Study Of F-band Base Station Antenna On Electrical Performance's Optimization

In the mobile communication system,the base station antenna works as the interface to take the function of signal transmission and reception.In order to improve the network speed and increase the signal coverage,the network operations provide much more requirement on base antenna electrical performance.For example,PIM(Passive Inter-Modulation)specification is required as low as-150dBc.And the integration is another development trend for antenna,most base station antennas have been implemented internal actuator for tilt adjustment,so there is new requirement for phase shifter.Actually the base station antenna is the foundation of network quality,once some issues of antenna happened,the signal will be disrupted,which causes high RSSI.For base station antenna manufacturers,the manual soldering and some process tooling control are applied,which depends on skills of operators.For phase shifters,the media coupling shifting is limit by its size and unsuitable for low frequency applications.During the new product development,it still depends on pilot run,but some variance of material and process cannot be well identified for risk control as the preventive action.In this work,a 600MHz frequency antenna developed for the North American 5G market is selected for study.In the phase shifter design,one to four air strip line coupled phase shifter is applied.According to the RF analysis method,transmission line and impedance matching theory,the return loss can be optimized by adjusting for trace on phase shifter.Depend on the tolerance analysis,the variance of the solder mask thickness for the phase shifter was identified as critical parameter by return loss simulation,and the process improvement of the supplier and the key parameter control of the process were added in advance to avoid the variance during mass run process.On the PIM parameters,a new selective-wave automatic soldering process is applied,and the DOE(design of experiment)is used to set up module to determine correlation of the soldering key parameters of PIM,and then PIM result can be predicted based on parameter setting.This method can reduce the times of experiments,effectively reduce costs,and systematically analyze the results.