Designing a 32 element array at 76GHz with a 33dB taylor distribution in waveguide for a radar system

Abstract

A compact linear pyramidal horn array for a personnel avoidance radar system for robotic vehicles was designed, fabricated and measured. The array will be used as the receive antenna in a system that is presented in a companion paper. The horn array is fed with a waveguide power divider that is designed to produce the required Taylor aperture distribution on the array front. The tapered aperture produces low sidelobes that are needed for low interference in the radar system. The 32-element array with 1.3 lambda element size and element spacing in the azimuth direction produces a narrow beam. The beam is scanned using a microwave switch that operates on two 8 stacked arrays for 16 scanning steps covering a scanning range of plusmn 15 degrees. The scanning arrays act as the receiving antenna, where insertion losses have to be minimized for low noise figures. The low loss is achieved using the waveguide divider. The integration of the array and the power divider in one structure helps in reducing the losses. The transmit antenna is a pyramidal horn of dimensions 2.6 lambda times 2.6 lambda, which produces the required broadbeam. The transmit and receive antennas' gain satisfy the requirements for the radar link.