[amsat-bb] Re: [Mw] Dish reflector density (and Kaguya)
oh2aue at sral.fi
Sat Dec 15 07:30:46 PST 2007
Loren Moline WA7SKT wrote:
CC:ing AMSAT-BB in case somebody wants to quit
the keyboard and do something cool for a change ;-)
> Is there anything that says what the maximum space or hole size in a not solid dish should be.
Depends on the thickness and hence fringe effects (the cutoff
is half a wavelength, but for all practical reasons (the
"thinness" of the material), you can take 10 - 20 % of the
> I have been told that a barbque grill antenna works better if you cover with 1/4" or smaller hardware cloth adhering to the curvature of the original dish shape.
Well, the grill design is linearly polarised, so for
circular polarisation (with a suitable feed also),
making the reflector more complete can give you up to
3 dB gain (circular over linear).
Tonight I used a +- 45 degree linearily polarised
W-LAN patch, outer dimensions 8 * 10 cm, with a
commercial preamp specified at 1.2 dB NF; solid
copy with the naked ear, even through double glazing
(i.e. the antenna is seeing a lot of ambient noise
This thing is extremely difficult to make non-audible
by the ear. I just did pretty much the ultimate test
and used a QBFH omnidirectional: no problem hearing
Kaguya by the ear.
What this means is you can hear the 2.2 GHz carrier
from the moon whilst mobile, no DSP, SDR, nothing...
"Life is too short for Sudoku"
More information about the AMSAT-BB