Patent ID: 6671494
Filing Date: 2003-12-30
Classification: H04B

Abstract:
A lightweight portable RF transmitter system, comprising:(a) an audio source having an output jack and having a signal ground conductor coupled to a first terminal of said output jack, said audio source having audio channels which output signals and which are coupled to second and third terminals of said output jack; and (b) an RF transmitter subsystem from which extends a cable having a plurality of wires wherein each one of said plurality of wires is correspondingly coupled to a terminal corresponding to said each wire coupled to first, second and third terminals, respectively, of an audio plug sized to mate with said output jack said first, second and third terminals of said audio plug being electrically coupled by first, second and third RF chokes to said first, second and third terminals, respectively, of said output jack when said audio plug is inserted into said output jack, said first, second and third RF chokes being the windings of a filar wire, common-mode radio frequency choke, and wherein said RF transmitter further comprises: (i) an antenna comprising a signal ground conductor coupled via a first wire of said cable and a first terminal of said audio plug and said first winding of said filar wire, common-mode radio frequency choke to said signal ground conductor of said audio source through said first terminal of said output jack when said output jack and audio plug are mated; (ii) an RF output comprising an RF ground output terminal coupled to said signal ground conductor of said transmitter; (iii) and an RF output terminal coupled via an autotransformer to said first terminal of said audio plug so as to be connected to said signal ground conductor of said audio source when said output jack and audio plug are mated, said autotransformer having a turns ratio selected to approximately match the output impedance of said RF transmitter to said input impedance of said antenna; and (iv) stabilizing means for stabilizing the frequency of transmission thereof to be as close as possible to the center of a selected channel for transmission, and wherein said stabilizing means further comprises: (1) a voltage controlled oscillator; (2) a loop filter; and (3) a phase lock loop chip having a microprocessor.