A Novel TSA Array for Automotive Radars at 79 GHz

Abstract:
The shift of the frequency band assigned for automotive radars from 24 GHz to 79 GHz led to
an increased research in the area of design of radars that operate at the new band from 76 to
81 GHz. The antenna plays a key role in the operation of a radar sensor. Designing an
antenna that provides high directivity and low side lobe level and at the same time to be small
in size and of low manufacturing cost in mass production is a challenging task for researchers.
In this work, investigations on Tapered Slot Antenna (TSA) arrays operating at 79 GHz
suitable to meet automotive radars demands were carried out. A Fermi-Dirac based TSA was
studied parametrically and optimized with the aid of CST microwave studio. The optimized
design was fabricated along with its attached feeding structures and shielded housing to
suppress unwanted feed radiation. The measurement of reflection coefficient indicated
wideband behavior (< -10dB) extending nearly over the whole E-band. Despite its small size
(3.75 by 7.5 mm) the antenna showed fairly high gain (≈10 dB). A 4 -element E-plane array
was built and a parallel feeding network was optimized to feed the array elements with equal
amplitudes and phases. The array was fabricated and measured showing a gain of 13.8 dB and
a side lobe level of 14 dB indicating that it is attractive candidate for employment in
automotive radar sensors, especially when the number of the array elements is increased.