| As geological disasters become more and more serious,anti terrorist activities are becoming more and more difficult,and the demand for geological detection is becoming more and more intense.The technology of TWR(Through Wall Radar)has developed rapidly in recent years.The ultra wideband through wall radar is a installations based on the impulse system to detect and analyze and imaging through time domain signals.The system is consists of three parts-the pulse source,the transceiver antenna,and the acquisition imaging system.Because the impulse system's radar is based on time domain signal detection,the impulse based UWB radar has the advantages of strong penetration and high resolution.The impulse system radar has many advantages,so it has great potential in many fields,such as wall penetration,ground exploration,air reverse stealth,and so on.At present,because of the low working frequency,the time domain antenna which impulse system's radar is needed has many problems such as the size is large,low radiation efficiency,highly difficult to circular polarization design,and low fidelity coefficient of time domain signal.For the field of impulse system,it is very important to design an antenna which can be used in time domain,small size,high efficiency and easy engineering.This article sets about this difficult problem,did a lot of research work,several wall penetrating radar antennas are designed in this paper.The main work and content of this design are divided into the following parts.First,the background and practical significance of the penetrating wall radar system are briefly analyzed and summarized,and the latest development status of the penetrating wall radar at home and abroad is investigated.The research and analysis of the spectrum of different time domain signal and penetration ability,combined with the latest development of the pulse source and the impulse system,the volume of the system and the actual situation,and ultimately determine the 300MHz-800 MHz and 800MHz-3GHz two band radar system as the scope of work,according to this frequency band,did research and designed work.Secondly,comparing and analyzing the UWB antennas of different frequency bands,the design scheme of using the dish antenna and the Vivaldi antenna as a penetrating radar antenna is determined.Referring to a large number of documents,the improved butterfly antenna is used as the transmitting and receiving antenna of the system at low frequencies.The band 0.16GHz-1GHz is designed,the relative bandwidth reaches 150.87% UWB antenna,and the miniaturization structure of the electric length is realized.For high frequency applications,the Vivaldi antenna is used as the research object,and a line polarized UWB antenna with frequency band covering 0.56GHz-3.5GHz and electric length is designed.After that,the circular polarization technology is studied and the Vivaldi circular polarization array antenna is designed.Through the analysis of the time domain and frequency domain,it shows that it has good performance.Finally,we test the two antennas designed,confirm the actual application performance of the system,accomplish the design goal,summarize the advantages and disadvantages of the two antennas,and put forward the prospect for the future development of the through wall radar antenna... |
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