Antenna vs Ground - interesting article FWIW
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"Vito" wrote
http://www.arising.com.au/people/Hol...ph/counter.htm Thank you, it was very interesting, but it states in part: Figure 2.0 illustrates the efficiency for various counterpoise systems and a dipole above ground. --- Actually, it only shows the effects of running a counterpoise under a dipole erected so close to the ground that it could never work properly (without a counterpoise). It is no help in determining if adding a counterpoise under a dipole that is already higher than one quarter wavelength above ground would help or not. If dipole efficiency is already between 90-100%, then the findings appear inconclusive as to whether any gain would be realized, ie: the 1.64 factor that might be possible from a perfect dipole with minimal earth-losses. Jack |
Jack Painter wrote:
Figure 2.0 illustrates the efficiency for various counterpoise systems and a dipole above ground. --- Actually, it only shows the effects of running a counterpoise under a dipole erected so close to the ground that it could never work properly (without a counterpoise). It is no help in determining if adding a counterpoise under a dipole that is already higher than one quarter wavelength above ground would help or not. If dipole efficiency is already between 90-100%, then the findings appear inconclusive as to whether any gain would be realized, ie: the 1.64 factor that might be possible from a perfect dipole with minimal earth-losses. 0.25 lambda = 40 m or ~130 ft on top band. Few of us have top band antennas that high. Did you not notice the working frequency of 1.825 MHz? If your antenna is already 90-100% efficient it seems fairly obvious that there is little more to get without sacrificing omni directionality. |
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