Substrate-Integrated Waveguide-Based 60-GHz Resonant Slotted Waveguide Arrays With Wide Impedance Bandwidth and High Gain

Conventional resonant-slotted waveguide arrays can only achieve a few percent of impedance bandwidth. This paper presents a new substrate-integrated waveguide (SIW)-based 60-GHz resonant-slotted waveguide array, which can achieve both wide impedance bandwidth and high gain. In the design, resonant slots with different resonant frequencies are arranged at unequal spacing along the SIW. The variance of the excitation voltages of different resonant slots is minimized to improve the arrays’ impedance bandwidth and gain. A
${\bf 4} \times {\bf 1}$
-element subarray is designed accordingly, which shows a
$- {\bf 10}\mbox{-}{\bf dB}$
impedance bandwidth from 56.5 to 66.7 GHz (16.6%) with a peak broadside gain of 11.5 dBi. Based on this subarray, three other arrays with
${\bf 4} \times {\bf 4}$
,
${\bf 8} \times {\bf 4}$
, and
${\bf 8} \times {\bf 8}$
-slot elements are designed, fabricated, and measured. Long nonresonant slots are placed between each two subarrays to improve isolation. Measured results of the three fabricated arrays show
$- {\bf 10}$
-dB impedance bandwidths of 20.8%, 22.4%, 18.8%, respectively, and peak broadside gain of 18.3, 19.9, and 22.8 dBi, respectively. The proposed structures exhibit wider impedance bandwidth and higher peak gain than their former counterparts.