The Design And Implementation Of The Dielectric Resonator Filter Used In The 4G Base Stations

In recent years,mobile communication business has entered a rapid development period,since the end of 2013 the MIIT issued the 4G licenses,for a short time about one year,the 4G users have already been more than one hundred million.From the 4G mobile communication spectrum division,communication spectrum gets higher and higher,spectrum resources is becoming more and more nervous,the filter as a device for receiving the useful signal in the mobile communication base station system and filtering the clutter signal,the performance is highly required,the metal cavity filter has been unable to satisfy the requirement of the 4G mobile communication data transmission.So,the high-performance dielectric cavity filter is the best choice for the lack of frequency spectrum resource in the 4G base station.This paper was based on the theory of microwave dielectric cavity filter design,in combination with the TD-LTE spectrum and the base-station filter technical index requirements,the AWR software was used to design and optimize the circuit and then got the key parameter values.While the selected dielectric resonator must meet the requirements of the base station application,the HFSS 13.0 software was used to study the dielectric filter structure parameters how to effect the performance of the microwave device.Through the system simulation and debugging,we have designed and implemented of an eight order dielectric cavity filter using cross coupling method,the overall performance of the dielectric filter implementation have reached:center frequency was 2.595GHz,relative bandwidth 1.54%,the loss less than 0.5 dB,there was a transmission zeros at about 2.545 GHz and 2 645 GHz,the rejection was greater than 70 dB outside of the band at about 30MHz,the second harmonic was about at 3GHz,The simulation results was reached the target.According to the results of full wave simulation,we have got the structure information of the dielectric filter in detail,then draw the three view drawing of the dielectric filter by the AutoCAD software,we must get strict in the process requirements to manufacture the filter.We have used the Agilent vector network analyzer E5071C for testing the transmission performance of the filter,the performance of the normal temperature environment have reached:center frequency was 2.595GHz,the relative bandwidth was slightly larger than 40 MHZ,the loss was less than 1.5dB in the band,the passband ripple was less than 0.5dB,the rejection at 2.545GHz was about 73dB and at 2.645 GHz was about 72dB.In addition,the transmission performance at different environment was no big difference between the normal temperature,such as in the low temperature,the high temperature and the high temperature with humid environment,the second harmonic was at about 2.92GHz in the different environment.The measured results was fit well with the simulation results and meet the technical requirements,and the microwave performance of the dielectric filter was close to the industrialized production.