Same interpretations and applications of the k- β diagram

The purpose of this paper is to present some interpretations of the dispersion characteristics of periodic structures, commonly referred to as the diagram, in terms of linear array theory, which is very familiar to the practicing antenna engineer. The location of the onset of the complex wave region on the diagram is shown to have considerable influence on the of the structure and consequently on the efficiency of radiation. It is shown why the waves are trapped for , and why one should expect efficient radiation when the propagation constant of the wave becomes complex near . The step-by-step procedure for applying the diagram to some antenna problems is presented. Also the multi-mode case is discussed briefly.