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![]() "Priz" wrote in message ups.com... I'm pressed for space outdoors so right now, I'm working with attic antennas and need some help. I was able to put a 60 foot loop of wire into my attic and am not having much luck getting it to load up. I configured the loop as an open loop, aka a dipole bent into a rectangle which is open at one corner and fed with 300 ohm twinlead at the other. I'm using an MFJ 911H 4:1 and 1:1 balun to tranform the twinlead to coax and a homebrew antenna tuner. Using an SWR analyzer, I find the only place I can get low SWR is near the 15 meter band and some frequency ranges above it, like 6meters and 2 meters. I was hoping the 60 foot length would help me get down to the lower bands with some compromise, but at least I was hoping to get there. The transmatch, which consists of 2 capacitors and 2 inductors isn't any help at all. I've used it in the past to load up random wires and such, but this project doesn't seem to be working. Anyone have any experience with this sort of antenna? Let me know what it is I'm doing wrong. Any advice is appreciated. An open loop is supposed to be 1/2 wavelength. A closed loop is supposed to be 1 wavelength +. A closed loop will sort of work on EVEN harmonics. Using a 4:1 balun is probably wrong, as is the 300 Ohm line. For 20 meters you would need about 72 feet of wire in a closed loop, 1:1 balun, and 1/4 WL of RG11, feeding into a random length of RG8. SWR will be less than 1.5:1 at resonance. For 40 meters you could use about 65 feet of wire in an open loop, fed with RG8; haven't tried this, but I think the SWR will be less than 2:1. Tam/WB2TT |
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