Open-ended waveguide antenna excitation with microstrip patch elements

In this paper, a new method is presented to excite an open-ended circular waveguide feed. A circular microstrip patch element is embedded near the bottom end of the waveguide, which excites the dominant TE11 mode at the aperture of the antenna. The technique is simple and capable of generating a relatively pure mode over a respectable frequency band. The technique eliminates the need of using a waveguide transition for the feeding network. In terms of volume, the proposed technique leads to a less bulky structure as opposed to the conventional probe excitation method in waveguides, which laterally occupies more space since it is perpendicular to the waveguide wall.