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On Jan 4, 11:54*am, Richard Clark wrote:
On Wed, 22 Dec 2010 05:13:39 -0800 (PST), Richard Fry wrote: Observations from watching the YouTube video... The gain units used in the video are therefore unconventional, and need further definition. Hi Richard, Leave it at unconventional - that word's definition is well understood. 3. The relative field radiated by a conventional 1/4-wave vertical monopole driven against a perfectly conducting ground plane always is maximum in the horizontal plane. Such a system radiates virtually 100% of the matched power applied to its input terminals. This reveals a common flaw found in vertical antenna analysis when compared to AM antenna measurement conventions. *Simply put, if you lift the antenna off of an infinite plane, you lose 3dB. *It is demonstrable with even the meagerest of antenna modelers. Chip's antenna is in the air, not on an infinite plane. *A solid disk replacing a field of radials does NOT constitute a replacement for an infinite plane such as to recover the 3dB. *This might account for the bookkeeping error in the vendor's favor. I believe somewhere in the tightly scripted presentation it was asserted that there was no "figure 8" pattern as one would expect of an antenna in free space. The antenna is "apparently" in an anechoic chamber - or free space as closely as can be approximated. *There are no reports of the far field envelope shape. So let's mark it up to Chip's usual technique of loose suggestion being passed off as a citation to then be wrapped back as a proof. Therefore the peak gain of that antenna system at resonance cannot be improved by putting a sleeve of any kind on the monopole. I would dispute that. *The evidence is sufficient insofar as the indication of change in the before/after display on instrumentation. Unless this is some form of parsing what "peak gain" means. *What you write immediately following already conforms to that instrument display: The sleeve may change the shape of the radiation pattern of the system without the sleeve, though, which could change the field intensity at the location of the receiving antenna used in the test. This could account for the ~3 dB improvement shown in their results when using the sleeve. And by what you say above, this is the entirety of it. *A thicker radiator - nothing less than has been covered in text for decades. You observe that below. 4. Nothing is shown in the video about the amount of matched power at the feedpoint with and without the sleeve. If that is not held constant then the test will be flawed. The instrumentation already takes care of that, and is discussed early in the presentation. *I was doing this kind of bench work, with this kind of instrumentation, in this band, 20 years ago. 5. The VSWR bandwidth of a monopole may be increased simply by using a larger cross-section conductor of "non-fractal" construction. Of course - but that information doesn't sell product. 73's Richard Clark, KB7QHC He is using a resonator to drive another radiater ( see constant impedance antenna system patent) The radiator that he is driving is of multiple wavelength as in a wire mesh where the multiple routes that can be taken by current flow provides an ultra wide frequency span as the reactance changes become smaller and smaller. The final radiator is a full wave or more closed circuit version which provides more gain than a fractional length over a ground plane Very simple use of a metamaterial which has been demonstrated in most universities of the day. |
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