When antennas are separated by normal distances, they can only "see"
each other electromagnetically (ie, radio waves). However, when they
are close they will experience capacitive and inductive coupling. Dual
pol antennas work fine when only receiving (as in those large satellite
dishes from the 80's that used 90° pol changes between adjacent
channels). I think you will always have trouble overloading the
receiver when transmitting with this setup.
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