Wideband 0.5–50 GHz double-ridged guide horn antenna using coaxial-to-ridge waveguide launcher

Ever-increasing bandwidth requirements from various industries drive the need for the ever-increasing bandwidth of antennas used for testing. Broadband Double-Ridged Guide Horn (DRGH) antennas are used extensively in antenna measurement and ElectroMagnetic Compatibility/Interference (EMC/I) testing. The current state-of-the-art broadband DRGH antennas reported in the literature for use in measurement applications cover bandwidth ratios as large as 36:1 (0.5–18 GHz). This paper presents the design and realisation of a DRGH antenna with a 100:1 bandwidth ratio (0.5–50 GHz). To achieve such a wide bandwidth, the ridge gap, width and feed were optimised, and a novel coaxial-to-ridge waveguide launcher section based on a typical Vivaldi antenna was developed. Backward radiation was reduced using an absorber-filled cavity. A prototype DRGH antenna was manufactured using additive manufacturing, also referred to as 3D printing. Simulated and measured results obtained in an anechoic chamber are presented.