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