Right-hand Circular Polarization Research Articles

C-Slot Circular Polarized Antenna for Hybrid Energy Harvesting and Wireless Sensing

This paper presents a new hybrid energy harvesting on electromagnetic solar for wireless energy harvesting of ambient from sensors of low-power devices. The axial ratio (AR) requirements produce Left-Hand Circular Polarization (LHCP) and Right-Hand Circular Polarization (RHCP) and simultaneously produce a 90-degree phase difference during energy harvesting, adopting a new design in designing a dual-feed broadband circular polarized (CP) antenna. To get the frequency band 2.3–2.4 GHz, we propose a C-Slot antenna with a circular patch dual feed. To estimate the diversity of the phase and magnitude output of the feed configuration under AR value, we used a 50 Ohm feed network output of the characteristic analysis for a dual feed CP antenna. An Axial ratio frequency range of less than 3 dB is achieved using polarization analysis with different branch channel couplers. To produce a DC output voltage, a high-frequency rectifier circuit embedded with a thin-film solar cell on the antenna is then connected to two T-junction power divider rectifiers, resulting in a high-efficiency design. A complete system-level analysis will include multiple signal classification methods of powered ambient RF energy using a wireless energy harvesting array that proposes a compact structure and demonstrates optimal configuration. Reliable operation in typical indoor environments indicates a self-contained sensor Node. Therefore, it has significant implications for powering small electronics and wireless sensor applications independently of the IoT Network or real implementation telecommunications industry.

Controlled circular dichroism with graphene-based metamaterial for terahertz wave

This article explores the design and analysis of a metal-graphene hybrid metamaterial structure tailored for tunable circular dichroism (CD) effects in the terahertz (THz) frequency regime. Chiral metamaterials have garnered considerable interest in photonics due to their versatile applications, including sensing, polarization manipulation, and chiral imaging. The proposed metamaterial unit cell features four meta-atoms with C4 rotational symmetry, composed of gold on a polyimide substrate. By strategically integrating the graphene sheets above the gold patterns, selective control over the absorption efficiency for the incident wave of left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) light is achieved. The study demonstrates that adjusting graphene chemical potential enables precise modulation of CD from 0.80 to 0.10 across a wide THz frequency spectrum. Furthermore, the article investigates the structure optical response for incident angles ranging up to 75°, revealing stable CD behavior up to 30° and intriguing dual-band effects beyond 50°. These findings underscore the potential of the proposed metamaterial for practical applications in photonics, sensing, and chiral imaging, offering tunable control over the CD effects in the THz regime.

A simple feed orthogonal excitation X-band dual circular polarized microstrip patch array antenna

This work represents a microstrip patch array antenna which is designed and analyzed for the application of circular polarization in X band frequency range. The proposed antenna array has a very simple microstrip line feeding mechanism and each patch is energized orthogonally to acquire circular polarization without the need for any phase shifters. The array antenna has a slot line in the ground to electrically couple the signals from the microstrip feed line to feed each patch. The outcome demonstrates that the antenna is capable of radiating both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The designed work has a return loss of -41.88 dB, that is the antenna is perfectly matched. The outcome also demonstrates the antenna’s strong gain and directivity capabilities, which are 12.87 dBi and 13.30 dBi, respectively. The antenna resonates circularly at a frequency of 10 GHz.

Reconfigurable Multifunctional Transmission Metasurface Polarizer Integrated with PIN Diodes Operating at Identical Frequencies

Herein, a reconfigurable multifunctional transmission metasurface polarizer, structured with double Jerusalem crosses and integrated with four PIN diodes, is presented. The bottom Jerusalem cross is rotated by 35∘ with respect to the top cross. Both numerical and experimental observations reveal that a linearly polarized (LP) outgoing wave is transmitted at approximately 4.0 GHz when subjected to a left-handed circularly polarized (LCP) or right-handed circularly polarized (RCP) incident wave. The transmission efficiency reaches -2.5 dB when all elements are in the ON state. Furthermore, active control of switchable PIN diodes operating in various statuses unequivocally demonstrates the ability to convert an incident wave polarized in the x or y direction to a LCP or RCP wave, respectively, within the identical frequency band, spanning from 3.6 GHz to 4.3 GHz. This conversion is achieved with a transmission coefficient of -3.5 dB or -4.2 dB at the peak frequency. The proposed metasurface polarizer presents a potentially dynamic method for simultaneously manipulating various polarization conversions of electromagnetic (EM) waves within a desired frequency band.

Spin-splitting and spin Hall effect of reflected Airy beams on the surface of topological insulator

We present an analysis of the enhanced spin Hall effect of light (SHEL) resulting from a reflected Airy beam off the interface of an air-topological insulator (TI). Our study suggests that the surface conductivity of TI film and the decay factors of Airy beams are crucial in increasing the spin-splitting distance and the spatial shifts of the left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) components. An apparent spatial shift asymmetry depending on the decay factors can be observed between the LCP and RCP components, where the coupling of intrinsic and extrinsic angular momentum will play a significant impact. The connection among the thickness of TI film, chemical potential and the incident frequency at the fixed decay factors is thoroughly examined to achieve the maximum of spatial shifts. We find that the coupling between the upper and lower surfaces’ conductivity could be responsible for the pronounced SHEL. These conclusions can be extended to other interfaces of comparable structures, such as insulators coated with a layer of two-dimensional Dirac material. Our work provides novel insights into the use of innovative beams incident on the surface of TI film and their potential applications in optical detection.

Reconfigurable transmissive metasurface with a combination of scissor and rotation actuators for independently controlling beam scanning and polarization conversion

Polarization conversion and beam scanning metasurfaces are commonly used to reduce polarization mismatch and direct electromagnetic waves in a specific direction to improve the strength of a wireless signal. However, identifying suitable active and mechanically reconfigurable metasurfaces for polarization conversion and beam scanning is a considerable challenge, and the reported metasurfaces have narrow scanning ranges, are expensive, and cannot be independently controlled. In this paper, we propose a reconfigurable transmissive metasurface combined with a scissor and rotation actuator for independently controlling beam scanning and polarization conversion functions. The metasurface is constructed with rotatable unit cells (UCs) that can switch the polarization state between right-handed (RHCP) and left-handed circular polarization (LHCP) by flipping the UCs to reverse their phase variation. Moreover, independent beam scanning is achieved using the scissor actuator to linearly change the distance between the UCs. Numerical and experimental results confirm that the proposed metasurface can perform beam scanning in the range of 28° for both the positive and negative regions of a radiation pattern (RHCP and LHCP beams) at an operational frequency of 10.5 GHz.

Chiral metasurface absorber with near-infrared excitation-induced dual circular dichroism

Microscopic components in metasurfaces allow precise control of electromagnetic waves, enabling chiral metasurface absorbers to adapt to different frequencies and wavelengths of electromagnetic waves, providing higher controllability. In this paper, we present a near-infrared chiral absorber utilizing a Metal-Insulator-Metal (MIM) structure, achieving selective absorption in the dual wavelength ranges of 1500–1750 nm and 2250–2750 nm. The absorber's structural layout adopts a pseudo-π configuration, featuring a unique design that establishes distinct resonance cavities between structural periods. This results in disparate responses to left-handed circularly polarized (LCP) light and right-handed circularly polarized (RCP) light, thereby attaining dual-band selectivity and adjustability. To illustrate the physical mechanism, we explore the electric and magnetic field distributions within this structure, offering deeper insights into the fundamental mechanism of selective absorption. This analysis illustrates that the charge distribution in different wavelength bands can vary with the polarization direction, forming orthogonal electric dipoles. Under the incidence of LCP and RCP, we achieved circular dichroism (CD) of 0.75 and 0.7, respectively. By adjusting parameters within individual resonance cavities, we achieve independent control over each resonance wavelength. This near-infrared chiral absorber provides unparalleled design flexibility, with implications for advancements in applications such as molecular detection and optical switching.

A broadband dual-polarized antenna for 5G wireless communication systems

This article presents a broadband dual-polarized antenna for the 5G wireless communication technology. A ring resonator is chosen with the purpose of enhancing the axial ratio (AR) and impedance bandwidth. Partial ground plane is chosen with a slot placed beneath the feedline. The dimensions of the antenna are 50 mm × 50 mm × 1.6 mm, and it is fabricated on a dielectric substrate made of FR4 material. The variation of antenna polarization is achieved through the function of PIN diode. When the diode is in the ON state, the antenna functions as a wideband antenna that exhibits right hand circular polarization (RHCP). The frequency range covered by this system spans from 4.5 GHz to 7.5 GHz. Conversely, it provides linear polarization (LP) within a frequency range that spans from 4.3 GHz to 5.3 GHz. The metrics of the prototype antenna are measured and tested. The CST full wave simulator is utilized for conducting simulations.

Investigating the impact of polarization on surface plasmon polariton characteristics in plasmonic waveguides under periodic driving fields

This study examines the impact of polarization in the driving field on the surface plasmon polariton (SPP) modes within plasmonic waveguides under the influence of a periodic driving field. Addressing a significant knowledge gap in the existing literature, we present a comprehensive investigation employing Floquet engineering techniques, with a specific emphasis on elliptically polarized fields as the dressing field. Our analysis reveals that the use of generalized Floquet states allows us to derive Floquet states for specific polarized dressing fields, such as linear, left-handed circular, and right-handed circular polarization. Remarkably, we demonstrate that Floquet states depend on the chirality of the dressing field’s polarization. Employing the Floquet-Fermi golden rule, we assess electron transport under various polarization types and find that the specific polarization type influence electron transport properties. However, we establish that the chirality of the polarization of the dressing field does not impact the transport properties. During our numerical analysis, we assess the alterations in SPP characteristics arising from two distinct types of polarization in dressing fields: linear polarization and circular polarization. Our results underscore the potential of employing a dressing field to effectively mitigate the propagation losses of SPPs in plasmonic metals, with the extent of improvement contingent on the specific polarization type. To quantify the performance enhancements of commonly used plasmonic metals under linearly and circularly polarized dressing fields, we employ a figure of merit (FoM). This study offers insights into the practical utilization of periodic driving fields as a powerful tool in advancing plasmonic communication within chip-scale environments.

Inducing Circularly Polarized Single-Photon Emission via Chiral-Induced Spin Selectivity.

One of the central aims of the field of spintronics is the control of individual electron spins to effectively manage the transmission of quantized data. One well-known mechanism for controlling electronic spin transport is the chiral-induced spin-selectivity (CISS) effect in which a helical nanostructure imparts a preferential spin orientation on the electronic transport. One potential application of the CISS effect is as a transduction pathway between electronic spin and circularly polarized light within nonreciprocal photonic devices. In this work, we identify and quantify the degree of chiral-induced spin-selective electronic transport in helical polyaniline films using magnetoconductive atomic force microscopy (mcAFM). We then induce circularly polarized quantum light emission from CdSe/CdS core/shell quantum dots placed on these films, demonstrating a degree of circular polarization of up to ∼21%. Utilizing time-resolved photoluminescence microscopy, we measure the radiative lifetime difference associated with left- and right-handed circular polarizations of single emitters. These lifetime differences, in combination with Kelvin probe mapping of the variation of surface potential with magnetization of the substrate, help establish an energy level diagram describing the spin-dependent transport pathways that enable the circularly polarized photoluminescence.

A Whole W-Band Multi-Polarization Horn Antenna Based on Boifot-Type OMT.

A wideband multi-polarized square-horn antenna based on an orthogonal mode transducer (OMT) is developed for working in the whole W-band in this paper. The designed antenna is capable of radiating multiple polarization modes as horizontal polarization (HP) and vertical polarization (VP) when as single-port excitation and left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) when as dual-port excitation, owing to the characteristic of the OMT with the transmitting of orthogonally polarized waves. A CNC-layered fabrication approach is proposed, which means that the antenna prototype integrating with a Boifot-type OMT, turning waveguide, twisting waveguide and phase shifter is divided into three layers along the vertical direction to be fabricated based on computerized numerical control (CNC) technology. In the design, the turning waveguide and twisting waveguide are employed to achieve plane consistency of the antenna branch ports. Furthermore, a phase shifter is designed to compensate the orthogonally polarized waves, which can keep the phase of the orthogonally polarized waves consistent in a wideband frequency range from 75 GHz to 110 GHz. A prototype is fabricated and measured to verify the performance of the proposed multi-polarization antenna, and the measured results agree well with the simulation ones. In the whole W-band, the value of return loss is better than 10 dB of all polarization modes, and the value of AR of the LHCP and RHCP is below 3.5 dB. The maximum gain of the antenna reaches up to 18.8 dBi at 110 GHz. In addition, regarding the layered structure, the possible layered assembly error analysis is discussed, which verifies the feasibility of the layered machining for this antenna.

Circular polarizer based on twisted double [formula omitted] thin film

We unveil a highly efficient circular polarizer based on twisted double Td − WTe2 thin film in the transmissive and reflective modes. This polarizer can transform a linearly polarized incident wave into a circularly polarized one with extremely high extinction ratios by simply adjusting the orientation of the incident polarization plane. The proposed structure provides switching between the right-handed and left-handed circular polarizations (RCP and LCP) in the output wave by tuning the frequency and, in particular, the polarization direction of the incident wave. Furthermore, the twist angle of the thin films can control the handedness of the converted wave to be either LCP or RCP. Owing to the high efficiency of the polarization conversion and accessibility of the realization of the proposed structure, it may have potential applications as a polarization manipulator in the optical sensing, communication, and defense industry.

Wideband Multi-polarization Reconfigurable Antenna based on Non-uniform Polarization Convert AMC Reflector

A novel design of wideband multi-polarization reconfigurable antenna is proposed, based on a non-uniform polarization convert artificial magnetic conductor (AMC) reflector. The proposed antenna consists of a radiator element and an AMC reflector. Firstly, a modified polarization convert AMC reflector is designed. The non-uniform AMC reflector causes an enhancement of 3 dB axial ratio (AR) performance. Secondly, a wideband linearly polarized monopole antenna is presented as the main radiator, utilizing the broadband characteristic of a C-shaped monopole. The polarization reconfigurability of the proposed antenna can be achieved by properly rotating the AMC reflector, which can be switched between linear polarization (LP), left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP). A prototype of the proposed antenna is fabricated and experimented with to validate the theoretical performance. The measured results show a -10 dB impedance bandwidth of 42.7% and 44.4% for LP and CP modes, respectively, and a 3 dB AR bandwidth of 20% for CP modes. In addition, the measured peak gain reaches 8 dBi/dBic. A good agreement is shown between the simulation and measurement, pointing to the good performance of the proposed antenna.

Genus Plasma-Based Self-Complementary Reconfigurable Intelligent Metasurfaces

AbstractThis paper investigates the radiation properties of plasma-based intelligent reflectarray surface (IRS) that utilizes self-complementary elements. The elements of the surface employ reconfigurable plasma conductivity to manipulate the polarization of electromagnetic waves in various Ka-band applications. The unit-cell of the IRS is composed of 2 × 2 sub-cells of 0.5 λo × 0.5 λo × 0.078 λo mm3. Each sub-cell contains three glass containers arranged in a triangle-rectangular-triangle configuration and filled with ionized plasma gas. When the IRS illuminated by a linearly polarized (LP) plane wave, the surface converts it into circularly polarized (CP) waves based on the plasma ionization state. It achieves dual-band polarization conversion at 7.3 GHz with bandwidth of 200 MHz and at 8.6 GHz with a bandwidth of 1.15 GHz. To enhance the polarization conversion bandwidth, a sequential arrangement of self-complementary unit-cell elements with different sizes is employed. An 8 × 8 genus reconfigurable IRS is utilized to generate both left-hand circularly polarized (LHCP) and right-hand circularly polarized (RHCP) waves from the upper and lower sides of the structure. The axial ratio (AR) bandwidth is maintained at 2.1 Hz for both surfaces. An LP horn antenna is used with the 8 × 8 genus reconfigurable IRS, resulting in a peak gain of 13.2 dBi, a side lobe level (SLL) of 6 dBi, and an AR bandwidth of 500 MHz. To further enhance the radiated gain, the ionized plasma within the self-complementary elements is controlled to focus the radiated power into a directive beam, resulting in an increased gain of 19.4 dBi.

Multi-band circularly polarized antenna for WLAN and WiMAX applications based on characteristic mode theory

Abstract A multi-band circularly polarized antenna is proposed for WLAN (2.4/5.3/5.8 GHz) and WiMAX (3.5 GHz) applications. The proposed antenna is constructed of a radiation patch and a reflecting metal ground. Characteristic mode theory is utilized to analyze the modes of the patch and based on these results the antenna is optimized. The −10 dB impedance bandwidths of the proposed antenna are 53.53% (2.4–4.15 GHz) and 47.28% (5.25–8.5 GHz), respectively. The antenna radiates left-handed circular polarization in the lower band and right-handed circular polarization in the upper band. A maximum gain of 10 dBic is achieved for the proposed antenna.

An all‐metal wideband circularly polarized single‐patch antenna based on TM11mode

AbstractThis paper proposes an all‐metal wideband circularly polarized (CP) single‐patch antenna based on TM11mode. The conventional square patch is divided into four small square patch units by loading metal shorting walls under the two vertical centerlines. The shorting walls are windowed to facilitate coupling between the adjacent units. When the TM11mode is excited, the coupling windows not only distribute energy but also provide the 90° phase difference required for CP radiation. An additional feeding network is not required, and its profile is less than 0.05λ0(λ0is the free space wavelength at the center frequency). Three minima in the axial ratio (AR) response are present. The results show that right‐hand circularly polarized (RHCP) radiation is achieved. The measured 3 dB AR bandwidth is 6.9%, ranging from 1.52 to 1.62 GHz, and the RHCP realized peak gain is 7.72 dBic. An all‐metal construction suitable for satellite communication systems is designed that has superior performance in harsh space environments.

Switchable and multifunctional terahertz photonic devices based on VO2-assisted phase encoded metasurfaces

Metasurfaces, especially coded ones, have gained significant attention for their excellent ability to control electromagnetic (EM) waves, opening up possibilities for a new generation of miniaturized devices. However, integrating multiple functionalities into a single metasurface while endowing tunable performance remains a challenge. In this study, we propose a strategy to design switchable and multifunctional terahertz (THz) photonic devices using complementary Gold-VO2 split resonant ring (GV-SRR) and complementary Gold-VO2 split resonant oblong (GV-SRO) structures. The designed devices can convert right-handed circularly polarized (RCP) light into left-handed circularly polarized (LCP) light in three frequency bands, corresponding to center frequencies fre.1 = 0.34 THz (narrowband), fre.2 = 0.50 THz (narrowband), and fre.3 = 0.80 THz (broadband). The phases of the reflected LCP wave can be independently modulated across different frequency bands by rotating the in-plane orientation of GV-SRR and GV-SRO separately. In addition, the overall phase reconstruction can be achieved through the state change of VO2. By arranging GV-SRR and GV-SRO in a defined encoding form, the engineered photonic devices can exhibit distinct and switchable capabilities in modulating EM wavefronts across various frequency ranges. As proof-of-concept examples, we have designed three encoded photonic devices, namely, a dynamic beam splitter (DBS), an achromatic and zoom metalens (AZM), and a switchable device between metalens and focusing orbital angular momentum (OAM) generator (MFOAM). These devices have potential applications in wireless communication, AR holographic displays, and information processing.

Investigation on a compact wideband omnidirectional circularly polarized antenna in an indoor propagation channel for 2.4 GHz application

SummaryIn this paper, for the first time, the capability of a compact low‐cost wideband omnidirectional circularly polarized (CP) antenna to suppress multipath fading characteristics in a typical indoor propagation channel for 2.4 GHz applications is investigated. A ray tracing method based on the geometrical optics and uniform theory of diffraction is applied to analyze an indoor propagation channel using the measured radiation patterns of the proposed antenna. The design uses a conventional monopole antenna with a circular ground plane to generate a vertically polarized electric field. Sequentially flag‐shaped stubs are then added to the ground plane to produce horizontally polarized electric field and to improve the impedance bandwidth of the proposed antenna. The antenna is designed for 2.4 GHz WLAN application with 10 dB impedance bandwidth of 25.5% and 3 dB axial ratio (AR) bandwidth of 24.5%. The polarization can be readily changed between the left‐hand circular polarization (LHCP) and right‐hand circular polarization (RHCP) by altering the direction of the coaxial probe (monopole) or varying the orientation of the printed bended stubs. Both the LHCP and RHCP prototypes of the proposed antenna are designed, fabricated, and tested, and the similar results are obtained.

A Low Profile Wideband Linear to Circular Polarization Converter Metasurface with Wide Axial Ratio and High Ellipticity

This paper introduces an ultra-wideband (UWB) reflective metasurface that exhibits the characteristics of a linear to circular (LTC) polarization conversion. The LTC polarization conversion is an orthotropic pattern comprising two equal axes, v and u, which are mutually orthogonal. Additionally, it possesses a 45° rotation with respect to the y-axis which extends vertically. The observed unit cell of the metasurface resembles a basic dipole shape. The converter has the capability to transform LP (linear polarized) waves into CP (circular polarized) waves within the frequency range 15.41–25.23 GHz. The band that contains its 3dB axial ratio lies within 15.41–25.23 GHz, which corresponds to an axial ratio (AR) bandwidth of 49.1%, and the resulting circular polarized wave is specifically a right-hand circular polarization (RHCP). Additionally, an LTC polarization conversion ratio (PCR) of over 98% is achieved within the frequency range between 15 and 24 GHz. A thorough theoretical investigation was performed to discover the underlying mechanism of the LTC polarization conversion. The phase difference Δφμν among the reflection coefficients of both the v- as well as the u-polarized incidences is approximately ±90° that is accurately predictive of the AR of the reflected wave. This study highlights that the reflective metasurfaces can be used as an efficient LTC polarization conversion when the Δφμν approaches ±90°. The performance of the proposed metasurface enables versatile applications, especially in antenna design and polarization devices, through LTC polarization conversion.

Dual-band terahertz reflective-mode metasurface for the wavefront manipulation of independent linear and circular polarization waves

Metasurfaces (MSs) are being extensively researched owing to their ability to modulate the polarization and wavefront of electromagnetic (EM) waves in a flexible manner, which usually offer significant advantages including ultra-thinness, low losses, and easy fabrication. However, conventional MSs typically operate well only with a single polarization. Here, we propose a novel design strategy for a terahertz (THz) reflective-mode MS that relies on a single unit-cell arrangement combining propagation phase and geometric phase. Our designed MS can achieve multiple wavefront manipulations in reflection mode, not limited to circular polarization (CP) transformation, but also enabling linear polarization (LP) conversion. The MS we propose consists of a periodic array of bilayered metal patterned resonator structures sandwiched by a dielectric substrate. The metallic resonator is made of the outer single-split-ring (SSR) and C-shaped slot (CSS), inner double-split-ring (DSR), and its complementary structure. With this design, the MS is capable of converting a LP wave to its orthogonal counterpart at lower frequency (f1=0.7THz) after reflection. Additionally, at higher frequency (f2=1.4THz), the proposed MS can also convert the right-handed CP (RCP) to left-handed CP (LCP) upon reflection or vice versa. The 2π phase full coverage of the orthogonal LP and CP waves can be achieved independently and simultaneously by adjusting the opening and orientation angles of the SSR based on propagation phase, and orientation angle of the DSR based on geometric phase. We numerically demonstrate beam deflection, planar focusing, and the vortex beam for both reflected orthogonal LP and CP waves with three representative MSs to provide proof of concept. These findings reveal the great potential for multifunctional devices for dual-polarization in imaging and communication systems.