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Robert Lay W9DMK wrote:
Just today, I made a careful measurement on an RG-8/U line of 5.33 meters length at 30 MHz and terminated with a 4700 + j 0 load. The Matched Line Loss of that line at 30 MHz is 0.9 dB per 100 feet, and its Velocity Factor is between 0.75 and 0.80 The input impedance was actually measured at 2.45 -j15 ohms for an SWR at the input of 22.25. The SWR at the load end was 94. Those two SWR's establish a total loss on the line of 0.15 dB. If one were to blindly apply the formula in The Antenna Book on page 24-9, the result obtained would be 4.323 dB. For your 1/4WL open stub on 10.6 MHz, with a stub impedance of 0.57 ohms, I calculate total losses of about 0.2 dB. -- 73, Cecil http://www.qsl.net/w5dxp |
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