A Multimodal Dielectric Waveguide-Based Monopulse Radar at 160 GHz

For highly integrated imaging systems above 100 GHz, the complexity and chip area increase significantly with an increasing number of channels. In addition, bulky dielectric lenses prevent applications in spatially restricted surroundings. The presented concept of an imaging monopulse radar with a mechanically flexible front end reduces the required chip area and allows the antenna to be placed in any desired position apart from the sensitive electronics. The radar system is based on a two-channel 160-GHz microwave monolithic integrated circuit (MMIC) feeding a flexible dielectric waveguide. Depending on the angle of the incidence signal, a sum mode (HE
₁₁
mode) and a difference mode (HE
₂₁
mode) are excited in the dielectric waveguide. MMIC and waveguide are connected by a self-aligning transition reducing the requirements for packaging accuracy. The required chip area of the transition is only 0.022λ
²
with a spacing between the on-chip antennas of λ/4. The measured ambiguity-free region between -18° and 15° is defined by the modified elliptical lens antenna focusing in the E-plane only. A mechanical bending of the flexible waveguide is possible down to a radius of at least 2 cm without affecting the angle estimation capability.