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Multimode multibeams are widely investigated, but are mostly generated by 3D bulky configuration or partitioned aperture for each beam. This paper proposes and analyzes a method to generate multimode multibeams using a planar single‐layer metasurface with shared aperture. The underlying principle is multiplexing tensor holographic metasurface with a superposition of modulated impedance surface. The multiplexed metasurface is an interference pattern of objective radiation and reference current to generate each beam. To validate the proposed method, this paper presents a multiplexed metasurface shared for two different beams. These two beams are with different modes, i.e., different beam types, different frequencies, different polarizations, and different focal depths. This multiplexed tensor holographic metasurface is theoretically analyzed, fabricated, and validated with matched results in simulation and measurement. The proposed method is promising to realize multiplexed tensor holographic metasurface for emerging wireless communication and radar front‐ends with compact aperture, low profile, light weight, and multiple functions. [ABSTRACT FROM AUTHOR]

A tensor holographic metasurface is proposed, to independently manipulate nondiffractive beams with orthogonal polarization and flexible propagation direction. To theoretically analyze the proposed topology, addition theory is developed to modulate surface impedance using tensor cells. Moreover, a polynomial formula is derived to express the equivalent surface impedance of tensor unit cells for pattern generation. To validate this concept, a tensor holographic metasurface is designed, fabricated, and measured. The well‐matched simulation and measurement results show that, for the first time, the proposed holographic metasurface with tensor unit‐cells, simultaneously generates two Bessel beams, not only with orthogonal polarization, but also with expected propagation direction rather than fixed along the broadside. Moreover, the proposed topology is promising to manipulate multiple beams not limited to two Bessel beams. [ABSTRACT FROM AUTHOR]

Cooray–Rubinstein formula has been extensively used for the evaluation of the horizontal component of the electric field generated by a lightning return stroke over a lossy ground. Considering the good characteristics of the formulation in terms of “step response” kernel $K_{\varepsilon }(t)$ corresponding to the ground surface impedance, proposed by Andreotti et al. recently, a new method for evaluating the Cooray–Rubinstein formula in the time domain is proposed in this paper. In this method, $K_{\varepsilon }(t)$ is first expressed by an integral of exponential function based on the integral formula of the modified Bessel function of the first kind, and then approximated by a piecewise exponential function using the Gauss numerical integration. Finally, taking advantage of the piecewise recursive convolution, the time-domain Cooray–Rubinstein formula for evaluating the lightning horizontal electric field can be calculated accurately and efficiently. The validity and efficiency of the proposed method are demonstrated by the comparisons with the methods in other literature. [ABSTRACT FROM AUTHOR]

The Cooray–Rubinstein formula has been widely used for evaluating the horizontal component of the electric field generated by a lightning return stroke over a lossy ground. An accurate and efficient time domain method is presented in this study, by means of piecewise recursive convolution. The recursive convolution is achieved by expressing the kernel function of the ground surface impedance by a piecewise exponential function, in which the integral form of the modified Bessel function of the first kind is evaluated using the trapezoidal numerical integration. Since the time‐domain analytical expression of the ground surface impedance kernel function has been adopted, the computational error can be directly controlled within a reasonable tolerance. The validity and efficiency of the proposed method are demonstrated by the extensive comparisons with the method in other literature. [ABSTRACT FROM AUTHOR]