In this letter, we present a design of a linear array of tilted dipoles to achieve radiation patterns with asymmetric angular filtering characteristics. To realize the asymmetric radiation, the dipole elements are spaced by a distance larger than half a wavelength, thus allowing for grating lobes to occur in the visible region. Moreover, the dipoles are loaded with artificial dielectrics to increase the front-to-back ratio and consequently to enable higher gain in certain desired angular regions. Based on the design, a linear array with ten elements is manufactured and tested. The measured results show the ability of such an array to achieve stable gain from broadside up to 90° scanning while implementing a stopband angular filter for negative scanning angles.@en

In this article, we investigate the radiation and impedance properties of arrays of tilted dipoles. A spectral periodic method of moments (MoM) is developed for the analysis of infinite arrays with arbitrarily tilted dipole elements, in free space or with a backing reflector. With the aid of this analysis method, the radiation characteristics of arrays of stacked dipoles over a ground plane are studied, explaining the variation of the patterns as a function of the interelement distance and the angle of inclination of the elements. Finite linear arrays of tilted dipoles are also investigated, to assess the dependence of the array characteristics on the number of elements. The developed method can be used to design arrays with nonsymmetric radiation patterns for angular filtering or pattern shaping.

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In this work, we present a study on the radiation and impedance properties of antenna arrays with tilted elements. We developed a spectral method of moments (MoM) for the analysis of doubly-periodic arrays with arbitrarily tilted dipole or stacked dipole elements, in free space or in the presence of a backing reflector. By using this analysis method, we study the radiation characteristics of arrays of stacked dipoles over a ground plane, highlighting the variation of the patterns as a function of the inter-element distance and the angle of inclination of the elements. The guidelines derived from the MoM analysis have been applied to the design of a linear array of tilted stacked dipoles.

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A five-layer frequency selective surface (FSS) composed of subwavelength elements with large harmonic rejection bandwidth is presented. The FSS design is based on an equivalent circuit model, where the interlayer interaction is only described with a single transmission line representing the fundamental Floquet wave. A prototype of the designed FSS is fabricated, and the measured response exhibits good stability over a wide conical incidence range up to 45°. The FSS is combined with a wide-scanning connected array of dipoles to implement a phased array with integrated filtering properties. A dispersion analysis is performed to define the distance between the array and the FSS that avoids the propagation of surface waves between the combined structures, allowing to maximize the radiation efficiency. The performance of the array combined with the FSS is experimentally characterized, showing high-order harmonic rejection better than 17 dB over a large bandwidth.@en

We present the design of a frequency selective surface (FSS) with large harmonic rejection bandwidth. The FSS comprises five metal layers, each consisting of a periodic array of subwavelength elements. The design is based on an equivalent transmission line model that includes only the fundamental Floquet mode. This model is valid under the condition that the unit cell size is smaller than the distance between layers. The multi-layer FSS has an overall height of one sixth of the free-space wavelength at the central frequency of operation. The simulated frequency response exhibits good stability over a wide conical incidence range, up to 45 degrees. A prototype of the designed FSS is fabricated and combined with a wide-scanning connected array of dipoles to implement an antenna element for phased array applications, with integrated filtering properties.

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In this work, the problem of enhancing the frequency selectivity property of an antenna array has been studied. A solution based on a multi-layer frequency selective surface (FSS), composed of sub wavelength elements is proposed. An equivalent circuit model is used for the design, under the assumption that the inter-layer interaction is dominated by a single Floquet mode. This approximation remains valid by keeping the unit-cell size comparable to the inter-layer distance. Results for generic oblique incidence are presented. Fast roll-off is achieved by using a 3 pole Chebyshev filter design. Moreover, the FSS is used in combination with a connected slot array antenna. The resulting structure allows to scan up to 45° in both principal planes with a relative bandwidth (S11<; -10 dB) of 15% around the central frequency f0 = 4.8 GHz. Higher order harmonics are rejected up to 18 GHz.@en