Conformal Tapered Substrate Integrated Waveguide Leaky-Wave Antenna

We demonstrate the capability to conform a substrate integrated waveguide leaky-wave antenna (SIW LWA) along an arbitrarily curved line by suitably tapering the leaky mode along the antenna length. In particular, it is shown that by means of locally adjusting the pointing angle of the radiated wave, a coherent plane-wave front in the far-field region can be obtained. Combined with the capability to taper the leakage rate along the antenna, this allows designing antennas with high illumination efficiency, which provides higher directivity when compared with previous conformal LWAs such as the half-mode microstrip LWAs (HMLWAs). These concepts have been validated with both measured and simulated results involving the proposed conformal SIW LWA as well as three different configurations of HMLWA: conformal tapered HMLWA, conformal nontapered HMLWA and conventional rectilinear HMLWA. The antennas have been designed to operate at 15 GHz, and in the case of the SIW LWA an analysis of its frequency scanning response has been performed.

I. Introduction

Conformal antennas are essential in applications where the generation of high directional patterns is required over curved surfaces, such as those encountered in mobile platforms (e.g., airplanes, automobile, trains) [1]. Phased arrays offer a suitable solution for such applications due to their capability to control the phase of each element individually and therefore provide beamforming agility. Despite such advantages, phased arrays are typically driven by phase shifters, leading to increased cost and manufacturing complexity. Due to their characteristics of high-gain and easy-feeding, leaky-wave antennas (LWAs) [2] offer an interesting solution for conformal high-gain narrowband applications (bandwidths ), which avoid the use of complex corporate feeding networks.