US Patent 7372420 Electronically scanned antenna with secondary phase shifters

An antenna module for an electronically scanned phased array antenna is provided. In various embodiments, the module includes a transmit/receive (T/R) module layer including a plurality of T/R modules. The module additionally includes an external phase shifter layer that includes a plurality of sets of secondary phase shifters. Each secondary phase shifter set is associated with a specific one of the T/R modules. Furthermore, the module includes a horn antenna layer having a plurality of antenna horns. The horn antenna layer is positioned between the T/R module layer and the phase shifter layer such that each horn is aligned between one T/R module and the associated one of the sets of phase shifters.