Don't forget that orientation becomes more important
as you move away from isotropic. Make sure that your
polarization is correct (i.e., that elements of the receive
antenna are in alignment; both vertical or horizontal or
at least at the same angle), and that you are in the
pattern on both ends. A quarter-wave or half-wave
will probably be the most forgiving of misalignment,
so anything else becomes more sensitive.
Also, be aware that other designs may, and probably
will, have a different feed impedance, requiring some
sort of matching circuit to the transmitter and receiver.
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