Advanced Dual Circularly Polarized Antenna for Automotive Radar Systems

Licentiatavhandling, 2022

Advanced driver assistance systems (ADAS) promise reliable support for collision
avoidance and cruise control. The demand for precise target classification
and road surface sensing requires a sensor revolution. In this regard, the automotive
radar system is highly expected to collect as much information as
possible. Especially, polarimetric radar systems have shown an advantage for
sensing and imaging. Automotive polarimetric radar requires an advanced
antenna system with high polarimetric capabilities, relatively small size, high
efficiency, and low-cost for mass production.
This thesis presents several 77 GHz advanced antenna models for various
ranges of automotive polarimetric radar systems. Gap waveguide technology
has been used to design two single-layer dual circular polarized antenna arrays,
which are suitable for automotive radar applications. The first antenna
is a dual circularly polarized low profile 8×1 array with wide impedance bandwidth
and axial ratio bandwidth (11 %), high port isolation (18.6 dB), and
moderate gain (14.8 dBi). The second design presented is an 18×8 series
fed planar array which is designed based on the leaky-wave principle and has
about 3.9 % bandwidth with 27.3 dBi gain. The achieved port isolation is
better than 17.5 dB.
The proposed antenna arrays can be easily integrated with the commercial
radar chip by using simple microstrip to gap waveguide transition. Therefore a
fully functional polarimetric radar front-end could be designed in the future.