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On Thu, 18 Sep 2008 06:59:35 -0700, John Smith
wrote: In building antennas, tank ciruits, etc., I very seldom whip out a programmable scientific calculator and delve into the depths of the maths which allow them to preform/function/"work." And what do you do when they don't work? Cut-n-try is a rather expensive way to build something that works. Given infinite time and materials, it will eventually result in a functional antenna. You could probably do that at HF frequencies where construction errors are about equal to calculation errors. However, don't try it at microwave frequencies. While it's possible to cut-n-try various microwave structures, it's messy, difficult, prone to error, and not very effective. The techniques used to build a coat hanger ground plane at VHF just are not going to work at X-band. The only way to get it close to right the first time is to calculate first, calculate again, have someone check the calculations, drink some wine, and check your calcs again. Then build it. A few times, I have just grabbed up some tubing/wire a variable condenser or two, and "eyeballed" the construction--past experience provided "ballpark" figures/placements/wiring, testing, trimming and adjusting got me the final result ... Yep. That will work at HF because the lower frequencies allow for much larger construction errors. Your antenna lengths could be off many cm and still work. Your xmitter can also tolerate a substantial VSWR and still be considered functional and useful. You match box could be grossly inefficient trying to match your constructed antenna, and work well enough. Now, try that at microwave frequencies, where every milliwatt is precious, where VSWR is too crude and reflection coefficient comes close to describing the ultimate goal of a perfect match, and where cm errors are disastrous. Some broadband antennas (helix and horn) are very forgiving and can be build fairly crudely. Others (stripline, phased arrays, cavity backed antennas, etc) have a higher Q and require more accuracy than the eyeball can provide. Mainly, I point this out so as not to "obsfucate" that layman, or discourage him ... the men who first started/awakened my interest in such things never gave any indication, to me, they had an understanding of calculus, only basic-math/algebra, and of course, geometry! Same here. My original mentors were operators first and technical types last. However, I saw the light (and the distinction) between amateur and professional when I went to college and saw that radio things were easier and better if they were calculated (and understood) first. I have several humorous examples of hams operating in a professional environment (engineering lab at a radio manufactory) and failing miserably using cut-n-try methods popularized by ham radio. Indeed, at least one passed away without ever expressing any real interest in learning it! There are suspicions that math may hasten one's demise. Perhaps he tried to do a calculation before he died? However, in Arts pursuits, an understanding would be a real advantage ... Agreed. Once he gets that understanding, he can work on the communications problem. Perhaps publish his works. After solving all that, he can possibly consider the applications and implementations. The twisted road towards technical nirvana is littered with the wreckage of failed great ideas. Incidentally, I was also going to bash your suggestion of ignoring patents. Might as well add that to my rant. Patent are confusing. Many of them are totally bogus. It's difficult to recognize the difference. However, at the bottom of every garbage dumpster lies a diamond. You have to sift through a huge amount of garbage in order to find the gem, but it's worth it. Just because a typical patent search returns bogus patents, doesn't mean you should ignore them. Most technical patents are legitimate and worth inspecting. If you want to know exactly how something works, the patents are the place to start. I haven't had time to look at the quantum comb filter antenna thing, but plan to do so eventually. During the dot.com heyday, I was doing sanity checks and technological assessments for a venture capitalist. Many business plans had technical problems. Some were based on bogus patents. Some held conflicting patents. Identifying these was more than the VC's staff could handle. I did fairly well, but still managed to miss a few. Anyway, sifting through patents was part of the exercise and a great learning experience. Often, a patent looks legitimate, but has a fatal flaw or omission in the middle of the claims. It's not easy. If you have the patience, it's possible to find these. Also, I assembled a small list of tech patents that appear to be bogus. I was going to post the list on the web but my attorney advised against it. Even holders of bogus patents can sue for damages. Oh well. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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