Target scattering characteristics for OAM-based radar

Abstract

The target scattering characteristics are crucial for radar systems. However, there is very little study conducted for the recently developed orbital angular momentum (OAM) based radar system. To illustrate the role of OAM-based radar cross section (ORCS), conventional radar equation is modified by taking characteristics of the OAM waves into account. Subsequently, the ORCS is defined in analogy to classical radar cross section (RCS). The unique features of the incident OAM-carrying field are analyzed. The scattered field is derived, and the analytical expressions of ORCSs for metal plate and cylinder targets are obtained. Furthermore, the ORCS and RCS are compared to illustrate the influences of OAM mode number, target size and signal frequency on the ORCS. Analytical studies demonstrate that the mirror-reflection phenomenon disappears and peak values of ORCS are in the non-specular direction. Finally, the ORCS features are summarized to show its advantages in radar target detection. This work can provide theoretical guidance to the design of OAM-based radar as well as the target detection and identification applications.

Analysis of electromagnetic scattering from typical targets for orbital‐angular‐momentum waves: Theoretical model

“…A circular antenna array is commonly used to generate the vortex electromagnetic waves with different modes, while a single receiving antenna located at the position near the circular array is used to receive the scattering field from the target for OAM-based radar system [22] (shown as Figure 1). To study this problem, we apply the plane wave decomposition method to the transmitted OAM wave and the superposition method to the scattered wave to reconstruct the received signal.…”

Beam Divergence Reduction of Vortex Waves With a Tailored Lens and a Tailored Reflector

“…where c is the speed of light [29]. As noted, due to the practical focus of the article, there is no need to discuss too much the theoretical part of the electric and magnetic field of the OAM waves.…”

RCS promotion in orbital angular momentum imaging radar with rotational antenna

“…It was concluded that the resolution performance of the OAM‐based imaging radar with infinite OAM modes was equivalent to that of conventional imaging radar [13]. Although the resolution performance cannot be improved by the OAM‐based imaging radar, many simulations have demonstrated that the radar cross sections (RCSs) are different for different incident OAM waves [14, 15]. In addition, experiments were also completed to confirm that the RCSs of complex target were different for different OAM modes [16].…”

“…The second one is to make RCS hardly reduce, such as lower carrier frequency and the polarisation radar [20, 21]. Both simulations and experiments have verified the fact that different RCSs can be acquired by emitting different OAM waves, which is similar to the polarisation radar [14–16]. Radio waves with only two kinds of polarisations are radiated in the polarisation radar system, while OAM waves with lots of different modes can be utilised in the OAM radar system.…”

“…Consequently, it takes too much time to generate large‐scale OAM mode signals. In addition, many researchers have explained that different OAM radio waves lead to different RCSs [14–16, 22]. Nevertheless, the RCSs of different OAM modes are considered to be the same in all azimuthal imaging models mentioned above.…”