Thin-structure aerial

DETAILED DESCRIPTION What is claimed is: 1.
An aerial comprising a sheet of dielectric having front and rear surfaces each covered with a layer of conductive material, the conductive layer on the front surface including: (a) at least one radiating slot; (b) at least one feed slot parallel to a radiating slot; (c) a conductive portion bounded by at least two of the slots in the layer; (d) a feed point in said conductive portion; and (e) means for defining sidewalls of a cavity which is disposed between said layers of conductive material, said side walls surrounding at least one radiating slot and said parallel feed slot.
2.
An aerial as in claim 1, characterized in that said means for defining sidewalls comprise conductive elements which interconnect the layers of conductive material covering the front and rear surfaces.
3.
An aerial as in claim 1, characterized in that said means for defining sidewalls comprises holes through the dielectric sheet having their sides covered by layers of a conductive material bringing the layer covering the front surface into contact with the layer covering the rear surface.
4.
An aerial as in claim 1, characterized in that said means for defining sidewalls comprises crenellations in the conductive layer covering the front surface, the depth of the crenellations being such that an impedance of substantially zero is obtained at the bottom of said crenellations.
5.
An aerial as in claim 1, 2, 3 or 4, characterized in that the feed point in the conductive portion is disposed between a radiating slot and a feed slot.
6.
An aerial as in claim 1, 2, 3 or 4 including a coaxial connector comprising a contact pin electrically-connected to the feed point and a flange electrically-connected to the layer of conductive material covering the rear surface of the dielectric sheet.
7.
An aerial as in claim 1, 2, 3 or 4 adapted to radiate a circularly polarized wave, characterized in that it comprises two radiating slots disposed perpendicularly to each other and in that the lengths of feed slots parallel to said radiating slots are selected so as to obtain phase-quadrature energization of the radiating slots