[R-390] r390 Alignement: Tuning r390 to the antenna via sig gen.

[face at netunltd.com.au]

Hello dere allbodies
 
Just a thought  Try this systems aproach
 
With all the unknown variables we seem to have, perhaps quickest way to
actually tune (unknown) antenna to Rx (unknown) impedance without
use of fancy Z bridges, etc:
 
1.    Make up a frame (lor simple loop aerial)  to match your sig gen
Zout n' frequencies of interest
 
2.   Stck sig gen and loop outside at fixed point as far back from
antenna as you can
 
3.    Tune sig gen to centre of band of interest (or at where its quiet
around there...
       like choose a daytime / nightime freq   thats poor propagation
wise)
 
4.    Tune in rx to gen sig, then adjust its  front end bits for best
signal strength.
 
5.    Check on band edges without touching anything for relative reading
to band centre.
 
Now your rx is best matched to the antennna charecteristics and the rx
Zin, no matter what 
it might happen to be, for that frequency.
 
 
Try out on differing frequencies, or the centres of the bands you want,
to see how antenna 
characteristics and Rx Zin influence received signals.
(The frame (loop) antenna output will change with frequency this way, as
may the sig/gen, swr etc,
but we are taking relative readings here for reference
so doesnt matter so much.)
 
Make the frame on a marked baseboard so you can repeat future  tests  at
same angle to antenna
(same location in backyard), of course)
 
Record all readings for future reference
 
Its cheap and dirty, and needs a sunny day / dry night, but more certain
this way as it considers most everything in the signal path 
without affecting results by tying stuff onto the front end.
 
Notes:
The magnetic field from the loop is more predictable and calculable than
the electric field.
(It is in fact, quite accurately calculable for emitted uV/m for a
given, accurately made up loop)
The antenna responds to both transmitted vectors anyhoo, so you are
reading a fairly
realistic result. 
This signal is more predictable than using standard frreq xmission and
you have your choice of frrequencies,
 
It gives you some exercise lugging sig gens around.(turns pears into
mars bars)
 
 
Just a thought.
 
Regards all
 
John Byers