Left-hand Circular Polarization Research Articles

A Polarization and Frequency Reconfigurable Microstrip Antenna for Vehicular Communication System Application

To face a complex wireless communication scenario, a flexible and tunable multi-functional antenna system should be employed to guarantee system quality. This paper presents a polarization and frequency reconfigurable microstrip patch antenna with a wide 3-dB axial ratio beam-width for vehicle communication systems. By controlling the p-i-n diodes, the proposed design can achieve four operating states: linear polarization (LP) in lower frequency bands between 1.45 and 1.47 GHz, and LP, left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP) in higher frequency bands between 1.50 and 1.53 GHz. The proposed antenna has an exceptionally low profile (0.02 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{0}$</tex-math></inline-formula> at 1.5 GHz) and a simple structure, consisting of a single-layer square patch with two annular ring slots and four switches placed at appropriate locations in the slots. P-i-n diodes, as the switchs, change the current distribution on the radiating patch to achieve the antenna's polarization and frequency reconfigurability. The proposed antenna was fabricated and tested, and the observed results are identical to those predicted by the simulation. The antenna has outstanding reconfigurable capabilities independent of frequency or polarization in the operational frequency range. Therefore, it can be well used for vehicular communication systems because of its multi-reconfigurability and stable mechanical property.

A Low-Profile 2D Passive Phased-Array Antenna-in-Package for Emerging Millimeter-Wave Applications

This article covers the implementation, calibration, and measurement aspects of a low-profile 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 4 passive phased-array antenna-in-package (AiP) employing the beamformer discussed in <xref ref-type="bibr" rid="ref9" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[9]</xref> . The antenna array comprises slot-coupled patch antennas with left-handed circularly polarized (LHCP) radiation. Microelectromechanical system (MEMS)-like tunable phase shifter (PS) functioning based on controlling the phase constant of a slow wave microstrip line is employed for the phase tuning. Measurement results show the antenna‘s main beam can be steered over an angular range of ±30° in both elevation and azimuth planes. The operating frequency bandwidth of the system ranges from 28 to 30 GHz. The peak directivity and the radiation efficiency of the antenna system are 18.48 dBic and 58% at Boresight at 29 GHz, respectively. The efficiency drops 16% when the steering angle reaches the maximum.

A Multi-Polarization Series-Fed Antenna Array Based on Eccentric Ring

A multi-polarization series-fed antenna working at 10 GHz is presented in this paper. The patch elements are built by eccentric rings which can realize the performance of circular polarization. The dual-port feeding allows us to switch the polarization of the antenna. The right-hand circular polarization (RHCP), left-hand circular polarization (LHCP), and Linear polarization (LP) polarization can be realized by properly feeding form. The changing of antenna polarization without switch controlling. Owing to the circular array arrangement, the antenna can form a compact structure. The key features of this array are multi-polarization and traveling-wave series-fed performance. The axial ratios are lower than 3dB measured. The |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> | is lower than -14 dB in the mentioned bandwidth. Then, a 4 × 4 MIMO array which has compact structure is designed and simulated. The circular array is processed and measured. The experimental and simulation results are in good agreement.

Additively Manufactured Dual Circularly Polarized Antennas With Bidirectional Same-Sense Radiation and Wide Bandwidth Characteristics

This communication presents two additively manufactured bidirectional circularly polarized (CP) antennas. Each antenna radiates the same-sense CP waves in opposite directions and has the capability of altering the CP state to either right-hand CP (RHCP) or left-hand CP (LHCP) by switching the feeding ports. They adopt the same scheme of combining a linearly polarized (LP) bidirectional source and two polarizers of the same type. Different polarizers, a single-slab dielectric polarizer (Ant 1) and a linearly tapered slot polarizer (Ant 2), are proposed and applied for them, respectively. The LP source adopts a circular waveguide-based structure. By altering the orthogonal degenerate modes in the waveguide, the CP states can be switched correspondingly. To validate the design ideas, prototypes of the two antennas are fabricated and tested. Experimental results show that the axial ratio bandwidth (ARBW) of Ant 1 and Ant 2 is 30.3% (4.9–6.66 GHz) and 17.9% (5.26–6.3 GHz), respectively. Within the ARBW, their gain is 8.4± 0.8 and 7.2± 1 dBic, respectively. These results demonstrate that both antennas exhibit the advantages of wide band, high gain, and ease of fabrication over the conventional designs.

K-/Ka-Band Shared-Aperture Phased Array With Wide Bandwidth and Wide Beam Coverage for LEO Satellite Communication

A K-/Ka-band shared-aperture endfire phased array antenna is presented in this article. The antenna has the properties of dual wide bandwidths, orthogonal circular polarizations (CPs), wide beam coverage, and high isolation between the K-band and Ka-band channels. In this work, a new array topology is proposed to enhance the design freedom and the periodicity of the antenna array. Then, the filtering structures used to reflect the crossband coupled power also enhance the isolation between the K-band and Ka-band channels. The crossband mutual coupling is reflected and reradiated to generate the wideband CP beams. The high-order parallel plate waveguide (PPW) mode is suppressed to realize the wide CP beam coverage. The working bands at the boresight are 17.7–21.2 and 27.5–31.0 GHz, respectively. The polarizations are right-hand CP (RHCP) in K-band and left-hand CP (LHCP) in Ka-band. The maximal scan angles are ±60°. The axial ratios (ARs) are below 3 dB at boresight and below 5 dB when the beam scans to ±60°. The isolation between the K-band and Ka-band channels is higher than 40 dB.

3D Printed Directive Beam-Steering Antenna Based on Gradient Index Flat Lens With an Integrated Polarizer for Dual Circular Polarization at W-Band

In this communication, the design of a circularly polarized (CP) perforated gradient index (GRIN) flat lens antenna with directive beam-steering properties is presented for millimeter-wave applications at W-band (75–95 GHz). The dielectric lens, fed by an open-ended square waveguide (SWG) located in the lens focal plane, enhances the radiation in a particular direction, generating a high-directivity beam with planar wavefront. The integration of a dielectric polarizer with the lens allows the conversion from a linearly polarized (LP) incident wave to a CP-emitted wave over the whole bandwidth. Horizontally and vertically polarized waves, achieved by the excitation of the fundamental SWG TE01 and TE10 modes are transformed into left-hand CP and right-hand CP waves, respectively. A ±30° scan range in both azimuth and elevation planes is demonstrated for the whole frequency range, attained by displacing the feed along the focal plane of the lens. Lens and polarizer are manufactured as a single piece by stereolithography (SLA) 3-D printing technology with Form 3 Formlabs 3-D-printer. Measured results show maximum measured directivity values that range from 23.5 to 23.8 dB, a remarkable circular polarization purity as a wide axial ratio bandwidth of 20.58% (< 3 dB), from 77.5 to 95 GHz, is achieved for the principal beam steers and an aperture efficiency for broadside beam direction between 90.32% and 57.34% in the frequency band of interest.

Magneto-Optical Spin Hall Effect Regulation at Terahertz Frequencies Based on Graphene–Gold Heterojunction

In this paper, we theoretically consider the magneto-optical spin Hall effect of light (MOSHEL) in a graphene–gold heterojunction structure at terahertz frequencies, and determine the maximum value of the transverse shift of the spin Hall effect of light (SHEL) in the designed structure by varying the terahertz frequency, the thickness of the metal layer, the Fermi energy level of the graphene, and the magnetic induction density. When the terahertz frequency was 1.2 THz, the metal layer thickness 50 nm, the Fermi level 0.2 eV, and the magnetic induction density B was 10 T, the SHEL shifts of left-handed circularly polarized (LHCP) and right-handed circularly polarized (RHCP) components was greatest at the critical angle (58°), with as value of 498μm, 1000 times larger than the visible light. At this point, graphene exhibited a significant magneto-optical effect, dramatically enhancing the splitting extrema of LHCP and RHCP. This structure will provide possibilities for enhancement of the transverse shift and efficient regulation of the optical spin Hall effect within the terahertz range.

Reflect–Transmit-Array Antenna With Independent Dual Circularly Polarized Beam Control

In this letter, we propose a dual circularly polarized reflect–transmit-array (RTA) antenna with independent beam control. It can transmit left-hand circularly polarized (LHCP) wave as transmitarray antenna and reflect right-hand circularly polarized (RHCP) wave as reflectarray antenna at 8.7–10.2 GHz. In addition, 360° phase shift for each circularly polarized wave can be achieved by rotating the top and bottom patches. A 20 × 20-unit cell RTA is designed, fabricated, and measured. For the LHCP radiation, the measured results show that the 3 dB gain bandwidth and axial ratio (AR) bandwidth are 13.7% (8.8–10.1 GHz) and 15.9% (8.7–10.2 GHz), respectively. For the RHCP radiation, the measured 3 dB gain bandwidth and AR bandwidth are 11.4% (9.1–10.2 GHz) and 12.6% (8.9–10.1 GHz). The peak aperture efficiencies for LHCP and RHCP radiations are 45.5% at 9.2 GHz and 41.8% at 9.6 GHz, respectively.

Compact dual-band circularly polarized antenna for wireless communications

P-shaped dual-band circularly polarized (CP) antenna for wireless communications with right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) is presented in this article. Optimized electrical volume of the proposed structure is 0.46? 0 ? 0.46? 0 ? 0.02? 0 mm3 at 4.4 GHz resonant frequency. The measured - 10 dB impedance bandwidths are 50.7% and 5.7% for (3.37-5.60 GHz) and (10.82-11.46 GHz) resonating bands at frequencies 4.4 GHz and 11.4 GHz respectively. The measured 3 dB impedance axial-ratio bandwidths for (4.65-5.13 GHz) and (11.21-11.52 GHz) bands are 9.7% and 2.7%. Agreement of simulation results with measured results ensure the excellent circular polarization at frequencies 4.96 GHz and 11.4 GHz.

A Polarization Reconfigurable 3D Printed Dual Integrated Quadrifilar Helix Antenna Array Embedded Within a Cylindrical Dielectric Mesh

This article presents a polarization reconfigurable dual integrated quadrifilar helix antenna array that is embedded within a cylindrical-shaped mesh of dielectric material. The entire structure is 3-D-printed and equipped with grooves to support the eight radiating elements and accordingly enforce the helical pitch and orientation. The dual antenna array, acting as one, features double fractional bandwidth (i.e., 30%) while exhibiting polarization reconfigurability by switching between left-handed and right-handed circular polarization states. More specifically, the proposed structure operates over the span of frequencies between 1.7 and 2.3 GHz while ensuring a circularly polarized behavior. The polarization reconfigurability is obtained by changing the phase excitation of the eight helical arms. Accordingly, a dedicated feeding network is proposed to achieve the required phase reconfiguration. A prototype is fabricated and tested as a proof of concept, where the measured results agree well with the simulated data. The 3-D-printed fabricated prototype reconfigures its circularly polarized behavior over the entire operating bandwidth with a maximum measured realized gain of 6.4 dBic, an axial ratio that varies between 0.5 and 2.5 dB, and cross-polarization levels of at least 20 dB along the direction of maximum radiation.

A Compact Broadband Circularly Polarized Wide-Slot Antenna With Axial Ratio Bandwidth Encompassing LTE 42 and LTE 43 Standards of 5G Mid-Band

This study presents a compact broadband wide-slot antenna with broadband left-hand circular polarization compatible with both LTE 42 and LTE 43 standards of 5G mid-band applications. The proposed antenna is fabricated on an FR4 dielectric substrate with overall dimensions of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.41\lambda _{o}\times 0.36\lambda _{o}\times 0.02\lambda _{o}$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{o}$ </tex-math></inline-formula> is the free space wavelength at the resonant frequency of the antenna. The antenna ground plane is etched to form a square radiating slot with a pair of rectangular ground stubs that are diagonally placed inside the slot. On the other side of the antenna, the feed line is loaded by horizontal and vertical stubs to improve the coupling between the feed line and the square slot. To generate a circular polarization, the feeding stubs cooperate with the pair of rectangular ground stubs to excite the radiating slot of the antenna at two different feeding points whose currents have approximately equal amplitude and 90° phase shift. The measured impedance bandwidth (BW) of the proposed wide-slot antenna is 16.2% (580 MHz along the band 3.3-3.88 GHz), while the observed axial ratio bandwidth (ARBW) is 12.2% (440 MHz in the 3.4-3.84 GHz band). The measured gain values are found to be larger than 2.5 dB along both standards of the 5G mid-band applications.

Spin-multiplexed full-space trifunctional terahertz metasurface [Invited

The widespread use of multifunctional metasurfaces has started to revolutionize conventional electromagnetic devices due to their unprecedented capabilities and exceedingly low losses. Specifically, geometric metasurfaces that utilize spatially varied single-celled elements to impart arbitrary phase modulation under circularly polarized (CP) waves have attracted more attention. However, the geometric phase has intrinsically opposite signs for two spins, resulting in locked and mirrored functionalities for the right-handed and left-handed CP beams. Additionally, the demonstrated geometric metasurfaces so far have been limited to operating in either transmission or reflection modes at a single wavelength. Here, we propose a double-layered metasurface composed of complementary elliptical and reversal ring resonator structures to achieve simultaneous and independent control of the reflection and transmission of CP waves at two independent terahertz frequencies, which integrates three functions of reflected beam deflection, reflected Bessel beam generation, and transmitted beam focusing on the whole space. The high efficiency and simple design of our metasurface will open new avenues for integrated terahertz metadevices with advanced functionalities.

Dual Circular Polarization Fabry–Pérot Resonant Antennas Based on Meta-Surface

A dual circular polarization Fabry–Pérot resonant antenna is proposed in this paper. The proposed antenna consists of a microstrip antenna radiator and meta-surface. Meta-surface is applied into the design of a Fabry–Pérot (FP) resonant cavity for generating two circularly polarized (CP) beams. When the meta-surface functions as a partially reflecting surface with a top C-gaps array, dielectric substrate with holes periodically arranged around the atoms and bottom metal plate with strip gaps, the proposed design would split an LP wave from the feed into the left-hand CP and right-hand CP waves by rotating the top C-gaps to form prescribed phase gradients. Simulation and measurement results show that the proposed antenna is capable of generating left-hand CP and right-hand CP radiation beams pointing at 18° and −18° at 14.9 GHz with a stable gain of over 22.7 dBic and an aperture efficiency of 25.7%. The proposed technique offers an efficient way to fulfill FP resonant antennas with specific characteristics using meta-surface for more advanced functionalities.

Decoupled Phase Modulation for Circularly Polarized Light via Chiral Metasurfaces

Metasurfaces have emerged as one highly vibrant frontier in the field of nanophotonics, since they enable some unique and practical means to modulate the phase, polarization, angular momentum, and spatial field distribution through structural engineering. However, the current methods of phase modulation based on the propagation phase and Pancharatnam–Berry phase are typically interrelated between two eigen spin states for each single-step modulation. It means that when the phase of left-handed circularly polarized (LCP) light is modulated by a metasurface, the phase of right-handed circularly polarized (RCP) light will change as well, imposing substantial constraints if spin-decoupled or spin-independent applications are sought. In this paper, we numerically and experimentally demonstrate a new phase modulation pathway based on chiral metasurfaces consisting of V-shaped plasmonic apertures, which enable fully decoupled phase modulation for the two eigen spin states. Two enantiomers are proposed to achieve the desired phase decoupling. Specifically, the enantiomer can manipulate the phase of the LCP component of a light beam without changing the phase of the RCP component, and vice versa. Our method expands the methods of phase engineering and can help us design novel devices for a wide range of applications, including polarimetric imaging, chiroptical detection, molecular spectroscopy, and quantum information processing.

Reconfigurable polarization and pattern microstrip antenna for IRNSS band applications

In this article, polarization and pattern reconfigurable antenna is designed for 2.492 GHz Indian Regional Navigational Satellite System (IRNSS) band. The proposed antenna consists of a square radiating element fed with quad coaxial probes for polarization reconfigurability. It is surrounded by switch loaded octagonal parasitic ring for pattern beamwidth reconfigurability. RF switch loaded Electronically feeding network is used to fed the proposed antenna. The right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) is realized by exciting feed ports in the antenna with 90° phase difference. At the same time switch loaded parasitic ring provides the pattern beamwidth reconfigurability for designed circularly polarized antenna. To verify the proposed design, a prototype is fabricated and tested experimentally. The measured axial ratio is well-below 3 dB in polarization mode. The measured 3 dB beam-width of the elevation gain patterns for the horizontal field component (Gϕ) varies between 107.40°∼113.51° and 74°∼77.55° in pattern reconfigurable modes. The maximum gain of 6.46 dBi is achieved in both polarization and pattern reconfigurable mode. The proposed antenna is intended for the IRNSS navigation receiver system and designed to minimize the effect of interference incident on the antenna by narrowing the pattern beamwidth near the horizon.

Compact Dual Circularly-Polarized Quad-Element MIMO/Diversity Antenna for Sub-6 GHz Communication Systems.

In this paper, a compact dual circularly-polarized (CP) planar multiple-input-multiple-output (MIMO) antenna is presented for a sub-6 GHz frequency band. The antenna consists of four identical resonating elements, which are placed in a mirrored-image pattern to obtain polarization diversity. Element 2 is a mirror image of element 1, and elements 3 and 4 are mirror images of elements 1 and 2. Each antenna element comprises an elliptical resonator, a 50-Ω microstrip feed line, and a rectangular stub integrated with the feed to increase the surface current path of the antenna, shifting the resonating frequency to the lower side. Additionally, the rectangular stub is lengthened towards the right side (along the +x-axis direction in the antenna element 1), which balances the magnitude and 90° phase variance among the horizontal (Ex) and vertical (Ey) fields. The proposed MIMO antenna supports both types of circular polarization, where radiators 1 and 3 radiate right-hand CP (RHCP) rays and radiators 2 and 4 radiate left-hand CP (LHCP) rays. Developing a compact-size MIMO antenna is a challenging task, especially when the antenna elements share the same ground plane and are placed less than half a wavelength apart. The mutual coupling in the proposed antenna is reduced by increasing the spacing between the elements without the use of any extra decoupling structure. Optimal spacing is maintained to achieve compact geometry with less inter-element correlation. The radiators are closely placed with an edge-to-edge spacing of 0.08λ0, where λ0 is the free space wavelength at 3.6 GHz. A peak gain of 5 dBi, efficiency of 90%, an envelope correlation coefficient (ECC) of less than 0.1, and isolation of more than 18 dB are obtained between different ports of the prototype antenna. The overall size of the antenna element is 17 mm × 17 mm × 1.6 mm, and the MIMO antenna is 40 mm × 40 mm × 1.6 mm.

Dual-Band Wide-Angle Reflective Circular Polarization Converter with Orthogonal Polarization Modes.

Herein a dual-band wide-angle reflective circular polarization converter, based on a metasurface was developed. The unit cell is composed of a split square ring and a nested square patch. The split square ring plays the role of creating polarization conversion. The square patch is useful for improving the quality of axial ratio. It was verified that the structure could transform the x-polarized incident wave into left-hand circular polarization in the lower frequency band, and to right-hand circular polarization in the higher frequency band. For y-polarized incidence, the transformation has orthogonal modes to that for x-polarized incidence. Moreover, the 3 dB axial ratio takes place in the ranges of 8.42-12.32 GHz and 18.74-29.73 GHz, corresponding to a relative bandwidth of 37.61%, and 45.35%, respectively. In addition, the polarization conversion efficiency is greater than 99% in the ranges of 8.65-11.83 GHz and 19.55-29.36 GHz. Furthermore, for oblique incidence, the axial ratio remains stable, even at 50° incidence, for the lower frequency band. Lastly, a prototype is fabricated and measured for experimental verification. The measured and simulated results were in good agreement. Compared with other designs in the literature, the proposed converter operates with good performance in dual-band, with high-efficiency, and with angular stability.

Dynamically switching the asymmetric transmission and monodirectional absorption of circularly polarized waves using cascade composite resonator-graphene meta-surfaces.

We propose a reconfigurable hybrid graphene meta-surface for modulating circularly polarized (CP) waves with dual functionalities of asymmetric transmission (AT) and monodirectional absorption. Such a meta-surface consists of three cascade dielectrics covered with identical metallic resonators and different patterned graphene sheets over the front and the back sides, respectively. The left-handed CP incidences will be transformed into right-handed CP counterparts efficiently with an AT-parameter of 0.8, and the state of transmission will be contrary when the incident CP waves are from the opposite direction. On the other hand, the proposed cascade composite resonator-graphene meta-surface can also function as a super monodirectional absorber to trap the forward incident CP waves at the same frequency range when we simply tune the Fermi energy of graphene. The proposed design should pave the way for building up more advanced meta-devices with multiple functionalities to manipulate CP waves.

Broadband Circularly Polarized Conical Corrugated Horn Antenna Using a Dielectric Circular Polarizer.

In this paper, a broadband left-handed circularly polarized (LHCP) corrugated horn antenna using a dielectric circular polarizer is proposed. Circularly polarized (CP) waves are generated by inserting an improved dovetail-shaped dielectric plate into the circular waveguide. Compared with the traditional dovetail-shaped circular polarizer, the proposed improved dovetail-shaped circular polarizer has a wider impedance bandwidth and 3 dB axial ratio bandwidth. A substrate-integrated waveguide (SIW) structure is designed as a wall to eliminate the influence of fixed grooves on the circular polarizer. The simulated reflection coefficient of the dielectric plate circular polarizer is less than -20 dB in the frequency band from 17.57 to 33.25 GHz. Then, a conical corrugated horn antenna with five corrugations and a four-level metal stepped rectangular-circular waveguide converter are designed and optimized. The simulated -10 dB impedance and 3 dB axial ratio (AR) bandwidths of the circularly polarized horn antenna integrated with the polarizer are 61% (17.1-32.8 GHz) and 60.9% (17.76-33.32 GHz), respectively. The simulated peak gain is 17.34 dBic. The measured -10 dB impedance is 52.7% (17.2-27.5 GHz).

A high gain dual circularly polarized X‐band antenna for CubeSat applications

AbstractIn this article, a dual circularly polarized high gain superstrate integrated X‐band antenna is designed and analyzed for CubeSat applications. The proposed antenna consists of a metallic patch, multilayer space qualified printed circuit boards, and a dielectric superstrate with a high relative permittivity on top of the patch to establish a suitable resonance condition for high‐gain operation. The driven patch is fed by a 3‐dB hybrid coupler for the generation of dual (left hand circular polarization and right hand circular polarization) circular polarization. The antenna exhibits an impedance bandwidth of &gt;18.5% (7.75–9.4 GHz) with a peak gain of &gt;16 dBiC. The achieved antenna performance makes it suitable for CubeSat missions at X‐band.