Tapered Transmission Line Research Articles

Superconducting nanowire single-photon detector with integrated impedance-matching taper

Conventional readout of a superconducting nanowire single-photon detector (SNSPD) sets an upper bound on the output voltage to be the product of the bias current and the load impedance, IB × Zload, where Zload is limited to 50 Ω in standard r.f. electronics. Here, we break this limit by interfacing the 50 Ω load and the SNSPD using an integrated superconducting transmission line taper. The taper is a transformer that effectively loads the SNSPD with high impedance without latching. At the expense of reduced maximum counting rate, it increases the amplitude of the detector output while preserving the fast rising edge. Using a taper with a starting width of 500 nm, we experimentally observed a 3.6× higher pulse amplitude, 3.7× faster slew rate, and 25.1 ps smaller timing jitter. The results match our numerical simulation, which incorporates both the hotspot dynamics in the SNSPD and the distributed nature in the transmission line taper. The taper studied here may become a useful tool to interface high-impedance superconducting nanowire devices to conventional low-impedance circuits.

Modeling Dynamic Response of Hydraulic Fluid Within Tapered Transmission Lines

This paper examines modeling of the laminar dynamic fluid responses within hydraulic transmission lines that have a tapered shape between the inlet and the outlet. There are excellent models available for fast simulation of pressure and flow dynamics within uniform lines; however, the established models for tapered lines either cannot be implemented in the time domain, are complex to implement, or have long simulation times. The enhanced transmission line method (TLM) structure is applied in this paper since it can be computed quickly in the time domain and has shown to accurately model the effects of frequency-dependent friction. This paper presents a method of optimizing the TLM weighting functions, minimizing the error between the TLM transmission matrix terms and a numerical ordinary differential equation (ODE) solution calculated using a boundary value solver. Optimizations have shown that using the TLM to model tapered lines can provide a fair approximation when compared in the frequency domain. Two-dimensional (2D) interpolation of a look-up table is possible allowing for quick selection of the optimized parameters. Further investigation into the effects of pipe wall elasticity and its inclusion into the TLM is also performed. Also, an experiment was performed to validate high frequency harmonic peaks present in the frequency response, which yielded acceptable results when compared to the theory, and the proposed tapered TLM. This model can be used in numerous applications where line dynamic effects must be accounted for, especially with digital hydraulic switched inertance converters where high frequencies are present.

A Compact Broadband Dual-Polarized Antenna Array for Base Stations

A compact ±45° dual-polarized broadband antenna array is proposed in this letter for base stations. For the sake of structural simplicity, low profile, and ease of mass production, printed dipoles are adopted as the dual-polarized antenna element. To achieve the broadband performance, radiators are designed to be spline-edged bowties, and they are fed by tapered transmission lines. Moreover, to improve the symmetry and stability of the radiation pattern, the Pawsey stub baluns are used to balance the antenna structure. Finally, an eight-element antenna array prototype backed by a folded reflector is fabricated and measured. The compact antenna array has a broad bandwidth of 68% (1.427-2.9 GHz) with a voltage standing-wave ratio less than 1.5 and stable radiation properties to provide international mobile telecommunication services over 2G/3G/LTE systems and Land S-bands released recently.

A compact resistively-loaded dipole antenna fed by a triangular tapered transmission line for imaging applications

This study proposes a compact resistively loaded dipole antenna (CRDA) for imaging applications. The triangular tapered transmission line has been introduced to feed the balanced structure of the CRDA and 78.5% of energy was successfully delivered to the end of the transmission line. The fabricated CRDA, which was fed by the triangular tapered transmission line, has been analyzed in terms of the characteristics of its reflected pulse and current distribution for image quality aspects by comparing it with a conventional dipole antenna (CDA). Using the CRDA, the imaging experiment for a perfect electric conductor (PEC) target and fabricated a multi-layered head phantom was performed. With this experiment, the target image has been successfully reconstructed by the delay and sum technique in the end.

Comments on “Microstrip T-Junction Power Divider With Exponentially Tapered Transmission Lines”

In the above paper, Smith and Sigmarsson [1] proposed a T-junction unequal power divider using exponentially tapered transmission line (ENTL) and uniform transmission line (UTL). However, the cutoff wavelength $\lambda _{c}$ defined in [1] and also in [2] , from which the definition of $\lambda _{c}$ has been adopted, are incorrect. So the entire analysis and design equations of [1] are questionable. Also, the authors have not shown the amplitude and phase imbalance variation over the frequency.

Response to Comments on “Microstrip T-Junction Power Divider With Exponentially Tapered Transmission Lines”

The authors recognize that the equation for the cutoff wavelength $\lambda _{c}$ in [1] is incorrect. It is unfortunate as it was directly used in the derivations in [2] . However, the authors would like to emphasize that by using the correct equation for $\lambda _{c}$ , the rest of the analysis in [2] is valid for the magnitude of the S-parameters, as was demonstrated in the comment by Sinha and Chatterjee [3] . In fact, this correction greatly improves the agreement between the theoretical, simulated, and measured responses. Using the corrected expression for $\lambda _{c}$ , updated results for Prototype 2 are shown in Fig. 1 .

Four-Arm Spiral Antenna Fed by Tapered Transmission Line

This letter presents a four-arm Archimedean spiral antenna with a novel integrated tapered transmission line feed structure. The center-fed spiral antenna consists of a radiation region with an Archimedean spiral configuration and a transmission region that comprises four spiral-shaped transmission lines with exponentially decreasing widths. The tapered transmission line, acting as an impedance transformer, provides a broadband matching network between the 50-Ω input impedance and the higher impedance of the radiation region. Using this design, a mode-1 spiral antenna attains a return loss of greater than 15 dB and a 3-dB broadside axial ratio throughout the 0.8–3-GHz band. The fabricated antenna demonstrates good agreement between the simulated and measured results.

Numerical estimation for TEM horn antennas with transmission line taper shapes

Numerical estimation for TEM horn antennas with transmission line taper shapes

Microstrip T-Junction Power Divider With Exponentially Tapered Transmission Lines

A method is provided for calculating the port parameters of an exponentially tapered power divider. Derived from the general solution for the input impedance of an exponentially tapered line, a design methodology for power dividing ratios from 2–10 dB is shown. An analytic formula for the power dividing ratio is expressed in terms of input impedances of the T-junction. Two devices are fabricated and measured. The resulting measurements are in agreement with the predicted power dividing ratios. The two devices operate over a frequency range 1.5–5 GHz and 1.75–3.5 GHz with power dividing ratios of 7.6 dB and 9.3 dB, respectively.

Lumped-element model of a tapered transmission line for impedance matching in a pulsed power system

In a pulsed power system, impedance matching is one of the significant factors for increasing the efficiency of the system. One of the most general methods for impedance matching is to use a tapered transmission line. Because the characteristics of a tapered transmission line are changed continuously according to its position, modeling the tapered transmission line by using lumped elements is difficult. In this study, we investigated a tapered transmission line to match the impedance of power supply to that of a load by using lumped elements especially in a pulsed power system. In modeling the tapered transmission line, we used the concept of a transmission, and we introduced an efficient modeling method. We propose a simulation model based on the investigation results. The results of the study will be useful for research on tapered transmission lines.

High-speed, high-voltage pulse generation using avalanche transistor.

In this work, the conduction mechanism of avalanche transistors was demonstrated and the operation condition for generating high-speed pulse using avalanche transistors was illustrated. Based on the above analysis, a high-speed and high-voltage pulse (HHP) generating circuit using avalanche transistors was designed, and its working principle and process were studied. To improve the speed of the output pulse, an approach of reducing the rise time of the leading edge is proposed. Methods for selecting avalanche transistor and reducing the parasitic inductance and capacitance of printed circuit board (PCB) were demonstrated. With these instructions, a PCB with a tapered transmission line was carefully designed and manufactured. Output pulse with amplitude of 2 kV and rise time of about 200 ps was realized with this PCB mounted with avalanche transistors FMMT417, indicating the effectiveness of the HHP generating circuit design.

Nonuniform transmission lines analysis by meshless point interpolation methods

AbstractThree meshless time domain methods are investigated for the solution of the telegrapher's equation applied to the nonuniform transmission line. The approach is based on a combination of the point interpolation methods and the leapfrog algorithm. The accuracy of the proposed methods is confronted with both the Finite‐Difference Time‐Domain (FDTD) and the wavelet expansion methods. The strong stability, the flexibility, and the fast convergence of the computing scheme are set in evidence from the computational results for two examples: the linear tapered transmission line and the transmission line balun. Copyright © 2015 John Wiley & Sons, Ltd.

Application of Particle Swarm Optimization to Microwave Tapered Microstrip Lines

Application of metaheuristic algorithms has been of continued interest in the field of electrical engineering because of their powerful features. In this work special design is done for a tapered transmission line used for matching an arbitrary real load to a 50{\Omega} line. The problem at hand is to match this arbitrary load to 50 {\Omega} line using three section tapered transmission line with impedances in decreasing order from the load. So the problem becomes optimizing an equation with three unknowns with various conditions. The optimized values are obtained using Particle Swarm Optimization. It can easily be shown that PSO is very strong in solving this kind of multiobjective optimization problems.

APPLICATION OF PARTICLE SWARM OPTIMIZATION TO MICROWAVE TAPERED MICROSTRIP LINES

Application of metaheuristic algorithms has been of continued interest in the field of electrical engineering because of their powerful features. In this work special design is done for a tapered transmission line used for matching an arbitrary real load to a 50Ω line. The problem at hand is to match this arbitray load to 50 Ω line using three section tapered transmission line with impedances in decreasing order from the load. So the problem becomes optimizing an equation with three unknowns with various conditions. The optimized values are obtained using Particle Swarm Optimi zation. It can easily be shown that PSO is very strong in solving this kind of multiobjective optimization problems .

切比雪夫渐变线TEM喇叭天线数值模拟

切比雪夫渐变线TEM喇叭天线数值模拟

Design, Realization, and Experimental Test of a Coaxial Exponential Transmission Line Adaptor for a Half-Impulse Radiating Antenna

This paper describes the simulation, design, realization, and experimental test of a tapered transmission line (TL) for adapting a broad-band impulse generator to a radiating antenna, for a frequency range of 50 MHz-1 GHz. Two different taper geometries are considered and discussed in the analysis: exponential and logarithmic. Two analysis methods are also used: 1) analytical equations obtained by applying the TL theory and 2) full-wave numerical simulations in both frequency and time domains using Comsol. It is shown that, in general, an exponential taper performs better than a logarithmic one, particularly at high frequencies. Time-domain simulations reveal that, for fast transient subnanosecond pulses, both tapers can be used equivalently and the signal does not suffer from any significant distortion while traveling along the tapers. We also show that analytical equations obtained using the TL theory are in very good agreement with full-wave simulation results and can be used advantageously in the design of tapers. This paper also presents the mechanical design and the realization of an exponential taper used for the connection of a 50-Ω pulser to a half-impulse radiating antenna (HIRA) having an input impedance of 100-Ω . The realized taper is fully characterized in the frequency domain using a vector analyzer and in the time domain using a reflectometer and shown to be performing in agreement with the simulations.

GAIN ENHANCEMENT OF REFLECTOR BASED IMPULSE RADIATING ANTENNAS: AN INNOVATIVE APPROACH

Conventional re∞ector based Impulse Radiating Antennas (IRA's) are designed with conical taper transmission line feed. A novel feed design approach is used to enhance gain of the IRA without increasing diameter of the re∞ector. This paper discuses conventional and new IRA designs of difierent input impedances. IRA with conventional feed and with new dipole feed is designed for both 200› and 100› input impedance category. The IRA with new feed design ofiers better gain compared to conventional IRA for both 200› and 100› input impedance category. These antenna designs are analyzed using the Finite Difierence Time Domain (FDTD) method and the result obtained shows that IRAs with new dipole feed ofiers better gain than IRAs with conventional feed for respective input impedance category without any compromise in time domain characteristics. A half IRA with new feed with input impedance of nearly 50› was realized and measured to establish the advantage of new dipole feed IRA.

Capacitance Modeling and Characterization of Planar MOSCAP Devices for Wideband-Gap Semiconductors With High-$\kappa$ Dielectrics

This paper presents a capacitance model and mobility extraction method through the use of tapered transmission line theory for accumulation-mode MOSCAP test structures. The analytical model accounts for the discrepancies commonly found when measuring the capacitance of nontraditional MOSCAP architectures. Through fabrication of a planar MOSCAP, this model accurately reproduced consistent capacitance density measurements for several device dimensions and high-κ dielectric thicknesses. In this paper, the theoretical basis of the model extracts the effective electron mobility of the accumulation channel in the semiconductor without fabricating a transistor.

An Eight-Way Radial Switch Based on SIW Power Divider

This paper presents a single-pole eight-throw switch, based on an eight-way power divider, using substrate integrate waveguide(SIW) technology. Eight sectorial-lines are formed by inserting radial slot-lines on the top plate of SIW power divider. Each sectorial-line can be controlled independently with high level of isolation. The switching is accomplished by altering the capacitance of the varactor on the line, which causes different input impedances to be seen at a central probe to each sectorial line. The proposed structure works as a switching circuit and an eight-way power divider depending on the bias condition. The change in resonant frequency and input impedance are estimated by adapting a tapered transmission line model. The detailed design, fabrication, and measurement are discussed.

Modeling of Electromagnetic Wave Propagation with Tapered Transmission Line

Tapered transmission line was used for impedance matching, for high voltage pulse, and atmospheric medium is applied to characteristic equation of tapered transmission line and reflection coefficient so that nonlinear load and circuit modeling of atmospheric medium was simulated by electromagnetic transient program (EMTP). A characteristic of atmospheric medium and Time delay are decided by inductance and capacitance of tapered transmission line. For electromagnetic wave propagation modeling, in this paper, tapered transmission line is implemented. It is difficult to model tapered transmission line directly. Other transmission line that can be expressed by the circuit is used. So object of this paper is efficient modeling of tapered transmission line.