scholarly journals Ultra-Thin Chiral Metasurface-Based Superoscillatory Lens

2022 ◽  
Vol 8 ◽  
Author(s):  
Jinxing Li ◽  
Guohui Yang ◽  
Yueyi Yuan ◽  
Qun Wu ◽  
Kuang Zhang
Keyword(s):  
High Efficiency ◽  
Imaging System ◽  
Focal Depth ◽  
Dielectric Substrate ◽  
Diffraction Limit ◽  
Ring Resonators ◽  
Center Frequency ◽  
Full Wave ◽  
Low Profile ◽  
Unit Cells

The metasurface-based superoscillatory lens has been demonstrated to be effective in finely tailoring the wavefront of light to generate focal spots beyond the diffraction limit in the far-field that is capable of improving the resolution of the imaging system. In this paper, an ultra-thin (0.055 λ0) metasurface-based superoscillatory lens (SOL) that can generate a sub-diffraction optical needle with a long focal depth is proposed, which is constructed by ultra-thin chiral unit cells containing two metal split-ring resonators (SRR) with a 90° twisted angle difference cladded on both sides of a 1.5 mm-thick dielectric substrate, with a high linear cross-polarized transmission coefficient around 0.9 and full phase control capability at 11 GHz. Full-wave simulation shows that SOL generates a sub-diffraction optical needle within 10.5–11.5 GHz. At the center frequency, the focal depth is 281 mm (10.3 λ0) within 105–386 mm, the full width at half maximum (FWHM) is 18.5 mm (0.68 λ0), about 0.7 times the diffraction limit, generally consistent with the theoretical result. The proposed ultra-thin chiral metasurface-based SOL holds great potential in integrating into practical imaging applications for its simple fabrication, high efficiency, and low-profile advantages.

scholarly journals Millimeter Wave Fabry-Perot Resonator Antenna Fed by CPW with High Gain and Broadband

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Xue-Xia Yang ◽  
Guan-Nan Tan ◽  
Bing Han ◽  
Hai-Gao Xue
Keyword(s):  
Millimeter Wave ◽  
Coplanar Waveguide ◽  
Dielectric Substrate ◽  
High Gain ◽  
Center Frequency ◽  
Impedance Bandwidth ◽  
Gain Bandwidth ◽  
Broad Bandwidth ◽  
Low Profile ◽  
Fabry Perot

A novel millimeter wave coplanar waveguide (CPW) fed Fabry-Perot (F-P) antenna with high gain, broad bandwidth, and low profile is reported. The partially reflective surface (PRS) and the ground form the F-P resonator cavity, which is filled with the same dielectric substrate. A dual rhombic slot loop on the ground acts as the primary feeding antenna, which is fed by the CPW and has broad bandwidth. In order to improve the antenna gain, metal vias are inserted surrounding the F-P cavity. A CPW-to-microstrip transition is designed to measure the performances of the antenna and extend the applications. The measured impedance bandwidth ofS11less than −10 dB is from 34 to 37.7 GHz (10.5%), and the gain is 15.4 dBi at the center frequency of 35 GHz with a 3 dB gain bandwidth of 7.1%. This performance of the antenna shows a tradeoff among gain, bandwidth, and profile.

scholarly journals Low-Cost Dielectric Substrate for Designing Low Profile Multiband Monopole Microstrip Antenna

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
M. R. Ahsan ◽  
M. T. Islam ◽  
M. Habib Ullah ◽  
H. Arshad ◽  
M. F. Mansor
Keyword(s):  
Microstrip Antenna ◽  
Dielectric Material ◽  
Low Cost ◽  
Cost Effective ◽  
Dielectric Substrate ◽  
The Finite Element Method ◽  
Radiation Patterns ◽  
Polymer Resin ◽  
Full Wave ◽  
Low Profile

This paper proposes a small sized, low-cost multiband monopole antenna which can cover the WiMAX bands and C-band. The proposed antenna of 20 × 20 mm2radiating patch is printed on cost effective 1.6 mm thick fiberglass polymer resin dielectric material substrate and fed by 4 mm long microstrip line. The finite element method based, full wave electromagnetic simulator HFSS is efficiently utilized for designing and analyzing the proposed antenna and the antenna parameters are measured in a standard far-field anechoic chamber. The experimental results show that the prototype of the antenna has achieved operating bandwidths (voltage stand wave ratio (VSWR) less than 2) 360 MHz (2.53–2.89 GHz) and 440 MHz (3.47–3.91 GHz) for WiMAX and 1550 MHz (6.28–7.83 GHz) for C-band. The simulated and measured results for VSWR, radiation patterns, and gain are well matched. Nearly omnidirectional radiation patterns are achieved and the peak gains are of 3.62 dBi, 3.67 dBi, and 5.7 dBi at 2.66 GHz, 3.65 GHz, and 6.58 GHz, respectively.

scholarly journals Single-Shot Waterless Low-Profile Photoacoustic System: Near-Field Volumetric Imaging In Vivo for Blood Vessels Based on Capacitive Micromachined Ultrasonic Transducer (CMUT)

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 995 ◽  
Author(s):  
Won Choi ◽  
Young Kim ◽  
Hyeong Jo ◽  
Joo Pyun ◽  
Soo Kwon ◽  
...  
Keyword(s):  
Tissue Characterization ◽  
Imaging System ◽  
Ultrasonic Transducer ◽  
Near Field ◽  
Center Frequency ◽  
Single Shot ◽  
Living Body ◽  
Low Profile ◽  
Capacitive Micromachined Ultrasonic Transducer

Intensive research on photoacoustics (PA) for imaging of the living human body, including the skin, vessels, and tumors, has recently been conducted. We propose a PA measurement system based on a capacitive micromachined ultrasonic transducer (CMUT) with waterless coupling, short measurement time (<1 s), backward light irradiation, and a low-profile ultrasonic receiver unit (<1 cm). We fabricate a 64-element CMUT ring array with 6.2 mm diameter and 10.4 MHz center frequency in air, and 100% yield and uniform element response. To validate the PA tissue characterization, we employ pencil lead and red ink as solid and liquid models, respectively, and a living body to target moles and vessels. The system implements a near-field imaging system consisting of a 6 mm polydimethylsiloxane (PDMS) matching layer between the object and CMUT, which has a 3.7 MHz center frequency in PDMS. Experiments were performed in a waterless contact on the PDMS and the laser was irradiated with a 1 cm diameter. The experimental results show the feasibility of this near-field PA imaging system for position and depth detection of skin, mole, vessel cells, etc. Therefore, a system applicable to a low-profile compact biomedical device is presented.

scholarly journals High-Efficiency Electromagnetic Wave Controlling with All-Dielectric Huygens’ Metasurfaces

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Zheng-bin Wang ◽  
Jin Shi ◽  
Jin-chang Chen
Keyword(s):  
High Efficiency ◽  
Physical Mechanism ◽  
Three Dimensional ◽  
Building Blocks ◽  
Side Lobe ◽  
Antenna System ◽  
Low Loss ◽  
Full Wave ◽  
Low Profile ◽  
Incident Waves

Subwavelength dielectric blocks with varying thicknesses are introduced to realize 0∼2πphase change. A Huygens’ metasurface composed of such nonuniform building blocks is shown to efficiently refract normally incident waves in a broadband. According to the same physical mechanism, we fabricate an electrically thin lens with concentric subwavelength dielectric blocks and integrate it with a patch antenna to form a three-dimensional (3D) ultra-low-profile lens antenna system. Full-wave simulation demonstrates the lens antenna’s excellent performances in high directivity, broadband, low loss, and low side-lobe levels.

scholarly journals Design of a Compact Dual-Band Microstrip Antenna Enabled by Complementary Split Ring Resonators for X-Band Applications

2018 ◽  
Vol 7 (3) ◽  
pp. 82-86 ◽  
Author(s):  
E. K. I. Hamad ◽  
M. Z. M. Hamdalla
Keyword(s):  
Microstrip Antenna ◽  
Split Ring Resonator ◽  
Ring Resonators ◽  
Dual Band ◽  
Split Ring ◽  
Full Wave ◽  
Radiating Element ◽  
X Band ◽  
Unit Cells ◽  
Tan Δ

In this paper, a design of highly effective dual-band microstrip antenna for X-band applications is developed. Dual-band response is obtained by etching four rectangular split ring resonator (RSRR) unit cells within the radiating element of a conventional patch initially designed to operate at 10 GHz. The proposed antenna is constructed on low lossy RT/duroid 5880 (ϵr = 2.2, tan δ = 0.0009) substrate of 20x20x1.575 mm3 total area. The antenna is tuned to operate at two resonant frequencies within 8 to 12 GHz depending on the geometric specifications of the RSRR's. A parametric study of different numbers of unit cells etched on the radiating element is investigated and discussed comprehensively through this study. Realized gain of about 6.2 and 6.8 dB at 8.8 and 10 GHz are attained. Consistent results are obtained between the measurements and simulation results using 3D full-wave FEM-base simulator.

scholarly journals Low-Cost, Low-Profile Wide-Band Radar Cross Section Reduction Using Dual-Concentric Phase Gradient Modulated Surface

Electronics ◽  
2021 ◽  
Vol 10 (13) ◽  
pp. 1552
Author(s):  
Yousef Azizi ◽  
Mohammad Soleimani ◽  
Seyed Hasan Sedighy ◽  
Ladislau Matekovits
Keyword(s):  
Cross Section ◽  
Low Cost ◽  
Wide Band ◽  
Radar Cross Section ◽  
Phase Gradient ◽  
Full Wave ◽  
Low Profile ◽  
Anomalous Reflection ◽  
Measurement Results ◽  
Unit Cells

Design criteria of low-cost, dual-concentric metasurface possessing wideband phase gradient (PG) are introduced. The radar cross-section reduction (RCSR) is explained by anomalous reflection that characterizes the superficial planar. The geometry consists of two single band RCSR modulated surfaces (MSs) that are triggered in each other. Each MS is built-up of square patch (SP) unit cells configured as a modulation structure to realize PG that causes anomalous reflection and monostatic RCSR behavior. Applying sinusoidal modulation to the sequence of the SP unit cells leads to the formation of PG along the surface and hence the intensity of the reflected wave is reduced for the broadside direction (θr=0∘). The proposed structure fabricated on a 0.8 mm thin FR-4 substrate extends over 249 × 249 mm2. It achieves a wide RCSR bandwidth from 20.9 GHz to 45.7 GHz (i.e., relative bandwidth of 75%) as designed in Dassault Systèmes (CST) Microwave Studio as a full-wave simulator and confirmed by the measurement results.

scholarly journals Polarization and Incidence Angle Independent Low-Profile Wideband Metamaterial Electromagnetic Absorber Using Indium Tin Oxide (ITO) Film

2021 ◽  
Vol 11 (19) ◽  
pp. 9315
Author(s):  
Sangmin Park ◽  
Geonyeong Shin ◽  
Hyun Kim ◽  
Youngwan Kim ◽  
Ick-Jae Yoon
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Incidence Angle ◽  
Wide Frequency Range ◽  
Ring Resonators ◽  
Frequency Range ◽  
Split Ring ◽  
Ito Film ◽  
Full Wave ◽  
Low Profile

We use indium tin oxide (ITO), one of the representative resistive materials, for the implementation of a metamaterial electromagnetic (EM) absorber with a high absorbance in a wide frequency range. Highly symmetrical split ring resonators made of ITO film are deposited on the polyethylene terephthalate with transparent and flexible features, and such a configuration causes the proposed absorber to be insensitive to polarization and incidence angles. The proposed absorber, with a profile of only 0.171, exhibits a wideband absorbance of 7.2 GHz to 27 GHz, with a 90% absorption criterion. A prototype is built, and all the computed expectations from the full-wave EM simulations in this work are verified experimentally.

scholarly journals Performance Improvement of Substrate Integrated Cavity Fed Dipole Array Antenna Using ENZ Metamaterial for 5G Applications

Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 125
Author(s):  
Shaza El-Nady ◽  
Rania R. Elsharkawy ◽  
Asmaa I. Afifi ◽  
Anwer S. Abd El-Hameed
Keyword(s):  
Coplanar Waveguide ◽  
Impedance Matching ◽  
High Gain ◽  
Dipole Antenna ◽  
Center Frequency ◽  
Antenna Element ◽  
Gain Enhancement ◽  
Radiated Power ◽  
Low Profile ◽  
Unit Cells

This paper exhibits a high-gain, low-profile dipole antenna array (DAA) for 5G applications. The dipole element has a semi-triangular shape to realize a simple input impedance regime. To reduce the overall antenna size, a substrate integrated cavity (SIC) is adopted as a power splitter feeding network. The transition between the SIC and the antenna element is achieved by a grounded coplanar waveguide (GCPW) to increase the degree of freedom of impedance matching. Epsilon-near-zero (ENZ) metamaterial technique is exploited for gain enhancement. The ENZ metamaterial unit cells of meander shape are placed in front of each dipole perpendicularly to guide the radiated power into the broadside direction. The prospective antenna has an overall size of 2.58 λg3 and operates from 28.5 GHz up to 30.5 GHz. The gain is improved by 5 dB compared to that of the antenna without ENZ unit cells, reaching 11 dBi at the center frequency of 29.5 GHz. Measured and simulated results show a reasonable agreement.

scholarly journals Breaking the acoustic diffraction limit with an arbitrary shape acoustic magnifying lens

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ali Abdolali ◽  
Hooman Barati Sedeh ◽  
Mohammad Hosein Fakheri ◽  
Chen Shen ◽  
Fei Sun
Keyword(s):  
Arbitrary Shape ◽  
Design Principle ◽  
Focused Ultrasound ◽  
Effective Medium Theory ◽  
Wide Spectrum ◽  
Diffraction Limit ◽  
Far Field ◽  
Biomedical Sensors ◽  
Focused Ultrasound Surgery ◽  
Unit Cells

AbstractBased on the transformation acoustics methodology, the design principle for achieving an arbitrary shape magnifying lens (ASML) is proposed. Contrary to the previous works, the presented ASML is competent of realizing far-field high resolution images and breaking the diffraction limit, regardless of the position of the utilized sources. Therefore, objects locating within the designed ASML can be properly resolved in the far-field region. It is shown that the obtained material through the theoretical investigations becomes an acoustic null medium (ANM), which has recently gained a significant attention. Besides the homogeneity of ANM, which makes it an implementable material, it is also independent of the perturbation in the geometry of the lens, in such a way that the same ANM can be used for different structural topologies. The obtained ANM has been implemented via acoustics unit cells formed by membranes and side branches with open ends and then was utilized to realize an ASML with the aid of effective medium theory. It is shown that the far-field results of an ideal ASML abide well with the results of the implemented sample, validating the proposed design principle. The presented acoustic magnifying lens has a wide spectrum of possible applications ranging from medical imaging, and biomedical sensors to focused ultrasound surgery.

scholarly journals Validation of Scolioscan Air-Portable Radiation-Free Three-Dimensional Ultrasound Imaging Assessment System for Scoliosis

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2858
Author(s):  
Kelly Ka-Lee Lai ◽  
Timothy Tin-Yan Lee ◽  
Michael Ka-Shing Lee ◽  
Joseph Chi-Ho Hui ◽  
Yong-Ping Zheng
Keyword(s):  
Ultrasound Imaging ◽  
Imaging System ◽  
Outcome Measurement ◽  
Three Dimensional ◽  
3D Ultrasound ◽  
Mean Difference ◽  
Assessment System ◽  
Absolute Difference ◽  
Data Sets ◽  
Low Profile

To diagnose scoliosis, the standing radiograph with Cobb’s method is the gold standard for clinical practice. Recently, three-dimensional (3D) ultrasound imaging, which is radiation-free and inexpensive, has been demonstrated to be reliable for the assessment of scoliosis and validated by several groups. A portable 3D ultrasound system for scoliosis assessment is very much demanded, as it can further extend its potential applications for scoliosis screening, diagnosis, monitoring, treatment outcome measurement, and progress prediction. The aim of this study was to investigate the reliability of a newly developed portable 3D ultrasound imaging system, Scolioscan Air, for scoliosis assessment using coronal images it generated. The system was comprised of a handheld probe and tablet PC linking with a USB cable, and the probe further included a palm-sized ultrasound module together with a low-profile optical spatial sensor. A plastic phantom with three different angle structures built-in was used to evaluate the accuracy of measurement by positioning in 10 different orientations. Then, 19 volunteers with scoliosis (13F and 6M; Age: 13.6 ± 3.2 years) with different severity of scoliosis were assessed. Each subject underwent scanning by a commercially available 3D ultrasound imaging system, Scolioscan, and the portable 3D ultrasound imaging system, with the same posture on the same date. The spinal process angles (SPA) were measured in the coronal images formed by both systems and compared with each other. The angle phantom measurement showed the measured angles well agreed with the designed values, 59.7 ± 2.9 vs. 60 degrees, 40.8 ± 1.9 vs. 40 degrees, and 20.9 ± 2.1 vs. 20 degrees. For the subject tests, results demonstrated that there was a very good agreement between the angles obtained by the two systems, with a strong correlation (R2 = 0.78) for the 29 curves measured. The absolute difference between the two data sets was 2.9 ± 1.8 degrees. In addition, there was a small mean difference of 1.2 degrees, and the differences were symmetrically distributed around the mean difference according to the Bland–Altman test. Scolioscan Air was sufficiently comparable to Scolioscan in scoliosis assessment, overcoming the space limitation of Scolioscan and thus providing wider applications. Further studies involving a larger number of subjects are worthwhile to demonstrate its potential clinical values for the management of scoliosis.

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