Key Specifications. Minimum Frequency: 76 GHz Maximum Frequency: 78 GHz Waveguide size: WR-12 VSWR(Max): 1.4:1 Insertion Loss: 0.8 dB Isolation (min) : 15 dB Forward Power (CW)(Max): 2 Watts Forward Power (Peak): 20 Watts Reverse Power (CW)(Max): 0.2 Watts Reverse Power (Peak): 2 Watts. WR-12 Waveguide Isolator from 76 GHz to 78 GHz, 15 dB min Isolation, UG-387/U Cover Flange, Brass. The PE-W12IR002 is a Waveguide Isolator offering 15 dB minimum isolation over the E band frequency range of 76 to 78 GHz. The design achieves high isolation with wide band performance and the WR-12 waveguide uses UG-387/U Cover compatible flanges on all ports and has a power rating of 2 watts (CW). Pasternack offers a wide variety of isolators and waveguide isolators to fit your needs. These are two-port devices that transmit microwave or radio frequency power in one direction only and block the signal in the opposite direction. They can be thought of as a diode for RF energy. Isolators are used to isolate equipment from the effects of conditions outside of the equipment. For instance they are used to prevent a microwave source being detuned by a mismatched load. Pasternack's waveguide isolators feature excellent insertion loss, full WR band high isolation and reliability.