Abstract The tungsten-p type silicon point contact diode was investigated as a video detector from 90 GHz to 474 THz. The diode responsivity was examined with respect to the applied pressure of the contact and the D. C. characteristics. An upper limit of approximately 2 THz is established for electromagnetic field detection, with thermoelectric effects appearing as the frequency is lessened. Typical responsivity values of 100v/w at 90 GHz, 2v/w at 890 GHz, 10⁻²v/w at...