  The gain, received power bandwidth, transient characteristics, and signal
fidelity of two time-varying electrically small antennas based on parametric
amplifier design are studied using practical QAM signals. Results show that
interference from the difference harmonic present in the response of
degenerate-mode parametric amplification decreases its signal throughput
relative to a reference linear time-invariant (LTI) receiver, despite its
apparent increased received power bandwidth in the frequency domain. The
analysis also demonstrates that a non-degenerate parametric receiver, lacking
this detrimental effect, exhibits increased signal throughput over the
reference LTI receiver.
