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## Re: [TenTec] NEC, ground, grounds, and radials.

 To: Discussion of Ten-Tec Equipment Re: [TenTec] NEC, ground, grounds, and radials. Steve Hunt Discussion of Ten-Tec Equipment Fri, 07 Jan 2011 22:29:48 +0000 mailto:tentec@contesting.com>
 ```Jerry, Please don't think I'm trying to be contentious, but your comment challenged my established view of what "dBi" represents. That led me on a literature search starting with my (very old) Masters Degree notes, antenna engineering reference books, and web sites. I can't find any material where the Isotropic reference power density is defined as anything other than the transmit power spread over a *complete sphere* - not a hemisphere - even where the antenna being compared is over real ground. In other words, consistent with EZNEC. In some cases the interpretations were explicit - for example "...... compared with the power density of an isotropic radiator in Free Space"; in others it could be inferred from the underlying maths. That's the interpretation I was taught, and yes it would certainly lead to a 3dB higher figure than your interpretation. I'm trying to understand whether your view is commonly held, or rather something you feel strongly about; if it's a commonly held view perhaps you could point me to some literature. I presume that someone like IEEE must have an unambiguous definition? 73, Steve G3TXQ On 06/01/2011 17:07, Dr. Gerald N. Johnson wrote: > As for the effects with ground planes and my claim of error. I base it > on this: Model a quarter wave vertical on a perfect ground plane. It > will show 3 dB more gain than a half wave dipole in free space. Yet the > theory of images in the ground plane insists that the quarter wave > vertical on the ground plane has a image of the other half making it the > exact equivalent of a half wave dipole. I claim that while the program > in free space is comparing the signal intensity from the antenna to that > of a perfect isotropic radiator located at the 0,0,0 origin of the axes, > that when the ground plane is present it cuts that isotropic radiator in > half, shielding half of its radiated power and so the reference to a > full isotropic radiator is 3 dB in error. 3 dB too much gain. > > _______________________________________________ TenTec mailing list TenTec@contesting.com http://lists.contesting.com/mailman/listinfo/tentec ```
 Current Thread Re: [TenTec] New and Improved Terminology, (continued) Re: [TenTec] New and Improved Terminology, Walt Amos Re: [TenTec] New and Improved Terminology, Steve Hunt Re: [TenTec] New and Improved Terminology, Rick - NJ0IP / DJ0IP Re: [TenTec] New and Improved Terminology, Steve Hunt Re: [TenTec] New and Improved Terminology, Paul Christensen Re: [TenTec] New and Improved Terminology, Steve Hunt Re: [TenTec] New and Improved Terminology (NVIS origins), Rick - NJ0IP / DJ0IP Re: [TenTec] New and Improved Terminology (NVIS origins), Rick - NJ0IP / DJ0IP Re: [TenTec] New and Improved Terminology (NVIS origins), Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials., Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials., Steve Hunt <= Re: [TenTec] NEC, ground, grounds, and radials., Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials., Steve Hunt Re: [TenTec] NEC, ground, grounds, and radials., Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials., Steve Hunt Re: [TenTec] NEC, ground, grounds, and radials., Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials., Steve Hunt Re: [TenTec] New and Improved Terminology (NVIS origins), John Graves Re: [TenTec] New and Improved Terminology (NVIS origins), d . e . warnick Re: [TenTec] New and Improved Terminology (NVIS origins), John Graves Re: [TenTec] New and Improved Terminology (NVIS origins), Rick - NJ0IP / DJ0IP