scholarly journals Linear-to-Circular Polarization Converter with Adjustable Bandwidth Realized by the Graphene Transmissive Metasurface

2021 ◽  
Author(s):  
Xinlei Zhang ◽  
Haining Ye ◽  
Yan Zhao ◽  
Haifeng Zhang
Keyword(s):  
Circular Polarization ◽  
Surface Current ◽  
Axial Ratio ◽  
Polarization Modulation ◽  
Polarization Converter ◽  
Circularly Polarized ◽  
Transmission Coefficients ◽  
Relative Bandwidth ◽  
Linearly Polarized ◽  
Resistance Modeling

Abstract A tunable linear-to-circular polarization converter (LTCPC) for the terahertz (THz) regime which consists of two conductive layers and a graphene transmissive metasurface layer separated by two dielectric layers is reported in this work. The equivalent surface resistance modeling method is adopted to investigate the peculiar electronic properties of graphene. The simulation results show that when the Fermi energy (Ef) is 1.1 eV, the linearly-polarized wave can be transformed into the circularly-polarized wave in the working band ranging from 0.9498 THz to 1.3827 THz (the relative bandwidth is 37.1%) with axial ratio (AR) less than 3 dB. Moreover, the bandwidth can be regulated to the desired one by varying the Fermi level of graphene metasurface via a bias voltage rather than manually modifying the structure. We have analyzed the mechanism of the polarization conversion, especially, the magnitudes and the phase difference of cross- and co-polarization transmission coefficients, AR curves, and surface current diagrams at y-polarized incidence. Our findings open up promising possibilities towards the realization of graphene controllable devices for polarization modulation, which has advantages of adjustability over traditional devices.

Design of Transmission Polarization Metasurface Converter

2021 ◽  
Vol 1035 ◽  
pp. 718-723
Author(s):  
Bo Wen Han ◽  
Si Jia Li ◽  
Xiang Yu Cao ◽  
Jun Gao
Keyword(s):  
Simple Structure ◽  
Axial Ratio ◽  
Polarization Conversion ◽  
Current Analysis ◽  
Polarization Converter ◽  
Circularly Polarized ◽  
Polarized Waves ◽  
Relative Bandwidth ◽  
Linearly Polarized ◽  
Simulation Results

The transmission polarization metasurface converter is an effective method to realize the polarization manipulation of the transmission waves, and it is also the research hotspot of metasurfaces. A new broadband transmissive polarization converter was proposed based on the metasurfaces converted incident linearly polarized waves into circularly polarized waves of transmission. The top and bottom layers of the unit were axisymmetric metal patches. The top and bottom layers of metal patches were overlapped and the shape was like an arrow. The thickness of the substrate was 4mm. The polarization conversion mechanism of metasurface was illustrated by parameter optimization and current analysis. The simulation results show that when the metasurface works in the frequency band of 6.71GHz~8.45GHz, the linearly polarized incident wave can be converted into a circularly polarized transmitted wave with axial ratio less than 3dB, and the relative bandwidth can reach 23%. The designed polarization converter has a simple structure and the potential application value in electromagnetic wave control of radio frequency devices.

scholarly journals Analysis of Circular Polarization of Cylindrically Bent Microstrip Antennas

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Tiiti Kellomäki
Keyword(s):  
Simple Model ◽  
Circular Polarization ◽  
Axial Ratio ◽  
Microstrip Antennas ◽  
Far Field ◽  
Circularly Polarized ◽  
Wearable Antennas ◽  
Linearly Polarized ◽  
Frequency Shifting

When circularly polarized (CP) microstrip antennas are bent, the polarization becomes elliptical. We present a simple model that describes the phenomenon. The two linear modes present in a CP patch are modeled separately and added together to produce CP. Bending distorts the almost-spherical equiphase surface of a linearly polarized patch, which leads to phase imbalance in the far-field of a CP patch. The model predicts both the frequency shifting of the axial ratio band as well as the narrowing of the axial ratio beam. Uncontrolled bending is a problem associated especially with flexible textile antennas, and wearable antennas should therefore be designed somewhat conformal.

A Broadband Circularly Polarized Cross-slotted Patch Antenna with Horizontal Meandered Strip (HMS)

Frequenz ◽  
2020 ◽  
Vol 74 (5-6) ◽  
pp. 191-199
Author(s):  
M. K. Verma ◽  
Binod K. Kanaujia ◽  
J. P. Saini ◽  
Padam S. Saini
Keyword(s):  
Circular Polarization ◽  
Patch Antenna ◽  
Impedance Matching ◽  
Axial Ratio ◽  
Impedance Bandwidth ◽  
Radiation Patterns ◽  
Circularly Polarized ◽  
Feeding Technique

AbstractA broadband circularly polarized slotted square patch antenna with horizontal meandered strip (HMS) is presented and studied. The HMS feeding technique provides the good impedance matching and broadside symmetrical radiation patterns. A set of cross asymmetrical slots are etched on the radiating patch to realize the circular polarization. An electrically small stub is added on the edge of the antenna for further improvement in performance. Measured 10-dB impedance bandwidth (IBW) and 3-dB axial ratio bandwidth (ARBW) of the proposed antenna are 32.31 % (3.14–4.35 GHz) and 20.91 % (3.34–4.12 GHz), respectively. The gain of the antenna is varied from 3.5 to 4.86dBi within 3-dB ARBW. Measured results matched well with the simulated results.

scholarly journals X-band compact dual circularly polarized isoflux antenna for nanosatellite applications

2017 ◽  
Vol 9 (7) ◽  
pp. 1509-1516 ◽  
Author(s):  
Eric Arnaud ◽  
Cyrille Menudier ◽  
Jamil Fouany ◽  
Thierry Monediere ◽  
Marc Thevenot
Keyword(s):  
Circular Polarization ◽  
Microstrip Line ◽  
Ground Plane ◽  
Axial Ratio ◽  
Horn Antenna ◽  
Azimuth Angle ◽  
Original Solution ◽  
Circularly Polarized ◽  
X Band

This paper presents an original solution to design a compact dual circularly polarized isoflux antenna for nanosatellite applications. This kind of antenna has been previously designed in our laboratory, for a single circular polarization. This antenna is composed of a dual circularly polarized feed and a choke horn antenna. This feed is a cross-shaped slot in the ground plane, which provides coupling between a patch and a ring microstrip line with two ports. It is located at the center of a choke horn antenna. The simulated antenna presents an axial ratio <3 dB and a realized gain close to 0 dB over a 400 MHz bandwidth (8.0–8.4 GHz) at the limit of coverage, i.e. 65° whatever the azimuth angle (φ) and the port. A 20 dB matching for each port and 13 dB isolation characteristics between the two ports have been achieved on this bandwidth. It has been realized and successfully measured.

Compact circular polarized CPW antenna for WLAN and biomedical applications

Frequenz ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Navneet Sharma ◽  
Anubhav Kumar ◽  
Asok De ◽  
Rakesh K. Jain
Keyword(s):  
Biomedical Applications ◽  
Impedance Matching ◽  
Ground Plane ◽  
Surface Current ◽  
Axial Ratio ◽  
Breast Tumors ◽  
Maximum Permissible Level ◽  
Circularly Polarized ◽  
Ism Band ◽  
Phantom Model

Abstract A compact, circularly polarized, CPW-fed antenna is proposed for wearable applications in ISM Band (5.8 GHz). The antenna is based on DGS, where the ground plane is responsible for impedance matching. The 10 dB impedance of the proposed antenna varies from 5.39 GHz to 5.94 GHz. The circular stub introduced in the ground plane mitigates the surface current and enriches the 3 dB axial ratio from 5.73 GHz to 5.92 GHz. Proposed antenna exhibits the LHCP and RHCP pattern of circular polarization, the antenna can effectively work for biomedical and wearable applications. The antenna is analyzed on the skin phantom model and the SAR value obtained is 1.218 W/kg, which is below the maximum permissible level. The proposed antenna is also used for the detection of breast tumors.

ANALYSIS PERFORMANCE OF SINGLY-FED CIRCULARLY POLARIZED MICROSTRIP ANTENNA FOR WIRELESS COMMUNICATION

2016 ◽  
Vol 78 (5-9) ◽  
Author(s):  
Muhammad Fauzan Edy Purnomo ◽  
Hadi Suyono ◽  
Panca Mudjirahardjo ◽  
Rini Nur Hasanah
Keyword(s):  
Wireless Communication ◽  
Circular Polarization ◽  
Microstrip Antenna ◽  
Axial Ratio ◽  
Microstrip Antennas ◽  
Impedance Bandwidth ◽  
Antenna Structure ◽  
Circularly Polarized ◽  
Large Bandwidth ◽  
Doubly Fed

The circularly polarized (CP) microstrip antennas, both of singly- and doubly-fed types, possess inherent limitation in gain, impedance and axial-ratio bandwidths. These limitations are caused mainly by the natural resonance of the patch antenna which has a high unloaded Q-factor and the frequency-dependent excitation of two degenerative modes (TM01 and TM10) when using a single feed. Many applications which require circular polarization, large bandwidth, and good performance, especially in the field of wireless communication, are still difficult to be designed by using antenna software. Some consideration to take will include the application target and design specification, the materials to be used, and the method to choose (formula, numerical analysis, etc). This paper explains and analyzes the singly-fed microstrip antenna with circular polarization and large bandwidth. This singly-fed type of microstrip antenna provides certain advantage of requiring no external circular polarizer, e.g. the 900 hybrid, as it only needs to apply some perturbation or modification to a patch radiator with a standard geometry. The design of CP and large-bandwidth microstrip antenna is done gradually, by firstly truncating one tip, then truncating the whole three tips, and finally modifying it into a pentagonal patch structure and adding an air-gap to obtain larger bandwidths of impedance, gain and axial ratio. The last one antenna structure results in a novelty because it is a rare design of antenna which includes all types of bandwidth (impedance, gain, and axial ratio) being simultaneously larger than the origin antenna. The resulted characteristic performance of the 1-tip (one-tip) antenna shows respectively 1.9% of impedance bandwidth, 3.1% of gain bandwidth, and 0.45% of axial-ratio bandwidth. For the 3-tip (three-tip) step, the resulted bandwidths of respectively impedance, gain, and axial ratio are 1.7%, 3.3% and 0.5%. The pentagonal structure resulted in the bandwith values of 15.67%, 52.16% and 4.11% respectively for impedance, gain, and axial ratio. 

A compact polarization reconfigurable stacked microstrip antenna for WiMAX application

2020 ◽  
pp. 1-16
Author(s):  
Murari Shaw ◽  
Niranjan Mandal ◽  
Malay Gangopadhyay
Keyword(s):  
Microstrip Antenna ◽  
Impedance Matching ◽  
Axial Ratio ◽  
Dual Band ◽  
Impedance Bandwidth ◽  
Circularly Polarized ◽  
Rectangular Slot ◽  
Substrate Layer ◽  
Linearly Polarized ◽  
Coaxial Probe

Abstract In this paper, a stacked microstrip patch antenna with polarization reconfigurable property has been proposed for worldwide interoperability for microwave access (WiMAX) application. The proposed antenna has two substrate layers: upper and lower layers with two radiating patches connected with the coaxial probe. Without the upper layer the lower square-shaped substrate layer having regular hexagonal radiating patch with probe fed acts as a linear polarized antenna with impedance bandwidth for (S11 ≤ −10 dB) is 370 MHz 10.56% (3.32–3.69 GHz) cover WiMAX (3.4–3.69 GHz) application band. The hexagonal radiating patch is perturbed with an optimum rectangular slot to enhance the impedance bandwidth of the antenna. The lower substrate layer having hexagonal patch with the same probe position is stacked with the upper square-shaped substrate layer with same sized square patch and the upper patch soldered with the coaxial probe. The overall stacked antenna generates a circularly polarized band when the opposite corner of the top square radiating patch of the upper layer is truncated with optimum size. In order to generate another circularly polarized band and to improve the input impedance matching of the stacked antenna, the top radiating patch is perturbed with two slots and a slit. The stacked circularly polarized antenna generates impedance bandwidth of 12.75% (3.23–3.67 GHz) for (S11 ≤ −10 dB) with two circularly polarized bands (3.34–3.37 GHz) and (3.66–3.70 GHz) as per (axial ratio ≤ 3 dB) for WiMAX application. Therefore, the proposed antenna can be used as linearly polarized or dual band circularly polarized according to requirement.

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