Flat-Topped Radiation Pattern Synthesis of a Conformal Leaky-Wave Holographic Antenna

A novel method to synthesize a flat-topped pattern in single-curvature conformal leaky-wave antennas (CLWAs) is presented. When synthesizing the antenna, aperture field estimation (AFE), the holographic principle, the transformation optic (TO) approach, and the effects of the geometrical parameters of a curved structure on the far-field radiation pattern are considered. In the design process, three software packages (HFSS, MATLAB, and CST) are used to achieve the desired far-field radiation pattern at the design frequency. The shaped beam is in the broadside direction at 10 GHz. This CLWA is composed of unit cells with square patches that are printed on a double-layer grounded substrate that consists of polylactic acid (PLA) and Rogers RO4003 having thicknesses of 4 and 0.127 mm, respectively. An edge-fed 1:8 power divider excitation with a substrate-integrated waveguide (SIW) structure is designed to illuminate the hologram. The proposed CLWA is fabricated and tested. The maximum realized gain of the novel antenna at the design frequency is about 13 dBi, and the weighted aperture efficiency of the proposed CLWA is about 0.86. There are also good agreement between the simulation and the measurement results of the proposed antenna frequency responses.