Dual-band Circular Polarization Research Articles

Compact Dual-Band Circularly Polarized Shared-Aperture Antenna for Satellite Communication Systems

A compact dual-band circularly polarized (CP) shared-aperture antenna is proposed for satellite communication. The antenna enables simultaneous dual-band functionality and CP radiation with right-handed CP in the Ku band and left-handed CP (LHCP) in the Ka band. The shared-aperture is implemented by integrating two independent subapertures, which function through frequency-multiplexed, resulting in a minimized profile (0.04 λ 0 ) and reduced complexity, making it an ideal choice for array applications. To enhance inter-frequency isolation, a circular arrangement of metal vias is incorporated. The measured results indicate that the antenna effectively encompasses a 3 dB axial ratio (AR) bandwidth of 15.6–16.5 GHz in Ku and 26.5–27.5 GHz in Ka bands. Additionally, it exhibits a broader 10 dB impedance bandwidth (IBW) and superior port isolation bandwidth exceeding 30 dB.

A dual-band dual-sense circularly polarized patch antenna using hybrid capacitive-inductive proximity-coupling feed

This paper presents a new proximity-coupling mechanism between a rectangular patch and a microstrip line with an open circuit terminal. The patch is located to cover both adjacent maximum-voltage (capacitive coupling) and maximum-current (inductive coupling) points of the standing wave on the feedline, and consequently, two orthogonal resonant modes with 90° phase difference are excited on the patch for generating a circularly polarized (CP) radiation. Based on this feeding mechanism, a dual-band dual-sense CP antenna is designed, which is composed of two linear rectangular patch arrays coupled to an open-ending microstrip line. It is realized on a single-layer substrate and its CP rotating sense in each band is opposite to each other. For verification, the antenna operating at 5.0 and 8.0 GHz are designed, fabricated, and tested. Noting that the design concept can be easily implemented to other frequency bands. The measurements result in an impedance-matching bandwidth of 4.72 – 5.10 GHz and 7.50 – 8.20 GHz. The antenna is left-hand CP for the lower band and right-hand CP for the upper band. In addition, the prototype shows a 3-dB axial ratio bandwidth of 4.93 – 5.02 GHz and 7.40 – 8.10 GHz and peak gains of 11.4 and 12.7 dBic at the lower and upper bands, respectively.

A Novel Dual-Band Circularly Polarized Wearable Antenna.

A circularly polarized wearable antenna operating in the 2.45/5.8 GHz ISM dual bands is proposed, which consists of a coplanar waveguide-fed rectangular monopole antenna and two parasitic branches. The monopole rectangular radiation patch can generate 2.45 and 7 GHz frequency bands and has linear polarization characteristics. By adding L-shaped parasitic branches and L-like grounded branches on both sides of the monopole, the 7 GHz operating frequency band can be moved to the 5.8 GHz frequency band, and circular polarization characteristics can be achieved in both the 2.45 and 5.8 GHz frequency bands. The size of the antenna is 48.7 mm × 42.1 mm × 1.016 mm. The simulated -10 dB impedance bandwidths of the antenna are 1.8-2.66 GHz and 5.48-6.98 GHz, respectively. The 3 dB axial ratio bandwidths are 2.34-2.67 GHz and 5.58-6.39 GHz, respectively, and it has dual-band circular polarization characteristics. In addition, the radiation characteristics of the antenna and its safety performance near the human body were analyzed. The antenna prototype has been constructed, and the measurement and simulation results have good consistency. The proposed antenna is suitable for application in wearable devices.

3-D-Printed Dual-Band Circularly Polarized Filtering Antenna With Self-Diplexing Property for Millimeter-Wave Applications

3-D-Printed Dual-Band Circularly Polarized Filtering Antenna With Self-Diplexing Property for Millimeter-Wave Applications

Dual-band Circularly Polarized Antenna with Wide Axial-ratio and Gain Beamwidths for High-precision BDS Applications

Dual-band Circularly Polarized Antenna with Wide Axial-ratio and Gain Beamwidths for High-precision BDS Applications

Dual-Band Circularly Polarized RFID Reader Antenna With Combined Dipole and Monopoles

Dual-Band Circularly Polarized RFID Reader Antenna With Combined Dipole and Monopoles

Design and Analysis of a Low-Profile Dual-Band Circularly Polarized Monopole Antenna Based on Characteristic Mode Analysis

This paper presents the design of a simple dual-band circularly polarized monopole antenna using characteristic mode analysis. First, a dual-band elliptically polarized “L”-shaped monopole antenna with a partial ground is designed; then, a rectangular stub and a parasitic structure on the ground plane are implemented to achieve dual-band CP operation. To enhance impedance bandwidth and generate circular polarization in the upper band, the rectangular stub is attached to the “L”-shaped strip. The parasitic structure is employed for simultaneous dual-band CP radiation. Characteristic mode analysis is undertaken to predict the performance of the antenna before excitation. The modal analysis which is undertaken before excitation shows the natural modes that can be excited by the antenna structure to generate a dual-band CP response. The analysis gives approximate bandwidths that can be achieved by the antenna even before excitation. The overall dimension of the antenna is 0.379 λ 0 × 0.379 λ 0 × 0.015 λ 0 , where λ 0 is the corresponding free-space wavelength at 5.7 GHz. The measured -10 dB impedance bandwidth (ZBW) is realized to be 75.9% (4.5 GHz–10 GHz). The measured 3 dB axial ratio bandwidths (ARBW) at the lower and upper bands are 6% (5.6 GHz–5.95 GHz) and 28% (6.65 GHz–8.82 GHz), respectively. The proposed antenna features a simple and compact structure for Wi-Fi, WLAN, WiMAX, and C band applications.

Dual-mode dual-band circular polarization device based on three-layer plasmonic metasurface

In this work, we proposed a three-layer metasurface with rotated gold split-rings as a polarization device that has two adjacent operating bands in two different modes. The proposed metasurface can be used as a circular polarization selector in transmission mode as well as a circular polarization converter in reflection mode. In transmission mode, it can transmit right- and left-handed circularly polarized light at the corresponding wavelengths of 2130 and 3040 nm with transmission efficiencies of 85.3% and 83.8%, respectively. In reflection mode, it can convert two types of circularly polarized light into those of the orthogonal state with conversion efficiencies of 70.3% and 77.3% in the opposite bands, respectively. The results of the theoretical calculation by transfer matrix method are consistent with these simulation results, and the current distribution results illustrate the coupling mechanism under the proposed chiral structure. In addition, the influence of parameters on circular dichroism was investigated, demonstrating the strong robustness of the structure. The proposed metasurface provides a new degree of freedom for multifunctional photonic integrated devices, which can be used for applications in optical communication and imaging.

Wide Dual-Band Circularly Polarized Diecletric Resonator: Innovative Integration of a Single Hybrid Feed and Thin Grounded Metasurface.

This article presents an application of a grounded substrate-based metasurface for hosting dielectric resonators (DRs), enabling a wide dual-band circularly polarized (CP) operation. The antenna structure comprises centrally positioned rectangular DRs, one above the other, along with a 7 × 7 square-slotted metasurface. The metasurface and DRs are hosted above a grounded substrate, which is fed through a single coaxial feed placed at a specific angle, employing a modified upper probe of the coaxial feed. The proposed hybrid technique utilizes the combined benefits of the feed angle and a well-matched metasurface, resulting in performance improvement. Notably, a measured impedance bandwidth of 88.1% for |S11| is achieved within the frequency range of 4.0 GHz to 10.3 GHz. Furthermore, the antenna design exhibits two overlapping measured 3-dB axial ratio (AR) bandwidths: 23.62% from 4.25 GHz to 5.4 GHz and 5.12% from 7.6 GHz to 8 GHz. The peak gain of the antenna is measured at 8.4 dBic. Consequently, this innovative single-feed antenna design, characterized by its compact profile, holds significant potential for realizing multi-band operations. Furthermore, the developed antenna is well-suited for deployment in indoor radio links and INSAT applications.

Dual-Band Circular-Polarized Microstrip Antenna for Ultrawideband Positioning in Smartphones With Flexible Liquid Crystal Polymer Process

This article proposes a dual-band circular-polarized (DBCP) microstrip antenna using flexible liquid crystal polymer (LCP) manufacturing process for ON-smartphone ultrawideband (UWB) positioning application. To achieve dual-band circular polarization in a low profile, the proposed antenna is designed with a cross-slot-loaded patch with four L-shaped feeding probes and a sequential phase feeding network. A circle of capacitive via fence is loaded surrounding the patch for area miniaturization, which is adaptive for the limited space of flexible printed circuit (FPC) in smartphones. Based on the UWB positioning protocol, a three-element antenna array is constructed in a low profile of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.015\lambda _{0}$ </tex-math></inline-formula> with required isolation of 17 dB. Experimental results show the overlapped bandwidth of the efficiency and the axial ratio (AR) covering the demand bands of 6.30–6.80 and 7.75–8.10 GHz. With the properties of dual wideband operation, circular polarization, and ultralow profile, the proposed antenna exhibits feasible solutions for the UWB positioning application in space-limited smartphones.

Design and validation of a dual-band circular polarization patch antenna and stripline combiner for the FSSCat mission

The FMPL-2 payload on board the 3Cat-5/A 6 Unit CubeSat, part of the FSSCat CubeSat mission, includes a dual L-Band Microwave Radiometer and a Global Navigation Satellite System Reflectometer, in one instrument, implemented in a Software Defined Radio. One of the design challenges of this payload was its Nadir looking Antenna, which had to be directive (> 12 dB), dual-band at 1400–1427 MHz and 1575.42 MHz, left-hand circularly polarized, and with important envelope restrictions, notably with a low profile. After a trade-off analysis, the best design solution appeared to be an array of six elements each of them being a stacked dual-band patch antenna, with diagonal feed to create the circular polarization, and a six to one stripline combiner. The design process of the elementary antennas first includes a theoretical analysis, to obtain the approximate dimensions. Then, by means of numerical simulations, prototyping, and adjusting the results in the simulations, the manufacturing errors and dielectric constant tolerances, to which patch antennas are very sensitive, can be characterized. A similar approach is taken with the combiner. This article includes the theoretical analysis, simulations, and prototype results, including the Flight Model assembly and characterization.

Metamaterial inspired square gap defected ground structured wideband dielectric resonator antenna for microwave applications

A metamaterial inspired dielectric resonator antenna (DRA) with square gap defected ground structure is proposed in the present work. Antenna has wideband characteristics with coverage of several commercial communication applications of Wi-Fi, WLAN, and satellite communications from 3.5 to 11.6 GHz. The metamaterial behavior of the proposed structure providing good impedance characteristics with peak realized gain of 7.7 dB and peak efficiency of 87% with dual band circular polarization from 4.2 to 6 GHz and 9.2–11.4 GHz respectively. The prototyped antenna model 1 without DRA providing good matching characteristics results and producing huge bandwidth of 8.1 GHz and the impedance bandwidth of 108%. DRA loaded antenna providing dual band circular polarization with axial ratio bandwidths of 36% and 28% respectively for wide range in the microwave communication applications.

Compact Hybrid Choke Rings for Dual-Band Circularly Polarized GPS Antenna

This letter presents the compact hybrid choke rings for the dual-band circularly polarized global positioning system (GPS) antenna, in order to suppress the surface wave propagation and reduce the back lobe levels. The designed dual-band circularly polarized antenna is center-fed and composed of two radiation patches. The novel compact hybrid choke rings are introduced to reduce the radiation back lobes and improve the front to back ratio effectively. The measured results show that the return loss of the antenna is greater than 10 dB and the bandwidth covers GPS L2 from 1.168 to 1.238 GHz and GPS L1 from 1.543 to 1.599 GHz. In the working bands, the front to back ratio of the proposed antenna is greater than 30 dB.

Hexagonal-Triangular Combinatorial Structure Based Dual-Band Circularly Polarized Patch Antenna for GAGAN Receivers

A multilayer gap-coupled dual band hexagonal microstrip patch antenna is presented for GPS Aided GEO Augmented Navigation (GAGAN) receivers. GAGAN is developed by AAI (Airport Authority of India) and ISRO (Indian Space Research Organization) exclusively for aviation purposes with the GPS frequencies L5 (1176.45 MHz) and L1 (1575.42 MHz). The proposed GAGAN antenna has three trapezoidal and four equilateral triangular patch resonators configured to form a gap-coupled hexagonal patch on the top layer and seven equilateral triangular patches with slots in between to form the middle layer. Both the layers are fed by a single coax feed to achieve a dual band compact microstrip antenna of size 55 mm x 55 mm x 3.2 mm. Instead of designing the hexagonal antenna conventionally from a circular patch antenna, the sides of the equilateral triangular patch are truncated to obtain the proposed compact hexagonal antenna as the triangular antenna occupies less area when compared to circular or square patches for a fixed frequency. To bring in novelty with improved performance, the combinatorial structured configuration has been explored through step-by-step optimization. The aspects of GAGAN requirements like circular polarization with a single input, dual band operation and high gain with gain flatness are achieved with this compact structured antenna when compared to square and circular patch antennas. The combinatorial structures such as perturbation and truncation introduced in the patches are responsible for exciting two near-degenerate orthogonal modes producing circular polarization (CP). A cross slot etched in the center patch results in gain enhancement with a gain above 3.2 dBi over a bandwidth of 20 MHz in both the bands. Five shorting pins are added to achieve high impedance matching and good CP with an axial ratio (AR) below 2 dB. The simulated and measured results are found to be in good agreement with greater than 20 MHz operational bandwidth exhibiting CP with an omni-directional radiation pattern having high cross polar levels of -22 dB. The size reduction achieved in the proposed design is 56.79% when compared to the conventional hexagonal patch antenna. The measured 10 dB impedance bandwidth is 2.7% and 2.1% for L5 and L1 bands respectively with a 3 dB AR bandwidth of 2.3% for L5 and 2.0% for L1, satisfying GAGAN requirements.

Miniaturized Triple-Band Circular- Polarized Implantable Patch Antenna for Bio-Telemetry Applications

This letter presents a triple-band antenna with circular polarization (CP) behavior embedded in a lossy tissue for bio-telemetry applications. The triple bands are the Industrial, Scientific, and Medical (868–868.6 MHz and 2.4–2.4835 GHz) bands and the midfield band (1.824–1.98 GHz). These bands are used for physiological information telemetry, power-saving, and wireless power transfer in medical devices. CP behavior at three bands is the key feature of the designed implantable antenna, compared with literature dual-band CP antennas. Moreover, the size of the designed antenna is compact of 50.8 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> . Finally, the specific absorption rate and link margin are calculated for the consideration of health safety and reliable communication aspects.

A High Angular Stability, Single-Layer Transmission Linear-to-Circular Polarization Converter for Dual ISM-Band Operation

This paper presents a planar metasurface structure for linear to circular polarization (CP) conversion at the industrial, scientific, and medical bands of 2.4 GHz and 5.8 GHz. The new unit-cell structure consists of two loaded symmetric cross-shaped stubs with a size of 0.26 λ × 0.26 λ in a single thin substrate with a thickness of 0.0064 λ. The design process and parametric study are presented to clarify the operating mechanism for each frequency. The unit-cell element is analyzed and simulated, which exhibits an axial ratio (AR) bandwidth of 15.8% and 12.6% at a 3-dB criterion with the same polarization mode at 2.4 GHz and 5.8 GHz, respectively. The proposed LP-to-CP converter achieves a stable AR bandwidth with an oblique incident angle up to 45°. Moreover, a dual-band linear polarization (LP) antenna is combined with an array of 4 × 4 unit cells to validate the polarization converting ability of the proposed metasurface. The LP-to-CP converter and the antenna are fabricated and measured. The measurement results show that the antenna obtains a good impedance matching and CP waves radiation at 2.33–2.51 GHz and 5.55–5.89 GHz. The integrated antenna with dual-band CP waves radiation is suitable for improving the transmission efficiency in communication and wireless power transfer applications.

Terahertz Wave Conversion From Linear to Circular Polarization by Graphene Metasurface Featuring Ultrawideband Tunability

This paper reports a detailed study of a graphene-based metasurface to function as tunable broadband linear to circular polarization converter in the terahertz gap. This device provides a wide polarization conversion band of 2.25 THz (3.75 THz to 6 THz) with an enhanced fractional 3-dB axial ratio bandwidth (FARBW) of 46.15%. The proposed structure consists of a simple tri-layer configuration where the meta-atom comprises a patterned graphene layer on a gold-backed silicon dioxide substrate. The proposed reflective-type linear to circular polarization converter (RLCPC) exhibits both right-handed and left-handed circular orientations of the reflected wave in two halves of the operating spectrum, further validated in terms of polarization ellipses developed by an inhouse code. The lack of experimental setup at the above said frequencies available to the authors in their country has been paid off by verifying the response using a detailed circuit model. The RLCPC maintains a thickness of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ_o</i> /7.69 with a lattice size of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ_o</i> /8.33. The structure also promises a stable wideband circular polarization conversion up to 20° and a dual-band circular polarization conversion up to 40° incident angle of the electromagnetic wave. This device can be useful for THz beam scanning antennas, RCS reduction and THz antennas for space and military radar applications.

3-D Printed Millimeter-Wave Metal-Only Dual-Band Circularly Polarized Reflectarray

This article presents 3-D printed metal-only dual-band millimeter-wave circularly polarized (CP) reflectarrays (RAs). The RAs’ unit cell (UC) is made of an anisotropic metal brick mounted on a full metal ground. In-plane rotating the metal brick introduces geometric Pancharatnam–Berry (PB) phase shifting, and vertically adjusting the position of the UC provides propagation phase shifting. The geometric PB and propagation phase shifting offer two different degrees of freedom, enabling independent wavefront shaping of CP wave over dual-band. Specifically, the low-band CP beam shaping solely depends on the propagation phase. In contrast, the high-band CP beam shaping depends on the geometric PB and the propagation phases. The coupling issue between dual-band is minimal because of the unique dual-band phase-shifting methods. In addition, 3-D printed dual-band left-hand CP (LHCP) horn antennas are designed, printed, and used as the feed. To demonstrate, two RA antennas with different dual-band CP beam directions are fabricated and measured.

Characterization of dual-band circularly polarized mushroom-shaped monopole antenna with modified ground plane

Abstract In this manuscript, an antenna design configured for dual-band circularly polarized (DBCP) characteristics is presented. The proposed design is quite compact (0.63 λ g × 0.63 λ g × 0.04 λ g) and comprises a mushroom-shaped monopole with a modified ground structure (MGS). In the proposed antenna structure, dual-band CP behavior is generated through a tunable side stub joined orthogonally with the feed patch and reshaping the wide square slot. The impedance bandwidth is measured as 2900 MHz ranging from 1.32 to 4.22 GHz in the lower frequency band (Band 1); however, 980 MHz from 4.78 to 5.76 GHz in the higher frequency band (Band 2). The 3-dB AR bandwidth is measured as 370 MHz (from 3.54 to 3.91 GHz)in the lower frequency band; whereas, it is measured as 650 MHz (from 5.07 to 5.72 GHz) in the higher frequency band. The measured gains spread from 2.5 to 8.3 dBi with a maximum gain of 8.3 dBi in the lower frequency band, whereas 4.8 to 7.05 dBi with a 7.05 dBi maximum gain in the higher frequency band, respectively. The cross-polar rejection is observed greater than 14 dB. Besides, 3-dB half-power beamwidths are seen as 86° &amp; 84°, and 87° &amp; 86° in the x-z and y-z planes for the lower and higher frequency bands, respectively.

Dual-Band Circular Polarizers With Versatile Polarization Conversions Based on Aperture-Coupled Patch Resonators

In this article, a class of low-profile dual-band circular polarizers based on aperture-coupled patch resonators (ACPRs) are proposed to achieve versatile linear-to-circular polarization (LP-to-CP) conversions. Initially, a dual-band dual-polarized bandpass frequency-selective surface (FSS), consisting of a composite array of two independent ACPRs subelements, is presented to obtain the desired transmission properties for vertically and horizontally polarized incident waves. The equivalent circuit model is then introduced to analyze the proposed FSS, exhibiting that transmission magnitude properties of vertically and horizontally polarized transmitted waves can be independently designed within these two passbands. Furthermore, two pairs of rectangular slots are introduced in the patches of these ACPRs subelements and extensively investigated to demonstrate that versatile phase differences between vertically and horizontally polarized transmitted waves with equal magnitude can be achieved. Based on this concept, within these two passbands, a right- or left-hand circularly polarized (RHCP or LHCP) transmitted wave is then attained by designing the vertical and horizontal components of a 45° tilted LP incident wave with equal magnitudes and ±90° phase difference, thus leading to dual-band LP-to-CP polarization conversions. To validate the design concept, two prototypes of dual-band circular polarizers with orthogonally and identically LP-to-CP conversions in each operation band are designed, fabricated, and measured. Experimental results have well revealed that our proposed structure has a few attractive advantages of ultrathin profile, low axial ratio, and flexible designs in LP-to-CP conversions and frequency band ratios.