24GHz active retrodirective antenna array

Abstract

A 24GHz active Van Atta planar antenna array proposed for increasing the vehicle radar echo in a vehicle collision avoidance system is designed and demonstrated. The antenna array contains two parallel linear sub-arrays. Each sub-array is composed of four receiving microstrip antennas, four transmitting microstrip antennas and four transistor amplifiers. At the angles of -40 degrees < theta < 40 degrees, except those very close to the specular direction (theta = 0 degrees), the measured backscattering field levels of the fabricated array have variations < 3dB and are at least 10dB higher than those of a metal plate of the same size.