A compact crossover using NRI-TL metamaterial lines

A compact NRI-TL metamaterial branch-line crossover is presented that has an area of λ/36 × λ/12, and is a factor of 81 times smaller than its analogous transmission-line counterpart. Circuit simulations reveal that it exhibits a 34% -10 dB |S₁₁| bandwidth, good isolation below -10 dB over a 22% bandwidth, and less than 0.5 dB insertion loss over a 15% bandwidth. Furthermore, the bandwidth of the device can be increased by incorporating additional branch-line sections into the structure.