Nullode
Figure 1: Russian RR-3, a gas discharge tube used in the ancient russian radar set “Bar Lock”
Figure 1: Russian RR-3 (Cyrillic: Разрядник РР-3), a gas discharge tube used in the ancient russian radar set “Bar Lock”
The so-called nullode is a gas discharge tube. It is a gas-filled tube without any electrodes. It operate by ionizing the gas with applied strong electromagnetic field to start electrical conduction. If the tube is fired, then this waveguide section works as short-cut circuit, all RF-energy will be reflected.
Gas discharge tubes are used in Radars as parts of the Duplexer.