Detailed calculation of modified radar equation for detecting meteorites buried within the ice by radio echo sounding

• Main Authors: Tajima,Katsusuke, Nishio,Fumihiko
• Language: English
• Published: 1984
• Subjects: Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/record/1715/files/KJ00000012347.pdf; https://nipr.repo.nii.ac.jp/records/1715

P(論文) The radar equation is usually given in free space and the field far from the radar transmitted is only studied. However, using the radar sounding apparatus to detect meteorite buried within the ice, we should consider the field near the radar transmitted. In this paper, the scattered field near the radar transmitted is calculated exactly and a more accurate radar equation is derived. Based on the detailed calculation of the modified radar equation the detectable domains indicate that the intensity of echo reflected from the meteorite buried in the ice is sufficient to be detected by the present radio echo sounding apparatus taking G_0=2 as the antenna gain and P_r/P_i=(10)^<-10> as the maximum sensitivity of the back-scattered power from spherical meteorite. The detectable domain for iron meteorite is larger than that for stony meteorite, indicating that if the diameter is identical, the detectable depth for iron meteorite must be deeper than that for stony meteorite. The detectable domain extends to a smaller diameter of meteorite and a larger depth using a higher frequency in the case of the Rayleigh scattering, but it should be noted that for iron meteorite, the frequency dependence on the detectable domain becomes reciprocal and shows resonance phenomena for the 400MHz at the diameter larger than about 10cm where the scattering aspect due to meteorite pieces dispersed in the ice changes from the Rayleigh scattering into the Mie scattering. In the maximum frequency of diameter of meteorite, about 20cm for the iron meteorite and 1cm for the stony meteorite, the detectable domain shows resonance phenomena for the iron meteorite by the electromagnetic wave of 400MHz at the depth of 10m, while for the stony meteorite the detectable domain is within 1m in depth. Therefore, a higher frequency should be applied to detect the stony meteorite. departmental bulletin paper