FM—CW地质雷达在有损耗的分层介质中的特性(上)

FM-CW geological radar performance in a lossy layered medium(1).

FM—CW地质雷达是一种通过发送周期性的连续调频(FM)线性扫描信号达到探测地下异物目的的仪器。由于其简单的硬件构成以及在较低功耗介质中雷达天线至地下异物的距离可通过FM—CW雷达信号来确定,在一些高分辨率探测的地质任务中,FM—CW地质雷达较为常用。本文针对一维和二维的情况,利用数学解析和数值分析的方法,提出了FM—CW雷达在无损耗和有损耗的地下分层中的模型,并利用FFT(快速傅立叶变换)和“距离等式”,根据接收信号的频谱,讨论了如何利用反演公同时将距离和介电常数转置的过程。另外,本文还讨论了多层地质结构信号的图像和频谱。

FM-CW geological radar is capable of detecting subsurface anomalies by using linear sweep frequency transmission of a periodically repetitive continuous FM signal. Due to the continuous-wave nature, the peak power of the FM-CW radar is usually in the range of hundreds of milliwatts. In cases where high resolution is necessary, the FM-CW radar is preferred because of the simple hardware structure and the availability of low-power components. The distance from the antenna to an anomaly can be determined by FM-CW in lossless media. In this paper, we present both analytical and numerical methods for modeling FM-CW radar performance in lossless and lossy layered formations for 1D and 2D cases. The FM-CW operating frequency is set in the range of 1-2MHz, and the sweep periods are 10ms and 2ms, respectively. An inversion formulation is discussed to invert the distance and dielectric constant simultaneously from the spectrum of the received signal by using FFT and the ’range equation’. The spectrum and images of multiplayer formations is also studied in this paper.