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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.
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.
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 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.
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 Negative Group Delay Circuits With Independent Group Delay and Transmission Loss/Gain Control
(2020-04-01)
Zhang, Tiedi
;
Yang, Tao
;
Chi, Pei-Ling
;
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 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.
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.
Tunable Bandstop Filter Using Distributed Coupling Microstrip Resonators With Capacitive Terminal
(2020-01-01)
Li, Qun
;
Chen, Xiong
;
Chi, Pei-Ling
;
Yang, Tao
;
電機工程學系
This letter presents a varactor-based tunable bandstop filter (BSF) using distributed coupling microstrip resonators with the capacitive terminal. Each distributed coupling microstrip resonator consists of a coupling microstrip line, a varactor, and a capacitive terminal which is a floating pad connected to the cathode of the varactor. The capacitive terminal serves not only as a bias pad for the control voltage but also as an intrinsic capacitive path to ground. Compared to the conventional inductive terminal with the metallized via, the capacitive terminal can be beneficial to realize much higher frequency responses by taking advantage of the capacitance to ground from the floating pad. High stopband suppression level is achieved by cascading multiple distributed coupling microstrip resonators. For demonstration, a tunable BSF prototype with the frequency tuning range of 11.3-16.5 GHz (37) is designed and fabricated. Measured and simulated results agree well and validate the design principle.
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.

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