scholarly journals Inductance Formula for Square Spiral Inductors with Rectangular Conductor Cross Section

2019 ◽  
Vol 8 (4) ◽  
pp. 80-88
Author(s):  
H. A. Aebischer
Keyword(s):  
Integrated Circuits ◽  
Comparative Study ◽  
Radio Frequency ◽  
Cross Section ◽  
Radio Frequency Identification ◽  
Maximum Error ◽  
Maximum Relative Error ◽  
Spiral Inductors ◽  
Spiral Coils ◽  
The Comparative Study

Planar spiral coils are used as inductors in radio frequency (RF) microelectronic integrated circuits (IC’s) and as antennas in both  radio frequency identification (RFID) and telemetry systems. They must be designed to a specified inductance. From the literature, approximate analytical formulae for the inductance of such coils with rectangular conductor cross section are known. They yield the direct current (DC) inductance, which is considered as a good approximation for inductors in RF IC’s up to the GHz range. In principle, these formulae can simplify coil design considerably. But a recent comparative study of the most cited formulae revealed that their maximum relative error is often much larger than claimed by the author, and too large to be useful in circuit design. This paper presents a more accurate formula for the DC inductance of square planar spiral coils than was known so far. It is applicable to any design of such coils with up to  windings. Owing to its scalability, this holds irrespectively of the coil size and the inductance range. It lowers the maximum error over the whole domain of definition from so far  down to . This has been tested by the same method used in the comparative study mentioned above, where the precise reference inductances were computed with the help of the free standard software FastHenry2. A comparison to measurements is included. Moreover, the source code of a MATLAB® function to implement the formula is given in the appendix.

scholarly journals Comparative Study of the Accuracy of Analytical Inductance Formulae for Square Planar Spiral Inductors

2018 ◽  
Vol 7 (5) ◽  
pp. 37-48 ◽  
Author(s):  
H. A. Aebischer
Keyword(s):  
Integrated Circuits ◽  
Radio Frequency ◽  
Radio Frequency Identification ◽  
Short Wave ◽  
Error Statistics ◽  
Four Dimensions ◽  
Spiral Inductors ◽  
Frequency Identification ◽  
Spiral Coils ◽  
Relative Errors

In the design of radio frequency (RF) microelectronic integrated circuits (IC’s) and of antennas for short-wave radio frequency identification (RFID) and telemetry systems, planar spiral coils are important components. Many approximate analytical formulae for calculating the inductance of such coils can be found in the literature. They can simplify the problem of designing inductors to a predefined inductance considerably. But the error statistics given by different authors cannot be compared because they are based on different or unknown domains of definition. Hence, it is not possible to decide which formula is best in a given case by merely studying the literature. This paper compares the maximum relative errors of six of some of the most cited formulae in the literature. To all formulae, the same domains of definition are applied. Each of them spans all four dimensions of the parameter space. Precise inductances are obtained numerically with the help of the free scientific and industrial standard software FastHenry2 and used as reference values to calculate the errors of the formulae. It has been found that the alleged maximum errors reported by some authors are far too optimistic. Only two formulae feature small enough errors to be useful in circuit design. The method and the domains of definition applied in the present study may also prove useful for the assessment of future formulae.

scholarly journals Inductance Formula for Rectangular Planar Spiral Inductors with Rectangular Conductor Cross Section

2020 ◽  
Vol 9 (1) ◽  
pp. 1-18
Author(s):  
H. A. Aebischer
Keyword(s):  
Aspect Ratio ◽  
Radio Frequency ◽  
Cross Section ◽  
Radio Frequency Identification ◽  
Maximum Error ◽  
Arithmetic Mean ◽  
Coil Design ◽  
Cross Sectional ◽  
Spiral Coils ◽  
Rfid Antennas

In modern technology, inductors are often shaped in the form of planar spiral coils, as in radio frequency integrated circuits (RFIC’s), 13.56 MHz radio frequency identification (RFID), near field communication (NFC), telemetry, and wireless charging devices, where the coils must be designed to a specified inductance. In many cases, the direct current (DC) inductance is a good approximation. Some approximate formulae for the DC inductance of planar spiral coils with rectangular conductor cross section are known from the literature. They can simplify coil design considerably. But they are almost exclusively limited to square coils. This paper derives a formula for rectangular planar spiral coils with an aspect ratio not exceeding a value between 2.5 and 4.0, depending on the number of turns, and having a cross-sectional aspect ratio of height to width not exceeding unity. It is valid for any dimension and inductance range. The formula lowers the overall maximum error from hitherto 28 % down to 5.6 %. For specific application areas like RFIC’s and RFID antennas, it is possible to reduce the domain of definition, with the result that the formula lowers the maximum error from so far 18 % down to 2.6 %. This was tested systematically on close to 140000 coil designs of exactly known inductance. To reduce the number of dimensions of the parameter space, dimensionless parameters are introduced. The formula was also tested against measurements taken on 16 RFID antennas manufactured as PCB’s. The derivation is based on the idea of treating the conductor segments of all turns as if they were parallel conductors of a single-turn coil. It allows the inductance to be calculated with the help of mean distances between two arbitrary points anywhere within the total cross section of the coil. This leads to compound mean distances that are composed of two types of elementary ones, firstly, between a single rectangle and itself, and secondly, between two displaced congruent rectangles. For these elementary mean distances, exact expressions are derived. Those for the arithmetic mean distance (AMD) and one for the arithmetic mean square distance (AMSD) seem to be new. The paper lists the source code of a MATLAB® function to implement the formula on a computer, together with numerical examples. Further, the code for solving a coil design problem with constraints as it arises in practical engineering is presented, and an example problem is solved.

A comparative study of RFID adoption patterns in retail

2021 ◽  
pp. 1-20
Author(s):  
Narges Kasiri ◽  
G. Scott Erickson ◽  
Gerd Wolfram
Keyword(s):  
Comparative Study ◽  
Radio Frequency ◽  
Radio Frequency Identification ◽  
Structural Model ◽  
Slow Pace ◽  
The Us ◽  
Frequency Identification ◽  
Insight Into ◽  
Current Stage ◽  
Over Time

Radio frequency identification (RFID) has been viewed as a promising technology for quite some time. Initially developed a couple of decades ago, the technology has been accompanied by predictions of imminent widespread adoption since its beginnings. A majority of retailers and other users are now using or planning to use the technology. This paper employs a combination of the technology-organization-environment (TOE) model and the 3-S (substitution, scale, structural) model to analyze the long journey of RFID adoption in retail. Top retail executives in the US and Europe were interviewed to investigate RFID adoption patterns based on differences in technological, organizational, and environmental circumstances. As the retail industry is moving into a post-adoption era, these results demonstrate the current stage of retail RFID adoption, identify factors playing important roles over time as motivators or impediments, and provide some insight into the slow pace of adoption.

scholarly journals Long-Span Wooden Structural Floors with Self-Tensioning System: Performance under Asymmetrical Loads

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
J. Estévez-Cimadevila ◽  
D. Otero-Chans ◽  
E. Martín-Gutiérrez ◽  
F. Suárez-Riestra
Keyword(s):  
Comparative Study ◽  
Cross Section ◽  
System Performance ◽  
The Self ◽  
Bending Moments ◽  
Structural Element ◽  
Long Span ◽  
Effective Performance ◽  
The Comparative Study

This study analyzes the performance of wooden structural floors equipped with the self-tensioning system patented by the authors, consisting of a force multiplying mechanism connected to a self-tensioning tendon, which is activated automatically when the load is applied to the structural element. The paper describes the system’s difficulties when the structural floor is subjected to asymmetrical loads. The proposed solution consists of anchoring the tendon by an adhesive connection in the central part of the piece yielding a favorable redistribution of the bending moments and an effective performance in terms of deformations. The comparative study focuses onπ-shape cross section pieces with spans of 12 m and 15 m, using sections without prestressing and with initial prestressing and self-tensioning system.

Development of an RFID-based security door system

2020 ◽  
Vol 1 ◽  
pp. 9-16
Author(s):  
Sunday Emakpor ◽  
Emmanuel Esekhaigbe
Keyword(s):  
Liquid Crystal ◽  
Integrated Circuits ◽  
Radio Frequency ◽  
Radio Frequency Identification ◽  
Liquid Crystal Display ◽  
Alarm System ◽  
The Public ◽  
Efficient Control ◽  
The Status ◽  
Frequency Identification

This paper describes the development of a two-factor radio frequency identification (RFID)-based security door authentication scheme that can provide efficient control facilities to restrict the entry of an unauthorised door user. The developed system consists of the RFID unit, a microcontroller programmed to control the operation of the door using a synchronous motor. The multiplexers that comprise integrated circuits combined with the liquid crystal display was utilized for displaying the status of the card user while the alarm system informs the public of an intruder. The experimental results are presented and discussed.

DID TUSCAN DIOCESES CONFESSIONALIZE IN THE SIXTEENTH AND SEVENTEENTH CENTURIES?

2003 ◽  
Vol 7 (3) ◽  
pp. 312-331
Author(s):  
Kathleen Comerford
Keyword(s):  
Seventeenth Century ◽  
Comparative Study ◽  
Cross Section ◽  
Educational Changes ◽  
Parish Clergy ◽  
The Comparative Study ◽  
The Impact

AbstractThis article explores several dioceses in Tuscany—Arezzo, Fiesole, Lucca, Montepulciano, Siena, and Volterra—in light of the foundation of diocesan seminaries, to determine if a new corps of priests was produced and if that corps instituted major changes. Historians refer to post-Tridentine attempts to strengthen the faith and power of groups and institutions by such processes as education as the parallel trends of confessionalism and confessionalization. Since these dioceses represent different economic, educational, and demographic levels of development, the comparative study of quantitative and qualitative measures in these regions addresses the impact of educational changes in the parish clergy in a significant cross-section of late-sixteenth and seventeenth-century Tuscany. Even in dioceses which were wealthy and which supported seminaries, the institutions had little influence, and therefore the slow and spotty improvements in the parishes and dioceses did not result in the confessionalization of the region, although limited confessionalism did occur.

EFFECT OF RADIO FREQUENCY IDENTIFICATION ON RECORDING HEAD IN WRITING PROCESS AT 125 KHZ LOW FREQUENCY

2009 ◽  
Vol 23 (17) ◽  
pp. 3619-3624
Author(s):  
APHAIPHAK PRATOOMTHIP ◽  
ANAN KRUESUBTHAWORN ◽  
CHIRANUT SA-NGIAMSAK ◽  
APIRAT SIRITARATIWAT ◽  
PONCHAI PAKPONGSIRI
Keyword(s):  
Radio Frequency ◽  
Radio Frequency Identification ◽  
Writing Process ◽  
Low Frequency ◽  
Maximum Error ◽  
Recording Head ◽  
Recording Heads ◽  
Frequency Identification ◽  
Current Error

This article presents the effect of Radio Frequency Identification (RFID) at 125 kHz on GMR recording heads. The study is mainly concerned with the RFID effect on recording heads in terms of the distance (r) between the antenna reader of the RFID and the recording head, the coil radius (a) of the antenna reader, and the angle (θ) between antenna reader and recording head. The maximum error of the writing current is found in this experiment of about 2.5% (where r < a). An increase of angle affects the writing current error when the radius increases. It is found that the writing current error decreases when r > a. SEM result shows that radiated fields of RFID do not visibly degrade the writer part but only disturbance to recording heads in testing is found.

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