Walter Maxwell’s interesting book, “Reflections”, has an in-depth discussion on non-resonant antennas and tuners. Highly recommended.
73, Ted, W2ZK On Sat, Jul 18, 2020 at 10:05 AM Lyn Norstad <l...@lnainc.com> wrote: > Exactly. > > -----Original Message----- > From: W2xj [mailto:w...@w2xj.net] > Sent: Saturday, July 18, 2020 7:37 AM > To: l...@lnainc.com > Cc: barrylaz...@gmail.com; elecraft@mailman.qth.net > Subject: Re: [Elecraft] Matching resonant antennas > > What is changing is the radiation pattern. As the frequency increases the > pattern becomes more sidelobes. Some of those sidelobes are bigger than the > main lobe and they radiate ‘somewhere’. > > Sent from my iPhone > > > On Jul 17, 2020, at 21:19, Lyn Norstad <l...@lnainc.com> wrote: > > > > Barry - > > > > +1 > > > > I use nothing but 600 ohm OWL (True Ladder Line) and a short piece of > coax connects to a 1:1 / 4:1 hybrid balun to allow matching the impedance > perfectly with my KAT500. > > > > The antenna is a 360' center fed EDZ (design frequency of 3.5 MHz). The > KAT500 matches it on all bands 160 - 6m (on 15m, it bypasses). > > > > The measured performance indicates excellent radiation on all bands. > > > > 73 > > Lyn, W0LEN > > > > > > -----Original Message----- > > From: elecraft-boun...@mailman.qth.net [mailto: > elecraft-boun...@mailman.qth.net] On Behalf Of Barry LaZar > > Sent: Friday, July 17, 2020 7:44 PM > > To: elecraft@mailman.qth.net > > Subject: Re: [Elecraft] Matching resonant antennas > > > > Wes, > > > > You're correct that open wire/ladder line transmission lines are > > not a panacea. But, in the average ham stations, open wire does overcome > > high losses with high SWR, or not so high SWR. What is needed is a look > > at the ARRL Antenna book for transmission line loss/100 ft. as a > > function of SWR. You see that on 10 meters running 10:1 SWR the total > > loss is around 1 db. And, as you go to the lower bands, losses become > > less. Typical 400 Ohm ladder line has a loss of 0.2 db at 10 MHz and 0.6 > > db at 100 MHz. Using these data and a little interpolation, I would use > > 0.4 db on 10 meters and a 10:1 SWR for this to be 0.8 db of additional > > loss for a total of about 1.2 db. Yes, I do use a balun and recommend > > them so add another 0.5 db. Add another 0.5 db for a good tuner and we > > end up with a total of 2.2 db. on 10 meters and less on 20 and it > > decomposes to an academic exercise on 40 and down. > > > > Coax on 10 starts out with a higher loss/100 feet. I will use what > > I use here in K3NDM, Times LMR400. That represents 0.4 at 10 MHz. and > > 1.4 db at 100 MHz. That will yield about 1.2 db/100 ft on 10 meters. Add > > 0.25 db for a 2:1 SWR and 0.5 for tuner loss and you end up with about > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to ted.roycr...@gmail.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
