Double-beam parallel-plate slot antenna

This paper presents the design and prototyping of a double-beam linear polarized parallel-plate slot antenna at 12-GHz band. Each beam is separated 27.7° and 27.3°, respectively, from broadside direction. Two different radiation patterns are generated, exciting the parallel plate from opposite sides. The radiating elements are composed by three parallel slots, the central slot is close to the resonance, while the side ones are designed to minimize the reflection inside the parallel plate. The length of the slots in the same row is kept constant (periodic walls), and the distance between columns is equal to 0.7 times the wavelength. The designs of the feeding networks and the design of the array of slots generate both beams, pointing toward Hispasat and Astra satellites simultaneously, at the same frequency band. The feeding networks are two microstrip circuits that excite two linear arrays of 24 patches, placed at both sides of the antenna, and generate both quasi-TEM mode plane waves inside the parallel-plate waveguide, propagating from one side to the other.