scholarly journals Dispersion Analysis of Periodically Loaded Transmission Lines with Twist Symmetry Using the Mode-Matching Technique

2020 ◽  
Vol 10 (17) ◽  
pp. 5990
Author(s):  
Oskar Zetterstrom ◽  
Guido Valerio ◽  
Francisco Mesa ◽  
Fatemeh Ghasemifard ◽  
Martin Norgren ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Dispersion Analysis ◽  
Phase Shifters ◽  
Mode Matching ◽  
Electromagnetic Devices ◽  
Higher Order Modes ◽  
Physical Insight ◽  
Coaxial Lines ◽  
Symmetric Structures ◽  
Good Agreement

A mode-matching formulation is presented and used to analyze the dispersion properties of twist-symmetric transmission lines. The structures are coaxial lines periodically loaded with infinitely thin screens, which are rotated with respect to each other to possess twist symmetry. The results obtained using the proposed formulation are in good agreement with those of commercial simulators. Furthermore, using the presented mode-matching formulation, it is demonstrated that the propagation characteristics in the twist-symmetric structures are linked to the scattering and coupling of the higher order modes. The physical insight offered by this analysis is valuable for the design of various electromagnetic devices, such as filters, antennas, and phase-shifters.

scholarly journals Cavitation Bubble Cloud Break-Off Mechanisms at Micro-Channels

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 215
Author(s):  
Paul McGinn ◽  
Daniel Pearce ◽  
Yannis Hardalupas ◽  
Alex Taylor ◽  
Konstantina Vogiatzaki
Keyword(s):  
Cavitation Bubble ◽  
Cavitation Inception ◽  
Wave Dynamics ◽  
Bubble Cloud ◽  
Cloud Dynamics ◽  
Micro Channels ◽  
Physical Insight ◽  
Cloud Process ◽  
Good Agreement

This paper provides new physical insight into the coupling between flow dynamics and cavitation bubble cloud behaviour at conditions relevant to both cavitation inception and the more complex phenomenon of flow “choking” using a multiphase compressible framework. Understanding the cavitation bubble cloud process and the parameters that determine its break-off frequency is important for control of phenomena such as structure vibration and erosion. Initially, the role of the pressure waves in the flow development is investigated. We highlight the differences between “physical” and “artificial” numerical waves by comparing cases with different boundary and differencing schemes. We analyse in detail the prediction of the coupling of flow and cavitation dynamics in a micro-channel 20 m high containing Diesel at pressure differences 7 MPa and 8.5 MPa, corresponding to cavitation inception and "choking" conditions respectively. The results have a very good agreement with experimental data and demonstrate that pressure wave dynamics, rather than the “re-entrant jet dynamics” suggested by previous studies, determine the characteristics of the bubble cloud dynamics under “choking” conditions.

scholarly journals RF-MEMS switches with AlN dielectric and their applications

2011 ◽  
Vol 3 (5) ◽  
pp. 509-520 ◽  
Author(s):  
Montserrat Fernández-Bolaños Badía ◽  
Pierre Nicole ◽  
Adrian Mihai Ionescu
Keyword(s):  
Transmission Lines ◽  
Rf Mems ◽  
Beam Steering ◽  
Phase Shifters ◽  
Center Frequency ◽  
Mems Switches ◽  
Rf Mems Switches ◽  
Mems Technology ◽  
Bandwidth Tuning ◽  
Rf Performance

This paper reports on the potential of RF-MEMS technology based on aluminum nitride capacitive dielectric and nickel-suspended membranes to provide RF circuit functions in reconfigurable front-end radios. The RF performance of capacitive switches, distributed MEMS transmission lines (DMTLs) phase shifters for beam steering and tunable filters, including center frequency and bandwidth tuning of bandpass and band-stop filters are presented. Detailed characterization based on S-parameter data demonstrates very promising figures of merit of all fabricated demonstrators from 5 to 40 GHz.

scholarly journals Highly Unequal Three-Port Power Divider: Theory and Implementation

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Duolong Wu ◽  
Adriana Serban ◽  
Magnus Karlsson ◽  
Shaofang Gong
Keyword(s):  
Transmission Lines ◽  
Directional Coupler ◽  
Feedback Mechanism ◽  
Power Divider ◽  
Electromagnetic Simulation ◽  
Planar Form ◽  
Measurement Results ◽  
Minimum Number ◽  
Wilkinson Power Divider ◽  
Good Agreement

A three-port power divider consisting of a directional coupler, a Wilkinson power divider, and two transmission lines connected to them is proposed. Theoretical analysis reveals that highly unequal power division can be achieved by a feedback mechanism of two transmission lines along with the coupling coefficient of the directional coupler and the power division ratio of the Wilkinson power divider. The three-port power divider inherits the performance characteristics of high isolation, low reflection coefficients at all ports, and the minimum number of components. The proposed power divider is designed at 5.8 GHz and fabricated and evaluated through measurements. It demonstrates that electromagnetic simulation results are in good agreement with theoretical prediction and measurement results. The three-port power divider is compact in the planar form, so it can be easily integrated into radio frequency front ends.

Coupled microstrip filters on multilayered dielectric media

2002 ◽  
Vol 80 (6) ◽  
pp. 675-685
Author(s):  
Ar. Koufogiannidis ◽  
K Siakavara
Keyword(s):  
Frequency Response ◽  
Transmission Lines ◽  
Insertion Loss ◽  
Design Procedure ◽  
Multiconductor Transmission Lines ◽  
Microstrip Lines ◽  
Dielectric Media ◽  
Microstrip Filters ◽  
Loss Method ◽  
Good Agreement

The work presented in this paper is an attempt to design filters with coupled microstrip lines on multilayered dielectric media using methods employed in other applications. A procedure was formulated for designing filters with the desired frequency response and smaller size using insertion loss method combined with the theory of multiconductor transmission lines. The frequency response was verified by considering that the filters act as cascaded four-port networks. The results were in a very good agreement with those expected from the theoretically design procedure. PACS No.: 84.40D

Compact filtering power dividers with wide upper stopband

2019 ◽  
Vol 11 (08) ◽  
pp. 765-773
Author(s):  
Gaoya Dong ◽  
Weimin Wang ◽  
Yuanan Liu
Keyword(s):  
Transmission Lines ◽  
Wave Transmission ◽  
Coupling Matrix ◽  
Power Dividers ◽  
Full Wave ◽  
Half Wave ◽  
Coupled Lines ◽  
Quarter Wave ◽  
Simulation Results ◽  
Good Agreement

AbstractA series of compact filtering power dividers (FPDs) with simple layouts are proposed based on coupling topology. The structure of the presented FPD1 is composed of three resonators and one isolating resistor. These FPDs can be designed based on coupling matrix filter theory. A half-wave transmission line is employed in FPD2 to introduce a transmission zero (TZ) locating at 1.27f0. The FPD3 is designed by replacing quarter-wave transmission lines in FPD2 with quarter-wave coupled lines, which will produce a TZ locating at 1.96 f0 and extend upper stopband bandwidth. For verification, three FPDs centered at 2.45 GHz are fabricated and measured. All measured results are in good agreement with the full-wave simulation results.

scholarly journals Quadruple-Mode Wideband Bandpass Filter with Improved Out-of-Band Rejection

Electronics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 300 ◽  
Author(s):  
Musab Hameed ◽  
Gaobiao Xiao ◽  
Ali Najam ◽  
Lina Qiu ◽  
Tayyab Hameed
Keyword(s):  
Rectangular Waveguide ◽  
Bandpass Filter ◽  
Transverse Magnetic ◽  
Center Frequency ◽  
Fractional Bandwidth ◽  
Compact Size ◽  
Coaxial Lines ◽  
Good Agreement

This paper proposes a method for designing a quadruple-mode wideband bandpass filter using off-centered perturbed metallic cylinders in a rectangular waveguide cavity with compact size and improved out-of-band rejection. Two off-centered perturbation cylinders were placed at the bottom of the rectangular waveguide cavity along with a pair of perpendicularly-fed coaxial lines, which excited four quasi-transverse magnetic (TM) modes to realize the desired passband. The height of the waveguide cavity and the shape of the perturbation cylinders were exploited to achieve an all quasi-TM modes filter with good out-of-band rejection and sharp skirt selectivity. The proposed filter operates at 2.93 GHz center frequency with 38% wide fractional bandwidth (FBW). The proposed filter is fabricated using aluminum. The measured and simulated results are in good agreement with each other.

Electronically controlled phase shifters based on right/left-handed transmission lines

2005 ◽  
Author(s):  
O.G. Vendik ◽  
L.B. Vendik ◽  
D.V. Kholodnyak ◽  
S.P. Zubko ◽  
E.V. Serebryakova
Keyword(s):  
Transmission Lines ◽  
Phase Shifters ◽  
Left Handed

MULTISLOT TRANSMISSION LINES AND MICROWAVE PHASE SHIFTERS BASED ON (Ba,Sr)TiO3 FILMS

2008 ◽  
Vol 96 (1) ◽  
pp. 51-59
Author(s):  
I. G. Mironenko ◽  
A. A. Semenov ◽  
A. A. Ivanov ◽  
P. J. Beljavski ◽  
Chong-Yun Kang ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Phase Shifters
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