Nonreciprocal Phase-Shift Composite Right/Left Handed Transmission Lines and Their Application to Leaky Wave Antennas

A new type of nonreciprocal phase-shift transmission line is proposed; it realizes the dominant right-handed mode in one direction of the power flow along the line, and the dominant left-handed mode in the opposite power direction. These right and left handed modes can have the same wave number vector at a specific frequency but there is no significant coupling effect. An equivalent circuit model is provided to explain its nonreciprocal transmission characteristics. A nonreciprocal phase-shift composite right/left handed transmission line is designed to satisfy specific performance parameters and fabricated as a ferrite microstrip line. The leaky wave radiation characteristics of the fabricated nonreciprocal line are investigated. An experiment and analyses confirm obliquely unidirectional leaky wave radiation from the line for the two different directions of the transmitted power.