Dynamic antenna tuner

Claim 1

For use with a transmitter of the type employing frequency shift keying modulation, a system for dynamically tuning the resonant frequency of the transmitter antenna to alternate between resonant frequencies in synchronism with the repetitive shifts in frequency caused by frequency shift keying modulation, said transmitter having a range of RF output signal operating frequencies which is large relative to the frequency shift caused by frequency shift key modulation, said system comprising: a dynamic tuning circuit operatively connected to the transmitter antenna in series circuit therewith, means for coupling the transmitter RF output signal into the series circuit of said antenna and dynamic tuning circuit, said dynamic tuning circuit comprising a first plurality of inductance and switch pairs, each pair comprising a discrete helical coil and a connect-disconnect switch, each connect-disconnect switch being individually controllable to selectively establish either one or the other of: (A) a connect condition of the helical coil in which the coil is connected into said dynamic tuning circuit so that at least a portion of the transmitter RF output signal is flowing therethrough, and (B) a disconnect condition of the helical coil in which the coil is disconnected from said dynamic tuning circuit with none of the transmitter RF output signal flowing therethrough, all of the helical coils of the first plurality of inductance and switch pairs being disposed in concentric relationship with respect to one another; a second plurality of inductor and switch pairs, each pair comprising an inductive loop element and a short circuit-open circuit switch, each short circuit-open circuit switch being operative to establish either one or the other of: (i) a short circuit condition of the paired inductive loop element, and (ii) an open circuit condition of the paired inductive loop element, the inductive loop elements of said second plurality of inductor and switch pairs being in inductively coupled relationship with the concentric arrangement of helical coils of the first plurality of inductance and switch pairs; and means for commonly operating all of the short circuit-open circuit switches of said second plurality of inductance and switch pairs in synchronous relationship with the frequency shift keying modulation to alternately short circuit and open circuit all of the inductive loop elements, said inductive loop elements of the second plurality of inductor and switch pairs when in their short circuited condition being operative to reflect a decrease of inductance into any helical coil which is connected into said dynamic tuning circuit.