A headphone receiver apparatus for use with low power transmitters
includes a pair of headphone speaker enclosures connected by a headband.
An antenna element in the form of a spring steel band or a plastic
cable/antenna band where one of the conductors is utilized as the antenna
is configured generally concentric with but offset from the headband and
the user's head by at least 0.5 inches over at least some length of the
antenna. Low-noise performance is improved by a low noise amplifier
incorporated before the receiver IC, and a bandpass filter interposed
between the low noise amplifier and the receiver IC. A base-loading
inductor is used to tune the antenna element to resonance, with or
without capacative end-loading. Lumped inductors, ferrite beads, or a
parallel resonant LC circuit may be used to isolate the shield conductor
at RF frequencies, and/or to reduce the loading of the other conductors.