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----- Original Message ----- From: Barry Kirkwood <bjk@ihug.co.nz> To: Bill Vogler <vogler@innercite.com> Sent: Friday, 15 December, 2000 10:01 AM Subject: Re: [Force 12 Talk] Linear Loading > Hello Bill et al. > Interesting questions. > I seem to recall people using the term back in the 60s. > > There are professional papers on lots of ways of shortening antennas with > distributed loading eg "Zig Zag" where the linear load could be considered a > single zig or inductive load by a trombone or U inductance instead of > multiple turns. > > If this approach is valid then the L of the linear load would equal the L > needed to achieve resonance by any other means. Hence no black magic. > > My intuitive approach as well as the above is to imagine the currents in the > legs of the antenna and linear load. This would give two legs with currents > aiding and one leg with current opposing. > > If this intuition is correct, the linear load would be lossless to a first > approximation as 2-1=1, neglecting other losses. > > Am no expert, but believe one of the highpower modelling programs like NEC > might handle linear loading. > 73 > end > Barry Kirkwood PhD ZL1DD > Signal Hill > 66 Cory Road > Palm Beach > Waiheke Island 1240 > NEW ZEALAND > www.waiheke.co.nz/signal.htm > ----- Original Message ----- > From: Bill Vogler <vogler@innercite.com> > To: <Force12Talk@qth.com> > Sent: Friday, 15 December, 2000 9:08 AM > Subject: [Force 12 Talk] Linear Loading > > > > Hello - > > > > I just got back into ham radio from a long layoff (1981). Around 1982 I > did > > graduate work at the MSEE level and took quite a few courses in > > electromagnetic theory and antennas. In those courses I don't remember any > > references to linear loading. > > > > What is linear loading? After reading both the ARRL antenna handbook and > > ON4UN's low band dxing book it appears that linear loading is some black > > magic technique to make an antenna mechanically shorter. Are there any > > references available that discuss this both intuitively and theoretically > so > > I could have a better feel on what is going on? Is linear loading the > > accepted name in academia, or is it referred to by some other name? > > > > Secondly, how do the designers at F12 and other companies model the linear > > loading circuits? Do they model it as discrete circuit components and > throw > > in some 'fudge' factors, or is there some analysis codes that can handle > > this situation? Boy that would be fun modeling my c4sxl with the electric > > field integral equation (EFIE) from scratch. I think I'll get right on > that. > > > > 73s > > > > Bill, w6qd > > > > > > > > > > > > -------------------------------------------- > > 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 > > > > > > > -------------------------------------------- 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 |
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