scholarly journals Improved Low-Profile Helical Antenna Design for INMARSAT Applications

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Shiqiang Fu ◽  
Yuan Cao ◽  
Yue Zhou ◽  
Shaojun Fang
Keyword(s):  
Pitch Angle ◽  
Satellite Communication ◽  
Design Method ◽  
Impedance Matching ◽  
Axial Ratio ◽  
Antenna Element ◽  
Helical Antenna ◽  
Copper Strip ◽  
Antenna Structure ◽  
Low Profile

A new low-profile variable pitch angle cylindrical helical antenna employing a copper strip as impedance transformer is proposed in this paper. Under the circumstance of a limited antenna height, the circular polarization performance of the antenna has been enhanced by changing the pitch angle and the input impedance matching has been improved by adjusting the copper strip match stub. The design method of the proposed antenna is given. The optimal antenna structure for INMARSAT application has been fabricated and measured. The measured results show that in the whole maritime satellite communication work band the VSWR is less than 1.2, its antenna gain is higher than 9 dBi, and the axial ratio is lower than 2.5 dB. The experimental results have a good agreement with the simulations. The proposed antenna is compact and easy tuning. It provides a promising antenna element for maritime satellite communication applications.

scholarly journals Impedance Enhancement of Textile Grounded Loop Antenna Using High-Impedance Surface (HIS) for Healthcare Applications

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3809
Author(s):  
Mohammed M. Bait-Suwailam ◽  
Isidoro I. Labiano ◽  
Akram Alomainy
Keyword(s):  
Impedance Matching ◽  
Loop Antenna ◽  
Healthcare Applications ◽  
Impédance Surface ◽  
Antenna Structure ◽  
Impedance Surface ◽  
High Impedance ◽  
Low Profile ◽  
Close Proximity ◽  
High Impedance Surface

In this paper, impedance matching enhancement of a grounded wearable low-profile loop antenna is investigated using a high-impedance surface (HIS) structure. The wearable loop antenna along with the HIS structure is maintained low-profile, making it a suitable candidate for healthcare applications. The paper starts with investigating, both numerically and experimentally, the effects of several textile parameters on the performance of the wearable loop antenna. The application of impedance enhancement of wearable grounded loop antenna with HIS structure is then demonstrated. Numerical full-wave simulations are presented and validated with measured results. Unlike the grounded wearable loop antenna alone with its degraded performance, the wearable loop antenna with HIS structure showed better matching performance improvement at the 2.45 GHz-band. The computed overall far-field properties of the wearable loop antenna with HIS structure shows good performance, with a maximum gain of 6.19 dBi. The effects of bending the wearable loop antenna structure with and without HIS structure as well as when in close proximity to a modeled human arm are also investigated, where good performance was achieved for the case of the wearable antenna with the HIS structure.

Dual circularly polarized multilayer MIMO antenna array with an enhanced SR-feeding network for C-band application

2017 ◽  
Vol 9 (8) ◽  
pp. 1741-1748 ◽  
Author(s):  
Mahdi Jalali ◽  
Mohammad Naser-Moghadasi ◽  
Ramezan Ali Sadeghzadeh
Keyword(s):  
Antenna Array ◽  
Tai Chi ◽  
Impedance Matching ◽  
Axial Ratio ◽  
Wide Band ◽  
Impedance Bandwidth ◽  
Antenna Element ◽  
Circularly Polarized ◽  
Mimo Antenna ◽  
Feed Network

Wide-band circularly polarized multi-input multi-output (MIMO) antenna array with a 2 × 4 feed network was proposed for C-band application. Different unique techniques were utilized in the proposed array to enhance the antenna characteristics, such as gain, 3 dB axial ratio bandwidth (ARBW), impedance tuning, and ruinous mutual coupling effects. A miniaturized dual-feed Tai chi-shaped antenna element with a pair of feeding points and a pair of eyebrow-shaped strips was presented for enhancing circular polarization (CP) purity and impedance matching. For a better improvement of CP features, a 2*4 MIMO sequentially rotated (MIMO-SR) feed network was used to achieve broader 3 dB ARBW. Besides, the MIMO feature of the feed network could control the left- and right-handed CP, respectively. Ultimately, specific forms of slot and slit structures were applied onto the top layer of MIMO feed network that provided a high isolation between the radiating elements and array network. Furthermore, the diversity gain (DG) was studied. The extracted measured results illustrated an impedance bandwidth of 3.5–8.2 GHz at port 1 and 3.5–8.3 GHz at port 2 for VWSR < 2 and 3 dB ARBW of 4.6–7.6 GHz at port 1 and 4.6–7.5 GHz at port 2. The peak gain of 9.9 dBi was at 6 GHz.

scholarly journals Design of Planar Microstrip Ultrawideband Circularly Polarized Antenna Loaded by Annular-Ring Slot

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhong-Hua Ma ◽  
Jia-Xiang Chen ◽  
Peng Chen ◽  
Yan Feng Jiang
Keyword(s):  
Impedance Matching ◽  
Axial Ratio ◽  
Fractional Bandwidth ◽  
Uwb Antenna ◽  
Compact Structure ◽  
Antenna Structure ◽  
Circularly Polarized ◽  
Annular Ring ◽  
Feed Line ◽  
Communication Devices

A miniaturized planar microstrip circularly polarized ultrawideband (UWB) antenna loaded by annular-ring slot is proposed and implemented in the paper. With the annular-ring slot loaded in the radiating patch of the antenna, the side of the radiating patch is connected by the asymmetric inverted L-shaped microstrip. At the same time, a quarter of a circle is cut off from the radiating patch. The above designed structure shows improvements on the operating frequency band and realization of the circular polarization radiation. A tapered microstrip is placed between the feed line and the radiating patch to achieve the slow-changing impedance transformation. The results of simulation and measurement demonstrate that the 3 dB axial ratio (AR) fractional bandwidth of the antenna structure achieves 21.25%. The peak gain within the 3 dB axial ratio bandwidth fluctuates between 3.74 and 4.59 dBi. The antenna shows good impedance matching in the ultrawideband range. With the compact structure of the UWB antenna, it has potential application in various wireless communication devices.

scholarly journals Chiral Dielectric Metasurfaces for Highly Integrated, Broadband Circularly Polarized Antenna

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2071
Author(s):  
Bruno Ferreira-Gomes ◽  
Osvaldo N. Oliveira ◽  
Jorge Ricardo Mejía-Salazar
Keyword(s):  
Impedance Matching ◽  
Axial Ratio ◽  
Satellite Communications ◽  
High Gain ◽  
Circularly Polarized ◽  
Low Profile ◽  
Millimeter Wave Antenna ◽  
And Performance ◽  
Magnetic Resonances ◽  
Magnetic Pairing

We report on the design of a low-profile integrated millimeter-wave antenna for efficient and broadband circularly polarized electromagnetic radiation. The designed antenna comprises a chiral dielectric metasurface built with a 2×2 arrangement of dielectric cylinders with slanted-slots at the center. A broadbeam high-gain with wide axial ratio (AR)<3 dB bandwidth was reached by pairing the electric and magnetic resonances of the dielectric cylinders and the slanted slots when excited by an elliptically polarized driven-patch antenna. This electric-magnetic pairing can be tuned by varying the cylinders diameter and the tilting and rotation angles of the slanted slots. The simulation results indicate impedance-matching bandwidths up to 22.6% (25.3–31.6 GHz) with 3-dB AR bandwidths of 11.6% (26.9–30.2 GHz), which in terms of compactness (0.95λ0×0.95λ0) and performance are superior to previous antenna designs. Since the simulations were performed by assuming materials and geometries easily implementable experimentally, it is hoped that circularly polarized antennas based on chiral metasurfaces can be integrated into 5G and satellite communications.

scholarly journals A Low-Profile Wideband Linear-to-Circular Polarization Conversion Slot Antenna Using Metasurface

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1164 ◽  
Author(s):  
Jian Dong ◽  
Chang Ding ◽  
Jinjun Mo
Keyword(s):  
Circular Polarization ◽  
Satellite Communication ◽  
Axial Ratio ◽  
Slot Antenna ◽  
Impedance Bandwidth ◽  
Polarization Conversion ◽  
Compact Structure ◽  
Low Profile ◽  
Unit Cells ◽  
Linearly Polarized

A new low-profile wideband linear-to-circular polarization conversion microstrip slot antenna based on a metasurface for C-band satellite communication applications is proposed in this paper. The metasurface basically consists of four unit cells with parasitic square cross gaps arranged in a 2 × 2 layout. By loading the metasurface on the microstrip slot antenna, linearly polarized (LP) waves from the source antenna are converted into circularly polarized (CP) waves. Then, by etching three more parasitic square cross gaps in the middle of the metasurface, enhanced impedance bandwidth and axial ratio bandwidth (ARBW) are achieved. Furthermore, an equivalent circuit and a phase analysis are presented to explain how a wide ARBW is realized by the metasurface. A final model with an overall size of 36 × 36 × 3.5 mm3 (approximately 0.65λ0 × 0.65λ0 × 0.06λ0 at 5.5 GHz) was designed and fabricated. The measured S11 bandwidth and 3 dB ARBW were 39.25% from 4.28 GHz to 6.37 GHz and 17.77% from 5.18 GHz to 6.19 GHz, respectively. As a result, the proposed antenna shows great potential for satellite communication applications due to its low profile and compact structure, wide impedance bandwidth, and wide axial ratio bandwidth.

scholarly journals An Artificial Magnetic Conductor-Based Wideband Circularly Polarized Antenna with Low-Profile and Enhanced Gain

Electronics ◽  
2021 ◽  
Vol 10 (17) ◽  
pp. 2121
Author(s):  
Lina Qiu ◽  
Gaobiao Xiao
Keyword(s):  
Impedance Matching ◽  
Axial Ratio ◽  
Center Frequency ◽  
Impedance Bandwidth ◽  
Orthogonal Polarization ◽  
Magnetic Conductor ◽  
Circularly Polarized ◽  
Artificial Magnetic Conductor ◽  
Low Profile ◽  
Simulation And Experiment

A broadband circularly polarized (CP) antenna with enhanced gain and low profile is proposed. Two identical dipoles with full wavelength are placed orthogonally to generate radiation waves with equal amplitude and orthogonal polarization. The arms of the dipoles are designed as stepped patches to enlarge the impedance matching bandwidth and axial ratio (AR) bandwidth. Crossed-dipoles with full wavelength are utilized as the main radiators to provide a wide operating bandwidth and enhanced gain, and an artificial magnetic conductor (AMC) structure is introduced as the reflector to reduce the profile of the whole antenna. Due to the introduction of the AMC structure, the antenna profile is reduced from 12.8 to 6.9 mm, that is, reduced to 0.14λ0 (where λ0 denotes the wavelength corresponding to the center frequency of the passband, 4.0–8.5 GHz). A simulation and experiment were carried out to verify the performance of the proposed antenna. Experimental results showed that the antenna realized an impedance bandwidth of 74%, an AR bandwidth of 67.7%, a peak gain of 12.1 dBic, and an average gain of 10.69 dBic.

A low-profile wideband circularly polarized MIMO antenna with pattern and polarization diversity

2019 ◽  
Vol 12 (4) ◽  
pp. 316-322 ◽  
Author(s):  
Prashant Chaudhary ◽  
Ashwani Kumar ◽  
B. K. Kanaujia
Keyword(s):  
Impedance Matching ◽  
Axial Ratio ◽  
Polarization Diversity ◽  
Circularly Polarized ◽  
Mimo Antenna ◽  
Low Profile ◽  
X Band ◽  
Monopole Antennas ◽  
Multiple Input ◽  
Linearly Polarized

AbstractThe present work describes a unique planar low-profile wideband circularly polarized Multiple-Input and Multiple-Output (MIMO) antenna operating in the X-band, with pattern and polarization diversity over the entire axial-ratio bandwidth (ARBW). The design is unique in the sense that a simple grounded stub introduced between two linearly polarized monopole antennas has been used to realize wideband circular polarization, pattern diversity, and high isolation between antennas. The ARBW of the MIMO antenna is 2.45 GHz (8.11–10.56) 3 dB and its impedance matching bandwidth is 3.52 GHz (8.07–11.59). The isolation is better than 20 dB. The antenna can be easily adapted to operate other frequency bands by simple frequency scaling. It has been fabricated on an FR-4 substrate and its performance has been compared against several existing available antennas.

scholarly journals A Liquid Metal Conical Helical Antenna for Circular Polarization-Reconfigurable Antenna

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Yun Zhou ◽  
Shaojun Fang ◽  
Hongmei Liu ◽  
Shiqiang Fu
Keyword(s):  
Liquid Metal ◽  
Circular Polarization ◽  
Pitch Angle ◽  
Axial Ratio ◽  
Experimental Results ◽  
Reconfigurable Antenna ◽  
Polarization Mode ◽  
Helical Antenna ◽  
Left Hand ◽  
Good Agreement

A novel polarization-reconfigurable conical helical antenna based on the liquid metal is presented. The antenna is implemented by using truncated structure, variable pitch angle, a matching stub, and a mechanical autorotation device. The experimental results show that a good agreement between simulations and measurements is obtained. The gain of the antenna achieves higher than 8 dBi in the work band (1525–1660.5 MHz), and the 3 dB axial ratio (AR) bandwidth reaches 410 MHz. The polarization mode of the antenna can be switched between right-hand and left-hand circular polarization.

scholarly journals Compact Broadband Circularly Polarized CPW-Fed Antenna with Characteristic Mode Analysis

2022 ◽  
Vol 2022 ◽  
pp. 1-11
Author(s):  
Wei Xu ◽  
Jingchang Nan ◽  
Mingming Gao
Keyword(s):  
Coplanar Waveguide ◽  
Impedance Matching ◽  
Axial Ratio ◽  
Mode Analysis ◽  
Center Frequency ◽  
Impedance Bandwidth ◽  
Characteristic Mode ◽  
Circularly Polarized ◽  
Low Profile ◽  
Compact Size

A compact circularly polarized (CP) antenna is proposed for low-profile and wideband operation based on characteristic mode analysis (CMA). A ring patch with a gap and two arc-shaped metallic stubs as the radiator is analyzed and optimized by CMA to figure out the orthogonal modes and operating frequency band for potential good axial ratio (AR) performance. The studies of these CP modes provide a physical insight into the property of broadband circular polarization. Such an in-depth understanding paves the way for the proposal of novel CP antenna with separation between the design of radiator and feeding network. A 50-Ω coplanar waveguide (CPW) is introduced and placed appropriately to excite the desired modes based on the information from CMA, which employs two asymmetric ground planes to improve the performance in terms of AR and impedance matching. The antenna with a compact size of 0.71λ0 × 0.76λ0 × 0.038λ0 (λ0 is the free-space wavelength at the center frequency of the 3-dB AR bandwidth) is fabricated and measured for validation. The realized gain varies from 1.6 to 3.1 dBic over the operating bandwidth characterized by the measured 10-dB impedance bandwidth of 83.8% (3.98–9.72 GHz) and 3-dB AR bandwidth of 70.3% (4.59–9.57 GHz), respectively.

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