High performance microstrip networks for multibeam and reconfigurable operation in mobile-radio systems

This paper presents the development of high performance multiport hybrid networks based on the Butler matrix concept in thick film microstrip technology to provide the multibeam and reconfigurable operation of antennas of DCS 1800 (ground mobile) base stations. This work was performed to meet the increasing demand for mobile communications that calls for the use of advanced components to improve the electrical performance and reduce the size of transceivers, in view of the integration of ground and satellite communication equipments. In what follows a survey of the various applications of these multiport networks is presented. Furthermore, the possibility of increasing the operation flexibility suggested the use of specific components able to carry out a close control of the phase. With regard to this fact, innovating types of phase-shifters, providing a very accurate slope equalization of the phase over a specified frequency band, were developed. All designs were performed using CAD Libra (software by Eesof) to operate over the 1.7-1.9 GHz band and prototypes were manufactured on Rogers RT6006 and RT5880 Duroid substrates. Finally, the microstrip technology used for DCS applications at 1.8 GHz can easily be transferred to satellite mobile systems at 1.6 GHz and to cellular based PCN (2-2.5 GHz band).