A New Method of Exciting Axial Slots Cut on a Circular Cylinder

A new method of exciting axial slots cut on a circular cylinder is presented. The interior volume of the cylinder is divided up into a number of wedge waveguides equal to the required number of slots along the circunference of the cylinder cross section. Each of these slots is thus excited independently by the corresponding wedge waveguide and its coupling can be controlled by changing its distances to the centerline of the waveguide curved wall. Theoretical expressions for the Value of the slot admittance in the wedge waveguide are given and compared with measurements on an X-band model. The new structure can be applied to microwave beacons and UHF broadcast transmitters requiring patterns which are more or less selective in the horizontal plane and narrow in the vertical plane.