Leaky-Wave Antennas Using Negative-Refractive-Index Transmission-Line Metamaterial Supercells

Leaky-wave antennas (LWAs) are designed based on supercells which are expanded versions of conventional negative-refractive-index transmission line (NRI-TL) unit cells. In the proposed LWAs with NRI-TL supercells, the number and values of inductors are reduced by half, decreasing the complexity of their design and reducing the Ohmic loss, which increases the antenna gain and efficiency. Compared with conventional NRI-TL unit cells, NRI-TL supercells operate over narrower bandwidth while showing proper Bloch impedance behavior over both left-hand (LH) and right-hand (RH) regions, leading to broadband impedance matching. Using coplanar waveguide (CPW) technology, closed-stopband LWAs based on NRI-TL supercells are designed, and their performance compared with that of the conventional unit cell LWAs. Finally, by using CPW supercells with a backing ground and vias, high-gain LWAs with sharp beams and suppressed backlobes are designed and realized.