Antenna impedance in a reentry environment

In-flight measurements of the impedance of - and -band waveguides radiating into a reentry plasma are compared with computed data. The vehicle utilized for the experiment was the Trailblazer II. The measurements were made during the reentry portion of the flight and received by -band telemetry. The computed data are obtained from the variational formulation for aperture admittance of waveguides radiating into an inhomogeneons plasma medium. The dominant TE10mode is assumed to exist over the aperture. The form employed here utilizes the piecewise solution of Riccatti equations which permits rapid evaluation of the resulting equation for the admittance.