RF PROBE TECHNIQUES FOR IONOSPHERIC MEASUREMENTS

Three radio frequency rf probe techniques - Standing Wave Impedance Probe, Plasma Frequency Probe, and Resonance Rectification Probe - have been simultaneously flown on rockets for ionospheric measurements. The results of the three probes are compared to establish the relationships between them. The Impedance Probe and Plasma Frequency Probe measurements are in general agreement with each other and with other independent measurements. A model of antenna- ionospheric interaction is used which neglects ion sheath and magnetic field effects. The Resonance Rectification Probe shows resonance effects including peaks and minima which are a function of probe dc bias. The frequency of the dominant resonance peak does not correspond to the plasma frequency, but is near a lower frequency of an impedance series resonance as measured by the Plasma Frequency Probe.