe from the individuals who are ‘self-appointed experts on all things antenna’. I became dis-abused of the notion that ONLY a 1/4 wave antenna was efficient when I went and studied in-depth the Kinstar broadcast antenna, and in particular, their field strength tests of the Kinstar reduced-height broadcast antenna and a full-sized vertical. In the same vein, the DLM by K1DFT was tested at the Navy’s sea water test range, and compared within a dB or so of expectations from a QW antenna, BUT, you don’t read that from ALL the SAEs (self appointed experts) on the web.
I see no reason to ‘die on the cross’ debating this, when I find it advantageous to use his DLM design (I’m one of the few who actually built and tested one on 40m WSPR a few years back) I’ll do so and leave the SAEs to debating how any angels can dance on the head of a pin.
Dan KB6NU says
Over the years, I’ve seen all kinds of reports of magic antennas that seem to defy the laws of physics. It just seems to me that if there was real value to these claims, aside from some very specialized applications, that there would be hundreds, if not thousands, of hams using these antennas, and you’d be able to buy them on eBay, if not from DX Engineering or HRO. Also, there would be at least a half dozen articles in QST or on eHam.net by now showing you how to build one.
_Jim says
Dan, how many Sterba Curtains does DX engineering sell? Yeah … my point.
Hams aren’t as “technical” (they are also CHEAPSKATES too) as you think, and having to tune more than one ‘parameter’ on an antenna can stump them, THAT’S WHY dipoles made out of 12 ga. THHN continues (exc for those stinky, lossy end-fed MyAntennas) …
Get familiar with the Kinstar broadcast antenna, that’s where my ‘set in concrete’ thoughts about antennas was changed. I still subscribe to ‘BES’, Bandwidth-Efficiency-Size, pick any two the the 3rd is a compromise … but in comparison to a full-size QW vert SOME compromise is possible; not ALL of a QW vert is involved in radiating energy. That’s where the DLM and it’s top loaded structure comes into play in conjunction with the lower Helix structure.
I have also built and tested the so-called EH style antenna, and here again I got results, but, in a configuration slightly different from those of Ted Hart. I tested with a feed system that was balanced, to eliminate feedline radiation … these tests are not as easy to perform at HF as at uWave freqs, but using WSPR one can get results with which to draw conclusions. Some hams claimed the EH was 10, 20 dB down, I saw, with my compromises (the test antenna was only 5 feet above ground!) maybe 5 dB average worse WHILE some dx ‘paths’ were showing equal … chalk it up to differences in polarization and path being worked. These tests on 40m with the EH were against a dipole at ~30 ft, so that accounts for some of the EH loss at only 5 ft.
BTW, the EH does not, IMO, work the way Ted Hart says they do … but that’s a story for another time (look up a similar “bipole” design by 9A4ZZ. Note in particular his radiation pattern, Yeah, I saw that same pattern.)
Not everything is as the SAEs say they are … okay, why am I here spilling ‘secrets’ I worked hard to discover? Dunno … glutton for punishment I suppose …