Higher-order cylindrical leaky waves–Part II: Circular array design and validations

The generation of higher-order cylindrical leaky waves (HOCLWs) by means of canonical electric or magnetic ring sources was discussed in Part I, where radiation formulas for such waves were also presented. In the second part of this sequence, the practical excitation of HOCLWs in a Fabry–Perot cavity antenna is discussed considering the use of ring sources in a discrete form, i.e., circular phased arrays of vertical electric or horizontal magnetic dipoles. Design guidelines for dimensioning the source radius and the number of array elements are presented in order to excite the desired waves with negligible unwanted higher-order azimuthal harmonics and negligible spurious radiation from the quasi-TEM cavity mode. Numerical results are provided for circular arrays with traveling-wave azimuthal excitation, in order to validate the theory presented in Part I and Part II. Furthermore, the salient features of conical radiation from HOCLWs in the far-field region are illustrated and their potential to produce beams carrying orbital angular momentum (OAM) in the near field is demonstrated through full-wave simulations.