Conformal dielectric-filled edge-slot antennas with inductive-post tuning

A class of circumferential-slot antennas, called edge-slot antennas, that are ideally suited for conformal mounting on conducting bodies of revolution has been developed. The simplest form of the antenna is a disk of dielectric substrate that is copper-plated on both sides and mounted between two parts of the conducting body so that the aperture coincides with the surface. The antenna is excited by a single coaxial stub at the center and is tuned for proper operating frequency by inductive posts that connect the two copper-plated sides of the disk. By varying the number and location of the inductive posts the operating frequency of a disk can be tuned over a 6:1 range. Instantaneous bandwidths of three percent are typical. In practice, plated-through holes are used as inductive posts to provide mounting and access holes. The single coaxial feed excites azimuthally symmetric fields that are not significantly distorted by the symmetrically placed inductive posts. Therefore, radiation patterns of edge-slot excited bodies display a high degree of azimuthal symmetry. The small size, light weight, and inexpensive fabrication procedure make the edge-slot antenna attractive for many applications.