A Switchable $S$ -/$C$ -Band Antenna Array With Dual Polarization and Modularity

Abstract

A switchable $S$ -/ $C$ -band antenna array is presented with dual polarization and modularity. A $2\times 2\,\,S$ -band antenna array can be reconfigured into a $4\times 4\,\,C$ -band antenna array within the same physical aperture. A narrow ground strip inside the slot-ring antenna is used to reduce the mutual coupling between antenna elements and suppress the null in the radiation patterns in the $C$ -band array. In addition, the vertical coaxial-to-microstrip transition allows for feeding the antenna array from behind the ground plane, making it modular. Dual polarization capability is achieved in each band. This antenna array shows 64.3% and 66.7% fractional bandwidth with 8.4 and 14.3 dBi gain in the $S$ - and $C$ -band operating states, respectively. The isolation between different antenna ports, radiation patterns at different frequency points, and input third-order intermodulation product of the antenna is measured. A triangular lattice is implemented for the $S$ -band array to minimize the physical spacing between the antenna elements, and therefore enable beam steering to large angles.