WR-28 Waveguide to Coaxial Adapters from Fairview Microwave are also known as waveguide to coax transitions. 2.9mm waveguide to coaxial adapters are in-stock and available for same day shipment. Fairview WR-28 Waveguide to Coaxial Adapters have a maximum frequency of 40 GHz and a max VSWR of 1.3. WR-28 Waveguide to Coaxial Adapters have a connector body material of passivated Stainless steel.