Unequally Spaced Resonant Slotted-Waveguide Antenna Array Based on the Infinite Wavelength Propagation Property of Composite Right/Left-Handed Waveguide

For the conventional resonant slotted-waveguide antenna array, all the adjacent element spacings along the waveguide must be equal to half the guide wavelength (??_g/2). In this letter, a novel resonant slotted-waveguide antenna array based on the infinite wavelength propagation property of composite right/left-handed (CRLH) waveguide is presented. The slot elements are unequally spaced to tailor the radiation pattern. To ensure that excitations of all the unequally spaced slot elements are in phase to generate a broadside beam, CRLH waveguide should work at the infinite wavelength propagation frequency. Three different nine-element antenna array examples are developed and simulated. The results show that the main-lobe beamwidth and pick sidelobe level (PSLL) performance improvements can be obtained in comparison with the conventional resonant slotted-waveguide antenna array.