A novel frequency selective surface (FSS) exploiting 2.5D miniaturised hexagonal rings (2.5D MHR) is proposed. It can obtain an ultra-wide stopband and an improved polarisation-independent property due to the compact hexagon arrangement of 2.5D MHRs. The −10 dB bandwidth of the proposed FSS is from 1.97 to 8.08 GHz, and the deviation of resonant frequencies at 30°under transverse electric/transverse magnetic polarisations is merely 0.006f 0. A prototype of the proposed FSS is fabricated and measured to validate the good consistency between simulations and measurements.

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Considering the three-dimensional (3D) trajectory, 3D antenna array, and 3D beamforming of unmanned aerial vehicle (UAV), a novel non-stationary millimeter wave (mmWave) geometry-based stochastic model for UAV to vehicle communication channels is proposed. Based on the analysis results of measured and ray tracing simulation data of UAV mmWave communication links, the proposed parametric channel model is constructed by a line-of-sight path, a ground specular path, and two strongest single-bounce paths. Meanwhile, a new parameter computation method is also developed, which is divided into the deterministic (or geometry-based) part and the random (or empirical) part. The simulated power delay profile and power angle profile demonstrate that the statistical properties of proposed channel model are time-variant with respect to the scattering scenarios, positions and beam direction. Moreover, the simulation results of autocorrelation functions fit well with the theoretical ones as well as the measured ones.

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Abstract-An ultra-wideband frequency selective surface (FSS) for wide incident angles is proposed. Its −3 dB bandwidth is from 3.49 GHz to 12.13 GHz, and the fractional bandwidth exceeds 110%. Some parasitic patches are appended to reduce the deviation of resonant frequency under wide-angle incidence. The proposed FSS exhibits an improved stability when the incident angles are in the range from 0 • to 60 • . The relative simulated and measured results are provided to validate its effectiveness.