Differential phase shifters using composite right/left handed transmission line

Three types of differential phase shifters using composite right/left handed (CRLH) transmission line (TL) are presented. Type 1 uses two CRLH-TLs. Type 2 uses a CRLH-TL combined with a conventional delay TL and the differential phase is designed at the medium operating frequency. Type 3 is the same as type 2 except that the differential phase is designed both at the lower and upper operating frequencies. Design methods for the three types phase shifters are given. From simulated results, it can be seen that type 1 is hard to work out of radiation area and types 2 and 3 can be easily designed to work out of radiation area. Compared with type 2, type 3 has a better broadband phase response.