Front End Design And Simulation Of Short Distance Rainfall Attenuation Measurement

Experts in the meteorological field have proposed the use of microwave networks to monitor urban rainfall in recent years.Based on the measurement of the rain attenuation value on the microwave network path and the establishment of the relationship model between rain attenuation and path rainfall intensity,we can get the rainfall intensity information on the microwave path.Microwave signals in the millimeter wave band are more sensitive to precipitation and rain particles such as rain and snow,so it is more practical to use these commercial links for rainfall observation in the advent of the 5G era.Because the coverage radius of the base station is short and the need for improving the accuracy of rainfall inversion,it is necessary to achieve a goal of measuring the weak rain attenuation value at a short distance.This paper presents a hardware design scheme that improves both gain and noise,and improves reception and identification of weak signals by increasing the gain of the RF front-end circuit and reducing noise.The main hardware solutions include low-side-lobe array antennas,low-noise power amplifiers and highly selective band-pass filters.Firstly,an X-bandlow side-lobe array antenna is designed.The result is that the operating bandwidth is greater than 1 GHz,the 3 dB beam width is about 20°,the side-lobe level is-16.2 dB and the gain is 17.3 dB.Secondly,designing an X-band low-noise power amplifier.The index is that the input return loss is lower than-10dB,the gain is greater than 32dB,the gain flatness is 1.5dB and the noise figure is lower than 1.8 in the 9.5GHz to 10GHz band.The last is a highly selective band-pass filter.Its results are that the passband bandwidth is between 9.6GHz to 10.4GHz,the input return loss is basically less than-lOdB,the insertion loss is substantially greater than-8dB and the parasitic passband attenuation is greater than 40dB.This paper makes a detailed exposition of X-band front-end RF circuit's each part design process.Through co-simulation tests,the input returnloss,gain,and noise figure and other performance indicators in the range of 9.2 GHz to 10.2 GHz are verified.The result is that the performance indexes all reaches the design requirements and measuring the weak rain attenuation can be achieved.Finally,some improvement measures and the notices needed attention in the actual production are given.Besides the prospect for building links in the future is put forward.