Composite Right/Left-Handed Ridge Substrate Integrated Waveguide Slot Array Antennas

A composite right/left-handed (CRLH) ridge substrate integrated waveguide (RSIW) is proposed and applied to slot array antennas, where the longitudinal slots are etched on the surface of CRLH RSIW, behaving as the radiating elements. Two slot array antennas are designed, fabricated, and measured, one with fixed slot offset, and the other one with varied slot offsets used for achieving low side-lobe level (SLL) of radiation patterns. Compared with the slot array antennas using CRLH rectangular waveguides, the investigated CRLH RSIW ones have the advantages of miniaturized size in transverse direction, relative low cost, low profile, and easy to integrate with other planar circuits. Besides, unlike other proposed planar CRLH leaky wave antennas (LWAs), slots of varied offsets can be adopted on the CRLH RSIW surface to achieve a tapered excitation. Thus the radiation patterns can be optimized for low SLL. In summary, this CRLH RSIW enables a tapered excitation in the beam-steering antenna design while keeps a relative simple structure.