Dual-polarization Research Articles

Aperture Fed Microstrip Dual Polarization Wide Scan Phased Array Antenna With Mutual Coupling Reduction

Aperture Fed Microstrip Dual Polarization Wide Scan Phased Array Antenna With Mutual Coupling Reduction

Microphysical Insights From Dual Polarization Spectral Observations in Updraft and Mixed-Phase Precipitation

Microphysical Insights From Dual Polarization Spectral Observations in Updraft and Mixed-Phase Precipitation

Performance Analysis of DP‐QAM‐Based Optical OFDM PON Employing Optical Multicarrier

This work proposes a new hybrid bidirectional standard single mode fiber (SSMF)/free space optical (FSO) dual polarization quadrature amplitude modulation (DP‐QAM) employing optical orthogonal frequency division multiplexing (OFDM). An optical multicarrier generator (OMG) source is utilized. The suggested model is simulated using VPI photonics software. Thirty‐two optical OFDM channels are used; each carrier’s 30 Gbps information data with DP‐QAM are employed to improve the performance of the fifth‐generation passive optical network (5G‐PON) for downstream and upstream transmission. In addition, 16‐QAM signals are used in DP. The impact of continuous wavelength (CW) lasers and high data rates in the proposed 5G‐PON has been investigated for DP‐QAM‐OFDM. The results reveal 0.96 Tb/s and 0.1 Tb/s for the downstream and upstream directions, respectively, under different turbulence effects. Furthermore, the simulation results show that the proposed model can achieve an SSMF length and FSO propagation ranges of 20 km and 2 km, respectively, with the symbol error rate (SER) (<10−9) and error vector magnitude (EVM) (<0.186).

Dual Polarization Dynamic Alignment of Integrated Phased Arrays

Dual Polarization Dynamic Alignment of Integrated Phased Arrays

Achievable Spectral Efficiency of Line-of-Sight MIMO Fixed Links with Compact Planar Antenna Arrays and Power Amplifier Limitations

Fixed Point-to-Point microwave wireless systems with high spectral efficiency are needed to meet the pervasive and increasing demand for capacity in back-haul networks of mobile radio systems. In this context, spatially multiplexed LoS-MIMO (Line-of-Sight Multiple Input Multiple Output) systems have been studied for about twenty years, particularly in the millimeter wave frequency bands (above 15 GHz). However, their deployment in real networks has been really limited, to the authors’ knowledge. This has been due to several factors, i.e. the practical possibility of using extremely high-level modulation formats (nowadays up to 8192-QAM), the joint use of co-channel dual polarization, and the availability of wider channel bands in the new high frequency ranges (e.g. E-Band). In addition, a crucial reason has been the difficulty of installing multiple antennas spaced apart in order to maximize the MIMO spatial multiplexing so providing the maximum capacity gain. This optimal antenna separation, even for the classical MIMO M×N\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$M \ imes N$$\\end{document} with M = 2 antennas at the receiver and N = 2 antennas at the transmitter, can be several meters, e.g. 5.71 m at 23 GHz on a 5 km link. In this article, we analyze the performance of LoS-MIMO systems where antenna separation is highly sub-optimal, for limiting the array size, and a satisfactory performance is made possible by the exploitation of specific bit loading and power allocation strategies and the setting of the working region of the RF transmitter power amplifiers to operate at a given Signal-to-Inter Modulation Distortion Ratio (SIMDR). The result is an overview of the advantages and drawbacks of compact LoS-MIMO from a wider perspective than in the existing literature, including fundamental aspects for the practical implementation of these systems. Performance is discussed in many cases of interest and compared with the state of the art SISO (Single Input Single Output) system.

A phase shift keying modulator integrated single‐feed circular polarization agile array antenna

AbstractThis paper proposes a novel design of a circular polarization agile array antenna using two phase shift keying (PSK) modulators. The proposed antenna includes four dual linear polarization microstrip patch antenna elements, two PSK modulators, two quarter‐wavelength slot transmission lines, microstrip‐slot line transitions, and a single feed network. The PSK modulator generates phase switching of either 180° or 0° of the vertical signals of each antenna element with the aid of the four diodes. The quarter‐wavelength slot transmission lines are added to adjust the 90° phase difference between orthogonal signals of the array antenna. By controlling the PSK modulators, the proposed antenna can achieve dual circular polarization switching capabilities. A prototype antenna is used to demonstrate the antenna concept. The measured results confirm the concept with a good agreement between the simulated and measured performances. The proposed antenna has no complex circuits for RF and DC signals, and it provides a compact structure.

The effect of amphiphilic monomer on the interaction between amphiphilic polyacrylamide and crude oil on the solid surface

Hydrophobically modified polyacrylamide (HMPAM) is one of most used amphiphilic polymers for polymer flooding in oilfield. The interaction between HMPAM and crude oil is key to the oil displacement efficiency of HMPAM. However, due to the lack of experimental research method, there is little research on this aspect. In this work, HMPAMs containing different types of amphiphilic monomers were prepared, their interactions with crude oil were studied by dual polarization interferometry (DPI) for the first time, and their adsorption conformations on the surface of crude oil were discussed. The DPI results directly shown that the influence of amphiphilic monomer type on the interaction strength was as follows: nonionic type > cationic type ≈ anionic type. This order was consistent with the adsorption capacity of amphiphilic monomer on the surface of crude oil, indicating that the interaction strength between HMPAM and crude oil mainly depended on the type of amphiphilic monomers. In addition, the DPI results indirectly shown that the effect of amphiphilic monomer type on the HMPAM molecular coiled conformation on the surface of crude oil was also determined by the adsorption capacity of amphiphilic monomer. The research results of this paper can provide useful information for the amphiphilic monomer selection from the perspective of improving oil displacement efficiency of HMPAM.

Robust, in-service, and joint monitoring of a dual-polarization transceiver IQ skew for a coherent DSCM system without channel impairment compensation.

A robust, in-service, and joint monitoring of a dual-polarization (DP) transceiver IQ skew for a coherent DSCM system is proposed and experimentally validated. Unlike traditional monitoring schemes, the proposed scheme realizes robust transceiver impairments monitoring without channel impairment compensation, including chromatic dispersion (CD), polarization variation, and carrier phase noise. This enhances the stability and precision of the monitoring process and reduces computational complexity by eliminating sophisticated DSP for impairment compensation. A complex system model for a single-tone signal is given first. Based on the model, the proposed scheme enables monitoring of the DP transmitter and the receiver IQ skew using the inserted frequency domain pilots (FPTs). Experimental results show that the proposed scheme can estimate the transceiver IQ skew within 16 ps with an estimation error of less than 0.2 ps and is robust to CD, polarization variation, phase noise, and amplified spontaneous emission noise. To the best of our knowledge, the proposed scheme achieves in-service transceiver IQ skew monitoring for coherent DSCM systems for the first time.

Anti-reflection metasurface synergizing plasma and lattice modes: an efficient route to wideband electromagnetic transparency under extreme angles

All-angle wideband electromagnetic (EM) transparency for dual polarizations is desired for many practical applications. Conventionally, surface-mount anti-reflection materials or films are usually used to reduce the reflection and thus enhance transparency. In this paper, we propose to achieve wideband EM transparency under extreme angles for both TE- and TM-polarizations using embedded anti-reflection metasurface. The metasurface is composed of a pair of long and short metallic strips, which can introduce both plasma and lattice modes into the original half-wave wall. The plasma mode can create an angle-stable transmission peak at a lower frequency while the lattice mode renders a transmission peak under extreme angles at a higher frequency due to scattering cancellation between short strips and the substrate. By synergizing the plasma, half-wave, and lattice modes consecutively, wide-band transparency can be achieved under extreme angles for TE polarization. Due to the anisotropy of the metasurface, wideband transparency under TM-polarization is maintained. This finally enables us to obtain wideband EM transparency for dual polarizations under extreme angles. More importantly, the metasurface can also be customized to operate best under any given incident angle. Prototypes were designed, fabricated, and measured. Both the simulation and experiment results verify our method. This work provides an efficient route to wideband EM transparency under extreme angles and may find wide applications in communication, radar, and others.

Dual-Wideband Antenna with Dual Polarization and Enhanced Front-to-Back Ratio for High-Speed Communication Applications

The proposed antenna introduces a dual-wideband, dual-polarization design, employing Y-shaped bowtie radiators strategically positioned on both sides of an FR-4 substrate. This configuration aims to achieve polarization diversity, a crucial aspect in enhancing the performance and efficiency of wireless networks. To achieve this, improvements were made in radiation characteristics, particularly the front-to-back ratio (FBR), through the incorporation of a ring reflector and director. This led to an impressive average FBR enhancement of 7.38 dB at the lower band (LB), and 4.94 dB at the upper band (UB), respectively. Furthermore, the reflector and director height in relation to the radiator was meticulously adjusted to achieve a low-profile structure of dimensions 0.340λ0 × 0.340λ0 × 0.126λ0 (at 0.698 GHz). The antenna features both horizontally and vertically positioned radiators, each fed by two ports. It demonstrates an extensive overlapping impedance bandwidth (IBW) (S11 < -10dB) of 0.68-0.99 GHz (37.8%), and 1.62-2.99 GHz (61.9%) in the LB and UB for both radiators, with port isolation exceeding 18 dB. Alongside dual polarization and an enhanced FBR, the radiator exhibits a gain beyond 4.8 dBi and a radiation efficiency better than 70%, making it an exceptional choice for applications requiring high-speed wireless communication.

A Broadband Suspended Plate Antenna with Dual Polarization for 2G/3G/Wi-Fi/4G/LTE

Design of a broadband, dual-polarized suspended patch antenna covering 2G/3G/Wi-Fi/4G bands (1710-2690 MHz) is presented. The prototype consists of two suspended plates and a feedline layer. Excitation of ±45 slant dual polarization is realized by a novel crossed elliptic-H slot. The prototype exhibits 48.7% impedance bandwidth (|S11|, |S22| &lt; −15 dB) in 1660-2730 MHz. Port isolation (|S21|) is obtained as &gt; 28 dB. In desired operating band, stable and symmetric radiation patterns with half-power beamwidths of 55-75 and 65-74 in E and H planes are measured, respectively. Gain variation lies within 8.3±0.8 dBi. Proposed antenna is low profile, has high port isolation and high front to back ratio without needing any secondary reflector ground plane. With these qualifications and performance specifications, it outperforms many of the similar works in the literature. Design considerations, simulations and measurement results of proposed antenna are presented and discussed.

Assessment of the Impact of Surface Water Content for Temperate Forests in SAR Data at C-Band

This study addresses the escalating challenges posed by forest drought and wildfires, emphasizing the critical need to monitor forest conditions to mitigate associated risks. While traditional optical sensors have proven valuable for vegetation surface water (VSW) assessment, their limitations in regions with persistent cloud cover prompt an exploration of the alternatives. The study advocates the efficacy of Synthetic Aperture Radar (SAR) systems, known for their cloud-penetrating capabilities and sensitivity to changes in dielectric properties. Leveraging Sentinel-1 C-band dual polarization SAR data, the research investigates the impact of Vegetation Surface Water (VSW) on backscatter coefficients in a temperate coniferous forest through the application of generalized linear models. Despite the challenges posed by precipitation and canopy characteristics, the study unveils detectable modulation in backscatter, particularly in VH polarization, indicating the potential of SAR-based methods in forest monitoring. The occurrence of rain on the day of Sentinel-1 image acquisition, and therefore the presence of VSW, triggers an increase of 0.35 dB in VV backscatter, and an increase of 0.45 dB in VH backscatter. The findings underscore the importance of considering surface water content in radar backscatter analyses for accurate biomass estimations and change detection, suggesting avenues for future research and potential correction mechanisms.

Unraveling How Membrane Nanostructure Changes Impact the Eye Irritation of Nonionic Alkyl Ethoxylate Surfactants.

Nonionic surfactants used in agri-spraying processes may cause varying degrees of corneal irritation when they come in direct contact with farmers' eyes, and the exact irritations are thought to be determined by how surfactants interact with corneal cell membranes. However, how nonionic surfactants interact with cell membranes at the molecular and nano levels remains largely unexplored. In this study, the interactions between nonionic surfactants (alkyl ethoxylate, C12Em) and lipid membranes were examined by membrane permeability measurement, quartz crystal microbalance with dissipation, dual polarization interferometry, confocal laser scanning microscopy, and neutron reflection, aiming to reveal complementary structural features at the molecular and nano levels. Apart from the extremely hydrophobic surfactant C12E2, all nonionic surfactants studied could penetrate the model cell membrane composed of a phosphocholine lipid bilayer. Nonionic surfactants with intermediate amphiphilicity (C12E6) rapidly fused into the lipid membrane and stimulated the formation of pores across the lipid bilayer, consistent with the cytoplasm leakage and fast cell necrosis observed from the cytotoxicity study of corneal cells. In comparison, while hydrophobic and hydrophilic surfactants [those with long and short ethoxylates (C12E4,12,23)] could cause mild structural alteration to the outer lipid layer of the membrane, these structural changes were insufficient to elicit large cytoplasmic leakage rapidly and instead cell death occurred over longer periods of time due to changes in the membrane permeability. These results reveal the strong link of surfactant-lipid membrane interactions to surfactant cytotoxicity and the association with amphiphilicity of nonionic surfactants.

Inverse design of polymorphic Dirac-like cone dispersion relationship in photonic crystals

Dirac-like cone linear dispersion relations in photonic crystals (PhCs) often endow them with unique properties, yet searching for such relations can be challenging. We introduce a generalized inverse design system that, given the dielectric constants and lattice of two-dimensional PhCs, can efficiently determine its structural parameters to obtain its Dirac-like cone dispersion. Employing this inverse design strategy, we design three types of Dirac cone PhCs, including triple degenerate, quadruple degenerate, and triple degenerate under dual polarization with the same frequency. Further investigations reveal a systematic relationship between the radius of the dielectric rods in these PhCs and their corresponding Dirac frequencies across varying dielectric constants. The zero refractive index characteristic is validated in two of the three PhCs studied, as confirmed through numerical simulations. Additionally, by leveraging our proposed inverse design method, we introduce an innovative shell dielectric rod model, which encapsulates a dielectric material, achieving a quadruple degenerate dispersion structure with dual Dirac cones. This research provides a potent tool for the inverse design of PhCs and expands its application in Dirac cone dispersion design.

Fast Switchable Lens Based on Dual Ferroelectric Liquid Crystal Polarization Converter with Charge Balancing

Fast Switchable Lens Based on Dual Ferroelectric Liquid Crystal Polarization Converter with Charge Balancing

Multi-feed multi-mode metasurface for independent orbital angular momentum communication in dual polarization

Multi-feed multi-mode metasurface for independent orbital angular momentum communication in dual polarization

Linear Ion Trap Mass Spectrometer (LITMS) Instrument Field and Laboratory Tests as Part of the ARADS Field Campaigns.

The highly compact Linear Ion Trap Mass Spectrometer (LITMS), developed at NASA Goddard Space Flight Center, combines Mars-ambient laser desorption-mass spectrometry (LD-MS) and pyrolysis-gas chromatography-mass spectrometry (GC-MS) through a single, miniaturized linear ion trap mass analyzer. The LITMS instrument is based on the Mars Organic Molecule Analyser (MOMA) investigation developed for the European Space Agency's ExoMars Rover Mission with further enhanced analytical features such as dual polarity ion detection and a dual frequency RF (radio frequency) power supply allowing for an increased mass range. The LITMS brassboard prototype underwent an extensive repackaging effort to produce a highly compact system for terrestrial field testing, allowing for molecular sample analysis in rugged planetary analog environments outside the laboratory. The LITMS instrument was successfully field tested in the Mars analog environment of the Atacama Desert in 2019 as part of the Atacama Rover Astrobiology Drilling Studies (ARADS) project, providing the first in situ planetary analog analysis for a high-fidelity, flight-like ion trap mass spectrometer. LITMS continued to serve as a laboratory tool for continued analysis of natural Atacama samples provided by the subsequent 2019 ARADS final field campaign.

All-fiber mode exchange of high-speed DP-QPSK signals using mechanical long-period fiber grating

Mode exchange (ME) can effectively improve the utilization of network resources in short-distance mode division multiplexing (MDM) communication systems. In this paper, a mechanical long-period fiber grating (LPFG) mode converter is used to realize the channel exchange of LP01- and LP11-mode dual-polarization (DP) signals, with the channel crosstalk of −14 dB or less. We experimentally tested the receiver sensitivities of two DP channels, which are dependent on channel crosstalk and polarization-dependent loss (PDL), and demonstrated the practicability of the real-time data transmission and exchange for 100 Gb/s dual-polarization quadrature phase shift keying (DP-QPSK) in multiple-input multiple-output free (MIMO-free) MDM system. The experimental results show that the ME system can provide the optical power margin of about 25 dB, capable of effectively supporting the metropolitan transmission and exchange between the data centers.

Compact and broadband dual-polarization waveguide crossing utilizing subwavelength-hole-assisted MMI couplers.

In this Letter, an ultracompact silicon-based waveguide crossing for dual polarizations is proposed and experimentally demonstrated using subwavelength-hole-assisted multimode interference couplers. Thanks to the flexible and easy dispersion engineering in the introduced subwavelength-hole-assisted multimode interference couplers, the reduced and equal beat lengths for dual polarizations are accessible via careful parametric optimization, consequently enabling a substantially reduced device size. Experimental results indicate that the proposed crossing (13.6 × 13.6 µm2 in size) features a low insertion loss of 1.03 dB (0.76 dB) and low crosstalk of -32.5 dB (-37.8 dB) at a central wavelength of 1550 nm for TE (TM) mode, with a broad bandwidth of ∼80 nm for crosstalk of <-18 dB.

Molecular engineering towards dual surface local polarization sites on poly(heptazine imide) framework for boosting H2O2 photo-production

The selective 2e− ORR reaction on polymeric carbon nitride framework is one of the most promising approaches for solar-driven hydrogen peroxide production. Poly(heptazine imide) (PHI) as a class of K+-incorporated crystalline carbon nitride framework, is highly active for photocatalytic H2O2 production. An upgrade on the H2O2 photoproduction performance of PHI is realized and the mechanistic insights are revealed in this work. By photochemical reaction, the electron withdrawing groups of hydroxyl group and cyano group are grafted on the surface of PHI frameworks. The dual polarization sites on the surface contribute significantly to the enhancement of the exciton dissociation. The optimized PHI with dual polarization sites exhibits a remarkable photocatalytic H2O2 production performance, which is 2 times of the active pristine PHI. Most importantly, the photochemical reaction method is generally applicable to improve the exciton dissociation of a wide range of polymeric carbon nitride frameworks with various structure and compositions; and the thiourea-derived polymeric carbon nitride framework with dual surface polarization sites exhibits a remarkable photocatalytic performance with a high H2O2 production rate of 40.5 mmol h−1 g−1.