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The distortion of the pattern that I'm referering to is mainly due to unbalanced current in a driven element. Feeding a balanced, symetrical element with an unbalanced feedline, except in certain special cases, will create unbalanced current. If the currents are unbalanced, the pattern will be disrupted; always, not sometimes. Whether the feedline radiates energy into space or couples it into a tower leg, does not matter as far as the current imbalance is concerned. Please see Weeks, W.L. , Antenna Engineering, McGraw-Hill, 1968, for an excellent dicussion of the balun issue. If you got 20-30 dB of front to rear out of a 2 element parasitic, congratulations are in order; you are the new world record holder! 73, Ken wa4dou@juno.com wrote: > Ken and Natan > I'm sorry but i believe you're propagating a "can sometimes happen" > into a virtual certainty. I once built a 2 element yagi that had 20-30 db > of front to side and f/b ratio in all directions. It used no balun and > was a killer antenna to Europe and Africa and South America. Lots of > signals totally disappeared when to the side or rear of that antenna. > Your computer modeling programs today say thats not possible. They also > claim that feedline radiation is always a problem, it just isn't always > so. If feedline radiation had been a problem with that antenna and with > my present one, then it would manifest itself as skewed patterns and f/b > f/s degradation. It doesn't. I'm still going to try my EB-1 on my C3SS. > I stand by all i wrote and ,once again, i encourage others to > experiment with both possibilities and decide for themselves and report > their findings in appropriate amateur forums. > 73 Roy WA4DOU > ------------------------------------------------------------------------- > ------------------------------------------------------------------------- > ----------------------------------------------------------------------- > On Mon, 15 Jan 2001 12:36:51 -0700 Ken Hirschberg <calav@flash.net> > writes: > > Hello, Roy - > > Suggest you measure the feed line over a length of half a wavelength > > to determine what currents are flowing on the outside. Then install > > the balun and repeat the measurement. If you find currents flowing > > on the outside of the feed line, then rest assured the pattern will > > be > > skewed. > > 73, Ken > > > > > > wa4dou@juno.com wrote: > > > > > Hello Frank and the gang, > > > While considerable debate still attaches itself to the whole > > subject of > > > baluns, i'd like to remind folks, especially those who run > > considerable > > > power and have one or more failures associated with their use, > > that it > > > has hardly been demonstrated that baluns are necessary in many > > instances, > > > despite the fact that the "benefit" of the use thereof is > > conducive to > > > near perfect theoretical performance in the mind of the user. > > > I have a F12 C3SS on a 53 ft. tower and have used it for nearly > > a year > > > without any balun whatsoever. During most of that time, i've had a > > Cal-Av > > > EB-1 balun which i intend to install in the Spring. Then i'll have > > a > > > "baseline" with which to judge the performance and necessity of > > using a > > > balun in my particular installation. So far, my impression of my > > antennas > > > f/s and f/b performance is consistent with the performance > > expectations > > > of a typical 2 element yagi. > > > I have had other yagis and quads with which i've sometimes used > > baluns > > > and sometimes not. I've even experienced 2 element yagi > > performance > > > (without benefit of a balun) that far exceeded theory on both f/b > > and f/s > > > in all directions. And i've definitely seen occasions where baluns > > were > > > desirable and did effect positive results. > > > That said, i'd like to encourage users and potential users to > > suspend > > > judgement and to evaluate their antennas, with and without and > > report > > > their findings in various appropriate forums. Efficiency dictates > > that > > > the simplest installation that achieves the desired result is > > always to > > > be desired. As a radio communications technician and ham of 39+ > > years, i > > > believe i'm capable of making accurate scientific observations in > > this > > > case. > > > 73 de Roy Lincoln WA4DOU > > > > > > ------------------------------------------------------------------------- > > > > > > ------------------------------------------------------------------------- > > > > > ----------------------------------------------------------------------- > > > > > > ________________________________________________________________ > > > GET INTERNET ACCESS FROM JUNO! > > > Juno offers FREE or PREMIUM Internet access for less! > > > Join Juno today! For your FREE software, visit: > > > http://dl.www.juno.com/get/tagj. > > > > > > > > > > > > -------------------------------------------- > > Force12Talk mailing list provided as a service by Force 12 Antennas, > > Inc. > > Force 12 Web site: http://www.qth.com/force12 > > > > Submissions: send to Force12Talk@qth.com > > To unsubscribe: send a blank e-mail to Force12Talk-leave@qth.com > > Force12Talk Message Archive: http://www.qth.com/force12/list/force12talk > > For problems with the list, contact n4zr@qth.com > > > > > > ________________________________________________________________ > GET INTERNET ACCESS FROM JUNO! > Juno offers FREE or PREMIUM Internet access for less! > Join Juno today! For your FREE software, visit: > http://dl.www.juno.com/get/tagj. -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. 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