Width-modulated microstrip line unit cell: A quasi-periodic combinational sequence for holographic array applications

Reflection of normally incident microwaves from a novel quasi-periodic High Impedance Surface is investigated. The quasi-periodic surface is formed by cascading similar, width-modulated microstrip line based unit cells. Parameter values in individual cells are changed to make the surface quasi-periodic. The reflections from quasi-periodic structures formed using sequences of different but similar unit cells are compared with the reflection from a truly periodic structure formed by identical unit cells. The effect of the order inside the quasi-periodic sequence is discussed. The proposed novel method enables efficient control the reflection phase and hence helps to reduce the design time for holographic surfaces and reflectarrays.