Engineering Leaky Wave Antennas: Modulated Impedance Surfaces and Radiative Characteristics

Abstract

This article investigates the leakage radiation phenomenon between adjacent sinusoidal impedance surfaces, focusing on various structural configurations and their effects. Initially, the radiation between symmetrically placed sinusoidal inductive-impedance surfaces is examined. Nonsymmetric and inverse nonsymmetric configurations incorporating complementary capacitive surfaces are then explored. To enhance the modulation coefficient, square unit cells are transformed into rectangular ones. The Taylor one-parameter distribution (TOPD) method is applied to control leakage values along the antenna, enabling precise engineering of the desired sidelobe level (SLL). Excitation of these structures is accomplished using Vivaldi and inverse Vivaldi transitions. Two prototypes are constructed and tested, demonstrating the ability to steer the main beams from backward to forward, passing through the broadside direction, while achieving bidirectional radiation—an achievement that is difficult to realize with conventional leaky wave antennas (LWAs). The proposed LWAs exhibit wide bandwidth and wide-angle scanning, making them suitable for advanced wireless communication applications. The fabricated prototypes operate effectively from 12 to 22 GHz, achieving a gain range of 10–16 dB.