Topband: null steering by phasing WA4FKI

[Michael Sapp]

> re: null steering by phasing,  WA4FKI

Hi Bill & Group: I have a pair of back-to-back EWEs positioned for NE-SW
reception. I use a Timewave ANC-4 to link the
rx antennas to the transceiver, as the unit has a separate rx input, gain
control, and tx/rx switching. It's called a "noise canceller" but really is
a hybrid combiner. I've seen times where I could peak or null a signal
using one EWE and my shortened TX ground plane
with the unit, while other times I was better off de-tuning the TX antenna
and letting the single EWE do it's own thing. I tried running 
both EWEs through the ANC-4 during the weekend SSB test, but the results
were so-so as there is only one gain control for the
"noise" antenna on this unit, so amplitude matching was difficult. MFJ
makes a similar unit, the MFJ-1025, which has gain controls for both
antenna inputs, which would seem to be preferred. I'm inclined to think two
EWEs at right angles would offer better phase steering, but have not tried
that yet. It might be worth looking into MJF's .PDF files to see if they
have a published schematic for the MFJ-1025 or MFG-1026 (the 1026 has a
built in rx antenna).

                        Mike, WA3TTS