The Ionosonde Juliusruh

Measuring principle

In the frequency range between 1 and 30 MHz short electromagnetic pulses are vertically transmitted into the ionosphere and are received after their ionospheric reflection. From the ionospheric echoes their amplitude, travelling time (virtual reflection height), Doppler shift, polarisation, and angle of incidences are derived and presented in the ionogram in dependence on frequency.

Since March 1995 an ionosonde of the type DPS (Digital Portable Sounder) is continuously running.

Technical Parameters

Frequency range

1 to 30 MHz in steps of 50 kHz

Peak power

250 W

Transmitting antenna

Crossed rhombus antenna (70 m tower)

Receiving antenna

4 crossed loop antennas

Height resolution

2,5 km

Observation data

  • Ionospheric standard parameters (among others critical frequencies and special heights of the ionospheric E-, Es-, F1-, and F2-layers)
  • Electron density profiles (100-250 km)


Example of an ionogram, observed by the ionosonde at Juliusruh on 20 January 2000, 9:30 UT. The echo traces (coloured) and the derived electron density profile (black curve) are shown. In the left part of the figure the ionospheric standard parameters, automatically derived from the ionogram, and the coefficients of the electron density profile are compiled

Current Signal


External Links

DIAS Project

DIDBase (UMass)