Wide Field of View Retrodirective Millimeter Wave Antenna Array With Pulse Modulation and Orthogonal Polarization States

This work presents novel techniques to realize a retrodirective millimeter wave antenna array with wide field of view. High gain arrays in phase conjugate configuration are used in combination with orthogonal polarization states and a novel pulse modulation technique to improve backscattering which finds its application in localization and enabling data transmission from sensor nodes. The proposed approach avoids the use of amplifiers thereby reducing the cost, complexity and power consumption of sensor nodes while providing a wide field of view. The basic building blocks of the proposed antenna array are compact one-dimensional (1D) slot arrays that can be designed with orthogonal linear polarizations. Their compact size limits the grating lobes under -10 dB level with respect to the main beam to enable 120° retroreflective field of view, thus, eliminating the reflections in undesired directions while providing 90° rotated linear polarization for the reflected signal with respect to the incident signal polarization. The orthogonal polarization states and compact size are achieved by using a two-layer structure and exploiting the characteristics of substrate integrated waveguide and rectangular cavities. Arrays are designed, prototyped and characterized to validate the proposed concepts.