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On 23 May 2005 14:27:05 -0500, Allen Windhorn
wrote: Anyone seen this particular combination? Appears to have very good performance. Hi Allan, Alas, yes, and nothing seems to have improved over the months - same spelling errors, lax reporting, sloppy presentation, and a smattering of conflicting claims: "Vincent’s Plano Spiral Top Hat antenna at 7 megahertz is half the size of a normal quarter-wave antenna operating at that frequency. :Note it says half the size, later this will be changed The URI antenna gain matched the performance of the ideal quarter-wave antenna, and its bandwidth was nearly twice as wide. :as usual, no specifics offered, later this "twice" will be changed. ... "In addition, the gain of Vincent’s capacity Top Hat DLM antenna, :in addition to WHAT? which incorporates a helix, a load coil, a capacitive top hat :it incorporates 3 items? or 2? Is the helix the coil? More change follows. utilizing radial spokes at the top of the antenna and a horizontal plane was nearly identical to the ideal quarter wave antenna. Its bandwidth was greater than 5 percent of the operating frequency :not twice the bandwidth anymore (and not even close to standard BW) and the antenna is more than 70 percent shorter than an ideal quarter wave antenna. :not half size - 30% size, but this changes again. "Vincent’s standard DLM antennas with a standard helix and load coil were also tested at various frequencies. All exhibited gains :it incorporates 2 items? Standard helix is the former coil above? nearly equal to the ideal antenna with bandwidths of 3 to 10 :well, what exactly is being compared to here? Ideal is 3? or is it 10? percent. The antennas were 33 to 40 percent shorter." :now we are LARGER than half size Let's see, we have a 30%, half size, 67% tall radiator with 3 (make that 2) loads that matches (nearly) the gain performance of a standard antenna exhibiting somewhere between 3% and 10% bandwidth. I note that the link (sic, the poor html authoring makes this simply a text inclusion) to the Navy test site is NOT to the Navy Test Report, but simply to the Navy test site (even the cfa web pages can produce a link like that). Tedious puffery at best. 73's Richard Clark, KB7QHC |
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