Radiation pattern compensation reverse time migration of Zhurong Mars rover penetrating radar

Mars Rover Penetrating Radar (RoPeR) equipped on China's Zhurong rover has been employed for investigating Martian geology characteristics. The migration algorithm is a common tool to map subsurface structures. However, RoPeR uses a monopole antenna with a tilted angle of 16 degrees. Migration methods depending on omnidirectional radiation antennas can lead to inadequate illuminations for subsurface-inclined geological structures. To overcome this limitation, this paper proposes a radiation pattern compensation reverse time migration (RPC-RTM) method to RoPeR data, which can achieve radiation pattern compensation by an opposite-placed tilted antenna. This study first examined the radiation patterns of horizontal- and tilted-placed monopole antennas, analyzing the response characteristics of antennas to scattering points and inclined interfaces. Then, we illustrated an RPC-RTM algorithm, which employed the opposite tilted antenna to propagate backward wavefields for radiation pattern compensation. Finally, numerical simulations were implemented to explore how different antenna placements influence the illumination of RTM images. Laboratory data were utilized to validate the RPC-RTM method and demonstrate its effectiveness. The proposed RPC-RTM applied RoPeR data to image the Martian subsurface structure. The results show that the proposed method produces high-quality imaging results in insufficient illumination areas and does not require a radiation pattern compensation function. This confirms the efficacy of proposed RPC-RTM method for penetrating radar data acquired through non-standard antenna deployment.