Planar Radiating Elements for Microwave Smart Array Antennas

In this paper we present two design experiences of radiating elements for smart antennas at f0 = 4.7 GHz and f0 = 14.925 GHz, respectively, for satellite link application. The first application requires a larger relative bandwidth (13%) so that a cavity backed patch solution was adopted to achieve the desired wide band still preserving a high radiation efficiency and a low inter-element coupling. The proposed cavity backed arrangement avoids surface wave launching, but it maintains a multilayer fully planar structure, easy to be manufactured and assembled. In the second higher frequency application, the requested narrower relative bandwidth (6%) was readily achieved with a standard slot coupled patch arrangement. Both the radiating elements were designed using a commercial simulation tool for planar multilayered structures. The design procedure will be presented as well as the predicted antenna performances, in terms of input and radiation parameters. Some prototypes for single elements and small array configurations are under construction and experimental results will be shown at conference time in comparison with software prediction.