| With the further development of mobile communications,the working frequency bands of the network are more and more,and the coexistence of 2G,3G,and 4G communication systems have made the base station resources increasingly tight,and the electrically adjustable antennas coexisting in multiple frequency bands have become the mainstream of applications.The performance of the phase shifters determines the beamforming effect of the multi-band electrically adjustable antennas;the filters keep the antennas with different frequency bands isolate and work in the same radome.However,the existing phase shifters and filters occupy a large space of the multi-band electrically adjustable antennas,hindering the process of miniaturization and weight reduction of the multi-band electrically adjustable antennas.How to integrate the phase shifter and the filter into one and realize miniaturization is of great significance.Starting from the technology of phase shifters in the past 30 years,this paper sorts out the evolution process and advantages and disadvantages of various types of phase shifters,and then selects the medium sliding phase shifter as the research direction,and carries out innovation and modular improvement,which makes it easy to multi-port,miniaturize,and have good intermodulation performance.Furthermore,this paper integrates the filter into the phase shifter cavity,thus combines two components into one.It eliminates the repeated space occupied by the filter and reduces the total volume while maintaining the original size of the phase shifter.Thus,the total weight and the size have been decreased,the number of cables interconnected between the two components has been reduced,and the overall layout of the antenna is optimized.In this paper,two kinds of phase shifters with filtering function are designed,covering 2G,3G,4G communication frequency bands(694-960 MHz and 1710-2690MHz).The test results of the physical prototypes show that the VSWR is less than 1.25 and the phase dispersion is within ±10° in the working frequency bands.The power distribution accuracy(amplitude fluctuation)is within ±1dB,and the suppression effect on the different frequency is above 15 dB.The measured values agree well with the simulated values.Finally,the phase shifters with filtering function of this paper are applied to the actual multi-band electrically adjustable antennas,which further validate the feasibility of the phase shifters with filtering function.The phase shifters with filtering function designed in this paper greatly reduces the size and cost of the multi-band electrically adjustable antennas,lays a foundation for the miniaturization of multi-band electrically adjustable antennas,and has good practical value in mobile communication networks. |
