Where the article under test is linearly polarized and the campaign exercises one orientation, a single-port dual-ridged horn gives more gain, less mass and one fewer cable than a quad-ridged alternative. Coverage of 18 to 40 GHz spans K and Ka band continuously, which is the range most millimetre-wave SATCOM and radar characterisation work occupies. Gain is 8 to 12 dBi across that span, a full 5 dB better at the lower end than the quad-ridged configuration, with 2:1 VSWR. The horn is machined from high-grade aluminium alloy for durability in daily laboratory use, rated -40 to +85 °C, at 38 x 20 x 30 mm (1.5 x 0.8 x 1.2 in) and 25 g. The low mass and small envelope allow mounting on a small positioner, a probe arm or directly into a fixture. HA-BB-001 is the quad-ridged configuration covering 10 to 40 GHz with dual-linear polarization. Custom gain, flare and interface configurations are available on request.