On Sep 26, 7:49*am, "Rectifier" wrote:
"Art Unwin" wrote in message

...

When modelling antennas and also building them it is obvious that
maximum gain comes about when resistance aproaches zero. Soooooooo
common sence says that the best antenna gain comes about when the anti
resonant point can be easily fed, welllll thats how my antennas work.
Unfortunatelly, the antenna was resonant on top band
but with a very low resistance so I have to start all over again. The
noise level did increase by 7 S units where modelling showed 9 dbi
gain ! Maybe I should use two radiators instead of the single one. O
well, I have to make changes so the anti resonance point is available
at top band. David, IT IS a topsy turvy world
so I am not available to listenning to the wobbly heads on the radio.
Oh shame for shame
Art

Uh, resistance? *Are you talking about DC resistance? *What about impedence?

You also stated, "Unfortunatelly, the antenna was resonant on top band but
with a very low resistance so I have to start all over again" after saying,
"maximum gain comes about when resistance aproaches zero." *Which is it? Is
your low resistance good nor not?

No. I have difficulty in feeding near zero resistances. I opt to feed
high resistive loads without regard
to SWR I just do not want a reactive load for transmitting. For
receiving the low resistance or even impedance
really is of no concernl. When I design a antenna say for top band I
want the near zero resitive load point to be about
the low end of the broadcast band which allows for coverage of all the
top band but makes the 80 metre band centered around the zero mark!.
The beam that I am building is not aimed at small volume but of a 4
foot antenna of ultra lightness so I can use a a pan and tilt
mechanism as used with CCD cameras. By the way this particular antenna
is an attempt to make one continous lobe for 180 degrees of a narrow
width without nulls. If this is successfull I will then place a dish
reflector( probably about 3 to 6 ft diameter depending on weight)
behind it and call it a day for the winter.
I promised to make a antenna for somebody so this continual testing
game just has to come to a halt
Regards
Art
I understand your reluctance to move away from the term impedance but
I prefer to refer to resistance in the absence of reactance.