An Ultra-Wideband Dual-layer Microstrip Planar Antenna for Radar Imaging System

In the context of radar imaging antenna design, today, the major challenge is to achieve ultra-wide bandwidth encompassing operations at low gigahertz range $(\lt 2$ GHz) with high gain which in turn provides better range resolution and penetration depth for target detection. In the last decade, the above-mentioned characteristics are met with complex antenna designs such as array configuration, complex FSS geometries, multilayer reflectors, superstrates, and metamaterials. However, even with these design technologies, it is challenging to design an antenna that operates at low gigahertz range with ultra-wideband and high gain characteristics. Attempts to achieve the afore-mentioned specifications results in larger antenna size which in turn makes it less useful for portable radar imaging systems. In this paper, a circular patch antenna design with defective ground structure (DGS) and a flat dielectric reflecting layer is proposed. The proposed antenna provides the operating impedance passband $(S_{11} \leq-10 dB)$ ranges from 1.03 GHz to 9 GHz. Furthermore, a detailed parametric analysis is also incorporated in the study for optimization of the various design parameters. The proposed antenna with the obtained characteristics can be effectively utilized in radar imaging systems.