A mobile communication device comprising: a processor to produce a data signal and an initial value of a phase difference; a vector modulator (221;471;506) to produce first and second signals based on said data signal, said first signal having a first phase and said second signal having a second phase, said first phase of the first signal differing from said second phase of the second signal based on said initial value of the phase difference; first and second antennas to transmit said first and second signals, respectively, wherein said mobile communication device is to receive from a receiving communication device a feedback signal pertaining to quality of the first and second signals as received at the receiving communication device, wherein said processor is to determine based at least on said feedback signal a modified phase difference value, wherein said vector modulator (221;471;506) is to produce first and second modified signals, said first modified signal differing from said second modified signal based on said modified phase difference value, said first modified signal having a first modified phase and said second modified signal having a second modified phase, wherein said vector modulator (221;471;506) is to modify said first signal by modifying a phase thereof in a first direction by approximately half the difference between the initial value and the modified value of the phase difference, and wherein said vector modulator is to modify said second signal by modifying a phase thereof in a second direction, said second direction being opposite to said first direction by approximately half the difference between the initial value and the modified value of the phase difference, and wherein said first and second antennas are to transmit said modified first and second signals, respectively. a processor to produce a data signal and an initial value of a phase difference; a vector modulator (221;471;506) to produce first and second signals based on said data signal, said first signal having a first phase and said second signal having a second phase, said first phase of the first signal differing from said second phase of the second signal based on said initial value of the phase difference; first and second antennas to transmit said first and second signals, respectively, wherein said mobile communication device is to receive from a receiving communication device a feedback signal pertaining to quality of the first and second signals as received at the receiving communication device, wherein said processor is to determine based at least on said feedback signal a modified phase difference value, wherein said vector modulator (221;471;506) is to produce first and second modified signals, said first modified signal differing from said second modified signal based on said modified phase difference value, said first modified signal having a first modified phase and said second modified signal having a second modified phase, wherein said vector modulator (221;471;506) is to modify said first signal by modifying a phase thereof in a first direction by approximately half the difference between the initial value and the modified value of the phase difference, and wherein said vector modulator is to modify said second signal by modifying a phase thereof in a second direction, said second direction being opposite to said first direction by approximately half the difference between the initial value and the modified value of the phase difference, and wherein said first and second antennas are to transmit said modified first and second signals, respectively.