Broadband Circularly Polarized Research Articles

Broadband CP corner-truncated microstrip antenna with irregularly hexagonal AMC for 2.45 GHz applications

This research proposes a compact broadband circularly polarized (CP) corner-truncated microstrip antenna with irregularly hexagonal artificial magnetic conductor (AMC) for 2.45 GHz WLAN applications. The corners of the radiating patch are diagonally truncated to realize circular polarization and improve axial ratio. A 5▪5 irregularly hexagonal AMC array is employed to enhance the axial ratio bandwidth (ARBW) and antenna gain. In addition, a tri-section meandering feedline is used to realize impedance matching and improve the impedance bandwidth (IBW). The AMC array is used to manipulate electromagnetic waves by suppressing surface currents and back lobe, resulting in reduced back radiation and enhanced front-to-back ratio. The simulated IBW and ARBW are 50.9% (1.86 – 3.13 GHz) and 19.3% (2.24 – 2.72 GHz) respectively, with a maximum gain of 8.9 dBic at 2.45 GHz. The measured IBW and ARBW are 42.42% (1.95 – 3.0 GHz) and 29.4% (2.03 – 2.73 GHz), with a maximum gain of 8.6 dBic. The simulated half power beamwidth (HPBW) of the proposed antenna scheme in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 67°, 62°, and 51°, respectively. The corresponding HPBW in the yz plane are 60°, 55°, and 62°. The simulated AR beamwidth in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 177°, 164°, and 88°, respectively. The corresponding AR beamwidth in the yz plane are 148°, 106°, and 124°. The simulated cross polarized (XP) levels at 2.45 GHz are below -19.35 dB for both planes. The measured HPBW in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 69°, 64°, and 50°, respectively. The corresponding HPBW in the yz plane are 65°, 54°, and 37°. The measured AR beamwidth in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 161°, 200°, and 104°, respectively. The corresponding AR beamwidth in the yz plane are 162°, 85°, and 90°. The measured XP levels at 2.45 GHz are below -15.62 dB for both planes. The radiation pattern is unidirectional. Essentially, the proposed broadband CP antenna scheme is suitable for the WLAN frequency band and other 2.45 GHz wireless communication technologies. The novelty of this research lies in the use of the tri-section meandering feedline and the irregularly hexagonal AMC array to enhance IBW and ARBW.

A Lightweight Broadband Circularly Polarized Stacked Patch Antenna Formed by Meshed Aluminum Disks for Inter-Satellite Communication

A Lightweight Broadband Circularly Polarized Stacked Patch Antenna Formed by Meshed Aluminum Disks for Inter-Satellite Communication

Broadband Circularly Polarized Microstrip Antenna With Customized Tilted Beam Based on Index-Modulated Folded Split Ring Resonator

Broadband Circularly Polarized Microstrip Antenna With Customized Tilted Beam Based on Index-Modulated Folded Split Ring Resonator

Broadband circular polarization selector and converter based on multilayer metamaterials with stacked split-rings

Broadband circular polarization selector and converter based on multilayer metamaterials with stacked split-rings

A Compact Broadband Circularly Polarized Antenna with Novel Tilt Fences for GNSS Applications

A Compact Broadband Circularly Polarized Antenna with Novel Tilt Fences for GNSS Applications

Broadband Circularly Polarized Printed Crossed-Dipole Antenna and Its Arrays for Cellular Base Stations

Broadband Circularly Polarized Printed Crossed-Dipole Antenna and Its Arrays for Cellular Base Stations

A Novel Design of Broadband Circularly Polarized Rectenna With Enhanced Gain for Energy Harvesting

A Novel Design of Broadband Circularly Polarized Rectenna With Enhanced Gain for Energy Harvesting

Development of a Broadband and High-Gain Circularly Polarized Array of Multilayer Slot Antennas for X-Band Wireless Communication Networks

This paper presents a wideband cavity-backed slot antenna array designed for X-band wireless communication systems. The antenna element consists of a circular slot combined with a cross-slotted patch; both are fed by an L-shaped microstrip line through proximity coupling to extend the impedance bandwidth and gain. The reduction of beam squint in the radiation patterns, caused by the asymmetric feed line, is achieved through intelligent optimization of the dimensions and position of the cross slot on the patch. Additionally, a back cavity is included to provide unidirectional radiation and enhance gain. The antenna exhibits right-hand circularly polarized (RHCP) radiation patterns with high gain over a wideband frequency range. To further improve the axial ratio (AR) bandwidth and gain, the antenna is utilized in a 2 × 2 array configuration with a sequential rotation feed network. The overall dimensions of the proposed array are 1.42 λ 0 × 1.42 λ 0 × 0.45 λ 0 , where λ 0 represents the wavelength at the center frequency of 10 GHz. The fabricated array is then tested, and the measurements show an impedance bandwidth of 60% (7 GHz-13 GHz) with S 11 < − 10 dB, a 3 dB AR bandwidth of 42% (7.45-11.65 GHz), and a peak gain of 11.14 dB. The simulated and measured results exhibit good agreement, validating the effectiveness of the design.

Characteristic Mode Inspired Broadband Circularly Polarized Folded Transmitarray Antenna

The circularly polarized (CP) antennas with high gains have gained growing interest due to their significant advantages, but the existing works usually suffer from narrow bandwidths. In this work, a novel circularly polarized folded transmitarray antenna (CPFTA) inspired by the characteristic mode analysis (CMA) method is proposed to achieve a broadband and high-gain CP radiation. The proposed CPFTA consists of a top-layer multifunctional metasurface (MTS), a bottom-layer polarization conversion metasurface (PCM) integrated with a linearly polarized (LP) microstrip feed source. Enabled by the CMA, the unit cell etched with an asymmetric U-slot of the MTS is optimized to generate two pairs of CP modes to broaden the bandwidth of the CPFTA. Moreover, a modified broadband E-shaped LP microstrip antenna is integrated with the PCM, resulting in a compact profile. A CPFTA prototype is fabricated and characterized to verify the effectiveness of the design. The measured results show that the fabricated antenna could obtain an impedance bandwidth of 31.7%, a 3 dB axial ratio (AR) bandwidth of 36.5%, and a 3 dB gain bandwidth of 30.1% with a peak gain of 22.35 dBic at 9.55 GHz.

A Compact Circularly Polarized Crossed Dipole Antenna with Wide Bandwidth using Split Ring Resonator and Parasitic Patches

A new compact broadband circularly polarized (CP) crossed dipole antenna using split ring resonator (SRR) and parasitic patches are presented. The proposed antenna is mainly composed of two orthogonal strip dipoles, two 90∘ phase delay lines, four SRRs, and four parasitic patches. The combination of the orthogonal strip dipoles and the delay lines forms a crossed dipole as the main CP radiator. The well-designed SRR can extend the current path and improve the current distribution of high-frequency without increasing the size of the antenna, thereby reducing the size of the antenna and increasing the axial ratio (AR) bandwidth of the high-frequency. The introduction of parasitic patches can improve the current distribution between the upper and lower cut-off frequency points of the bandwidth, and make up for the defects of the insufficient bandwidth of the crossed dipole and the SRR, thereby realizing broadband CP radiation. To verify the antenna, a physical prototype is fabricated. The measured results show that the impedance bandwidth (IBW) of 69.1% (1.38-2.84 GHz), and a wide AR bandwidth of 57.7% (1.43-2.59 GHz). In addition, the designed antenna achieves a stable gain in the working band and a certain band-edge selectivity. Such a single-fed, simple structure and the wideband CP antenna is an excellent candidate for communication systems such as ISM (2.4 GHz), WiBro (2.3-2.39 GHz)and Inmarsat.

A Low-Profile Compact Broadband CP DRA for RF Energy Harvesting Applications

In this letter, a low-profile circularly polarized (CP) chamfered rectangular dielectric resonator antenna (RDRA) is designed and investigated for radio frequency energy harvesting (RFEH) applications. The proposed modified RDRA comprises of dielectric resonator (DR) made up of Alumina material (ε r = 9.9) mounted on the PEC ground plane. Dual unequal triangular-shaped vertical slits are engraved on the rectangular DR for generating the orthogonal modes with CP characteristics. The optimized antenna offers an impedance bandwidth (IBW) of 51.4% (2.25–3.81 GHz) and axial ratio bandwidth (ARBW) of 14.8% (3.25–3.77 GHz), respectively. The peak realized gain and maximum radiation efficiency are 7.18 dBi and 97.8% in desired frequency bands. Due to the wide impedance and AR bandwidths with realized gain and radiation efficiency, the optimized antenna is suitable for integration with a rectifier circuit for RF energy harvesting applications. A rectifier circuit with a single shunt diode topology is also designed for rectification purposes. The rectifier achieved 67.16% RF-DC power conversion efficiency (PCE) at 3.5 GHz and 5dBm input power. At 0dBm input power, the rectifier achieved 60.26% PCE. The effective input power range, during which the PCE maintains above 50%, is calculated to be 15.2 dBm from −3.5 to 11.7 dBm.

E‐shaped patch with reactive impedance surface for high gain and broadband circularly polarized antenna

SummaryA low‐profile circularly polarized (CP) antenna with high gain and broad bandwidth is aimed at 5‐GHz Wi‐Fi applications using a symmetrical E‐shaped patch. Initially, the radiating element is modeled as a symmetrical E‐shape. An array of 4 × 4 rectangular patches are arranged periodically to make up a reactive impedance surface (RIS) structure. Furthermore, the RIS structure is deployed in the middle of a symmetrical E‐shaped radiating patch and a perfect electric conductor (PEC) ground plane. As a result, the broadband CP is achieved with high gain. The above‐mentioned combinations have achieved a −10‐dB reflection coefficient bandwidth of 21.4% (4.92–6.1 GHz) and a 3‐dB axial ratio (AR) bandwidth of 15.5% (5.25–6.1 GHz), and the antenna has attained a gain of 7.45–7.53 dBic.

Reconfigurable Antennas for RF Energy Harvesting Application: Current Trends, Challenges, and Solutions from Design Perspective

Due to the widespread use of low-power embedded devices in both industrial and consumer applications, research into the use of alternate energy sources has been sparked by the requirement for continuous power. Due to its accessibility and ability to be implanted, RF energy is always taken into consideration among the traditional energy sources that are currently available. There is a significant necessity for efficient RF front-ends, which must provide effective circular polarization (CP) features, effectiveness, feasibility from a design standpoint, and optimal usage of ambient RF signals accessible in the environment. So, for understanding their utilization in RF energy harvesting, a metasurface reflector-inspired CP-printed reconfigurable antenna integrated with a Greinacher voltage divider (GVD) rectifier circuit is reported. It offers broadband CP with fractional bandwidth > 25%, CP gain > 8.35 dBic, and directional radiation with the 3 dB angular beamwidth > 100° in the 3.5/5 GHz bands. With the integration of the rectifier circuit, a theoretical DC output > 4.8 V at 12 dBm is obtained. The acceptable impedance bandwidth, axial ratio bandwidth, antenna gain, antenna efficiency, and directional radiation with a 3 dB angular beamwidth value are studied and subsequently matched with the trade-offs (usage of diodes, complexity of DC biasing circuits, and attainment of polarization reconfigurability) obtained from the state of the art. A comprehensive study of the reconfigurable antennas is reported to highlight the findings as a widespread solution for these limitations in RF energy harvesting application.

Compact and Broadband Circularly Polarized Implantable Antenna for Wireless Implantable Medical Devices

This letter presents a compact and broadband circularly polarized (CP) implantable antenna for wireless implantable medical devices (WIMDs) in the 2.4 GHz Industrial, Scientific, and Medical (ISM) band. The proposed antenna consists of a main radiator, a stacked parasitic structure, and a full ground, with its entire dimension of 9.8 × 9.8 × 0.889 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . For size reduction, a modified square ring with a mitered cross inside is adopted as the main radiator. By splitting one arm of the mitered cross, the compactness can be further improved while exciting the potential CP radiation. The stacked parasitic structure not only ensures a satisfactory 3-dB axial ratio bandwidth of 28.7%, but also helps to achieve a -10-dB impedance bandwidth of 30%, with a peak realized gain of -24.7 dBi. The antenna was integrated into two types of dummy WIMDs and analyzed in the human phantoms (scalp and heart) to evaluate its device-level performance and robustness. A fabricated prototype was measured in the minced pork, and the measured results agree with the simulated ones.

P‐62: Broadband In‐Cell Polarizer Using Solution‐processed Broadband Quarter‐Wave Plate and Photo‐aligned Polarizer

We demonstrate a kind of in‐cell solution‐processed broadband circular polarizer made of liquid crystal polymer and a photo‐aligned polarizer on top, using the coating technique and chemical treatment. The transmittance and reflectance spectrum shows a high ambient contrast ratio (ACR) improvement for the light‐emitting display system.

Chiral Metasurface Enabled Circularly Polarized OAM-Generating Folded Transmitarray Antenna With High-Gain Low-Profile and Broadband Characteristics

A broadband low-profile high-gain folded transmitarray antenna (FTA) is proposed to generate orbital angular momentum (OAM) with circular polarization. A chiral metasurface is employed as the top layer with the function of reflecting anticipant circularly polarized (CP) incident waves while transmitting the orthogonal ones. The geometric phase is then introduced to achieve 360° coverage of the transmission phase without affecting the reflection one. To obtain a high-gain and compact planar source, a 2 × 2 patch antenna array, integrated with the bottom metallic ground, is selected as the feed. Two proof-of-concept prototypes for vortex beam generation are constructed and experimentally measured. Both simulated and measured results demonstrate that <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> =–1 and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> =+1 OAM mode beams can be generated from 8.7 GHz to 9.5 GHz, and the measured maximum gains for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> =–1 and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> =+1 reach 18.1 dBi and 18.3 dBi with the corresponding peak aperture efficiencies of 6.1% and 6.4%, respectively. Meanwhile, the axial ratios (ARs) of the peak of far-field patterns are less than 3 dB over the entire operating frequency range, providing broadband CP vortex beams. The proposed high-gain low-profile broadband FTA antenna shows a promising perspective in OAM-based wireless communication.

Dual-mode bidirectional multifunctional chiral metamaterial based on self-complementary resonators

In this paper, we propose an intrinsic chiral metamaterial (ICM) consisting of two metal self-complementary resonators, dielectric layer, and an embedded continuous vanadium dioxide (VO2) layer, which can operate in reflection and transmission modes and tailor different polarization manipulations for circular and linear polarized waves in opposite incident directions. When VO2 is in metallic state, the ICM can achieve broadband and narrowband circular polarization conversions at 1.52–2.50 THz and 2.93 THz for opposite propagating directions, respectively; when VO2 is in an insulating state, it shows a strong asymmetric transmission (AT) effect at 2.43 and 3.19 THz for forward and backward linear polarized waves. In addition, the physical mechanisms of different polarization operations are explained by analyzing the surface current and electric field distributions, multiple interference model, and near-field distributions in detail, and the circuit models are introduced to verify the simulated results. Furthermore, we investigate the influence of structural parameters on performance. The proposed ICM has important implications for the development of polarization detectors, frequency selectors, etc.

P‐7.13: Photo‐induced Rotation Alignment for Ultra‐thin Circular Polarizer and Its Applications

An in‐cell broadband circular polarizer using liquid crystal polymer (LCP) is proposed in this paper. Specifically, a polarizer with photoalignment technology is combined on the top of it. An enhancement of the ambient contrast ratio (ACR) is achieved, which shows potential in the application of light‐emitting display (LED).

A Broadband Circularly Polarized Single-Layer Metasurface Antenna Using Characteristic-Mode Analysis

In this work, we propose a low-profile single-layer coplanar waveguide (CPW)-fed metasurface (MTS) antenna with broadband circular polarization (CP) radiation. With the help of characteristic-mode analysis (CMA), a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textbf {3}\times \textbf {4}$ </tex-math></inline-formula> MTS is analyzed to reveal the useful modes supported by the structure. Consequently, two modes with orthogonal current distribution, broadside radiation, and nearly <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{90}^{\circ} $ </tex-math></inline-formula> phase difference over a wide frequency band are chosen as operation modes. Moreover, the modal near field of the aforementioned modes shows that, unlike conventional microstrip patches, the entire proposed MTS supports two kinds of extraordinary TM modes, namely, e-TM30 and e-TM04. Accordingly, a rotated CPW feeding line is used to excite the two modes without adding an extra layer as reported in the literature, making the design simpler and easier to manufacture. Based on that, a low profile antenna of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textbf {0.058}\lambda _{0}$ </tex-math></inline-formula> has been designed and fabricated. The measured results show an impedance bandwidth (IBW) of 25% (4.870–6.26 GHz), 3 dB axial ratio (AR) band of 19.42% (5.30–6.44 GHz), and a maximum gain of 8 dBi.

The Design of Broadband Circularly Polarized Multi-beam Antenna with Linearly Polarized Feeding Source and Transmitarray Unit

The Design of Broadband Circularly Polarized Multi-beam Antenna with Linearly Polarized Feeding Source and Transmitarray Unit