Pencil beam radiation pattern from a single-layer substrate-integrated waveguide leaky-wave antenna with simple feeding

A central feeding array radiating at broadside and manufactured in substrate-integrated waveguide (SIW) technology is shown in this work. The single-layer array consists of N = 8 line-source leaky-wave antennas (LWAs), which are designed to satisfy the splitting condition (α = β) of the leaky mode. The LWAs are arranged in a radial configuration, in this manner, by properly designing the SIW width W and the spacing between SIW vias P for each SIW LWA, the leaky mode can be independently controlled to fulfil the splitting condition, and all the individual beams from each SIW LWA can merge into one at broadside direction (θ = 0°) for a given design frequency. The two-dimensional radiating surface allows obtaining a pencil beam radiation pattern, which is linearly polarised because of the radial arrangement. A prototype with a radiating length of L_A = 60 mm for each SIW LWA, and a total radius of R = 73 mm has been manufactured for a design frequency of 15 GHz. Input matching, gain and radiation patterns at several planes have been measured and compared with full-wave simulations, obtaining good agreement between them.