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On Sep 14, 3:18*pm, "Richard Fry" wrote:
"Art Unwin" wroteThese were shore based installations probably in Hawaii or some island. With respect to resonance, moving away from such as well as changing from 15 degrees (Frank's 30 degrees divided by two) would provide a pattern of distinct advantage which the navy is constantly looking for. *For a whip tipped at an angle of 15 degrees can provide a forward pattern of gain which can be a big deal __________ Art - The graphic linked below is the work of George H. Brown of RCA Labs, from a 1936 paper published in the Proceedings of the IRE. It is a plot of surface wave field intensity vs.monopole height, including the distance to the "fade zone" where nighttime skywave radiation returns to earth to via reflection from the ionosphere to interfere with the surface, or ground wave. In it please note: 1. Maximum field strength does not occur at electrically resonant heights of the monopole (that is, where its feed point terminal reactance is zero). I will look at the URL later Now I put the resonance as second to equilibrium as with equilibrium the need for a ground plane is negated In general terms broadcast stations want equal radiation around the point of installation knowing that the decibel is not discernable in their audiance ears 2. The characteristics plotted are not related to azimuth, therefore the performance of a broadcast monopole will not be enhanced by "tipping." *If it was, AM broadcast stations would have been doing so starting 70 years ago. That is what Harrison said. He also said we have one method of radiation so why do we need another? Brown had no reason to isolate horizontal propagation from vertical propagation and because construction is way more simple relative to Earth there is no reason to reinvent the wheel. The Yagi method of radiation is a very good approximation even tho it disregards the weak force as it deals more with total gain versus the polarity of the field. Present day science have more demands on radiation than Brown would realize. My wife nearly died last year because of a slight misdirection at the hospital when a needle nicked the liver when the medical people placed to much reliance on provided measurements that were beyond the capabilities of the equipment. As science grows so does understanding and so does use of radiation which has requirements way beyond a radio station Regards Art http://i62.photobucket.com/albums/h8...fVerticalMonop... RF |
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