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Based on another thread a few weeks back in which Horizontal dipoles
were being compared to Vertical antennas, and from a little chiding from Roy, W7EL, I decided to do some testing on my own personal versions of the two. My setup is: Icom IC-761 Antenna 1 - Homebrew OCF dipole at ~ 50 feet. Antenna 2 - Butternut HF6V -ground mounted and 18 radials on the ground. Part one of this experiment is to calibrate the S-meter. I found that trying to calibrate the thing with on-air signals was a nuisance, and probably wouldn't be as accurate, so I used a signal generator. I started out with a +20 signal, then worked my way down. +20 start S9 -18 db S8 -23 db S7 -26 db S6 -29 db S5 -32 db S4 -35 db S3 -37 db S2 -39 db S1 -41 db All in all, I would have to say that the meter tracks very well from S8 to S4, and the only place that wasn't that great was from S9 to S8. But considering the transient nature of the signals we are receiving, I would have to day that the S-meter is of reasonably close accuracy. With my newly calibrated S-meter I am ready to start looking at what the two different antennas are doing for me. I have a coaxial switch to jump back and forth between the two. My initial impressions are that there are some surprises. The difference in noise levels varies by antenna by band. On some bands the vertical is noisier, and on others it is the OCF dipole. Especially intriguing is that on PSK mode, where I can see several signals at one time, switching between antennas will attenuate some signals, while other signals increase in strength. I think that my vertical works better than I gave it credit for, but If I definitely want *both* antennas. Next installment will be the band to band comparison of the two antennas with some numbers. Installment three will be an investigation of that PSK signal strength business. - 73 de Mike KB3EIA - |
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