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 arch...@mail-archive.com
