Topband: How to orient the receive antenna?

[Steve Babcock]

>> Furthermore, has anybody had experience making the various small receiving
>> loops even smaller than suggested in the articles? 

I am planning to build a small 1/2 scale rotatable version of the Delta rx
antenna used on Clipperton, described by Earl K6SE in the recent QST
article, and explained in John ON4UN's  book. Bamboo poles and a small T.V.
rotor should work.  Gain is WAY DOWN as you can see, but hopefully, my
pre-amps will work.
Please note: I have modeled this antenna with my shunt fed tower at various
distances and the pattern is DESTROYED even at great distances (up to 250
feet).  You must detune your x-mit tower when on RX.
  I will report the results in about 3 weeks when i get it built.  I use
coax loops and they often work well...great nulls.

 I have corresponded with Earl as follows:

Earl:
I just modeled a 1/2 scale version of your delta on MININEC:  14' base,
11' sloping wires, 30' off the ground.  I found with 970 ohms termination
i got great F/B of 46 db on 160 and 34 db on 80 (at 30 deg angle).  The
gain is way down at -47 dbi on 160 and -37 dbi on 80, but some small
EWE's are like this.

de Steve VE6WZ.

"I modeled the same antenna (1/2 scale) at 30' high in EZNEC at 3.6 MHz.
I had to reduce the termination resistor value to about 935 ohms to get
rid of the reactance at the feedpoint, though.  The pattern was quite
good, with a 37.3 dB F/B at the same elevation angle (28.7 deg) as max
signal over "good" soil.  Gain was about -36 dBi.  I didn't check it at
1.83 mHz, but the gain would probably be 10 dB less there, as you
mentioned."

73, de Earl, K6SE

Good luck. de Steve VE6WZ.



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