Measured Performance of Low-Sidelobe Narrow-Wall Slotted Waveguide Planar Antenna in Millimeter-Wave Band

Low sidelobe slotted waveguide antenna is developed in the millimeter-wave band. Millimeter-wave technologies are expected to apply to automotive radars and high-bit-rate mobile communication systems because high gain and narrow beam-width is possible even though the physical size of the antenna aperture is small. Waveguide antenna is advantageous for high gain applications since the feeding loss is small in the waveguide. Sidelobe level should be low because sidelobe causes miss-detection in radar applications and interference in communication systems. In the design of low-sidelobe slotted waveguide array antenna with traveling-wave excitation, wide range of slot radiation control is required since difference is large between assigned slot-couplings around the input port and around the termination. We have already developed a slotted waveguide planar array antenna composed of post-loaded slots [1] and feeding circuit of post-loaded T-junctions [2]. In order to confirm the potential range of radiation control for these components, we design the antenna with sidelobe lower than −30 dB for target in this paper. Design and measured performance of the developed antenna are presented in this paper.