For a noise canceling unit to work, the noise antenna has to:
1) pick up the same noise that your main antenna is picking up that you
are trying to cancel
and
2) the power ratio and phase relation of the noise to the desired signal
on the noise antenna has to be different than on the main antenna.
Usually you will want the noise higher, relative to the signal, on the
noise antenna, although this may not be absolutely necessary. With
adjustment the gain and phase controls you could probably make it work
either way.
What absolutely will not work is having the signal to noise power ratio
and phase relation exactly the same on both the main antenna and the
noise antenna. In that case whenever you adjust to cancel the noise, you
will also cancel the signal.
So making a noise antenna with the identical directional characteristic
of the main antenna is probably not going to work.
DE N6KB
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