Neural Network Characterization of Reflectarray Antennas

An efficient artificial neural network (ANN) approach for the modeling of reflectarray elementary components is introduced to improve the numerical efficiency of the different phases of the antenna design and optimization procedure, without loss in accuracy. The comparison between the results of the analysis of the entire reflectarray designed using the simplified ANN model or adopting a full-wave characterization of the unit cell finally proves the effectiveness of the proposed model

New Unit-cell Elements for Perforated Dielectric Transmitarray

In the recent years the interest for Transmitarrays (TA) antennas increases, since they represents a good solution for obtaining high gain and beam steering, with a configuration that coupled the advantages of lenses and planar arrays. Among the different possible technological solution adopted for the realization of a Transmitarray, a particularly convenient seems to be the one adopting a perforated dielectric layer: the resulting antenna is characterized by ease of manufacturing, that could be done also adopting a 3D additive manufacturing technique, low cost, low profile and low losses. The idea behind the realization of a perforated dielectric TA is that of locally changing the phase of the transmission coefficient properly acting on the size of the hole in the dielectric, through which it is possible to control the effective dielectric constant of the substrate, maintaining the S21 amplitude as much as it is possible close to 1 . Different solutions have been presented in literature, aimed to improve the performances of the transmitting layer, playing with the shape and the number of hole in each unit-cell and/or the number of dielectric layers. In fact it was notice that increasing the number of layers, and especially adding one layer on each side of the transmitting one acting as a sort of matching element between the unit cell of the TA and the air, the antenna performances increase (M.Wang, S. Xu, F. Yang and M. Li, 2016 IEEE Int. Symposium on Antennas and Propag. and URSI/USNC National Radio Science Meeting). Starting from these considerations, here a new type of unit-cell has been introduced: it consist in a three layer structure, where a square hole is drilled in the center of the unit-cell of the middle layer and its size d is used to control the phase of the transmission coefficient, while in the upper and lower layers the hole has a linearly tapered shape. The structure has been designed to work in E-band and the adopted dielectric material has a dielectric constant εr = 6.15. The unit cell has been simulated with CST using the infinite array method. The variation of the amplitude and phase of S21 with d is plotted in Fig.1. These results show that, while the phase variation covers a range even larger than 360°, the amplitude of S21 has minimum variations, confined between -0.7 and -0.2 dB. Results on the design and analysis of an entire TA adopting this type of unit-cell will be provided at the Conference

Beam Steering mm-Waves Dielectric-only Reflectarray

In this paper, some numerical results on the possibil-ity to design a 3D-printable dielectric ReflectArray (RA) antenna with beam steering capabilities are presented. The adopted unit-cell consists of a single-layer dielectric element perforated with a square hole, whose side is varied to change the phase of the reflection coefficient. Since the unit-cell behavior is quite stable with the direction of arrival of the incident field, it is used to design a 52 × 52 reflectarray working in Ka-band. Its numerical characterization proves that the RA is able to provide less than 2 dB of gain losses over a scanning range of ±30° in the vertical plane

Perforated Dielectric Reflectarray in Ka-band

This paper proposes a single-layer perforated dielectric reflectarray antenna that operates in Ka-band. The unit-cell is made up of a dielectric element perforated by a centered square hole, whose size is used to control the phase of the reflection coefficient. This cell has been used to design a 52x52 offset reflectarray working at 30 GHz, whose numerical analysis proves that it has good radiation features. The proposed configuration is particularly convenient since Additive Manufacturing processes can be exploited for its fabrication

Beam Scanning Capabilities of a 3D-Printed Perforated Dielectric Transmitarray

In this paper, the design of a beam scanning, 3D-printed dielectric Transmitarray (TA) working in Ka-band is discussed. Thanks to the use of an innovative three-layer dielectric unit-cell that exploits tapered sections to enhance the bandwidth, a 50 × 50 elements transmitarray with improved scanning capabilities and wideband behavior has been designed and experimentally validated. The measured radiation performances over a scanning coverage of ±27° shown a variation of the gain lower than 2.9 dB and a 1-dB bandwidth in any case higher than 23%. The promising results suggest that the proposed TA technology is a valid alternative to realize a passive multibeam antenna, with the additional advantage that it can be easily manufactured using 3D-printing technique