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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. ======================================== Instead of using a balun and asymmetric matching unit (transmatch) I would suggest you use a matching unit to suit a twin feeder directly ,like the EZEE Match or the Link Coupler as per the ARRL Antenna Book of which I do have the 18th edition ,where the coupler can be found on pages 25-11 and 25-12. A variety of matching units to suit twin feeders can also be found on the web site of PA0FRI. In your current setup you could use a 1:1 Balun and clip a current sensor on 1 lead of the twin feeder to determine where there is a Current maximum for a mid-band frequency . For this purpose you might have to extend the twin feeder and coil the extension inside the shack. You would then possibly need a different length coiled up extension for different bands. Have a look at Cecil Moore's Web site . Frank GM0CSZ / KN6WH Frank GM0CSZ / KN6WH |
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