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On Nov 15, 5:49*pm, Jeff Liebermann wrote:
On Sat, 14 Nov 2009 22:23:05 -0800 (PST), Art Unwin wrote: Cebic found when comparing different style programs that some behaved well in certain circumstance where others did not. True. *When circumstances dictate that I pay attention and I'm in a good mood, most programs behave normally. *However, when circumstances are not so favorable, such as last week when I replaced my septic tank, all of the software I was using literally stunk. Fact is that most users use fractional wavelength designs, usually a half wavelength, that is not resonant at repeatable points where the area around the datum line of a sine wave is never equal when generated around a tank circuit. Last time I checked, the definition of a half wave automagically includes any external or magical factors that might change its length. For example, if you submerge the antenna under water, the increased dielectric constant will cause the half wave length to somewhat shorten. *While the previous length has changed, the new shorter length is still a half wavelength. Very true, but the measured length is never repeatable. Only at the point of a period is where it is repeatable which is how a cycle comes into being. The reason for this is "voltage over shoot" which gets smaller with every cycle but never disappears. Overshoot can easily be fixed with a Cutts Compensator. http://en.wikipedia.org/wiki/Cutts_compensator Ofshoot can be essentially removed or minimised by just the addition of a resister but such methods are not included in antenna computer programs. Every time you cycle your antenna, the recoil tends to make the barrel climb a bit. *This is the cause of the overshoot. *A suitable Cutts Compensator attached opposite the feed point should help prevent overshooting the target. Thus when programs are used based on fractional wavelength radiators the results will never show 100% accountability and in fact efficiencies derived will be in the order of 92%! 95.718% of all statistics are wrong. *If you're using single digit accuracy and single digit significant figures, 92% rounded off is equal to 100%. Again what ever trips your trigger, horse shoes or Maxwells equations. Only when accurate metrics are inserted in a program can the accuracy of Maxwell's equations be shown and the half wave length can never be stated accurately. If the radiator is of a wavelength then one is not using a "fudge" figure in the calculations and *then becomes possible to attain total accountability with efficiency of 100%. regardles of what type program is used. Half wave wire dipoles do tend to be resonant somewhat shorter than the free space wavelength. *That's due to sales and value added tax placed on antennas by the government. *You'll always come out a bit short when dealing with them. *However, the last time I checked, the cut length was only about 5% shorter than the free space half-wave length. *Did the antenna tax increase to 8%? If one is to use exact equations, as are Maxwell equations, then one must also use measurements that are also exact and repeatable and that is definitely not fractional wavelengths! My antennas are exact and repeatable. *Not only that, I can also repeat my mistakes every time. Yes you have shown evidence of that. What one gains from this aproach is that any radiator of any shape, size or elevation can provide figures in the order of 100% as long as the radiator is a multiple of a wavelength where it is *resonant at exact and repeatable measurements. Perhaps. *If you buy your antennas out of state or on eBay, you can avoid paying the 5% antenna length tax. *However, you are required to pay Use Tax on any out of state purchases where the vendor neglected to collect the antenna tax and forward it to the Calif Franchise Tax Bored: http://www.ftb.ca.gov/current/usetax.shtml If anybody can give pointers that refute the accuracy of the above I would be very interested in hearing them Why? *You haven't proven your point, demonstrated the phenomenon, or otherwise provided anything worth tearing apart. *For all I know, your antennas are shorter than expected because of magic, enchantment, sloppy construction, mis-measurement, or all the aforementioned. Anyway, the problem is easily solved. *Just increase your AC power line voltage about 5% and your numbers should increase by the same amount. Maybe true but physics demands accuracy which explains the heavy useage of constant added to justify the use of an equal sign. Same thing goes for the myriad of particles invented that are not seen or measurable. This because those who delve in physics sometimes replace a constant with a new invented particle that can substantiate equilibrium or its cousin "equal" -- Jeff Liebermann * * You know, a well known former ham Stephen Best got hold of a new antenna program that had strict adherence to Maxwells laws. The program relied on Poynting circle as being representitive for all forces in radiation. The program ,probably more than I can afford. produced a radiator that was not straight according to the old wives tale that is propagated by hams. It showed something like a tennis ball where multiple wavelengths of radiator were stuffed inside and where balance or equilibrium was obtained. In his study which was around a half wave radiater produced a radiation pattern that was a perfect hemisphere that all on this group stated was impossible to attain. ( actually it was based on a full wave where the ground plane supplied the mirror image) Possibly in our time, that will make it into the newer physics books, that will force the re thinking of radiation. This paper is on the WWW but I leave it to you to show that it must be in error as it is not yet in the books! At the same time opponents will bring forwards Toms adage W8TI, that for maximum efficiency a radiator must be straight, thus leaving him with the onus of showing that Steven Best efforts were all wrong by the use of the soon to be corrected theory corrections before old theories are fully discounted where all may read it for themselves in a book. Art Art 150 Felker St #D * *http://www.LearnByDestroying.com Santa Cruz CA 95060http://802.11junk.com Skype: JeffLiebermann * * AE6KS * *831-336-2558 |
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