Simulation of passive microwave penetration features in dry medium

The simulation of passive microwave penetration features in dry medium is very important to estimate the dry medium thickness, especially to retrieve the lunar regolith thickness, which is one of the Chinese lunar exploration missions. Based on layered dry medium model and radiative transfer equation, the microwave penetration features in dry medium are studied in the paper. The results show that the microwave can penetrate bigger depth in low frequencies than that in high frequencies. There exists a maximum penetration thickness th_max(f) to every frequency, and th_max(f) declines sharply with the increasing of frequency. The brightness temperature increases monotonically with the dry medium thickness if the thickness is smaller than th_max(f). The dielectric constants of the dry medium play an important role in evaluating the microwave penetration features. According to the results, a look-up table between dry medium thickness and brightness temperature is generated, which provides a new and efficient way to extract the thickness of dry medium.