Tunable negative refractive index metamaterial in microstrip line for antenna applications

A solid tunable negative refractive index metamaterial is fabricated in a microstrip line using commercial available polycrystalline Yttrium Iron Garnet slabs and periodic copper wires. A clear tunable nonreciprocal 1 GHz wide passband that peaks at -10 dB is achieved near the negative refractive index region with a bias field of 3.4 kOe. Comparing with the previous tunable negative index metamaterial designs, this one is mechanically solid and relatively low loss, which can potentially be applied as substrates for antennas based on microstrip line.