Design of monopulse radial line slot antennas

The authors propose the design of one radial line slot antenna with two simultaneous beams, one broadside beam and one conical beam. The antenna is a radial line slot antenna, with the slots placed on the upper plate in concentric rings. The radiation element is a slot pair, designed for getting left hand circular polarization. The antenna has been designed for working between 13.4 and 14 GHz. Both beams are obtained independently through very simple excitation circuits. The conical beam is obtained by feeding directly with a coaxial probe, just in the center of the antenna, while the broadside beam is obtained by feeding through a microstrip circuit and four post excited with a difference phase equal to 90/spl deg/. Comparing both radiation patterns, amplitude and phase, theta and phi angles can be obtained.