Axial Ratio Beamwidth Research Articles

Compact triple-band ring-shaped printed antenna with circular polarization

This research proposed a planar printed antenna with circularly polarized (CP) ability. The antenna can supply an impedance bandwidth (│S11│<−10 dB) of 60% (2.3–4.3 GHz), 32.4% (4.8–6.8 GHz), 5.5% (7–7.4 GHz), and 24.4% (8.6–11 GHz) in the operative frequency band. The designed antenna has a 3 dB polarization axial ratio (AR) bandwidth (BW) of 88% (1.4–3.6 GHz), 11.3% (5–5.6 GHz), and 1.15% (8.6–8.7 GHz). The patch antenna dimensions are 20mm × 20 mm. To enhance AR bandwidth, an inverted L-formed strip line is added to the radiator to generate two electric fields with 900 phase differences. The measurement maximum gain of this patch antenna is about 7 dBi from 2.5 to 4.4 GHz. This structure has a wide AR beam width from – 30° to +110° at 2.4 GHz, – 70° to +70° at 5.2 GHz, and – 60° to +20° at 8.65 GHz. The CP antenna exhibits a miniaturized size and low-cost structure with suitable CP radiation characteristics.

Dual band four port MIMO antenna with dual circular polarization for Wi-Fi/WiMAX applications

The planar compact four port circularly polarized printed MIMO antenna described in this article is small and intended to support Wi-Fi and WiMAX applications. Suggested four E-shaped monopole elements make up the dual circularly polarized (CP) MIMO antenna that has two left hand CP (LHCP) elements and two right hand CP (RHCP) elements. An I shaped strip is used to join separate ground planes of designed E shaped monopole antenna to have same voltage levels. A good diversity performance is achieved with an envelope correlation coefficient (ECC) of less than 0.15. The 60 mm × 60 mm antenna is designed from FR4 material, which is inexpensive and has a 1.6 mm thickness. Using a high-frequency structure simulator (HFSS), the suggested MIMO antenna is designed and optimized. The measured findings demonstrate the circular polarization, 3-dB axial ratio beamwidth, impedance bandwidth of 2.11 GHz −2.42 GHz and 3.40 GHz-3.51 GHz, adequate axial ratio bandwidth (ARBW) of the suggested MIMO antenna along with high isolation of −17 dB, gain of 3.43 and 2.09 dBic at 2.4 GHz and 3.5 GHz respectively, TARC (Total active reflection coefficient) of less than 0 dB, a CCL (Channel capacity loss) of lesser than 0.4 bits/sec/Hz, and an MEG (Mean effective gain) value of less than 3 dB.

A single-feed circularly polarized antenna with a low vertical profile and hemispherical axial-ratio beam coverage

ABSTRACT A novel wide axial-ratio beamwidth (ARBW) circularly polarized (CP) antenna with a single layer substrate fed by a single probe is proposed. It consists of an inner annular slotted radiator containing eight outer sector units with arc branches, a ground plane, and eight grounded vias. The antenna has an ARBW covering the upper hemisphere and has a low vertical profile. The ultra-hemispherical ARBW is formed by ingeniously merging the endfire omnidirectional CP radiation pattern with the boresight CP radiation pattern. The two radiation patterns can be excited by a central coaxial probe without an additional feeding network. An antenna prototype of dimensions 1.15 × 1.15 × 0.02 (λ 0 3) is fabricated and measured to validate the design concept. Measured results show that the impedance bandwidth of the proposed antenna is 2.0% (3.328–3.394 GHz) and the 3 dB axial ratio (AR) bandwidth is 1.3% (3.332–3.374 GHz). The 3 dB AR beamwidth can cover more than 217° and the maximum gain is 0.79 dBic at 3.35 GHz. A good agreement between the simulated and measured results is obtained.

A Single Layer Low Axial Ratio Circularly Polarized Planar Wide-Angle Scanning Phased Array

This paper proposes a circularly polarized planar wide-angle scanning phased array radar. The structure of the proposed array element is a windmill-type patch with an octagon-shaped series power divider. The proposed array exhibits a low axial ratio because the element has a wide 3-dB axial ratio beamwidth and the array topology uses the sequential rotation technique. Test results show that the proposed 8 × 8 uniform planar array can realize two-dimensional circularly polarized scanning from −60° to +60° in the working band of 3.43–3.48 GHz. The coverage gains of θ = ±60° are about 3 dB lower than the gain when the main beam points at θ = 0°. Moreover, in the scanning mentioned above airspace, the scanning beam axial ratio is below 0.5 dB in the xz-plane (φ = 0°) and yz-plane (φ = 90°) and below 1.4 dB in the D-plane (φ = 45°). Another notable feature is the single-layer structure, and its profile is only 0.08λ0 at the center wavelength. This good low- axial ratio and low-profile characteristics make the proposed array potentially applicable to low-orbit satellite communications.

A compact ultra‐wide‐beam quasi‐coaxial‐structure fed crossed‐dipole

AbstractA compact ultra‐wide‐beam crossed‐dipole antenna for K‐band phased arrays is proposed. The superior wide beamwidth is achieved by loading four vertical parasitic structures around the dipole patches. A quasi‐coaxial feeding structure is proposed as the antenna size is limited in K‐band, and it cannot be coaxially fed by the conventional feeding method. This structure is constructed by using PCB through‐plated vias, achieving a compact design. The antenna has a compact size of 0.37λ × 0.37λ × 0.35λ (λ is the free space wavelength). The simulated and measured results show that a half‐power beamwidth of more than 140° (from −71° to 72°) and an axial ratio beamwidth of 100° (from −51° to 49°) can be realized.

Multiband circularly-polarized stacked elliptical patch antenna with eye-shaped slot for GNSS applications

Abstract This paper introduces a tri-band stacked elliptical patch antenna featuring a right-handed circular polarized, designed to operate at the L2, L5, and L1 Global Navigation Satellite System bands. Initially, an elliptic patch is constructed and fed by a probe feed to generate TM110 and TM210 modes at resonance frequencies calculated using Mathieu functions. The probe position is precisely adjusted to excite the quasi-orthogonal mode of TM110 to generate circularly polarized (CP) waves at the L2 and L5 bands. Subsequently, an eye-shaped aperture is engraved into the elliptical patch to enhance the axial ratio (AR) beamwidth in the L2 and L5 bands and stimulate the orthogonal mode of TM210 to produce CP waves at the L1 band. Lastly, a stacked partially elliptical parasitic element is placed beneath the upper slotted elliptical patch to enhance the orthogonality of TM210 surface current versions and thus improve the AR beamwidth at the L1 band. The proposed antenna shows low reflection coefficient values at 1.12–1.33 (L2/L5), and 1.5–1.66 GHz (L1). The AR beamwidths are 133/213∘, 167/163∘, and 36/103∘ at two orthogonal cutplanes at L5, L2, and L1 bands, respectively. The antenna also has decent gains of 6–6.9 dBic across the three bands.

Two-dimensionally high AR performance beam scanning utilizing randomly-rotated single-PIN-diode elements for circularly-polarized programmable metasurface

In this paper, we introduce a novel technique that utilizes randomly rotated elements (RREs) for the cross-polarization and axial ratio (AR) control of a circularly polarized programmable metasurface (CPPMS). We evaluate the CPPMS performance by comparing RREs layout with uniform elements (UEs) layout, and analyze far-field radiation parameters for 50 groups of CPPMS with different RREs layouts. Simulation results demonstrate consistent and improved performance across various RREs layouts, showcasing reduced cross-polarization and enhanced AR beamwidth. To validate these findings, we design a 1-bit CPPMS in Ku-band comprising 20 × 20 elements with the optimal RREs layout, and conduct measurements in an anechoic chamber. The CPPMS prototype achieves high gain (22.34 dBi), low cross-polarization (-20.5 dB), and a narrow 3 dB AR beamwidth (8.93°). Notably, it offers wide-angle beam scanning capabilities of up to ±60°. The gain bandwidth at -3 dB ranges from 14.54 to 16.65 GHz, with a relative bandwidth of 7.3%, while the 3 dB AR bandwidth extends from 14.24 to 16.07 GHz. Consequently, the proposed 1-bit CPPMS exhibits high-performance two-dimensional AR beam scanning, presenting promising applications in satellite communications.

Design of circularly polarized antenna with wide overlapped axial‐ratio and gain beamwidths for upper hemispherical coverage

AbstractIn this letter, a circularly polarized antenna with wide overlapped axial ratio and gain beamwidth is proposed for upper hemispherical coverage. By bending half of the dipoles to the vertical direction, and connecting eight metal columns to the ground, the half‐power beamwidth (HPBW) of all cut planes can be increased effectively. On the basis, one reactive impedance structure is applied as the reflector to achieve unidirectional radiation, as well as increase the 3‐dB axial ratio beamwidth (ARBW) of the antenna. Miniaturized four‐feed networks are utilized to provide excitation, and the shielding technique is applied to reduce its influences on the antenna radiation performances. Measurements show that the proposed antenna can operate in the range of 1.51–1.59 GHz, which covers the upper band of global navigation satellite system (GNSS). Besides, at 1.561 GHz, the measured HPBWs and 3‐dB ARBWs are larger than 131° and 135° in all cut planes. The wide overlapped beamwidth of the proposed antenna with small size indicates the potential applications in high‐precision GNSS navigations.

A Wideband Differentially Fed Circularly Polarized Slotted Patch Antenna with a Large Beamwidth

A wideband differentially fed circularly polarized (CP) antenna featuring a slotted patch design with a large beamwidth is presented. The final design of the differentially fed CP antenna, aimed at achieving high gain and a wide axial ratio (AR) bandwidth, involves coupling a differential bending dipole antenna to the slotted patch in the same plane. The presented differentially fed CP antenna demonstrates characteristics of a large AR beamwidth, as verified by simulation and experiment. The measured AR beamwidths of 132.3° in the &lt;i&gt;xoz&lt;/i&gt; plane (phi = 0°) and 116.2° in the &lt;i&gt;yoz&lt;/i&gt; plane (phi = 90°) are realized at 5.5 GHz. The measured result exhibits broadband performance with a -10-dB impedance bandwidth of 78.8% (3.81–8.76 GHz), a 3-dB AR bandwidth of 36.7% (4.78–6.93 GHz), and a maximum gain of 10.2 dBic.

Circularly Polarized Leaky Wave Array With Wide Axial Ratio Beamwidth and Low Sidelobe

Circularly Polarized Leaky Wave Array With Wide Axial Ratio Beamwidth and Low Sidelobe

High-Gain Dual-Band Aperture-Shared CP Patch Antenna With Wide AR Beamwidth for Satellite Navigation System

This paper presents a compact dual-band, high-gain, light-weight, circularly polarized (CP) microstrip patch antenna with wide axial ratio (AR) beamwidth for multiple satellite communication, positioning and navigation systems The antenna consists of a main dual-frequency coplanar metal frame radiator, a circular metal capacity-loaded radiator, and some coaxial feeding probes. Due to the use of air dielectric, the maximum right-hand circularly polarized gain of the antenna is up to 6.2 dBic in the lower bands and 6.3 dBic in the upper bands. By utilization of dual-frequency coplanar patch and metal capacity-loaded technology, the dimensions of the aperture-shared CP antenna are only 0.38 λ × 0.38 λ × 0.04 λ. To increase the 3-dB AR beamwidth, a novel vertically grounded shorting sheet is introduced. The 3-dB AR beamwidth ranges from −120° to 100° at 1.227 GHz and from −90° to 95° at 1.575 GHz. As a result, the proposed antenna is an excellent candidate for high gain, wide AR beamwidth and compact air dielectric antenna.

A Ku/K‐band wideband crossed dipole circularly polarized array with low profile

AbstractA low‐profile Ku/K band circularly polarized phased array antenna based on crossed dipole and four parasitic elements is presented. Four parasitic patches and the outline of dipole arms which are designed as an exponentially gradual curve are intended to broaden impedance bandwidth. For better integrated design, the plated through holes at the bottom of substrate replaces the metal cavity, aiming to enhance the radiation characteristics of the positive direction. The small angle sequential ro0tation tech is adopted to further increase the axial ratio (AR) bandwidth. The 8 × 8 antenna array is operated from 15.5 to 23.5 GHz (41%), with the size of 56 mm × 56 mm × 2.54 mm. In the operating frequency, the array demonstrates an average peak realized gain of 24.3 dBic and has a 3‐dB AR beamwidth with scanning angle from −60° to 60° in the plane of ɸ = 0° and ɸ = 90°.

Dual-band circularly polarized asymmetric dipole array antenna for GPS L1 and L2 bands

A dual-band, circularly polarized (CP) asymmetric dipole array antenna for Global Positioning System (GPS) applications with a wide beam is presented in this paper. The proposed antenna comprises two different-sized printed crossed dipoles with integrated baluns fed by an asymmetric feeding network to achieve dual-band functionality. Using two branch-line couplers with different dimensions in the feeding network performs Right-Hand Circular Polarization (RHCP) operation at GPS L1 and L2 bands. According to the experiments, the proposed antenna has wide impedance bandwidths of 24.82% (1139.5–1462.4 MHz) and 14.82% (1500.4–1740.5 MHz), and 3 dB Axial-Ratio (AR) bandwidth of 37.4% (1132.3–1653.2 MHz) to cover the GPS L1 and L2 bands. Furthermore, at 1227 MHz frequency, the antenna has a gain of 4.65 dBic, and a 3 dB AR beamwidth of 148.2° facing the sky. Also, at 1575 MHz frequency, a gain of 5.25 dBic and a 3 dB AR beamwidth of 139.3° are achieved.

A Simple Single-fed Left/Right-Hand Circular Polarization Antenna for GPS Applications

A simple single-feeding circular polarization (CP) antenna with controlled left/right-hand characteristics is proposed and investigated for GPS L2 band applications. To achieve the CP characteristics, four arc-shaped cutting corners with different sizes are removed from a circular patch to give 90∘ phase difference to implement CP. By adjusting the radius of the four arc-shaped cutting corners, the antenna can be controlled to get left/right-hand circular polarization (L/RHCP). The proposed CP antenna is modeled, simulated, fabricated and measured, and the results demonstrate that the antenna provides an axial ratio beamwidth over 180 MHz, and impedance bandwidth of 20 MHz for L/RHCP. Additionally, the devised CP antennas have good directional radiating patterns, making them suitable for GPS L2 band applications.

Design of Wideband GNSS Antenna With Wide-Angle Circular Polarization and Anti-Multipath Performance for High Precision Marine Positioning

In the paper, a wideband GNSS antenna with wide-angle circular polarization and anti-multipath performance is proposed. By using the coupled feeding formed by arc-T-shaped patch, wide bandwidth is obtained. Eight short-circuit pins are loaded around the radiation patch for widening the 3-dB axial ratio (AR) beamwidth at the GNSS frequencies and reducing size. Furthermore, two groups of bent metal-branches are loaded on the slotted ground for front-back ratio (FBR) enhancement at the GNSS frequencies. To provide uniform circular polarized (CP) excitation with small occupied area, a compact wideband quadrature feed network with amplitude imbalances within 1 dB and phase imbalances within 5° is designed which covers the GNSS band. For validation, a prototype is fabricated. Measurement results show that an overlapped bandwidth of more than 45% is obtained for 10-dB return loss and 3-dB AR. At the frequencies of 1.207 GHz, 1.227 GHz, 1.247 GHz, 1.561 GHz, 1.575 GHz and 1.602 GHz, the measured 3-dB AR beamwidths and FBRs are all larger than 200° and 20 dB, respectively, which demonstrates the potential of high precision positioning at GPS L1/L2, BDS B1/B2, GLONASS L1/L2, and Galileo L1/E5b bands.

A High-Gain Circularly Polarized Antenna Array Based on a Chiral Metastructure

In this article, a chiral metastructure absorber (CMMA) is combined with a circularly polarized (CP) antenna array based on a sequential-phase feed network, and the differential absorption of left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) by CMMA unit is used to improve the axial ratio beamwidth (ARBW) of CP antenna array by absorbing the cross-polarization of the antenna array. The proposed CMMA unit achieves good circular dichroism at 4.9–5.2 GHz, which improves the ARBW of the antenna in this frequency band. In addition, the feed network of the antenna proposed in this article is in three-dimensional (3-D) form to reduce the coupling between the feed network and the radiation patches, so that higher gain can be obtained. The measured impedance bandwidth of the antenna is 80% (2.81–6.81 GHz), the axial ratio (AR) bandwidth is 70.8% (3.68–7.22 GHz), and the peak gain is 15.28 dBi.

Axial ratio beamwidth enhancement of a low-profile circularly polarized antenna using defected ground structures

AbstractThis article explores the possibilities of incorporating a defected ground structure (DGS) for widening the 3 dB axial ratio beamwidth (ARBW) of a simple low-profile planar circularly polarized (CP) antenna. Two pairs of DGSs are etched symmetrically along the diagonals of the ground plane to overcome the limited 3 dB ARBW performance of a crossed-slotted circular-shaped planar CP antenna. Here, one pair of DGSs is orthogonal to another pair of DGSs. The distance between the pairs of DGSs plays a key role in enhancing the 3 dB ARBW by 40.62%. A gap of 0.18λ0 is considered between the DGSs to maintain the symmetrical electric field distribution in the substrate. It also helps to reduce orthogonal current components and provides uniformly distributed patch surface currents. These phenomena collectively help the proposed CP antenna to exhibit right-handed circular polarization radiation with the 3 dB ARBW of 186° and 188° in the E-plane and H-plane, respectively. The measured results yield impedance bandwidth (S11 ≤ −10 dB) of 2.6% (2.283–2.342 GHz), CP bandwidth of 0.9% (2.294–2.315 GHz), gain higher than 4.8 dBic, and total antenna efficiency more than 64% across the entire CP band.

Broad axial ratio bandwidth circularly polarized with wide angle coverage planar monopole antenna

A G-shaped circularly polarized broad axial ratio bandwidth (ARBW) and high gain monopole antenna is proposed. The proposed design is imprinted on low cost, lossy FR4 substrate with relative permittivity 4.4 and loss tangent 0.025. The physical dimension of the proposed antenna is 0.36λ0×0.39λ0×0.02λ0. The G-shaped patch is developed by modifying conventional monopole radiator to create circular polarization (CP) for strong horizontal and vertical current components. The stubs, L – shaped, and T-shaped parasitic strips (PSs) are loaded at the finest positions on the ground layer of the antenna to improve the performance of ARBW and gain. The achieved percentage impedance bandwidth (IBW), ARBW, angle coverage and gain are 106%, 97%, 102° (3 dB axial ratio beam width from −46° to + 56° in XZ – plane) at 4.26 GHz and 5 dBic respectively. The fabricated antenna is reliable for IEEE standard WLAN and broadband wireless communication system.

Circularly Polarized Corporate-Feed Beam-Scanning Array With Low Profile

A low-cost low-profile circularly polarized (CP) corporate-feed beam-scanning array is presented. As the main part of the feed network, we found that the sidewall reflection of the parallel plate waveguide (PPW) is the major reason for the deterioration of the beam-scanning performance at large angles. Therefore, a hybrid feed network composed of PPW and substrate integrated waveguide (SIW) is proposed. Mechanical beam-scanning is realized by a planar parabolic reflector-based line source generator (LSG). To expand the beam-scanning range, an SIW delay line-based phase compensation structure is introduced after theoretically analyzing the phase deviation generated by the LSG. The CP radiation is realized by improved CP antenna elements with a wide 3 dB axial ratio (AR) beamwidth. These CP antenna elements are fed by a corporate-fed network to avoid the frequency-dependent squint beam. A K-band prototype of an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times14$ </tex-math></inline-formula> array is fabricated and measured to verify the design. According to the measured results, the beam-scanning range of 0°–51° in elevation with the peak gain of 22.3 dBi is realized. The gain variation and ARs in this scanning range are less than 2.9 and 2.5 dB, respectively.

A reconfigurable polarization converter and related application as horn antenna cladding

In this paper, a transmissive reconfigurable polarization converter (RPC) based on an active metasurface is proposed, which can regulate the ideal plane wave and the spherical wave as a cladding of the horn antenna. The metasurface unit is composed of a single-layer F4B dielectric substrate and two double-cross metal strips with a p–i–n diode on the top and seven vertical metal strips on the bottom. One RPC prototype with 15 × 15 units has been fabricated and measured when it regulates an ideal plane wave. By controlling the states of diodes, the RPC can realize the linear-to-circular polarization conversion (LCPC) or the linear polarization maintaining (LPM) function from 2.5 to 3.64 GHz. Furthermore, the RPC is used as the cladding of a horn antenna for high integration in practical applications. The measured results show that this RPC-antenna system can still achieve LCPC or LPM function from 3.1 to 4.5 GHz. It is worth mentioning that the 3 dB axial ratio beam width of RPC can cover from −65° to 65° in LCPC. The proposal has advantages of a wideband, simple biasing network, and easy fabrication and integration, which can be widely applied in modern wireless communication systems.