A multibeam array using RF mixing feed

Multiple beams can be produced and independently scanned with a single photonic series feed without using multiple sets of phase shifters. This is accomplished by mixing two counter-propagating signals to generate the required phase distribution for each beam. The linear progressive phase is proportional to the sum of two control frequencies, but the output frequency is equal to the constant beat frequency controlled by a phase locked loop. This design can be extended to 2-D scan by cascading two such feeds in the two orthogonal planes. Test results of a 2-element (X-band) transmit array constructed to demonstrate the operation of two simultaneous beams are reported.