A compact multi-band hybrid ring (rat-race) coupler utilizing a ring of composite right-handed and left-handed (CRLH) transmission lines (TLs) and multiple ports, provides miniaturization and the ability to operate at arbitrary frequency bands unlike conventional couplers. The hybrid ring is made compact, such as by constraining phase delay contributions |φ1|, |φ2|≦270°. The coupler can be used in many applications, for example as a mode decoupling network in a dual-band front-end MIMO system. The inclusion of a CRLH delay line is also described which alters the phase relationship of the signals and is particularly well suited for extending pattern diversity in response to frequency.