A dual-band antireflection metasurface for air-ground impedance matching in ground penetrating radar

Abstract

In ground-penetrating radar (GPR) detection, the impedance mismatch between air and the material under tested (MUT) creates a strong reflection at the air-ground interface. It substantially restricts the GPR’s detecting depth by reducing the electromagnetic energy fed into the ground. This paper describes a dual-band antireflection metasurface for an air-ground impedance matching layer (IML) with central frequencies of 1.0 GHz and 2.5 GHz. Its dual-band feature relies on two distinct inner and outer closed resonant ring topologies. The destructive interference theory instructs the design and optimization of the proposed IML. Through simulation and experiment, the dual-band IML can adequately eliminate reflection at the air-ground interface and enhance transmission from the air to the MUT for GPR applications. Real-world GPR experiments demonstrate that a hazy basement interface is clearer when IML is positioned at the ground’s surface. Owing to the passive and electrically thin properties of IML, the proposed approach offers a feasible impedance matching solution for GPR and through-wall radar detection. Moreover, it also has application potential in multi-band GPR and can be extended to microwave and millimeter-wave imaging systems.