On Fri, 4 Apr 2008 09:57:55 -0600, "Bob Crantz"
wrote:


"Goofball_star_dot_etal" wrote in message
.. .

It is not just a question of squeezing the energy from a sphere into a
hemisphere. If the antenna and its image are separated by a number of
wavelengths nulls occur in the polar plot, so that you cannot simply
claim that a gain of more than 3dB violates the Conservation of
Energy. Principle of Superposition rules. Amen!

Amen!

Alright, you got me. Is that 6 dBi?

No, 'regular' common or garden dB.

f so, then I agree. Otherwise I don't
see how. Do you have a reference, example or link showing this 6 dB(dipole)
of gain for two end to end antenna separated by multiple wavelengths.

Does this help?
http://books.google.co.uk/books?id=o...hbV18#PPA91,M1

(Foundations of Antenna Theory and Techniques By Vincent F. Fusco.
page 91 )
" ....this leads to a 6dB power gain."


If one transmitter gives 1mV into a receiver the addition of a second
identical transmiter at the same distance and in phase, will give 2mV.
This is a 4 x increase in power, 6dB. You have doubled the total tx
power (3dB) so you have an antenna gain of 3dB. In the case of an
image in a 'ground plane mirror', there is no extra tx power and still
the same 6dB gain. The missing 3dB that came from the second
transmitter comes from the power that would have gone into space,
below the ground plane.