Browsing by Author "Yang, Tao"

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A 1.1-3.1-GHz Tunable Quadruplexer with Compact Size and Bandwidth Control
(2019-01-01)
Chi, Pei-Ling
;
Chi, Yu-Wen
;
Yang, Tao
;
電機工程學系
;
Department of Electrical and Computer Engineering
This paper proposes a varactor-tuned quadruplexer that allows simultaneous control of the center frequency and bandwidth of each channel and independent control on different channels. To achieve compactness, each channel consists of only a dual-mode resonator where the even- and odd -mode resonances contribute to a two -pole response. The fabricated prototype shows that, for the input return loss greater than 10 dB, the available tuning ranges of the channel frequency and the 3 -dB bandwidth are 1.1-1.4 GHz and 100-140 MHz, 1.55-1.9 GHz and 120-150 NIIIz, 2.05-2.4 GlIz and 190-240 MHz, and 2.63-3.1 GlIz and 240270 NHIz, respectively, for channels 1, 2, 3, and 4. The channel insertion loss is less than 5 dB and isolation is greater than 25 dB for all tuning states. The quadruplexer has a footprint of 0.45 lambda(g) x 0.25 lambda(g), where lambda(g) is the guided wavelength at 1.1 GHz.
A 1.3-2.08 GHz Filtering Power Divider With Bandwidth Control and High In-Band Isolation
(2016-06)
Chi, Pei-Ling
;
Yang, Tao
;
電機學院
;
College of Electrical and Computer Engineering
This letter proposes a varactor-based filtering power divider that allows for reconfigurable operating frequency and bandwidth with high in-band isolation. A simple but effective tuning scheme was used to attain good impedance matching and isolation for all tunable states. Experimental results show that, for input return loss > 16.6 dB, the center frequency and 1 dB constant absolute bandwidth can be tuned from 1.3 to 2.08 GHz and from 70 to 130MHz, respectively. Moreover, this work demonstrates > 26 dB output isolation, < +/- 0.23 dB magnitude imbalance, and < +/- 1.3 degrees phase imbalance. Measured and simulated results are in good agreement.
A Fully Tunable Two-Pole Bandpass Filter
(2015-05-01)
Chi, Pei-Ling
;
Yang, Tao
;
Tsai, Tsung-Ying
;
電機資訊學士班
;
Undergraduate Honors Program of Electrical Engineering and Computer Science
In this letter, a two-pole tunable combline filter that allows for operational agility of the center frequency, passband bandwidth, and locations of upper and lower transmission zeros is proposed. To increase the tunable range of constant absolute-bandwidth for all frequency tuning states, a novel T-type bandwidth-control network was devised between resonators to flexibly tune the coupling coefficient without limitations imposed by the available varactor capacitance. By use of tunable source-load coupling, two tunable transmission zeros were produced on both sides of the passband to significantly improve filter selectivity and to dynamically afford interference suppression. A second-order 1.7-2.7 GHz filter with 1 dB constant bandwidth tuning from 50 to 110 MHz and transmission zero locations tuning from 300 to 700 MHz with respect to the passband was developed and fabricated. Good agreement was obtained between the simulated and experimental results.
A general analytical model for head response to oscillatory pumping in unconfined aquifers: effects of delayed gravity drainage and initial condition
(2019-03-08)
Huang, Ching-Sheng
;
Tsai, Ya-Hsin
;
Yeh, Hund-Der
;
Yang, Tao
;
環境工程研究所
Oscillatory pumping tests (OPTs) provide an alternative to constant-head and constant-rate pumping tests for determining aquifer hydraulic parameters when OPT data are analyzed based on an associated analytical model coupled with an optimization approach. There are a large number of analytical models presented for the analysis of the OPT. The combined effects of delayed gravity drainage (DGD) and the initial condition regarding the hydraulic head are commonly neglected in the existing models. This study aims to develop a new model for describing the hydraulic head fluctuation induced by the OPT in an unconfined aquifer. The model contains a groundwater flow equation with the initial condition of a static water table, Neumann boundary condition specified at the rim of a partially screened well, and a free surface equation describing water table motion with the DGD effect. The solution is derived using the Laplace, finite-integral, and Weber transforms. Sensitivity analysis is carried out for exploring head response to the change in each hydraulic parameter. Results suggest that the DGD reduces to instantaneous gravity drainage in predicting transient head fluctuation when the dimensionless parameter a(1) = epsilon S(y)b/K-z exceeds 500 with empirical constant epsilon, specific yield S-y, aquifer thickness b, and vertical hydraulic conductivity K-z. The water table can be regarded as a no-flow boundary when a(1) < 10(-2) and P < 10(4) s, with P being the period of the oscillatory pumping rate. A pseudo-steady-state model without the initial condition causes a time-shift from the actual transient model in predicting simple harmonic motion of head fluctuation during a late pumping period. In addition, the present solution agrees well with head fluctuation data observed at the Savannah River site. Highlights. An analytical model of the hydraulic head due to oscillatory pumping in unconfined aquifers is presented. Head fluctuations affected by instantaneous and delayed gravity drainages are discussed. The effect of the initial condition on the phase of head fluctuation is analyzed. The present solution agrees well with head fluctuation data taken from field oscillatory pumping.
A pi-type Isolation Network for Improvement of Matching and Isolation in Reconfigurable Multifunctional Bandpass Filter
(2019-01-01)
Zhu, Xu
;
Yang, Tao
;
Chi, Pei-Ling
;
Xu, Ruimin
;
交大名義發表
In this paper, a method for improving the output impedance match and isolation between output ports of the reconfigurable single-to-balanced (SE-BAL), power-dividing (PD) and single-ended (SE) multifunctional filter is presented. By adding the varactor-tuned pi-type isolation network to the outputs of the tunable multifunctional filter, both the matching and isolation at the output ports are improved to a large degree over the full tuning range. Compared to the original standalone multifunctional filter, the measured output return loss and isolation of the filter with pi-type isolation network are improved by more than 10 dB at center frequency of each tuning state under the SE-BAL and PD filtering mode, while the measured output return loss and isolation for the SE filtering mode still keeps better than -20 dB in the whole tuning range.
A Reconfigurable In-Phase/Out-of-Phase and Power-Dividing Ratio Power Divider
(2017-01-01)
Chi, Pei-Ling
;
Chi, Yu-Wen
;
Yang, Tao
;
資訊工程學系
;
電機工程學系
This paper presents a varactor-based power divider with reconfigurable power-dividing ratio and reconfigurable in-phase or out-of-phase phase relation between outputs. By properly controlling the tuning varactors, the power divider can be either in phase or out of phase and each with a wide range of tunable power-dividing ratio. The proposed microstrip power divider was prototyped and experimentally characterized. Measured and simulated results are in good agreement.
Analysis of radially convergent tracer test in a two-zone confined aquifer with vertical dispersion effect: Asymmetrical and symmetrical transports
(2019-09-05)
Huang, Ching-Sheng
;
Tong, Chenchen
;
Hu, Wei-Shan
;
Yeh, Hund-Der
;
Yang, Tao
Radially convergent tracer test (RCT) with an extraction well and a tracer injection well is commonly conducted for determining aquifer dispersivity associated with the spreading of contamination plume. A variety of analytical models for RCT have been proposed, but the effects of skin zone and vertical dispersion are rarely explored. In addition, little attention is paid to the validity of those analytical models assuming asymmetrical tracer transport (ATT) as radially symmetrical transport (RST) toward the pumping well. This study develops a new analytical model for RCT subject to the above-mentioned effects in a confined aquifer with a skin zone around the wellbore. The Laplace-domain solution of the model for a continuous or instantaneous input is developed. A finite element solution (FES) for AFT is also developed to verify the Laplace-domain solution based on RST. Results suggest ATT can be regarded as RST in predicting the breakthrough curve (BTC) at the pumping well when four quantitative conditions are met. A lumped dimensionless parameter dominates those two effects on the BTC. Both the FES and Laplace-domain solution agree with monitored concentration data from a field RCT.
Folded Substrate Integrated Waveguide Based Composite Right/Left-Handed Transmission Line and Its Application to Partial H-Plane Filters
(2013-02-01)
Yang, Tao
;
Chi, Pei-Ling
;
Xu, Ruimin
;
Lin, Weigan
;
電機資訊學士班
Composite right/left-handed (CRLH) transmission line structures based on the folded substrate integrated waveguide (FSIW) are presented and discussed in this paper. This FSIW-based CRLH (FSIW-CRLH) transmission line exhibits much lower cut-off frequencies as compared to the ordinary FSIW of the same footprint, and furthermore, it requires only one-half width of the conventional substrate integrated waveguide (SIW) based CRLH (SIW-CRLH) transmission lines while possessing the same dispersion characteristics. In addition, the proposed structure offers the advantage of a high quality factor for preventing the guided-wave circuits from radiation as suffered in the previous open CRLH transmission line structures when operated in the fast-wave region. All of the aforementioned properties lend the proposed FSIW-based CRLH transmission lines best suited to miniaturized and guided-wave microwave applications. In this paper, a comprehensive study on the FSIW-CRLH transmission structures is conducted by means of its dispersion relation and Bloch impedance. In addition, two partial H-plane filters are implemented here to demonstrate the capabilities of miniaturization and high quality factor based on the proposed FSIW-CRLH structures. The resultant filters are shown to have about 80% size reduction as compared to the conventional FSIW filters, and 59% size reduction as compared to the SIW-CRLH filters. To the best of our knowledge, it is the first time that the partial H-plane filters are implemented utilizing both the dispersion behavior of the CRLH transmission structures and the structural benefits of the FSIW configuration.
High-Gain Patch-Fed 3D-Printing Fresnel Zone Plate Lens Antenna for 60-GHz Communications
(2018-01-01)
Chi, Pei-Ling
;
Pao, Chi-Hsien
;
Huang, Ming-Hui
;
Yang, Tao
;
電機工程學系
This paper presents a high-gain Fresnel zone plate lens antenna designed for 60-GHz systems. Manufactured with the 3D printing technology and fed by a simple patch on the substrate, the proposed Fresnel lens antenna allows for low-cost fabrication and easy integration with planar circuitry. Experimental results show that the prototype antenna can achieve a 10-dB impedance bandwidth from 56.6 GHz to > 67 GHz and the peak gain of 14 similar to 20 dBi across the bandwidth, corresponding to gain enhancement of 9.2 similar to 10.9 dB.
New Analytical Models for Flow Induced by Pumping in a Stream-Aquifer System: A New Robin Boundary Condition Reflecting Joint Effect of Streambed Width and Storage
(2020-04-01)
Huang, Ching-Sheng
;
Wang, Zicheng
;
Lin, Ye-Chen
;
Yeh, Hund-Der
;
Yang, Tao
A Robin type boundary condition (BC), commonly adopted at stream-aquifer interface, excludes a term associated with streambed accounting for the effects of streambed storage and width. This study presents two new analytical models for describing confined flow induced by pumping in a stream-aquifer system. One model considers a single-zone aquifer and treats the streambed as a lagging Robin BC with a time lag parameter related to the effects. The other considers a two-zone aquifer consisting of aquifer and streambed zones. A Dirichlet BC for stream water level is specified at the edge of the streambed. The time-domain solutions of both models are developed to describe spatiotemporal drawdown and temporal stream filtration/depletion rate (SDR). The finite element solutions (FESs) of both models are also built. Results suggest the lag time equals the half of the squared streambed width divided by the streambed hydraulic diffusivity. The effects of streambed width and storage on SDR should be considered when their lumped parameter exceeds 0.1. Neglecting their effects causes 25% difference in SDR when the lumped parameter equals 10. Based on the FESs, the use of the lagging Robin BC takes nearly a tenth of computing time of obtaining accurate steady-state SDR for the simulation of the two-zone aquifer. In addition, the present solutions agree to a field SDR experiment conducted by Hunt et al. (2001, ). To conclude, this study presents two new models for describing groundwater flow in a stream-aquifer system and explores the joint effect of streambed width and storage on SDR. Key Points Two new analytical solutions are developed to estimate aquifer drawdown and stream depletion rate in a pumped stream-aquifer system One treats streambed as a Robin type boundary based on the lagging theory while the other considers streambed as a finite-width zone The lag time in the Robin boundary equals the half of squared streambed width divided by the streambed hydraulic diffusivity
Novel 1.5-1.9 GHz Tunable Single-to-Balanced Bandpass Filter With Constant Bandwidth
(2016-12)
Chi, Pei-Ling
;
Yang, Tao
;
電機工程學系
;
Department of Electrical and Computer Engineering
A novel tunable single-to-balanced bandpass filter is proposed in this letter. It consists of pairs of stepped-impedance resonators (SIRs), which are connected by back-to-back varactors in between. Based on such a simple structure, the filter can cover from 1.5 GHz to 1.9 GHz with constant absolute bandwidth, and exhibit differential outputs in each tuning state. The amplitude and phase imbalances between each differential outputs are less than 0.7 dB and 3 degrees, respectively, in the passband of each tuning state.
Novel 1.5-2.4 GHz Tunable Single-to-Balanced Diplexer
(2016-10)
Chi, Pei-Ling
;
Yang, Tao
;
電機學院
;
College of Electrical and Computer Engineering
A novel tunable single-to-balanced diplexer are proposed in this letter. The single-to-balanced diplexer consists of pairs of stepped-impedance resonators (SIRs), which are connected by back-to-back varactors in between. The diplexer can cover from 1.5 to 2.4 GHz, with constant absolute bandwidth. Moreover, the single-to-balanced diplexer exhibits differential outputs in each tuning state. Simulations and measurements are in excellent agreement. To the authors\' best knowledge, it is the first tunable single-to-balanced diplexer based on printed circuit board (PCB) technology that has been reported so far for multi-standard communication systems.
Novel Compact Partial-H Plane Filter Based on the Composite Right/Left-Handed Transmission line in Folded Substrate-Integrated Waveguide
(2012)
Chi, Pei-Ling
;
Yang, Tao
;
電機資訊學士班
;
Undergraduate Honors Program of Electrical Engineering and Computer Science
A novel compact partial-H plane bandpass filter based on the composite right/left-handed (CRLH) transmission line in folded substrate-integrated waveguide (SIW) is proposed in this paper. The proposed filter consists of four identical CRLH resonators that resonate at the negative first-order resonant mode and occupy very compact physical sizes. Furthermore, the resonators were designed to be implemented in the folded SIW structure for suppressing the inherent fast-wave radiation phenomenon of the CRLH structure. As a result, the proposed filter combines the advantages of the CRLH structure for miniaturization and the SIW for high quality factors. Therefore, the resulted filter requires much smaller size as compared to the conventional SIW partial-H plane filter while exhibiting a much higher quality factor as compared to the conventional CRLH bandpass filters. A filter prototype with center frequency at 4.8 GHz was designed, fabricated and tested to demonstrate these features. Measured results agree well with the theoretical results.
Novel Evanescent-Mode Cavity Filter With Reconfigurable Rat-Race Coupler, Quadrature Coupler and Multi-Pole Filtering Functions
(2020-01-01)
Lai, Junchen
;
Yang, Tao
;
Chi, Pei-Ling
;
Xu, Ruimin
;
電機工程學系
A novel evanescent-mode cavity filter with multiple reconfigurable functions including filtering rat-race coupler, filtering quadrature coupler and multi-pole filtering is proposed in this paper. It simply consists of four substrate integrated waveguide (SIW) evanescent-mode cavity resonators which are arranged in a ring loop. By loading piezoelectric actuators on top of each resonator and inserting varactors between adjacent resonators, the structure can achieve multiple reconfigurable functions among filtering rat-race coupler, filtering quadrature coupler and single-ended multi-pole filters, in addition to continuously frequency, independent bandwidth, and power-division tuning. Measurement shows that the filtering quadrature coupler corves a frequency range of 2.08-3.00 GHz with insertion loss of 2.99 & x00B1; 0.31dB, while the filtering rat-race coupler corves a frequency range of 2.31-2.71 GHz with insertion loss of 2.97 & x00B1; 0.13dB; The single-ended filter can be switched among two-pole, three-pole, and four-pole with frequency range of 2.38 to 3.01 GHz, 2.47 to 3.08 GHz and 2.53 to 3.00 GHz, respectively. Good agreement is obtained between simulated and measured results.
Novel Reconfigurable Filtering Rat-Race Coupler, Branch-Line Coupler, and Multiorder Bandpass Filter With Frequency, Bandwidth, and Power Division Ratio Control
(2020-04-01)
Zhu, Xu
;
Yang, Tao
;
Chi, Pei-Ling
;
Xu, Ruimin
;
電機工程學系
In this article, for the first time, a novel four-port coupler with reconfigurable multifunctions of filtering rat-race coupler (FRC), filtering branch-line coupler (FBC), and conventional single-ended two-port multipole bandpass filter (BPF) is proposed. It simply consists of four varactor-loaded stepped-impedance resonators that are arranged symmetrically. Through appropriate coupling-type (electrical coupling or magnetic coupling) conversion, 90 degrees or -90 degrees phase shift between the adjacent resonators can easily be obtained and works as a key factor in the transformation between different filtering coupler modes. With this simple configuration, the proposed coupler achieves reconfigurable FRC and FBC with not only operating frequency tuning over a wide tuning range but also bandwidth and power division ratios (PDRs) control for each filtering mode. In addition, by imposing open circuit at any two ports, the four-port coupler can be converted to the conventional single-ended two-port BPFs with reconfigurable filter orders of second, third, and fourth. The measured results show that the FRC and FBC can continuously cover the frequency ranges of 1.21-1.67 and 1.2-1.61 GHz with -1-dB bandwidth tuning of 60-120 and 55-110 MHz, respectively. The 3- and 6-dB PDRs have been demonstrated for both filtering coupler modes. In single-ended two-port BPF mode, the frequency tuning ranges are measured of 1.12-1.6, 1.16-1.6, and 1.2-1.61 GHz, respectively, for the proposed two-port second-, third-, and fourth-order BPFs. Measured and simulated results are in good agreement, validating the proposed design method.
Novel Reconfigurable Negative Group Delay Circuits With Independent Group Delay and Transmission Loss/Gain Control
(2020-04-01)
Zhang, Tiedi
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Yang, Tao
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Chi, Pei-Ling
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電機工程學系
;
Department of Electrical and Computer Engineering
A novel reconfigurable negative group delay (NGD) circuit based on branch-line coupler is proposed in this article. It consists of two branch-line couplers that are connected by two varactors with different capacitance values. By simply adjusting the capacitance values, both the transmission gain/loss and group delay (GD) values of the proposed circuit can be independently adjusted as desired. Full theoretical analysis has been given to verify the reconfigurable NGD responses. To compensate for the transmission loss, an active NGD circuit is also proposed by inserting two simple amplifiers in the transmission paths. The active circuit can also achieve independent transmission gain/loss and GD by tuning the amplifiers' gain with fixed capacitance value. Passive and active prototypes were designed, fabricated, and tested to demonstrate the proposed techniques. The experimental results show that NGD of the proposed passive circuit can be adjusted from 0 to -90 ns, while the gain varies from -14 to -53 dB. The GD of active circuit can also be adjusted from 0 to -80 ns, while the gain varies from 17 to -18 dB. These experimental results agree well with simulations.
Novel Reconfigurable Single-to-Balanced, Power-Dividing, and Single-Ended Filter With Frequency and Bandwidth Control
(2019-02-01)
Zhu, Xu
;
Yang, Tao
;
Chi, Pei-Ling
;
Xu, Ruimin
;
電機工程學系
In this paper, a novel tunable filter with reconfigurable single-to-balanced (SE-BAL), power dividing (PD), and single-to-single-ended (SE) filtering functionalities is proposed, for the first time, without any additional switching circuit. The proposed filter only consists of three stepped-impedance resonators, which are loaded and connected by varactors in between. With a very simple and compact configuration, the proposed filter achieves multiple reconfigurable functionalities between SE-BAL filtering, PD filtering, and conventional SE bandpass filtering. Moreover, the reconfigurable SE-BAL, PD, and SE bandpass filter can not only offer continuously frequency tuning over a wide tuning range but also have independent bandwidth tuning and maintain good phase/amplitude balance in each tuning state. The proposed filter is designed and fabricated with the microstrip line technology; the measured results show that the SE-BAL, PD, and SE filtering functions can be continuously tuned from 1.02 to 1.32, 0.96 to 1.27, and 1 to 1.28 GHz, with 1-dB bandwidth tuning from 30 to 60, 30 to 110, and 70 to 130 MHz, respectively. The amplitude and phase imbalances of the SE-BAL and PD bandpass filter are less than 0.4 dB, 1.3 degrees and 0.5 dB, 1.5 degrees, respectively, in the passband of each tuning state. Good agreement was obtained between simulated and measured results.
Novel Tunable Isolation Network Used in Ring-Type Single-to-Balanced, Power-Dividing, and Single-Ended Filter With Arbitrary Power-Division Ratios
(2020-02-01)
Zhu, Xu
;
Yang, Tao
;
Chi, Pei-Ling
;
Xu, Ruimin
;
電機工程學系
In this article, a novel tunable isolation network and a novel ring-type reconfigurable single-to-balanced (SE-BAL), power-dividing (PD), and single-to-single-ended (SE) bandpass filter is proposed. The tunable isolation network consists of a simple $\pi $ -type resistive network with tunable varactors, while the proposed filter consists of three ring-type stepped impedance resonators (SIRs) connected by varactors in between. By simply combining the proposed tunable isolation network and the proposed ring-type reconfigurable filter, it can achieve multiple reconfigurable functions among SE-BAL filtering, PD filtering, and conventional SE filtering with fully matched three ports, arbitrary power-division ratios (PDRs), high output isolations, and excellent amplitude and phase balance, in addition to continuous frequency and independent bandwidth tuning. The proposed filter is demonstrated using the microstrip line technology. The measured results show that the SE-BAL, PD, and two SE filtering functions can continuously cover the frequency ranges of 1.03-1.61, 1.01-1.53, 1.03-1.56, and 1.06-1.48 GHz with -1-dB bandwidth tuning of 35-80, 50-140, 60-130, and 70-140 MHz, respectively; the 1-, 3-, and 5-dB PDRs have been demonstrated for both SE-BAL and PD filtering modes. The measured output return losses and isolation are better than 19 and 18 dB, respectively, for SE-BAL filtering mode and 20 and 16 dB, respectively, for PD filtering mode. Good agreement is obtained between the simulated and measured results.
Review of analytical models to stream depletion induced by pumping: Guide to model selection
(2018-06-01)
Huang, Ching-Sheng
;
Yang, Tao
;
Yeh, Hund-Der
;
交大名義發表
;
環境工程研究所
Stream depletion due to groundwater extraction by wells may cause impact on aquatic ecosystem in streams, conflict over water rights, and contamination of water from irrigation wells near polluted streams. A variety of studies have been devoted to addressing the issue of stream depletion, but a fundamental framework for analytical modeling developed from aquifer viewpoint has not yet been found. This review shows key differences in existing models regarding the stream depletion problem and provides some guidelines for choosing a proper analytical model in solving the problem of concern. We introduce commonly used models composed of flow equations, boundary conditions, well representations and stream treatments for confined, unconfined, and leaky aquifers. They are briefly evaluated and classified according to six categories of aquifer type, flow dimension, aquifer domain, stream representation, stream channel geometry, and well type. Finally, we recommend promising analytical approaches that can solve stream depletion problem in reality with aquifer heterogeneity and irregular geometry of stream channel. Several unsolved stream depletion problems are also recommended.
Single-Layer Dual-Band Balanced Substrate- Integrated Waveguide Filtering Power Divider for 5G Millimeter-Wave Applications
(2020-06-01)
Chi, Pei-Ling
;
Chen, Yi-Ming
;
Yang, Tao
;
電機工程學系
;
Department of Electrical and Computer Engineering
A single-layer substrate-integrated waveguide (SIW) filtering power divider (FPD) with fully differential operation at 28 and 39 GHz is proposed in this letter. This FPD consists of three SIW cavities where the differential and common modes of each cavity were properly designed to form three-pole dual passbands, facilitate deployment of isolation resistors, and introduce transmission zeros while attaining high in-band common-mode rejection. To improve the output return loss and isolation in dual bands, a novel and simple approach to find the proper location of isolation resistors is presented. At operating frequencies, the measured differential-mode input or output return loss, minimum insertion loss, isolation, and common-mode suppression are >14.1 dB,< (3 + 2.2) dB, >14.9 dB, and >30.3 dB, respectively. The amplitude and phase imbalances between outputs are < 0.48 dB and <4.2 degrees, respectively.