On 9/30/2012 5:37 AM, [email protected] wrote: > So am I correct in my understanding or just totally out in the weeds.
There may be more to it than that. First, no matter what feedline or matching system you use, there should be a serious common mode choke at the feedpoint. Second, is this a single band loop, or a multi-band antenna? The feedpoint impedance is likely to be very different on each band. A section of transmission line is often a better matching technique for single band antennas. For a multi-band antenna, it would help to know the feedpoint Z on all bands and choose a feedline on that basis. The length of the line can also be an issue. This is the sort of question that is best answered by constructing a simple model of the antenna using EZNEC. A stripped down version comes free with the ARRL Antenna Book, and is sufficient to model a simple loop at the level you need, and you can buy a more capable version for about $50. One of the major reasons for choosing some feedline other than coax is that higher impedance lines have lower loss. This matters a lot more for long runs than for short ones. Decent 4:1 impedance transforming "baluns" are not cheap, and many hams would be better off spending that money on better coax. 400 ohm line may have much lower loss than coax if the feedpoint Z is 500 ohms, but coax may have much lower loss if the feedpoint Z is 10 ohms. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
