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The investigation of radiation field in the moon is important for the moon subsurface detection and vertical magnetic dipoles (VMD) are especially useful as sources and probes. The present work focuses on the radiation field inside the moon excited by a VMD located on or near the moon's surface. Analytical expressions are derived with approximate method. Contributions of the fields come from two parts: the series expansions of low-order terms using the multiplication iteration method, and the integrals of highorder terms using the asymptotic method. Meanwhile, the field of high-order terms is close to the total field. Compared with the calculation's direct sum, our method has advantages of accuracy and is suitable for the large-size model. For a source-receiver system on or near the homogeneous moon, it is found the waves propagating inside the moon can be described in terms of ray optics. Based on the formulas, various modes of reflection are taken into account, and the intensity of the primarily reflected waves is calculated numerically. Furthermore, effects of propagation distance and angel, the operating frequency, as well as the height of the source are considered to demonstrate the properties of the field. Particularly, the proposed method and formulas have applications to the moon interior exploration.INDEX TERMS Moon exploration, vertical magnetic dipole, ray optics, electromagnetic wave.

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A landmark feature of the Weyl system is that it possesses the Fermi arc surface states. In this work, we demonstrate that the Fermi arc surface states connect the vacuum state and the Weyl points of gyromagnetic metamaterials (GMs). The nonzero Chern numbers and Berry phases show the nontrivial topological property of the GMs in momentum space. Full-wave simulations demonstrate that the chiral surface waves on the boundary between the GMs and vacuum state can achieve robustness against sharp corners of step-type configurations. Remarkably, the topological switch can be realized by adopting the Fermi arc surface states between two different GMs. We theoretically prove that the physical mechanism of realizing topological switch is caused by different gap Chern numbers of the material system. Moreover, the direction of the topological switch can be operated by manipulating the gyromagnetic parameters of the GMs in the “button” region. Our work may provide more flexibility for the flexible and robust topological devices.

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Abstract. In this paper, the electromagnetic pulse due to a delta-function current excitation has been derived on the planar surface of a perfect conductor coated by a dielectric layer. The approximate expression of wave component is obtained when both the transmitting source and the receiving antennas are located on the surface of the dielectric. When the thickness of the intermediate layer is subjected to the condition of k 1 l<<0.6, this physical model is applied to the microstrip circuit. Analysis and computations of the wave components are carried out on the microstrip circuit, including the surface trapped wave vector which had been ignored in former studies. It is shown that the trapped-surface-wave terms should have been taken into consideration as the main contribution in total transient field in the far-field radiations.