Research On Key Technology Of RF Front-end Based On Amorphous Flat Air-ground Ad-hoc Network Platform

Amorphous flat air-ground Ad-Hoc network introduces air node carried by UAV to eliminate ground interference,which can effectively extend the communication distance of nodes.However,in some complex environments,it is impossible to maintain long-distance communication and network stability only by relying on air relay nodes.In order to further enhance the stability of the network topology,this paper focuses on the three key modules of the RF front end:RF switch,low noise amplifier and power amplifier.By combining the RF front end with the nodes of the self-organizing network,the receiving/transmitting branches of the nodes are separated,and the stability of the network topology is enhanced.This design mainly completes the following work:(1)In order to control the transmission and reception of RF signals in the nodes,a high isolation SPDT RF switch is designed based on 0.18 ?m CMOS technology,which is suitable for the 2.4GHz frequency band.The switch controls the transmission and reception of signals by changing the excitation voltage,and eliminates the interference of out-of-band signals by means of a cascade band-pass filter.The simulation results show that the insertion loss of the RF switch is less than 1.5dB,the isolation is greater than 40dB,and the compression point of 0.1 dB is 38dBm in the operating frequency band 2.4GHz-2.5GHz,which meets the performance requirements of the Ad-Hoc network platform.(2)In order to enhance the signal receiving ability of the node,a two-stage cascaded low noise amplifier(LNA)is designed using the ATF-54143 transistor from Avago.The LNA is cascaded with the input end of the node to form a receiving branch.After circuit optimization,the simulation results show that the noise coefficient of LNA in the working frequency band is 0.515dB,the gain is greater than 30dB,the return loss is less than-15dB,and the 1dB input power compression point is-12dBm.(3)Based on the AFT27S010N transistor of NXP Corporation,a power amplifier(PA)is designed to improve the signal transmission distance.PA and the RF switch output terminal cascade,forming the node transmission branch.After optimized by ADS software,the simulation results show that the gain of PA in the working frequency band is greater than 19dB,the return loss is less than-15dB,the 1dB output power compression point is 41.19dBm,and the amplifier efficiency is 56.207%.(4)Finally,the network topology experiment is carried out,and the experimental results show that the RF front-end module can separate the transceiver branch of the node and effectively enhance the stability of the network topology.