Simulation And Testing Of Ultra Wideband Shielded Antenna For Ground Penetrating Radar

With the rapid development of China's economy,ground penetrating radar is playing a more and more important role in many fields,such as construction engineering quality detection,traffic facility quality detection,pipeline rapid detection,geological disaster prevention,archaeology,mineral resources exploration,lunar exploration,geotechnical engineering investigation and military exploration.As an important part of the end of the ground penetrating radar,the characteristics of the antenna will directly affect the detection capability of the ground penetrating radar.Therefore,it is of great significance to improve the performance of the antenna for the application of ground penetrating radar in practice.The main purpose of this paper is to simulate and produce GPR antenna with ultra wideband frequency characteristics,good shielding performance and high detection precision,so as to improve the detection capability of GPR.Since the concept of ground penetrating radar is put forward,the research of antenna which is matched with it has been an important research direction of GPR.Through the continuous efforts of scholars at home and abroad in recent decades,the types of GPR antenna and the loading methods of improving the performance of the antenna are also varied.Based on the bow tie antenna,the influence of different loading methods on the antenna is discussed,and the best loading scheme is analyzed.It is of great significance to improve the signal to noise ratio of GPR and improve the detection precision.The first study of the bow tie antenna was in 1952.The Brown and Woodward systems studied the radiation characteristics of a triangular patch antenna.It was found that the bow tie antenna has a wider bandwidth than a cylindrical dipole antenna and has a smaller size compared to the double cone antenna,which is convenient for application.In the actual work of ground penetrating radar,the underground geological structure is complex and there are many interference from the ground,which requires the antenna to have wider bandwidth and good direction.In general,the metal back cavity is placed on the back of the bow tie antenna,which can shield the interference from the electromagnetic waves from the air,and reduce the radiation of the antenna to the air,and to a certain extent weaken the direct wave.However,the metal shield has a great influence on the signal of the antenna.The signal can easilyreflect the multiple waves back and forth between the antenna and the shield,and the appropriate absorbing material can increase the antenna bandwidth to weaken the reflection wave in the mask.In the aspect of increasing the bandwidth of bow tie antenna,the way of resistance capacitance hybrid loading is difficult to realize.The resistive load of antennas is mainly divided into centralized resistive loading and distributed resistance loading.The distributed resistance loading refers to the continuous loading of the antenna in the antenna,which makes the current weaker in the antenna,and then a non reflective resistance loading at the end of the antenna at the end of the antenna.This loading method can effectively increase the bandwidth of the antenna,but it will also seriously reduce the radiation efficiency of the antenna,and it is difficult to implement in practice.Centralized resistance loading means that a single or multiple resistors are loaded at the end or other locations of the antenna.Compared to distributed loading,the centralized resistance loading has less loss on the radiation efficiency of the antenna and is easier to implement.In this paper,the bow tie antenna,shielding wave absorbing antenna and resistive loading antenna are simulated by electromagnetic simulation software HFSS.According to the simulation results,combined with the practical problems to be solved,the suitable antenna size,shield size,absorbing material,loading resistance and mode and so on are optimized.Based on the simulation results,the antenna is fabricated and tested to test the detection performance of the antenna.The actual test results show that both the absorbing shielding antenna and the resistance load antenna can effectively improve the bandwidth of the bow tie antenna,eliminate the trailing of the time domain signal and improve the shielding performance of the antenna.It is of great significance to improve the detection precision of the ground penetrating radar and improve the signal to noise ratio of the radar signal.