Underground object detections usually employ ground penetration radar (GPR). However, GPR produces data taken only from the earth's surface. This paper proposes radio through the earth (TTE) propagation path or received signal profile for three-dimensional detection. The propagation model and the three-dimensional propagation line equation are employed. Collections of transmission paths are classified into two-part, blocked and unblocked signals. Both classified signals are compared for signal processing. The study reveals that a number of the transmission path is a function of vertical edge to probe n, the deep of edge l, and transmitter step s. It is suggested the blocked signal paths are used for signal processing analysis as the volume is usually smaller than the evaluated space.