Ridge loading extends the useful bandwidth of the waveguide well beyond a plain rectangular aperture, which is what makes 10 to 40 GHz possible in one horn. The trade is gain flatness, hence a 3 to 11 dBi specification across the range rather than a single figure. Sweeping an article across four bands without changing antennas removes three re-alignments, three cable swaps and three opportunities for a calibration to drift. Dual-linear polarization on separate ports covers both orientations without rotating the horn. VSWR is 2:1 across the range with 40 dB directivity. The horn is machined from high-grade aluminium alloy for durability in daily laboratory use, rated -40 to +85 °C, at 30 x 30 x 46 mm (1.2 x 1.2 x 1.8 in) and 45 g, light enough for a small positioner or an in-chamber fixture. HA-BB-002 is the single-port dual-ridged configuration covering 18 to 40 GHz at higher gain. Custom apertures, gains and interfaces are available on request.