Smith Chart Research Articles

Death and Rebirth in a Southern City: Richmond's Historic Cemeteries by Ryan K. Smith (review)

Reviewed by: Death and Rebirth in a Southern City: Richmond's Historic Cemeteries by Ryan K. Smith Lynn Rainville (bio) Ryan K. Smith Death and Rebirth in a Southern City: Richmond's Historic Cemeteries Baltimore: Johns Hopkins University Press, 2020 328 pages, 52 black-and-white illustrations ISBN: 9781421439273, $34.95 HB Not everyone's daily perambulations include a walk by or through a cemetery, but after reading Ryan K. Smith's book you might change your habits. In his latest book, Death and Rebirth in a Southern City: Richmond's Historic Cemeteries, Smith sets out an ambitious goal: to survey three hundred years of urban history by reviewing the concomitant changes to a city's burial grounds. This approach allows him to survey local community ideas about and attitudes toward Native Americans, enslaved and free African Americans, elite and poor Whites, as well as Christian and Jewish communities. By keeping his focus on one southern city—Richmond, Virginia—he is able to survey the diversity of mortuary traditions within that locale throughout numerous eras. As he insightfully observes, "The realm of the dead played an active part in all stages of the city's growth, providing a parallel history still capable of surprise" (10). Smith charts out a second and very timely goal: to explore the individuals (many of whom are recent transplants to the city) who have dedicated countless hours to preserving these sites and/or fighting to protect them. His interviews with these individuals are an important component of his research and this book. Smith's book is a welcome addition to the somewhat crowded field of cemetery studies. Most manuscripts focus upon either one burial ground in great detail or a specific type of cemetery, such as urban cemeteries influenced by the Rural Cemetery Movement, over time. While both approaches have their advantages, each are often too specialized for wider audiences. It is less common to find a scholar who is willing to research the burial grounds used by different ethnic, socioeconomic, and religious groups, while also covering a broad timeframe. In order to cover this wide range of topics, Smith organized his manuscript into eight chapters, plus an introduction and epilogue. The introduction connects the historic research to the function and importance of these sites in the present. In his first chapter, "The Churchyard," Smith integrates biographical examples from specific individuals into broader trends within Virginian history. By tracing specific deaths, such as the demise and burial of Parson Robert Rose (1703–1751), Smith provides a concrete example of how a person's identity and status in life dictates their burial options. In the next chapter, "The African Burial Ground," he traces the scant historic evidence for early African and African American burials and integrates them alongside the archaeological, topographical, and legal documentation. The accompanying figures and maps for this chapter are excellent and help the reader see that the sacred burial spaces for Black Americans are now hidden under modern highways and buildings. This chapter also provides an important overview of the preservation battles that have surrounded historic African American burial grounds in Richmond and provides a necessary context for the elite burials in nearby Shockoe Hill Cemetery (surrounded by sites such as the poorhouse and a Jewish burial ground). Chapter 3, "The New Burying Ground," discusses that cemetery in Shockoe Hill—originally for Whites only—which contains the bodies of Richmond's most prominent families, including governors, Revolutionary War heroes, congressmen, and professionals including ministers, physicians, businessmen, and lawyers. The multicentury trajectory of burials at this site enables Smith to track the evolution of mortuary traditions, the design of cemetery landscapes, and the function of these grounds to display and interpret the gradual desegregation of this formerly White [End Page 126] cemetery, and he also weaves individual biographies into larger historic narratives in a compelling fashion. As with most of the chapters in this book, the author discusses contemporary efforts to protect this site, including the formation in 2007 of the Friends of Shockoe Hill Cemetery, which cares for the site. This cemetery has an interesting challenge in the present: to reconcile "its position as 'a white aristocratic burial ground' set within a...

복소결합부하를 이용한 3.5 GHz 대역의 고효율 비대칭 도허티 전력증폭기 설계

In this study, a high-efficiency asymmetric Doherty power amplifier (DPA) based on a complex combining load (CCL) is presented. The CCL method extends the range of output back-off (OBO). This article provides a graphical design method using the Smith chart for the CCL-DPA load network. The proposed asymmetric DPA is designed using 6 and 10 W GaN-HEMTs for carrier and peaking amplifiers, respectively. With 3.5～3.6 GHz continuous-wave signal excitations, the implemented asymmetric CCL DPA exhibits a DE of 60.0～64.7 % and a PAE of 54.8～59.9 % at a maximum output power of 42.0～43.0 dBm. In addition, it has a DE of 51.3～51.6 %, and a PAE of 46.7～47.6 % at an output power of 35.0 dBm. Using an LTE signal with a PAPR of 7.5 dB and a signal bandwidth of 20 MHz, a power gain of 10.7～11.5 dB, a PAE of 44.0～45.1 %, a DE of 48.1～48.5 %, and an ACLR of −31.1 dBc are achieved. Using DPD linearization, ACLR is improved to −49.3/−50.4 dBc at an average power of 35.0 dBm.

Iconic Circles [Microwave Bytes

Discusses the Smith Chart. Ever since Phillip Hagar Smith's seminal article [1], it has been a fruitful topic for authors, in particular those who wish to vandalize it in various ways, so finding anything new to say on the subject is a bit challenging. But I thought it might be at least entertaining to give some of my own recollections on the subject. It is argued that the role of the Smith chart has gradually transitioned from a raw calculation aid into a valuable format for the visualization of device and network characteristics. It is ironic that the rapid calculation ability of the modern computer may have usurped the calculation function of the chart but has greatly enhanced its use as a meaningful display format.

An improved analytical method for triple stub matching (Stubs in Parallel)

In this paper we give the new improved analytical method of triple stub tuner for matching the load impedances to provide the maximum power transfer between a generator and a load. The stubs are connected in parallel with the line at the appropriate distances from the load. The characteristic impedances of the transmission line and the stabs are different. The paper points on the determination of the length for the first stub near the load. The limit lengths for the first and the second stub are found for which the matching is possible. The length of the third stub is directly obtained from the matching conditions. Even though there is not the unique solution for the triple stub matching we also shoved the existence of unique solutions under some conditions. The special cases are also treated. The results of this method are verified by those obtained using the Smith chart and there are in exceptionally good agreement. Even though there are not many papers on this subject this work could be useful for engineers, and physicist which work in this domain.

Ultra wide-angle and broad-band metamaterial absorber based on magneto-electric dipole structure

An ultra wide-angle and broad-band magneto-electric dipole like metamaterial absorber (MEDMA) was proposed. The trapezoidal resistance films on the top layer and the upright resistance films in the middle are both equivalent to electric dipoles. The metal back plate together with the resistance films on the top layer are equivalent to magnetic dipoles. The radiation characteristics of magnetic dipole and electric dipole determine that the composite structure can achieve low back radiation effect and equal E-plane and H-plane patterns. According to reciprocity principle, the composite structure will also have a better absorption performance when it is used as an absorber. Simulation results show that the absorption of the MEDMA is more than 90% under TM polarized waves of 3.4–8.0 GHz as the incident angle changes from 0° to 80°. For TE polarized waves of 3.2–9.0 GHz, the absorption with the incident angles of 0°–50° is more than 80%. The absorption performance for each part of the MEDMA was analyzed by the surface current distributions, and the impedance matching characteristics was demonstrated by Smith chart. This work may provide a technical way in stealth research.

Performance and size comparison of two-stage and three-stage axial turbines for a nitrogen gas Brayton cycle coupled with a sodium-cooled fast reactor

A nitrogen (N2) Brayton cycle is considered as an alternative to the conventional steam Rankine cycle to overcome essential risk during pressure boundary rupture accidents with sodium-water reaction in a steam-generator of a sodium-cooled fast reactor (SFR). The objectives of this study are to estimate the turbine performances after proposing three-dimensional (3-D) blade designs and to suggest an option of detailed turbine design for N2 Brayton cycle-SFR applications. A free-vortex design method was applied in the 3-D design. Three candidates, including two- and three-stage designs, were selected from the Smith charts. Aerodynamic losses were investigated and compared through computational fluid dynamics analyses for the cases selected above. According to the results, rotor blade with milder curvature increased proportions of secondary and tip leakage losses among the total aerodynamic loss. When comprehensively considering the turbomachinery size and cycle thermal efficiency, the size of the two-stage turbine could be reduced to under 55% of the three-stage turbine size, resulting in no significant decrement of the cycle efficiency.

Design of a 50-W Power Amplifier With Two- Octave Bandwidth and High-Efficiency Using a Systematic Optimization Approach

A wideband and highly efficient power amplifier (PA) is designed using a simple and systematic approach. This method employs an optimization process to set the input impedance of the matching networks in optimal regions on the Smith chart, obtained using conventional load-pull/source-pull simulations, in both the fundamental and second harmonics. The developed design method led to a GaN PA whose measurements showed an output power of 46.8–48.1 dBm and a drain efficiency of 57%–71% in a two-octave bandwidth from 0.8 to 3.2 GHz.

Design of a multi‐octave power amplifier using broadband load‐pull X‐parameters

AbstractThe design of a multi‐octave power amplifier (PA) based on a broadband load‐pull X‐parameter model is described for the first time in this work. A 10‐W GaN package transistor is employed for model X‐parameter model extraction. Once the model is extracted, it is compared with the equivalent circuit model provided from the device manufacturer, and it is found that the X‐parameter model accuracy is comparable to that of the original circuit model. In particular, the X‐parameter model can accurately determine the areas of the load Smith chart leading to optimal output power and drain efficiency, essential considerations for extracting maximum device performance. A Chebyshev low‐pass architecture is utilized for both the input and the output matching network designs. Finally, a multi‐octave bandwidth PA, from 0.6 to 2.3 GHz, is designed. Simulation results of the broadband X‐parameter model and the measured results of the realized PA are compared, with a high fidelity match evident, thus demonstrating the efficacy of the design procedure of multi‐octave PA with broadband X‐parameters. The output power of the realized PA across the operating frequency band remains between 39.51 and 42.41 dBm, while the drain efficiency remains above 60%, reaching as high as 73% around 2 GHz. The gain of the PA is greater than 11 dB over the complete frequency band.

Doherty Power Amplifier Based on Asymmetric Cells With Complex Combining Load

This article presents a Doherty power amplifier (DPA) based on asymmetric cells with a complex combining load (CCL). In this study, a new and intuitive design technique using the Smith chart is proposed for developing the load network of the CCL-DPA. The peaking amplifier consists of a larger cell size compared to that of the carrier amplifier in order to achieve higher power gain and peak output power in comparison with the conventional CCL-DPAs based on symmetric cells. For verification purposes, the proposed asymmetric CCL-DPA was designed and implemented using 6- and 10-W GaN-HEMTs for the carrier and peaking amplifiers, respectively. For the 1.68-GHz continuous-wave signal, the asymmetric CCL-DPA exhibited a power-added efficiency (PAE) of 68.0% and a drain efficiency (DE) of 73.9% at a peak output power of 43.5 dBm. When an output power back-off of 9.5 dB was used, a PAE of 52.0% and a DE of 54.7% were achieved. Using the long-term evolution signal with a peak-to-average power ratio of 9.6 dB and a signal bandwidth of 10 MHz, a PAE of 53.6%, a DE of 56.4%, and a power gain of 13.5 dB were obtained at a power level of 34.0 dBm. Using a digital predistortion technique, an adjacent channel leakage power ratio of -48 dBc was achieved at the same power level.

Bandwidth Enhancement of Microstrip Patch Antenna Using Metasurface

Abstract In this article, bandwidth enhancement of a microstrip patch antenna using a new kind of metasurface is discussed. This new geometry is used to generate new resonances in antenna and with an optimal position of the metasurface in relation to antenna we can overlap the resonances and obtain a large bandwidth. The proposed antenna showed a bandwidth from 5.1 GHz to 8.0 GHz what can it able to be applied in WiFi 5 and 6. Numerical results were obtained with Ansys HFSS software. A prototype was built and measurements for S11, Smith chart and gain were performed. Numerical and experimental results are in good agreement.

On optimum impedance pattern for accurate wideband noise parameter characterization

At least four source impedances are required to characterize the noise parameters of a two-port network. The accuracy of the noise parameters depends on the configuration of the employed source impedances (pattern). The configuration of a specified pattern, generated generally by an impedance tuner, changes with frequency, and as such, the accuracy is usually degraded in a wideband characterization. To realize a low-error wideband noise characterization, the present article thoroughly investigates the method of choosing a four-source impedance pattern. A Monte Carlo simulation-based approach is proposed to obtain the desired impedance patterns. The measurement and simulation results show that the noise parameters are accurately extracted when an impedance pattern is configured by a source impedance located near the center of the Smith chart and three other impedances located as close to the edge as possible with interphase separations of at least 45°. While the interphase separations remain unchanged, the impedance pattern rotation around the center of the Smith chart does not affect the accuracy of the extracted noise parameters, as demonstrated analytically here. The resultant impedance pattern realizes a wideband characterization from f0 to 3.5f0 without using an impedance tuner. The obtained accuracy is comparable to methods employing a redundant number of source impedances.

WITHDRAWN: Design and characteristics response of spiral patch monopole antenna on FR4 substrate

Abstract This paper describes the design aspects and development of the Monopole antenna on FR-4 using a single spiral patch technique with the optimized performance parameters that support dual band wireless communication techniques that are working on different applications with improved efficiency and impedance bandwidth to meet present and future wireless demands. This designed antenna covers the frequency ranges from 1.5 GHz to 3.5 GHz for L and S-band applications. Ansys HFSS is used to design and simulate the desired antenna. Using Vector Network Analyzer MS2027C-Anritsu, Return loss, VSWR, and impedance (Smith chart) values are measured and validated. E field and H field Radiation patterns are alo measured and validated using anechoic chamber.

Bandwidth Analysis of a Broadband Amplifier with Two-Stage Matching System Using the Smith Chart

This paper describes a novel trace structure for the analysis and design of two-stage Broadband Frequency Low Noise Amplifiers based on standard Smith chart procedures and program algorithm realization. The method allows to put the transistor's S-parameters and details of the source and load networks and to interactively explore the effects of these quantities on design variables such as gain, noise figure and stability. It also facilitates the design of two-element matching networks to transform the source and load impedances to optimum values to achieve the desired gain and noise performance. The extended Smith chart concept is proposed to enable the advanced graphical interpretation of devices containing complex properties. This methodology is based on the Smith chart concept, and makes it easy to deal with devices containing signal sources, nonlinearity, very high Q factors and negative resistances. The concept of explaining the use of the Smith chart in combination with using modern tools as MATLAB scripts is exemplified in graphical forms. Phyton-based program contains the algorithm for parameters calculation. It explains the procedure that must be used to solve the two-stage impedance-matching problem. The point of this proposal is using of Smith chart plane for the graphical processing for its application to oscillator analysis. To demonstrate the effective usage of this methodology an interpretation and analysis of the oscillator, especially in terms of gain, noise and stability, are provided. The practical relevance concludes results of multistage design using impedance matching LC networks for the intersection level. The values of the parameters of the integrated microcircuit confirm the possibility of using the calculation methodology considered in the paper. The proposed solution is validated with extensive RF measurements at 3.5 GHz and is benchmarked against several frequency ranges for noise, stability and gain values. The methodology shown in the paper can be used in the development and design of modern microwave amplifiers, as well as for research and analysis of the efficiency of existing devices.

Electromagnetic band gap based in Peano fractal geometry for harmonic suppression

AbstractIn this paper, an electromagnetic band gap structure with fractal geometry based on Peano curves is proposed to suppression of degenerated modes. The geometry is characterized by the inclusion of air slots into the substrate, under the feed line, of a rectangular microstrip patch antenna. The parameters analyzed are the input impedance using the Smith chart, the reflection coefficient (S11), radiation diagram and the electric field distribution of the propagation modes. The simulated results were compared with the measured results, obtained from manufactured prototypes and show that the proposed structure can be used to attenuate and suppress higher‐order modes.

The 3D Smith Chart: From Theory to Experimental Reality

The Smith chart was primarily developed, extended, and refined by Phillip Hagar Smith [1] in a series of works published [2]-[4] between 1939 and 1969. Smith was born in Lexington, Massachusetts, in 1905. He majored in electrical communications at Tufts University and joined the Radio Research Department of Bell Telephone Laboratories (now Bell Labs) in 1928. While there, in around 1930, Smith started work on the diagram that was to become the Smith chart. He submitted the initial version to Electronics Magazine in 1937; the magazine finally published his diagram in 1939 [2]. The MIT Radiation Laboratory started using the chart. In 1940, and in 1944 Smith published a second article that incorporated further improvements, including the use of the chart with either impedance or admittance coordinates. In 1952, Smith was elevated to IEEE Fellow for his contributions to the development of antennas and the graphical analysis of transmission-line characteristics. The first issue of Microwave Journal (1958) published a biography of Smith to acknowledge the importance of his contributions. In 1969, he wrote the book Electronic Applications of the Smith Chart in Waveguide, Circuit and Component Analysis; he retired from Bell Labs in 1970. In 1975, he received the IEEE Microwave Theory and Techniques Society?s Special Recognition in Microwave Applications award for the Smith chart, and in 1994 he was elected to the New Jersey Inventors Hall of Fame.

SPICE modeling for RF kink effect in body contacted PD‐SOI nMOSFETs

AbstractIn order to simulate anomalous RF kink effect where S21‐ and S22‐parameters in high‐resistivity partially depleted silicon‐on‐insulator MOSFETs with body contact rotate clockwise in the lower and upper semicircles of Smith chart, respectively, a new SPICE BSIMSOI4 macro model including empirical voltage‐dependent equations of current sources, inductance, capacitance, and resistance has been proposed. The accuracy of the empirical model is verified in the wide voltage range by comparing it with measured S‐parameters from 0.01 to 15 GHz.

Evaluation of the effect of dose change of Fe3O4 nanoparticles on electrochemical biosensor compatibility using hydrogels as an experimental living organism model

Morphological, structural, optical and dielectric properties, which provide important information about the technological applications of pure and different dose (2.5%, 5.0%, 7.5% and 10.0%) Fe3O4 nanoparticles (NPs) doped hydrogels were analyzed in detail in this study. The complex dielectric parameters of all the samples are related to the electrode/interface polarization (grain boundary), dielectric relaxation and grain effects in accordance with the Maxwell-Wagner theory and Brownian motion in the broadband frequency regions. Experimental plane plots of the complex electrical modulus for all the samples are explained by the Havriliak and Negami relaxation model represented by two relaxation times (α and γ) associated with resistances created by grain boundary (α) and grain (γ). In the high frequency region, complex electrical modulus plane plots of all the samples were compatible with the Cole-Cole relaxation model corresponding to the equivalent electrical circuit (RC) in the Smith Chart diagram. Koop's theory and electron hopping mechanism formed between Fe3+ and Fe2+ ions in the octahedral lattice are effective on the electrical conductivity values of the samples. As the molarity of Fe3O4 NPs increased, the logarithmic conductivity values of all samples, which a function of the angular frequency and defined by the Jonscher Power Law, Nearly Constant Loss and Super Linear Power Law conductivity mechanisms, were generally increased. From the experimental results, it was concluded that the hydrogels with high doses of Fe3O4 NPs can be used as an electrochemical biosensor in bio-systems since it has the high dielectric, capacitance, low impedance and conductivity values.

Machine learning-based broadband GaN HEMT behavioral model applied to class-J power amplifier design

AbstractA novel, broadband, nonlinear behavioral model, based on support vector regression (SVR) is presented in this paper. The proposed model, distinct from existing SVR-based models, incorporates frequency information into its formalism, allowing the model to perform accurate prediction across a wide frequency band. The basic theory of the proposed model, along with model implementation and the model extraction procedure for radio frequency transistor devices is provided. The model is verified through comparisons with the simulation of an equivalent circuit model, as well as experimental measurements of a 10 W Gallium Nitride (GaN) transistor. It is seen that the efficiency prediction throughout the Smith chart, for varying fundamental and second harmonic loads, across a wideband frequency range, show excellent fidelity to the measured results. Device dc self-biasing is also modelled to allow prediction of power amplifier (PA) efficiency, which is shown to be highly accurate when compared with corresponding measured data. Finally, a class-J PA is constructed and measured across the frequency with a large-signal input tone. The resulting measured and modelled values of key PA performance figures are shown to be in excellent agreement, indicating the model is suitable for broadband PA design.

Design and Simulation of Half Wave-dipole Antenna for LTE Applications Using CST microwave Studio

One of the most important and widely used Radio frequency (RF) antennas is the dipole antenna. This is commonly used on its own and is also integrated into many other prototypes of the RF antenna, where it is the guiding factor for the antenna. An effort has been made in this project to study the latest half wave dipole antenna for LTE Applications. The dipole antenna, which is nearly one-half wavelength long, is known as the half-wave dipole antenna. The antenna was designed for resonating at the frequency of 2.6 GHz. For the simulation and design calculations CST is used. In this project various factors of antenna such as the return loss, standing wave ratio from Smith charts, Real power Vs Frequency, VSWR, E-field and H-field distribution, gain and radiation pattern are also evaluated.

A Combined Broadband Model for GaN HEMTs in Admittance Domain Based on Canonical Piecewise Linear Functions

In this article, a new large-signal transistor model is proposed. The model combines the advantage of both compact modeling and behavioral modeling techniques, resulting in a new modeling methodology. The intrinsic part of the model is based on the black-box poly-harmonic distortion (PHD) framework, which is implemented using the canonical piecewise linear (CPL) functions. Thus, the new intrinsic model can cover a broad operating frequency band, across a wide range of input powers, using a compact set of model parameters. While at each fixed operating frequency and input power, the model can also accurately predict device behavior over the complete Smith chart. For the extrinsic model, the traditional extrinsic parasitic network is used, enabling access to the intrinsic device plane, as required for waveform engineering. This work examines intrinsic admittance domain models implemented using both the linear and quadratic poly-harmonic expansions. An <inline-formula> <tex-math notation="LaTeX">$8 \times 125\,\,\mu \text{m}$ </tex-math></inline-formula> GaN HEMT device with a 0.25-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> gate feature size and a commercial 10-W GaN HEMT is used during the simulation and experimental model validation. Model implementations show excellent interpolation and extrapolation capability over the frequency band across a range of input power levels in both the frequency domain and the time domain.