University of California

Pei-Ling Chi

Tatsuo Itoh

Cheng-Jung Lee

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 |&#x3c6;|, |&#x3c6;|&#x2266;270&#xb0;. 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.

Compact dual-band metamaterial-based hybrid ring coupler

A diplexing apparatus and method which utilizes composite right/left-handed (CRLH) phase-advance/delay lines combined with a coupler. By engineering CRLH-based transmission lines with desired phase responses at two arbitrary frequencies of interest, the connected CRLH delay line and/or CRLH coupler are excited in a manner such that signals at designated frequencies are separated to the corresponding output ports of the hybrid coupler. Benefits of the apparatus include elimination of design complexities such as optimization of the interconnection junctions and the harmonic spurious suppression involved in conventional filter-based diplexers. In addition, channel isolation is beneficially achieved from the isolation property of directional couplers. Measured insertion loss on the implementations was found to be less than 1 dB, with isolation greater than 20 dB in the dual bands. A high level of agreement was observed between simulated and measured results.

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Pei-Ling Chi