A Planar Dual-Polarized Microstrip 1-D-Beamforming Antenna Array for the 24-GHz Band

A planar linearly dual-polarized mm-wave antenna array is designed, fabricated, and investigated in detail. The requirements are two orthogonal polarizations with good purity and suitability of the array column for 1-D beamforming applications. Since single-layer fabrication without using vertical interconnection accesses is another important requirement, the chosen radiating elements are square microstrip patches, fed at two orthogonal edges. The array feeding is designed in series microstrip line fashion, providing a highly compact structure. In that way, 1-D beamforming agility is gained, when multiple array columns are arranged side by side and the individual columns are fed with appropriate phases. The sidelobe level of the array columns is decreased by implementing an amplitude taper within the series array, following the Dolph-Chebychev distribution. A fast scattering parameter calculation procedure is presented to achieve an efficient simulation and design process. The simulated and measured antenna properties are very stable over a bandwidth of 500 MHz around the center frequency proving that such a challenging dual-polarized design can be successfully implemented at millimeter-wave (mm-wave) frequencies with just one metallization layer on a grounded substrate. The design parameters and the design procedure are demonstrated in a step by step manner to give sufficient insight into the process together with the possibility of reusing the antenna array itself, as well as the underlying concepts.