Research On The Broadband Active Receiving Antenna Based On Non-Forster Circuit

Passive antennas are constrained by the bandwidth-gain-volume theory,and it is difficult to achieve wideband,high gain,and miniaturization at the same time.Compared with passive antennas,active antennas composed of non-Foster circuits and electrically small antennas can break through the limitations of the Bode-Fano criterion and achieve better broadband and miniaturization characteristics in the short-wave frequency band.This paper mainly studies the non-Foster circuit and the electrically small antenna,then completing the design of the active receiving antenna.The main contents include:1.Single-stage non-Foster circuit matched passive monopole antenna was simulated and analyzed.First,the passive electrically small monopole antenna loaded with the inductor was designed and tested,and the input impedance characteristics of the antenna in the frequency range of 10 MHz to 20 MHz were obtained.Secondly,according to the basic theory of non-Foster circuit,the operational amplifier was used to simulate and verify the single-stage non-Foster circuit in the circuit simulation software ADS.On this basis,the realization process of single-stage non-Foster circuit matched passive monopole antenna was simulated and analyzed.In order to achieve the best effect of impedance matching,the equivalent circuit of the imaginary part of the antenna was obtained according to the input impedance characteristic of the antenna,so as to replace the latter matching circuit in the single-stage non-Foster circuit,and the simulation optimization was continued.Finally,the single-stage non-Foster circuit can cancel out the imaginary reactance of the passive monopole antenna.2.Two-stage non-Foster circuit matching passive monopole antenna was researched and designed.Firstly,a two-stage non-Foster circuit with non-inverting input-in-phase input output was used as the research object,carried out the theoretical analysis,completing the simulation design and analysis of two-stage non-Foster circuit matching passive monopole antenna in ADS.The use of a two-stage non-Foster circuit not only canceled out the imaginary reactance of the passive monopole antenna,but also converted the real resistance into a positive pure resistance.In order to fully realize the impedance matching with the 50?transmission line,the broadband passive matching network was designed combining with the simple real frequency method and the direct optimization method,then the simulation design of the active monopole antenna was finally completed.The simulation results show that S₁₁ of the active monopole antenna is less than-15 dB and the voltage standing wave ratio?VSWR?is less than 1.25,indicating that the active monopole antenna can be well matched with the 50?transmission line.At the same time,the-10 dB S₁₁ relative bandwidth of the active monopole antenna is about 66.6%,and the receiving gain is 8.5 dB in the frequency range of 10 MHz to 16.5 MHz,and 2.5 dB in the frequency band of 16.5 MHz to 20 MHz,indicating that the active monopole antenna has been achieved the broadband and high gain.In addition,the simulation results were basically consistent with the actual test results,verifying the feasibility of the active monopole antenna.