Time Domain Broadband Antenna Design And Its Application In The System

As exploring the object under ground by electromagnetic wave, the ability ofexploration depends on the frequency of radiating signal. The electromagnetic wavewith high frequency has better resolution response, and the electromagnetic wave withlow frequency has stronger penetrating ability. The signal with rich frequencyspectrum for ground penetrating can solve the conflict between resolving power andpenetrating ability. In these years, the ground penetrating radar with no carrier-wavehas been widely used in archeology, geology and military. For general exploringobjects requirement, narrow pulse signal with tens millimicro second to millimicrosecond has the frequency spectrum from DC to thousands MHz. So the antenna forGPR not only has better radiating ability to ground, but also has wide band in timedomain. The antenna design has become the most important technique for GPR.At present, the antenna for radiating narrow pulse signal may mainly be TEMhorn, bowtie and resistive antenna. The bowtie antenna which has broad band, lowring and simple structure is the main antenna for GPR. In this paper, first thefrequency band of the antenna can be determined by analyzing the frequencyspectrum of the transient pulse to be radiated, and the structure sizes of the antennasuch as bowtie, resistive loading bowtie and nonreflecting resistive loading bowtiecan hereby be found easily with the presented method. Then an effective method isproposed for the design of the transient back-cavity bowtie antenna forground-penetrating radar (GPR) applications, which is based on the demand that themaximum energy of the transient signal ought to be emitted downward to the earth inGPR. Last the proposed method for the antenna design has been validated byexperiments and numerical simulation results. Otherwise, a GPR system, based onsuch-designed antenna with good performance in the buried-object detections, wasdeveloped with success.