Band-switching SAW antenna duplexers for US-PCS

A band-switching SAW antenna duplexer has been studied as one of the candidate of a SAW antenna duplexer for CDMA based PCS in the United states (US-PCS). An antenna duplexer for US-PCS requires filters of very steep characteristic because of the very narrow cross-band width. However, it seemed difficult to develop a full band SAW duplexer consisting of normal ladder-type filters using a 36°Y-cut LT substrate. Therefore, we proposed the band switching SAW duplexer for US-PCS. This duplexer consists of two duplexers: one for the lower 35 MHz band and the other for the upper 25 MHz band. These two duplexers were packed in a 9×7×1.5 mm³ ceramic package, and switch circuits were formed on a circuit board. In addition, we used 4-layered AlMgCu/Ti/AlMgCu/Ti electrodes to deliver power durability. This duplexer satisfies required specifications for US-PCS and results indicate that it is one solution to developing a PCS duplexer with SAW filters.