US Patent 7403082 Dual mode antenna switch module

A dual mode antenna switch module (ASM) comprises a UMTS TX port; a UMTS RX port; and a UMTS duplexer, comprising a common port, a TX port coupled to the UMTS TX port and an RX port coupled to the UMTS RX port. The ASM further comprises an antenna port; at least one GSM TX port; and at least one GSM RX port. A multi-port switch has respective ports coupled to the antenna port, the at least one GSM TX port, the at least one GSM RX port, and the common port of said UMTS duplexer. The common port of said duplexer has a reflection co-efficient at said connected multi-port switch port with a magnitude in the range 0.8 to 1.0 and with a phase, φ, where −210°≦φn×360≦−150° where N is an integer.