Substrate Integrated Image Guide Array Antenna for the Upper Millimeter-Wave Spectrum

A compact linear array antenna fed by substrate integrated image guide (SIIG) at 94 GHz is presented. The SIIG is a low-loss dielectric waveguide which is synthesized directly on a high dielectric constant substrate or semiconductor wafer. Such a low-cost approach of integration allows for the development of directive low profile antennas for future commercial millimeter-wave products. Special attention was directed towards the radiation elements that are fabricated in printed circuit technique on top of the SIIG. Their novel design provides a wide tuning range for the radiation coefficient and excellent linear polarization purity. In addition, an optimized reflection compensation technique effectively reduces the overall return loss and permits frequency scanning through broadside direction without suffering from a stop band due to distributed Bragg reflection. Published theory concerning the scan range of this class of frequency-scannable array antennas is extended in this work. Detailed design guidelines are given along with simulation and measurement results of a prototype. The 2 cm long implementation produced a fan beam with 11 dB gain.