Patent ID: 7885619

Claim:
Apparatus for use in a radio transmitter, comprising: a first antenna; a second antenna; a power amplifier having an input for receiving a transmit signal and an output signal provided to the first antenna and to the second antenna for diversity transmission of the output signal to a radio receiver; a phase shifter for shifting a phase of the output signal by a first amount before transmission over the second antenna so that a relative phase shift exists between the output signal transmitted from the first antenna and the output signal transmitted from the second antenna; a power splitter for splitting the output signal into a first magnitude provided to the first antenna and a second magnitude provided to the phase shifter, electronic circuitry connected to control the phase shifter and configured to vary the first amount of phase shift applied by the phase shifter; wherein the first and second magnitudes are variable and the electronic circuitry is configured to receive information from the radio receiver associated with the first amount of phase shift and information associated with an amount by which the electronic circuitry should vary the first and second magnitudes based on a magnitude difference between signals received from the first and second antennas.