2-D Annular Leaky-Wave Antenna with Wideband Broadside Radiation

We propose the design of a two-dimensional radially periodic annular leaky-wave antenna (LWA) offering high-gain broadside radiation over a wide bandwidth. The device is planar and made by a metal strip grating placed over a grounded dielectric slab. The unit cell of the corresponding linearized version of the structure has been properly designed to suppress the open stopband, whose presence would significantly affect the radiation performance around broadside. An in-house method-of-moment code is used to retrieve and validate the complex modal behavior of the periodic structure, whereas the radiation features have been analyzed performing full-wave simulations of a prototype fed by a simple source. The results show that, thanks to the directive radiation generated by a leaky-wave field over the aperture, which is supported by a fast spatial harmonic with optimized attenuation constant, stable and wideband broadside radiation can be obtained.