Grid-Array Antennas Obtain Ultrawideband Performance

Grid-array antennas (GAAs) are planar array antennas that are formed by radiating elements and transmission lines. They can provide a number of advantages, such as high gain and easy construction. Recently, GAAs have been proposed to enable automotive radar technology. But many of these antennas can only achieve narrowband performance. It is therefore essential to develop GAAs with ultrawideband (UWB) performance for automotive radar sensors. To achieve this, a group of researchers from both the SSN College of Engineering and Anna University in India recently designed a GAA with an enhanced bandwidth. The proposed design is targeted for automotive UWB radar sensors that operate in the 24-GHz frequency range.

The GAA was fabricated on a 1.6-mm-thick Rogers RO3003 substrate. The team implemented an amplitude-tapering technique, which utilizes variable-sized radiating elements. This can provide several advantages in comparison to a GAA with uniform-sized radiating elements. To demonstrate the benefits of the amplitude-tapering technique, both forms of GAAs were built and tested. When measured over a frequency range from 21 to 27 GHz, the amplitude-tapered GAA achieved a lower voltage-standing-wave-ratio (VSWR) than the GAA with uniform-sized radiating elements. An impedance bandwidth of 25% was attained by the amplitude-tapered GAA, as well as radiation bandwidth of 10.4%. It was also demonstrated that the side-lobe levels (SLLs) can be reduced when using this technique. See “Bandwidth-Enhanced Grid Array Antenna for UWB Automotive Radar Sensors,” IEEE Transactions on Antennas and Propagation, Nov. 2015, p. 5,215.