ea7qd
New Member
Posts: 7
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Post by ea7qd on Apr 16, 2015 16:50:25 GMT -5
Hi all, I recently installed an antenna type OCF (80/20, W8JI). The greater length is 33,40 m and shorter part 8,35 m. The antenna is fed by a 12,25 m home made open line. I've used my AIM 4170 to determine the impedance at the end of the line. And here is the problem. The end of the line is very close to the radio room and only I have to use a short length (4,5 m) RG-58 between the analyzer and the end of the line. I have made two measurements. The first with a balun 1:1 at the end of the RG-58. The second one, without balun. Obviously, the results are different. In my opinion, this antenna is not symmetrical and the correct measurement should be made without balun. But I'm not sure. What is your opinion? Thanks for your comments. José , EA7QD
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Post by Bob on Apr 18, 2015 14:39:08 GMT -5
Hola Jose, It would be interesting to see which measurement method gives results closest to the modeling results from a program like EZNEC. It is possible to mount the AIM right at the feed point of the antenna. In that case you want to put a balun on the comm line to the PC. A 9V battery can be installed inside the AIM case, if desired. There is a picture showing this in an application note included with the AIM software package. Click: Help -> Applications ->Connect to Antenna.
--73/Bob
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