Just for the sake of curriosity: what if a RASER "Radio (frequency)
Amplification by Stimulated Emission of Radiation" device existed?
50 db would become acceptable and common place overnight, huh? MASER's
exist, why now long wavelength? Sure the antenna at HF would be the size of
the pentagon, but Bill Gates wouldn't blink an eye! grin

Regards

--
I would like to point out, I do appreciate the "Been there--done that!"
posts. Indeed, now your observations, comments and discourse should be
filled with wisdom--I am listening!!!
" wrote in message
news:P2o4e.22497$NW5.1099@attbi_s02...

"Richard Harrison" wrote in message
...
Art, KB9MZ wrote:
"O.K. Reg, I`ll take you up on the 50 dB F/B."

It requires good balance for such cancellation.

Yes, it will not come by accident but Reg has said that 50 db F/B is
"silly"!
Why would he say that without back up evidence? He also did not offer
a max F/B that was obtainable in theory. I have seen computor results
that offer 50 db F/B based on NEC, Can I trust gain if F/B cannot
be trusted? Obviously 50 db is hard to get but is it beyond the realms
of possibility?
The F/B that you offered is a bit unfair but then it is an antenna and
Reg did not qualify his statement.
I personaly modelled a antenna that comprised of a driven element
with the remaining elements acting as reflectors only. And we all know
that extra reflectors are a waste of time for H.F.( grin ) but they do
give
very high F/B figures.
I wonder what a corner reflector antenna would provide

Regards
Art KB9MZ......XG


Kraus gives the gain for a 100-meter dish near Bonn, Germany on page 676
of the 3rd edition of "Antennas". Gain is a function of frequency and
varies from about 48 dB at 300 MHz to about 98 dB at 150 GHz. I don`t
know if shielding has been added to make this a "high-performance" dish
but I would wager that this enormous radio ear and mouth has an
excellent front-to-back ratio. Probably exceeds forward gain at some
azimuths and elevation angles.

Arnold B. Bailey has a lot to say anout a "connected" (driven) element
and a parasitic reflector, starting about on 447 of "TV and Other
Receiving Antennas", Bailey says:
"The optimum spacing for highest gain of a parasitic reflector is S=0.15
wavelength plus or minus 0.025. Here the relleector is operated at Q=+1
(longer than resonant) and the gain in direction 1 is approximately 5.5
dB. Reasonable compromise for a less critical system is to use a spacing
of 0.2 wavelength and a parasitic element longer than resonant (at
Q=+1). This case gives a gain in direction 1 of 5 dB."

On page 440 Bailey says: The front-to-back ratio ---is 17.5 dB in this
case, and the Y/X ratio only about 9 dB, where +X represents the optimum
direction.---" A picture is worth 1000 words.

Best regards, Richard Harrison, KB5WZI