Design of a Broadband Antenna Array With Compact Surface-Wave Antenna Elements

This letter presents a 1 × 16 surface-wave phased array that exhibits compact size, high gain, and broadband characteristics. The antenna element consists of a surface wave launcher, a tapered radiating structure, and a large metallic ground. The width of the single element is only 0.56
${{\boldsymbol{\lambda }}_0}$
at the center frequency. Despite its compact design, the antenna achieves a wide bandwidth by employing a tapered metallic ridge and a cone-shaped coaxial probe. The metallic ridge is critical to enhance the bandwidth and smoothen the transition from the parallel-plate waveguide to the radiating structure. When arranging 16 antenna elements to form a linear array, some metallic stacks are introduced between adjacent antenna elements to adjust the mutual coupling so that an excellent return loss can be achieved over the operating frequency range (6.2–12 GHz). Two prototypes of the proposed array with radiation beams pointing at
${0^\circ }$
and
${30^\circ }$
, respectively, have been fabricated. The measured results agree well with the simulated ones.