Input reflection coefficient of a basic dielectric-filled edge-slot antenna

A theory is developed for the inpurt reflection coeffecieint as a function of frequency for a basic Dlelectric-Filled Edge-Slot (DFES) antenna recently developed experimentally by the Harry Diamond Laboratories [1]. These antennas belong to a class of circumferential slot antennas that are suited for informal mounting on conducting bodies of revolution so that the radiating aperture coincides with the surface. The simplest form of the antenna consists of a disc of dielectric substrate that is copper-plated on both sides and mounted between the two halves of a conducting body of revolution. It is excited at the center by a single coaxial stub and can be tuned for proper operating frequency by using a number of passive inductive posts that connect the two conducting surfaces of the substrate. The input reflection coefficients of the antenna are found to be minimum at some discrete frequencies called the operating frequencies where the antennas radiates most efficiently.