Multi-Beam Radiation Properties of Higher-Order Space Harmonics-Enabled Leaky-Wave Antenna

In this work, we investigate the inherent physical behavior of higher-order space harmonics (HSH) along one-dimensional periodic leaky-wave antenna (ID-periodic LWA) structures. The interdependency of even n$\in$[-2, -4] and odd n$\in$[-1, -3] HSH on each other is examined in detail and a method is devised and demonstrated for analyzing their radiation properties which allow us to develop a multi-beam antenna (MBA) without using any feeding network. In addition, the scanning range of n$\in$[-1, -2, -3, -4] space harmonics is studied and their limitation is discussed. The proposed concept is then validated by designing an LWA utilizing the substrate integrated waveguide (SIW) technology in which the n$\in$[-1, -2] space harmonics are used for achieving a MBA exhibiting wide scanning capability. The experimental results obtained in this work shows a good agreement with the simulation and analysis counterparts.