A Quasi-Uniform Transversely Slotted SIW Leaky-Wave Structure with Enhanced Beam-Scanning Rate for Millimeter-Wave Applications

A quasi-uniform transversely slotted substrate integrated waveguide (SIW) leaky-wave structure with enhanced beam-scanning rate has been proposed and studied in this paper for millimeter-wave applications. By adopting a long inductive transverse slot in each unit cell while keeping a small period length, the sensitivity of effective phase constant (i.e. the slope of effective phase constant versus frequency) of the unit cell can be increased significantly, thereby resulting in a quasi-uniform leaky-wave antenna with a fast beam-scanning property. The working principle is elaborated with an equivalent circuit model of the unit cell, and both of circuit-based and full-wave simulations are conducted to verify the design concept. To do the demonstration, a limited frequency band from 34 to 36 GHz (5.7%) has been designated specifically to implement the proposed leaky-wave antenna. Furthermore, a taper design with -25 dB Taylor distribution is carried out for the antenna to achieve a low sidelobe radiation. A prototype is then fabricated and tested. Experimental results show that the beam can be scanned from 17
^o
to 58
^o
with low sidelobe levels over such a narrow bandwidth. The simulated and measured results are in a good agreement.