Reapeatability of Weather Radar Calibrations Using Solar and Untethered Sphere Techniques

Complete weather radar calibration requires a measurement of the effective antenna gain. Several methods have been used to accomplish this measurement, including solar flux measurement and the observation of a metal sphere borne aloft by helium filled balloons. Solar flux measurements are easy to perform and are widely used, although they measure only the receive performance of the system. Untethered sphere calibrations are less frequently used although they do have the advantage of freedom from ground clutter interference and measure both the transmit and receive radar performance. This paper looks at the results of approximately a dozen of these calibration experiments taken over the period of a year. The consistency of results and experiment techniques are considered.