Nullode

Nulloden; Above in a toroid shape for coaxial conductors , on the right in the form of a chamber as a waveguide termination

A nullode is a special form of a gas discharge tube and has no electrodes . It only consists of a gas-filled glass vessel.

A gas discharge can only occur in it through an electromagnetic field.

application

Nullodes were used in RADAR receivers to protect the receiver from the strong transmission pulse. This, among other things, makes it possible to use the same antenna for transmitting and receiving. The internal nullode is ionized by the high-frequency transmission pulse and now represents a short circuit or a damping barrier in the reception path. After the transmission pulse has ended and the ionization has subsided, the reception path is then undamped again. Later developments received electrodes for generating an auxiliary discharge or setting a resonance frequency, but were still referred to as nullodes.

Nullodes have the shape of a toroid (for use in coaxial lines) or chambers (for use in waveguides ).

There are for this task and externally through the electrodes and high-voltage impulse triggerable RF switch for waveguide .

See also

Examples of other electrodeless gas discharges:

• Sulfur lamp
• Induction lamp

Web links

• Picture and link to data of the coaxial nullode LG71 (Telefunken)
• Stop tubes (nullodes)

Individual evidence

1. ^ HR Schlegel, Alfred Nowak: Impulstechnik Fachbuch-Verlag Siegfried Schütz GmbH, Hanover 1955, p. 558ff.