1,721,160 research outputs found
Linear-to-Circular Polarization Transmission Converter Exploiting Meandered Metallic Slots
Full text linkA novel wideband linear-to-circular polarization transmission converter composed by a cascade of two identical fully-metallic Frequency Selective Surfaces (FSSs) separated by an air gap is presented. The adoption of meandered slots patterned on a metallic layer, along with an interwoven FSS unit cell geometry, allows achieving up to 25 % of 3 dB Axial Ratio (AR) bandwidth for a normally impinging plane wave. Moreover, by exploiting the FSS unit cell compactness, the converter provides a prominent robustness to oblique incidence, and it is therefore suitable to be employed in radomes and dichroics. As a proof of concept, a prototype of the proposed converter is manufactured and tested for assessing the design approach
Characteristic Modes Theory Exploitation for the Design of Transmission-Type Polarization Converters
No full textA novel strategy for the design of a transmission-type polarization converter of linearly polarized (LP) plane waves is proposed. More in detail, a general and straightforward approach based on the exploitation of the characteristic modes analysis (CMA) for identifying the frequency selective surface (FSS) unit cell is described. The excitation of two current modes on the proposed FSS unit cell, both exhibiting a circularly polarized (CP) radiated field, are provided to obtain an efficient polarization rotator. Measurement campaigns confirm the benefits of adopting CMA as well as the remarkable performance
Design of a Transmission-Type Polarization-Insensitive and Angularly Stable Polarization Rotator by Using Characteristic Modes Theory
Full text linkA novel design strategy for realizing a transmission-type polarization rotator of linearly polarized (LP) plane waves by exploiting the characteristic modes (CMs) theory is described. Design guidelines for the excitation of two current modes on a frequency selective surface (FSS), both exhibiting a circularly polarized (CP) radiated field, are provided to obtain the polarization rotation. The proposed converter exhibits remarkable performance also in the case of oblique incidence and a polarization-insensitive response thanks to the FSS unit cell compactness along with its fourfold rotational symmetry. Specifically, it provides a 3 dB cross-polar transmission percentage bandwidth up to 16.5% with a minimum insertion loss (IL) of 0.1 dB for a normally impinging plane wave whereas in case of an incidence angle of 60° the 3 dB cross-polar transmission percentage bandwidth turns out to be around 14% with a minimum IL of 0.7 dB. Measurements on a realized prototype are in good agreement with simulations, confirming the reliability of the proposed theoretical study
Analysis of Performance Enhancement of Clustered-Based Phased Arrays Employing Mixed Antenna Element Factor
No full textA novel strategy for the design and optimization of large-scan phased arrays is proposed. Active electronic beam-scanning antennas offer an unparalleled set of degrees of freedom, but they can be expensive, require complex radio frequency frontends, a suitable thermal management, and generally undergo a loss in directivity due to the pattern shape of the unit radiating element. A solution to these problems can be offered by an approach that reduces the number of transmit/receive modules (TRMs) and phase shifters (PSs) by a simple and fast clustering strategy based on Penrose tessellation that operates on the regular lattice of the radiating elements. More importantly, the proposed scheme adopts a mixed-mode element factor that proves to be effective in guaranteeing a remarkable scan efficiency and robustness with respect to array elements failures. The optimization process aims to maximize the minimum gain along the main beam during the scan as well as minimizing the peak sidelobe level (PSLL), while reducing the number of TRMs
Low Profile 3-D Printed Transmitarray for Future 6G Wireless Communications
No full textA preliminary investigation of the possibility to exploit three-dimensional (3D) printing technology for the fabrication of a transmitarray (TA) is addressed. More in detail, both dielectric and metallic unit cells are designed with the purpose of providing a non-uniform phase profile of the TA panel to collimate the main beam at broadside direction (θ=0°)
Exploitation of Triangular Lattice Arrays for Improved Spectral Efficiency in Massive MIMO 5G Systems
No full textA thorough analysis of the performance of planar arrays with a regular periodic lattice is carried out and applied to massive multiple-input-multiple-output (MIMO) systems operating within 5G NR n257 and n258 frequency band. It is shown that, among different arrangements with uniform spacing, a triangular lattice guarantees the reduction of the Average Side Lobe Level (ASLL), a better angular scan resolution of the main beam within a predefined angular sector and a lower mutual coupling level among elements. Moreover, single beam and multibeam application scenarios are considered for the performance comparison and both cases assess the remarkable features offered by a triangular arrangement. Particular attention is paid to illustrate, for different propagation channel scenarios, the effects of the array lattice on overall system performance including average gain as well as Signal-to-Interference plus Noise Ratio (SINR) and Sum Spectral Efficiency (SSE). The obtained results prove that a regular and periodic triangular lattice is appealing for arrays to be adopted in massive MIMO 5G systems
Low Profile Dual Linearly Polarized 1-bit Transmitarray Exploiting Two Metallic Layers
No full textA novel azimuth-independent dual linearly polarized (LP) transmitarray (TA) based on a polarization rotator is presented. The exploitation of either right-handed circularly polarized (RHCP) or left-handed CP (LHCP) scattered field is at the basis of the proposed TA. The employed unit cell guarantees a low insertion loss as well as a crosspolar transmission phase difference of 0 or 180. The TA unit cell response is insensitive to any angular rotation of the panel, or the primary feed, along . The conceived dualpolarized 1-bit TA allows achieving up to 16.5 % of 3 dB gain bandwidth (BW3dB) with a maximum gain around 22 dBi and a peak aperture efficiency of 30.4 %. Unlike the previously reported dual-polarized TAs, this novel structure consists of a very thin dielectric layer, namely 0.08 0 at central frequency, comprising only two metallic layers making it a cost-effective solution as well as compliant with the increasingly strict profile requirements imposed by many of the future terrestrial and non-terrestrial wireless communication paradigms such as vehicular communications or SatCom systems. As a proof of concept, a prototype of the proposed dual-polarized 1-bit TA is manufactured and tested for assessing the benefits of this design approach
A Compact CubeSat Antenna with Beamsteering Capability and Polarization Agility: Characteristic Modes Theory for Breakthrough Antenna Design
No full textIn this article, we propose a novel compact radiating system for a 1 U CubeSat. The designed antenna benefits from characteristic modes theory (CMT), which provides guidelines to advantageously exploit the hosting platform as part of the radiating system. The effect of the small satellite on the resonance frequency and pattern shape is therefore intrinsically taken into account. The employed inductive-coupling exciters are nonresonant half-loops that offer a huge saving in terms of space and weight requests. Additionally, the proposed S-band antenna provides the remarkable feature of scan-beam capability, in circular polarization (CP) as well as linear polarization (LP), which is not found in any other compact radiator. The overall angular coverage spans more than 90° with an axial ratio (AR) lower than 3 dB and within the half-power beamwidth (HPBW), and therefore a 360° angular coverage is guaranteed if four of these minimally invasive radiators are placed on the small satellite. Measurements are in positive agreement with simulations and confirm the estimated good performance of this innovative solution
Wide-Scan and Energy-Saving Phased Arrays by Exploiting Penrose Tiling Subarrays
Full text linkA partitioning scheme based on Penrose-inspired subarrays is proposed for wide-scan planar phased arrays. The regular triangular lattice adopted for the arrangement of the antenna elements is organized into irregularly-shaped tiles that exploit the properties offered by the Penrose tessellation. The novel array architecture ensures a remarkable reduction of the Transmit/Receive modules without harming the scan angle range and peak side lobe level thanks to the optimization based on the Pareto front that is able to tackle conflicting objectives. The performance of the proposed approach are assessed in different scenarios and prove the robustness and flexibility of the new tiling architecture. Moreover, a thorough analysis is carried out to highlight the unique feature of the partition scheme of offering a noteworthy reduction of the energy consumption
Penrose Tiling Subarrays for Large-Scanning and Energy-Saving Phased Array
No full textA novel partitioning scheme based on Penrose tessellation subarrays has been proposed for phased array design. More in detail, the radiating elements of a phased array arranged on a regular and periodic lattice are grouped into irregularly-shaped tiles by exploiting the features offered by the aperiodic Penrose tessellation. The preliminary results reveal that the novel array architecture ensures a remarkable reduction of the Transmit/Receive modules without compromising the performance in terms of scan angle and peak side lobe level
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