Design Of Multi-port Phase Shifter Adopted In Electrically Titled Antenna

Compared to the traditional mechanical tilted antenna, the electrically titled antenna hasbetter performance in frequency reuse and coverage optimization. By using the electricallytitled antenna, we could realize a real-time network adjustment during the normal functioningof the base station system. Besides, due to the synchronous decline of signal level, theradiation pattern will keep its shape and will not result in additional interference. These are inaccordance with increasingly sophisticated networking and thus the electrically titled antennais widely used. As an essential component of the electrically titled antenna, the phase shiftercontrols the signal phase of radiating elements to implement beam scanning function. Thedesign of multi-port phase shifter adopted in electrically titled antenna is of great significanceto the antenna system.Two kinds of multi-port phase shifter are designed in this thesis. One is eight-port phaseshifter in a single-layer cavity and the other is ten-port phase shifter in a two-layer cavity.Firstly, the development process of phase shifter and the application requirement of mobilecommunication antenna system are summarized to demonstrate that the dielectric phaseshifter is suitable for the electrically titled antenna. Secondly, the defects of phase shifter sofar and the design method are analyzed, then two new phase shifters are presented. Throughthe establishment of the equivalent stripline model, phase-shift unit design and impedancematching are elaborated. Based on the computer simulation design, the prototypes ofmulti-port phase shifter are developed. The voltage standing wave ratio, phase dispersion andinsertion loss of these two phase shifters are compared by using microwave network. Finally,the ten-port phase shifter is adopted in the electrically titled antenna.The feeding network for radiation pattern beamforming is designed according to the portcharacteristics of ten-port phase shifter. The equivalent circuit performance and the radiationperformance of the antenna including the phase shifter are measured to analyze how the phaseshifter effects beam scanning. The results show that the base station antenna operated at band1.71GHz~2.17GHz could achieve10°continuous downtitling by using this ten-port phaseshifter. The performances of the antenna are higher than the national standards, and the firstside lobe suppression is remarkably well. This thesis could be reference for the research innovel phase shifter. What’s more, this multi-port phase shifter occupies preferablepracticability and can be adopted in high-performance antenna.