A Periodic Coplanar Strips Leaky-Wave Antenna With Horizontal Wide-Angle Beam Scanning and Stable Radiation

Abstract

A periodic leaky-wave antenna (LWA) with unidirectional horizontal radiation and wide-angle beam-scanning capacity through broadside is presented. The proposed antenna is made of a slow wave coplanar strips line with open-ended slots and short-ended slots etched on the two strips, respectively. The energy leaks mainly from the open-ended slots, contributing to the horizontal radiation of the antenna. Consequently, the constraint of the ground plane on the radiation patterns is reduced, suggesting the potential of the proposed structure to break the scanning range limitation of the traditional LWAs. The scanning range of LWAs is determined theoretically by the normalized phase constant. Therefore, the slow wave structure is utilized to ensure the normalized phase constant of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n = -1$ </tex-math></inline-formula> harmonic varying from −1 to 1. Subsequently, a pair of extended slots are introduced to the slow wave LWA unit cell to eliminate the open-stopband (OSB) effect. As a validation of the proposed antenna, a prototype with broadside frequency of 10 GHz is designed, fabricated, and measured. The measured results are in good agreement with the simulated results. It is shown that the fabricated antenna scans from −75° to 83° in the horizontal plane with eliminated OSB and measured gain variation of 2.65 dB.