A multibeam phased array antenna system

A method and an apparatus for a multibeam phased array antenna transmission based on heterodyning to produce the RF transmission signals with appropriate phase shift and thereby reducing the effect of certain space constraints in the confined area of the transmitter as higher and higher frequencies of transmission are employed. In the present invention, RF signals at an intermediate frequency, not the ultimate frequency of transmission, comprise the signal frequencies of a beam forming network which provides input to a multiplexed power divider (20). The power divider outputs the phase shifted signals to an input at each of a number of multiplexed combiners (22). The output of each combiner is fed to a mixing device (23) which then shifts the input frequency to a higher frequency, using an appropriate local oscillator signal. The mixer outputs are coupled to separate power amplifiers (26), whose outputs are fed to the elemental radiators (33). The use of a lower primary frequency in the power divider and the combiner stages permits the use of conventionally sized components, rather than miniature elements normally associated with millimetre-wave circuitry.