Open cavity sensors for attitude control using a scanning reference source

Open aperture cavity structures measure attitude angles when illuminated by one or more scanning references sources. In general, the structure has a complex modal response, which depends upon the geometry and the angular orientation of the source. The cavity modal structure of the sensor changes in response to the angular motion of the projectile upon which it is mounted. Thus, it is possible to extract roll, yaw and pitch angular angles by tracking the changes in the spatial pattern of the electric field inside the cavity of a sensor mounted on a moving projectile. We present a numerical design of a rectangular cavity sensor, constrained to a particular azimuth response. Angular response of the sensor, measured in an anechoic chamber, is in good agreement with the expected numerical prediction. Recovery of the azimuth angle, from the measured power, is possible by using a synchronized reference source.