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R F Impedance

NSSDCA ID: 1960-014A-01

Mission Name: Explorer 8
Principal Investigator:Dr. Joseph A. Kane


To measure electron concentration in the ionosphere, the change in capacitance of a dipole antenna on the satellite's equator was measured by using the antenna capacitance to control the frequency of an oscillator. A sweep generator started the probe oscillator on an 80-ms up-and-down sweep in frequency. Every time the probe oscillator swept past 6.5 MHz, a signal passed a crystal filter. Two pulses occurred during each 80-ms sweep, but the times the pulses occurred, in relation to the start of the sweep, were modified by the capacitance of the antenna, which was an integral part of the oscillator-tuned circuit. A computer calculated the time intervals and relayed this information to the telemetry system. By this means, the electron density was measured every 40 ms. Considering the satellite's velocity, this experiment was capable of detecting ionospheric inhomogeneities as small as 300 m.

Alternate Names

  • Explorer8/RFImpedance


  • Space Physics: Ionospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Dr. Siegfried J. BauerOther InvestigatorNASA Goddard Space Flight Center
Dr. Joseph A. KanePrincipal InvestigatorNASA Goddard Space Flight Center
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