scholarly journals Fundamentals of Lossless, Reciprocal Bianisotropic Metasurface Design

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 197
Author(s):  
Luke Szymanski ◽  
Brian O. Raeker ◽  
Chun-Wen Lin ◽  
Anthony Grbic
Keyword(s):  
Plane Wave ◽  
Quality Factor ◽  
Impedance Matching ◽  
Polarization Rotator ◽  
Wave Refraction ◽  
Matching Layer ◽  
Polarization Control ◽  
Circular Polarizer ◽  
Unit Cells

Lossless, reciprocal bianisotropic metasurfaces have the ability to control the amplitude, phase, and polarization of electromagnetic wavefronts. However, producing the responses that are necessary for achieving this control with physically realizable surfaces is a challenging task. Here, several design approaches for bianisotropic metasurfaces are reviewed that produce physically realizable metasurfaces using cascaded impedance sheets. In practice, three or four impedance sheets are often used to realize bianisotropic responses, which can result in narrowband designs that require the unit cells to be optimized in order to improve the performance of the metasurface. The notion of a metasurface quality factor is introduced for three-sheet metasurfaces to address these issues in a systematic manner. It is shown that the quality factor can be used to predict the bandwidth of a homogeneous metasurface, and it can also be used to locate problematic unit cells when designing inhomogeneous metasurfaces. Several design examples are provided to demonstrate the utility of the quality factor, including an impedance matching layer with maximal bandwidth and a gradient metasurface for plane wave refraction. In addition to these examples, several metasurfaces for polarization control are also reported, including an isotropic polarization rotator and an asymmetric circular polarizer.

scholarly journals Design of an S-Band Phased Array with Modified Dipoles

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Meng Xiang ◽  
Yu Xiao ◽  
Bin Xi ◽  
Yue Zhang ◽  
Shiyou Xu
Keyword(s):  
Antenna Array ◽  
Impedance Matching ◽  
Equivalent Circuit Model ◽  
High Gain ◽  
Wide Angle ◽  
Cross Polarization ◽  
Matching Layer ◽  
Unit Cells ◽  
Operating Bandwidth ◽  
Polarization Level

A wideband, low cross-polarization, high-gain, and wide-angle scanning antenna array is presented in this paper. The antenna array contains 8 subarrays in the horizontal dimension, and each subarray contains 4 unit cells. A two-side printed dipole with an amendatory equivalent circuit model is adopted, and the metal vias are introduced in the element design to ameliorate the cross-polarization level. A radome, acting as the wide-angle impedance matching layer, is introduced to achieve wide-angle scanning. A prototype of a 4 × 8 array is fabricated and measured. The results show that the operating bandwidth of aperture efficiency (BWAE) above 60% is about 26.7% from 2.6 GHz to 3.4 GHz. The measured scanning loss in the H-plane is 2.7 dB when scanning up to 60° with active voltage standing wave ratio (VSWR) <3, and the gain can achieve 21 dB at 3 GHz with a cross-polarization level below −30 dB at all angles.

A multi-octave microwave 6-bit true time delay with low amplitude and delay variation in 65 nm CMOS

2021 ◽  
pp. 1-10
Author(s):  
Yakov Gutkin ◽  
Asher Madjar ◽  
Emanuel Cohen
Keyword(s):  
Time Delay ◽  
Insertion Loss ◽  
Impedance Matching ◽  
Least Significant Bit ◽  
Delay Cell ◽  
True Time Delay ◽  
Unit Cells ◽  
True Time ◽  
And Performance ◽  
Low Amplitude

Abstract In this paper, we describe the design, layout, and performance of a 6-bit TTD (true time delay) chip operating over the entire band of 2–18 GHz. The 1.15 mm2 chip is implemented using TSMC foundry 65 nm technology. The least significant bit is 1 ps. The design is based on the concept of all-pass network with some modifications intended to reduce the number of unit cells. Thus, the first three bits are implemented in a single delay cell. A peaking buffer amplifier between bit 4 and bit 5 is used for impedance matching and partial compensation of the insertion loss slope. The rms delay error of the TTD is <1 ps over most of the frequency band and insertion loss is between 2.5 and 6.3 dB for all 64 states.

scholarly journals Microwave absorption and mechanical properties of double-layer cement-based composites containing different replacement levels of fly ash

2018 ◽  
Vol 25 (4) ◽  
pp. 707-714 ◽  
Author(s):  
Yuefang Zhang ◽  
Shunhua Liu ◽  
wanJun Hao
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Double Layer ◽  
Impedance Matching ◽  
X Ray Diffraction ◽  
Replacement Ratio ◽  
Matching Layer ◽  
Optimal Replacement ◽  
Zn Ferrite ◽  
Absorbing Layer

Abstract Double-layer absorbing cement-based composites with the thickness of 10 mm were prepared, including different replacement levels of fly ash (FA) in the absorbing layer as well as the matching layer for impedance matching. Waste polyethylene terephthalate bottle fragment was introduced as electromagnetic transparent reinforcement aggregate. Carbon black was used to be original absorbent in the absorbing layer. The microstructure and electromagnetic parameters of FA were closely looked at through scanning electron microscope, X-ray diffraction, and analyzer of vector network. The absorption and mechanical properties of cement-based composites were tested. It turned out that when the optimal replacement ratio of FA in the absorbing layer and matching layer gets to 50%:30%, the minimum value of reflection loss achieves −22.3 dB at 13.2 GHz; also, the value of absorption bandwidth that is effective (<−8 dB) is 6.4 GHz. Ni-Zn ferrite proves to be a feasible absorbent that is additional for the matching layer compared to what is added to the absorbing layer. The compressive strength of all the mixtures decreased, while the flexural strength decreased first and then increased with the rise of the FA replacement level.

scholarly journals Design of Cavity-Backed Bow-Tie Antenna with Matching Layer for Human Body Application

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 4015 ◽  
Author(s):  
Jeong ◽  
Park ◽  
Lee
Keyword(s):  
Reflection Coefficient ◽  
Human Body ◽  
Electromagnetic Interference ◽  
Impedance Matching ◽  
Human Head ◽  
Impedance Match ◽  
Broadband Antenna ◽  
Matching Layer ◽  
Antenna Performance ◽  
Bow Tie

This paper presents the broadband antenna for the microwave radiometric sensing of internal body temperature. For broadband operation, the bow-tie antenna was designed and backed with a cylindrical cavity, which decreased environmental electromagnetic interference and also improved the directivity of the antenna. The broadband impedance-transforming balun in microstrip form was also designed to feed the bow-tie antenna, and was located inside the cavity. An impedance-matching dielectric layer (IMDL) was introduced on top of the bow-tie antenna, for impedance match with the human body with high permittivity. The fabricated antenna was measured in free space with the IMDL removed, showing an input reflection coefficient lower than −10 dB from 2.64 to > 3.60 GHz with antenna gain over 6.0 dBi and radiation efficiency over 74.7% from 2.7 to 3.5 GHz. The IMDL was re-installed on the cavity-backed bow-tie antenna to measure the antenna performance for the human head with relative permittivity of about 40. The measured reflection coefficient was as low as −28.9 dB at 2.95 GHz and lower than −10 dB from 2.65 to > 3.5 GHz. It was also shown that the designed antenna recovered a good impedance match by adjusting the permittivity and thickness of the IMDL for the different parts of the human body with different permittivities.

ON-CHIP INDUCTORS OPTIMIZATION FOR ULTRA WIDE BAND LOW NOISE AMPLIFIERS

2011 ◽  
Vol 20 (07) ◽  
pp. 1231-1242 ◽  
Author(s):  
J. DEL PINO ◽  
SUNIL L. KHEMCHANDANI ◽  
ROBERTO DÍAZ-ORTEGA ◽  
R. PULIDO ◽  
H. GARCÍA-VÁZQUEZ
Keyword(s):  
Quality Factor ◽  
Noise Figure ◽  
Impedance Matching ◽  
Broad Band ◽  
Wide Band ◽  
Design Guidelines ◽  
Low Noise ◽  
Low Noise Amplifiers ◽  
Integrated Inductor ◽  
On Chip

In this work, the influence of the inductor quality factor in wide band low noise amplifiers has been studied. Electromagnetic simulations have been used to model the integrated inductor broad band response. The influence of the quality factor on LNA performance of the inductors that compound the impedance matching networks, inductive degeneration and broadband load has been studied, obtaining design guidelines for optimizing the amplifier gain flatness. Using this guidelines, an LNA with wideband input matching, shunt-peaking load, and an output buffer was designed. Using Austria Mikro Systems BiCMOS 0.35 m process, a prototype has been fabricated achieving the following measured specifications: maximum gain of 12.5 dB at 3.4 GHz with a -3 dB bandwidth of 1.7–5.3 GHz, noise figure from 4.3 to 5.2 dB, and unity gain at 9.4 GHz.

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