Design Of Ground Penetrating Radar Antenna

Among various technologies for underground material detection and imaging,ground penetrating radar(GPR)has become one of the most competitive detection methods with its nondestructive and efficient imaging characteristics.Antennas are key elements of GPR system,its performance directly affects the detection ability of the system.In this thesis,the types of antennas suitable for pulsed GPR system are introduced in detail.The basic performance parameters such as impedance bandwidth,gain,directivity and radiation patterns,frequency characteristics,ringing effect and so on are also introduced in detail.Based on extensive research and theoretical basis,two GPR antennas are designed in this thesis,namely,TEM horn antennas loaded with dielectric lens and shielded bowtie antenna loaded with matematerial lens.The design of TEM horn loaded with dielectric lens can be divided into two parts.One part is the design of the TEM horn.The ridge used in the design achieve a impedance bandwidth of 100MHz-2GHz.The other part is the design of the dielectric lens antenna.Single lens loading and double lens loading are analyzed,TEM horn with double lens loading has the highest gain,but the radiation electric field pulse produces distortion.The single lens loading TEM horn has an operating bandwidth of 260MHz-2GHz,the maximum gain can reach 17 dB,the radiation pulse ringing and trailing is small,and the radiation patterns is unidirectional,which is suitable for application in GPR system.The design of shielded bowtie antenna loaded with matematerial lens is mainly divided into two aspects,one is the design of shielded bowtie antenna and the other is the design of matematerial lens.The designed resistive loaded bowtie antenna is placed in a conducting rectangular cavity with parasitic stubs,the antenna gain is increased by 6dB,the low frequency bandwidth is slightly expanded,and the radiation pattern become unidirectional from omnidirectional.The matematerial lens is loaded at the aperture of the shielded bowtie antenna,the gain of the antenna increased by2 dB,and the side lobe decreased at higher frequencies.