Investigation of Open-Cavity Radiators and Backfire Antennas. Part I. Open-Cavity Antennas

摘要

This research investigates the radiation and circuit properties of an open-cavity radiator. This antenna consists of a simple, open-ended circular cavity with a primary radiator, placed at an appropriate location inside the cavity. If a reflecting disk is placed at the aperture of this radiator, it becomes a short 'backfire' antenna. The waveguide excitation theory is employed to find the field excited in the cavity. The aperture field is then determined by summing the propagating modes at the open end of the cavity, and the radiation field is calculated based on the aperture field. The input resistance of the radiator is obtained from the total radiated power carried by the propagating modes and the input current of the primary radiator. Various primary radiators such as a dipole, a dipole array, a transmission line, and a circular loop are considered. An experimental study has been conducted parallel with the theoretical analysis and a satisfactory agreement has been obtained between theory and experiment. (Author)