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Antenna systems based on hemispherical lenses allow full azimuth scanning or electronically controlled sector scanning. The article presents a numerical simulation of a broadband multi-beam antenna system based on a hemispherical metamaterial lens made of parallel printed circuit boards with metal diffusers of small electrical dimensions. The effective parameters of a metamaterial based on printed Jerusalem crosses with welded-in transverse metal pins are investigated. The selected geometric dimensions of the metamaterial made it possible to reduce the effect of anisotropy. Directional patterns are considered when a lens is excited by a system of broadband vibrators with two orthogonal polarizations. For each polarization, conclusions are drawn about the operating range and the magnitude of the losses. The results obtained in this work are planned to be used in the future in the design of wideband lens antennas from parallel printed circuit boards.

The Direction of Arrival (DOA) estimations of systematic errors are caused by diffraction distortions of the measured spatial structure of a electromagnetic field. These distortions result from scattering of incident waves on the antenna system and nearby scatterers (mobile carrier body, antenna mast, underlying surface, etc.) in wide frequency band, including the resonant frequencies of nearby objects. This article proposes a method for minimizing the DOA estimation systematic error by forming an additional virtual receiving channel—a Virtual Antenna Array (VAA). The VAAs were formed by use of classical apparatus of electrodynamics—the Huygens-Kirchhoff principle, the method of equivalent fields and sources, and the quasistatic approximation of the field based on the theory of analytical functions of the complex variable (Cauchy integral, Laurent series). The proposed method does not require calibration of the antenna system or a priori information about the geometry and material properties of the scatterers (dry or wet soil, opened or closed vehicle doors, etc.). Therefore, it gives good results in cases of mobile and stationary arrays, or changing carrier body geometry.

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The use of a printed Luneberg lens is promising for powering ultra-wideband phased array antennas with full-azimuth scanning. This article describes in detail the model for constructing a flat Luneberg lens based on a printed circuit with curved conductors. A certain pattern(pattern) with a relative permittivity er1 was etched on the copper-coated substrate. This was done in order to realize the value of the refractive index. By printing a grid of intersecting conducting lines, a refractive index of was achieved in the center of the lens. The diameter of the Luneburg lens antenna was chosen to be 28.6 cm, which corresponds to 12,4l0 (l0 is the wavelength of free space) to achieve a half-power beam width of 5 at an estimated frequency of up to 20 GHz. Since the design of the Luneberg lens is based on geometric optics, the lens diameter must be a multiple of the wavelength to limit diffraction effects. Operating frequencies up to 20 GHz were selected. The lens was sampled into single cells. If the unit cell size is small enough, the lens can be described as a medium with a certain effective refractive index. As a result, this propagation theory can be used for lens design. The substrate used for the lens was 1 mm thick, the material used was Rohacell 31HF, which has a permittivity of 1,046 and a loss tangent of tg(d) = 0,002.