Miniaturized Substrate Integrated Waveguide Slot Antennas Based on Negative Order Resonance

Miniaturized waveguide slot antennas using negative order resonance are proposed and developed in this paper. The design of these novel resonant-type antennas is based on the study of a composite right/left-handed (CRLH) substrate integrated waveguide (SIW) starting from the dispersion diagram and the equivalent circuit. These proposed CRLH resonators are realized by etching the interdigital slot on the surface of the SIW. The slot acts as a series capacitor as well as a radiator leading to a CRLH antenna application. Two types of slot antennas, which are open-ended and short-ended, respectively, are proposed and discussed. The short-ended antenna, which represents a quasi-quarter-wavelength resonator, is characterized by a cavity-backed slot antenna thus providing a high gain. On the other hand, the open-ended antenna exhibits a small size owing to a quasi-half-wavelength operation in the left-handed (LH) region. Four antennas with one or two unit cells are fabricated and measured. Compared with the existing CRLH patch antennas and waveguide slot antennas, our antennas show advantages in terms of simplicity, low-profile, high efficiency, easy fabrication and integration with other circuits.