76 GHz alternating-phase fed single-layer slotted waveguide arrays with maximum gain and sidelobe suppression

High-gain and mass-producible planar antennas are in demand for millimeter wave applications. A single-layer slotted waveguide array is a promising candidate for these applications. The simple structure, consisting of only two parts, a slotted plate and a groove feed structure, is suitable for mass-production. Alternating-phase fed arrays with uniform aperture distribution for maximum gain and a Taylor distribution for sidelobe suppression of -25 dB were tested at 76 GHz. High gain and high efficiency performance of 34.8 dBi and 57%, respectively, are achieved by an aluminum antenna designed for uniform aperture distribution with 6° backward beam tilting. The experiments reveal that the antenna efficiency is improved by 15%, by changing the material from stainless steel to aluminum, and by 10%, by changing the beam tilting angle from 3° to 6°. The measured sidelobe levels of the antennas designed for Taylor distribution are -20 dB in the H-plane and -23 dB in the E-plane. Satisfactory sidelobe suppression with high efficiency is confirmed by measurement.