scholarly journals Exploiting space-time duality in the synthesis of impedance transformers via temporal metamaterials

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Giuseppe Castaldi ◽  
Victor Pacheco-Peña ◽  
Massimo Moccia ◽  
Nader Engheta ◽  
Vincenzo Galdi
Keyword(s):  
Frequency Conversion ◽  
Impedance Matching ◽  
Wave Impedance ◽  
Space Time ◽  
Time Varying ◽  
Antireflection Coatings ◽  
Microwave Engineering ◽  
Time Harmonic ◽  
Quarter Wave ◽  
The Time Domain

Abstract Multisection quarter-wave impedance transformers are widely applied in microwave engineering and optics to attain impedance-matching networks and antireflection coatings. These structures are mostly designed in the spatial domain (time harmonic) by using geometries of different materials. Here, we exploit such concepts in the time domain by using time-varying metamaterials. We derive a formal analogy between the spectral responses of these structures and their temporal analogs, i.e., time-varying stepped refractive-index profiles. We show that such space-time duality grants access to the vast arsenal of synthesis approaches available in microwave engineering and optics. This allows, for instance, the synthesis of temporal impedance transformers for broadband impedance matching with maximally flat or equi-ripple responses, which extend and generalize the recently proposed quarter-wave design as an antireflection temporal coating. Our results, validated via full-wave numerical simulations, provide new insights and deeper understanding of the wave dynamics in time-varying media, and may find important applications in space-time metastructures for broadband frequency conversion and analog signal processing.

scholarly journals Unidirectional amplification with acoustic non-Hermitian space−time varying metamaterial

2022 ◽  
Vol 5 (1) ◽  
Author(s):  
Xinhua Wen ◽  
Xinghong Zhu ◽  
Alvin Fan ◽  
Wing Yim Tam ◽  
Jie Zhu ◽  
...  
Keyword(s):  
Time Domain ◽  
Frequency Conversion ◽  
Space Time ◽  
Time Varying ◽  
Impulse Responses ◽  
Experimental Realization ◽  
Material Gain ◽  
Time Varying Systems ◽  
Hermitian Space ◽  
The Time Domain

AbstractSpace−time modulated metamaterials support extraordinary rich applications, such as parametric amplification, frequency conversion, and non-reciprocal transmission. The non-Hermitian space−time varying systems combining non-Hermiticity and space−time varying capability, have been proposed to realize wave control like unidirectional amplification, while its experimental realization still remains a challenge. Here, based on metamaterials with software-defined impulse responses, we experimentally demonstrate non-Hermitian space−time varying metamaterials in which the material gain and loss can be dynamically controlled and balanced in the time domain instead of spatial domain, allowing us to suppress scattering at the incident frequency and to increase the efficiency of frequency conversion at the same time. An additional modulation phase delay between different meta-atoms results in unidirectional amplification in frequency conversion. The realization of non-Hermitian space−time varying metamaterials will offer further opportunities in studying non-Hermitian topological physics in dynamic and nonreciprocal systems.

scholarly journals A trade-off design of microstrip broadband power amplifier for UHF applications

2020 ◽  
Vol 10 (1) ◽  
pp. 919
Author(s):  
Mohamed Ribate ◽  
Rachid Mandry ◽  
Jamal Zbitou ◽  
Larbi El Abdellaoui ◽  
Ahmed Errkik ◽  
...  
Keyword(s):  
Power Amplifier ◽  
Transmission Lines ◽  
Impedance Matching ◽  
Wave Impedance ◽  
Large Signal ◽  
Active Device ◽  
Quarter Wave ◽  
Lumped Elements ◽  
Signal Simulation ◽  
Matching Techniques

In this paper, the design of a Broadband Power Amplifier for UHF applications is presented. The proposed BPA is based on ATF13876 Agilent active device. The biasing and matching networks both are implemented by using microstrip transmission lines. The input and output matching circuits are designed by combining two broadband matching techniques: a binomial multi-section quarter wave impedance transformer and an approximate transformation of previously designed lumped elements. The proposed BPA shows excellent performances in terms of impedance matching, power gain and unconditionally stability over the operating bandwidth ranging from 1.2 GHz to 3.3 GHz. At 2.2 GHz, the large signal simulation shows a saturated output power of 18.875 dBm with an output 1-dB compression point of 6.5 dBm of input level and a maximum PAE of 36.26%.

An Acoustic Gray Scale for Scanning Acoustic Microscopy and Diagnostic Ultrasound

1979 ◽  
Vol 1 (1) ◽  
pp. 89-100 ◽  
Author(s):  
R. D. Weglein
Keyword(s):  
Impedance Matching ◽  
Diagnostic Ultrasound ◽  
Wave Impedance ◽  
Acoustic Microscopy ◽  
Scanning Acoustic Microscopy ◽  
Gray Scale ◽  
Acoustic Microscope ◽  
Quarter Wave ◽  
Scanning Acoustic Microscope ◽  
Single Material

The principle of a true acoustic gray scale standard is presented and experimentally applied to the Scanning Acoustic Microscope (SAM). The implementation is based on the impedance matching property of a quarter wave impedance transformer through which precise changes in reflection coefficient may be produced in a single material. The performance of the first implementation designed for 375 MHz operation is described and the implications of its use are discussed in detail. The application of the principle to diagnostic ultrasound is also treated.

scholarly journals In-situ monitoring for liquid metal jetting using a millimeter-wave impedance diagnostic

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tammy Chang ◽  
Saptarshi Mukherjee ◽  
Nicholas N. Watkins ◽  
David M. Stobbe ◽  
Owen Mays ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Millimeter Wave ◽  
Manufacturing Systems ◽  
Wave Impedance ◽  
In Situ Monitoring ◽  
Full Wave ◽  
Drop On Demand ◽  
The Time Domain ◽  
Metal Droplets

AbstractThis article presents a millimeter-wave diagnostic for the in-situ monitoring of liquid metal jetting additive manufacturing systems. The diagnostic leverages a T-junction waveguide device to monitor impedance changes due to jetted metal droplets in real time. An analytical formulation for the time-domain T-junction operation is presented and supported with a quasi-static full-wave electromagnetic simulation model. The approach is evaluated experimentally with metallic spheres of known diameters ranging from 0.79 to 3.18 mm. It is then demonstrated in a custom drop-on-demand liquid metal jetting system where effective droplet diameters ranging from 0.8 to 1.6 mm are detected. Experimental results demonstrate that this approach can provide information about droplet size, timing, and motion by monitoring a single parameter, the reflection coefficient amplitude at the input port. These results show the promise of the impedance diagnostic as a reliable in-situ characterization method for metal droplets in an advanced manufacturing system.

A new strategy to reduce edge chipping using stress wave impedance matching

CIRP Annals ◽  
2021 ◽  
Author(s):  
Yifan Zhang ◽  
Yuyang Zhao ◽  
Jundong Xu ◽  
Mengqi Rao ◽  
Yuehong Yin
Keyword(s):  
Stress Wave ◽  
Impedance Matching ◽  
Wave Impedance ◽  
Edge Chipping ◽  
New Strategy

scholarly journals Optimization of spaceflight millimeter-wave impedance matching networks using laser trimming

2021 ◽  
pp. 1-7
Author(s):  
K. Parow-Souchon ◽  
D. Cuadrado-Calle ◽  
S. Rea ◽  
M. Henry ◽  
M. Merritt ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Millimeter Wave ◽  
Impedance Matching ◽  
Wave Impedance ◽  
Low Noise ◽  
Device Performance ◽  
Interface Circuits ◽  
Interface Circuit ◽  
Noise Amplifier

Abstract Realizing packaged state-of-the-art performance of monolithic microwave integrated circuits (MMICs) operating at millimeter wavelengths presents significant challenges in terms of electrical interface circuitry and physical construction. For instance, even with the aid of modern electromagnetic simulation tools, modeling the interaction between the MMIC and its package embedding circuit can lack the necessary precision to achieve optimum device performance. Physical implementation also introduces inaccuracies and requires iterative interface component substitution that can produce variable results, is invasive and risks damaging the MMIC. This paper describes a novel method for in situ optimization of packaged millimeter-wave devices using a pulsed ultraviolet laser to remove pre-selected areas of interface circuit metallization. The method was successfully demonstrated through the optimization of a 183 GHz low noise amplifier destined for use on the MetOp-SG meteorological satellite series. An improvement in amplifier output return loss from an average of 12.9 dB to 22.7 dB was achieved across an operational frequency range of 175–191 GHz and the improved circuit reproduced. We believe that our in situ tuning technique can be applied more widely to planar millimeter-wave interface circuits that are critical in achieving optimum device performance.

scholarly journals Application of Multi-Branch Cauer Circuits in the Analysis of Electromagnetic Transducers Used in Wireless Transfer Power Systems

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2052
Author(s):  
Milena Kurzawa ◽  
Cezary Jędryczka ◽  
Rafał M. Wojciechowski
Keyword(s):  
Power Systems ◽  
Field Model ◽  
Wireless Power Transfer ◽  
Equivalent Model ◽  
Power Transfer ◽  
Wireless Power ◽  
The Finite Element Method ◽  
Harmonic Field ◽  
Time Harmonic ◽  
The Time Domain

In this paper, the feasibility of applying a multi-branch equivalent model employing first- and second-order Cauer circuits for the analysis of electromagnetic transducers used in systems of wireless power transfer is discussed. A method of formulating an equivalent model (EqM) is presented, and an example is shown for a wireless power transfer system (WPTS) consisting of an air transformer with field concentrators. A method is proposed to synthesize the EqM of the considered transducer based on the time-harmonic field model, an optimization algorithm employing the evolution strategy (ES) and the equivalent Cauer circuits. A comparative analysis of the performance of the considered WPTS under high-frequency voltage supply calculated using the proposed EqM and a 3D field model in the time domain using the finite element method (FEM) was carried out. The selected results of the conducted analysis are presented and discussed.

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