Synthesis Procedure for Thinned Leaky-Wave-Based Arrays With Reduced Number of Elements

We proposed a synthesis method to design thinned leaky-wave-based arrays. The array elements are small waveguide apertures opened on a ground plane. A superstrate (impedance sheet, dielectric slab, etc.) is placed above the array. The array elements excite leaky-wave modes between the ground plane and the superstrate, enhancing the aperture efficiency of the final antenna. An iterative optimization procedure based on a convex l(1) minimization is used to reduce the number of array elements, maintaining the radiated field within a predefined mask. All the embedded element patterns are evaluated for each source through a fast Green's function spectral approach, taking into account the effects of the mutual coupling during the optimization procedure. The use of a superstrate provides array structures with a reduced number of elements and enhanced aperture efficiency with respect to configurations without superstrate. The level of the grating lobes is also controlled during the optimization. A parametric study is performed to understand the capabilities of the leaky-wave-thinned array varying the reflectivity of the superstrate. As an example, an array of 18 elements working over a 7% fractional bandwidth is synthesized, providing a reduction by a factor of 4 in the number of elements when compared to a configuration with the same requirements, but without superstrate.