Topological Insulator Antenna Arrays
Yaakov Lumer, Nader Engheta
Abstract
Photonic topological insulators are systems in which the propagation of their edge states is robust to scattering and reflection. Usually, topological systems are discussed in a lossless system, where the dynamics is Hermitian. Here, we investigate, theoretically and numerically, the topological edge states as feed lines to antenna arrays, a way to leak energy out of the system, in a controlled and efficient way. We use the reflection-free property of the edge states to overcome entirely the issue of impedance matching and show how the design of a leaky wave antenna array, made by cascading several antenna ports one after the other, can be made significantly simpler when reflection is completely avoided. Finally, we consider the extension of our results to photonic systems that are time-invariant, in which the topological protection is weak and edge modes are reflection-free only to a certain class of defects.