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The purpose of this paper is to propose a fast, accurate and efficient algorithm for assessment of input impedance and consequently the evaluation of transient impedance of the grounding electrode.

The mathematical model is based on the thin wire antenna theory and related Pocklington integro-differential equation in the frequency domain, which is numerically treated via Galerkin-Bubnov variant of the indirect boundary element method (GB-IBEM). Two different approaches, scattered voltage method (ScVM) and induced electromotive force – boundary element method (IEMF-BEM), for input and transient impedance are discussed in detail. Extensive numerical experiments have been undertaken to analyze numerical sensitivity of the methods.

Although it was widely used so far, the ScVM, was shown to be unsuitable for the grounding impedance assessment because results are dependent on the number of elements used in the numerical solution. On the other hand, the other method, IEMF-BEM is rather stable, with the respect to the number of elements used and with excellent convergence rate. In addition, IEMF-BEM is much simpler to implement as it requires only multiplication of matrices already assembled within the procedure of current distribution calculation, as opposed to the ScVM which requires numerical integration of quasi-singular integrals which, by it self, can be very demanding.

The IEMF-BEM is originally developed by the authors and used for the first time for grounding impedance assessment. It is simple and very efficient and can easily be extended to arbitrary grounding configurations.

Recent advancements in the domain of smart communication systems and technologies have led to the augmented developments for very large scale integrated circuit designs in electro-magnetic applications. Increasing demands for low power, compact area and superior figure of merit–oriented circuit designs are the trends of the recent research studies. Hence, to accomplish such applications intended for optical communications, the transimpedance amplifier (TIA) was designed.

In this research work, the authors present a multi-layer active feedback structure which mainly composes a transimpedance stage and a gain stage followed by a low pass filter. This structure enables to achieve improved input impedance and superior gain. A simplified cascaded amplifier has also been designed in a hierarchical topology to improvise the noise effect further. The proposed TIA has been designed using Taiwan Semiconductor Manufacturing Company 45 nm complementary metal oxide semiconductor technology. Moreover, the thermal noise has been analyzed at −3 dB bandwidth to prove the reduction in thermal noise with increase in frequency for most of the devices used in the designed circuit.

The proposed differential TIA circuit was found to obtain the transimpedance gain of 50.1 dBO without applying any external bias current which is almost 8% improvised as compared to the conventional circuit. In addition to this, bandwidth achieved was 2.15 GHz along with only 38 W of power consumption, which is reasonably 100 times improvised in comparison of conventional circuit. Hence, the proposed differential TIA is suitable for the low power optical communications applications intended to work on low supply voltage.

The designed work is done by authors in university lab premises and is not copied from anywhere. To the best of the authors’ knowledge, it is 100% original.

This study aims to realize a sensorless metal object detection (MOD) using machine learning, to prevent the wireless power transfer (WPT) system from the risks of electric discharge and fire accidents caused by foreign metal objects.

The data constructed by analyzing the input impedance using the finite element method are used in machine learning. From the loci of the input impedance of systems, the trained neural network (NN), support vector machine and naive Bayes classifier judge if a metal object exists. Then the proposed method is tested by experiments too.

In the test using simulated data, all of the three machine learning methods show high accuracy of over 80% for detecting an aluminum cylinder. And in the experimental verifications, the existence of an aluminum cylinder and empty can are successfully identified by a NN.

This work provides a new sensorless MOD method for WPT using three machine learning methods. And it shows that NNs obtain high accuracy than the others in both simulated and experimental verifications.

The purpose of this paper is to build a neural network (NN) inverse model for the multi-band unequal-power Wilkinson power divider (WPD). Because closed-form expressions of the inverse input–output relationship do not exist, the NN becomes an appropriate choice, because it can be trained to learn from the data in inverse modeling. The design parameters of WPD are the characteristic impedances, lengths of the transmission line sections and the isolation resistors. The design equations used to train the NN inverse model are based on the even–odd mode analysis.

An inverse model of a multi-band unequal WPD using NNs is presented. In inverse modeling of a microwave component, the inputs to the model are the required electrical parameters such as reflection coefficients, and the outputs of the model are the geometrical or the physical parameters.

For verification purposes, a quad-band WPD and a penta-band WPD are designed. The results of the full-wave simulations verify the validity of the design procedure. The resulting NN model outperforms traditional time-consuming optimization procedures in terms of computation time with acceptable accuracy. The designed WPDs using NN are implemented by microstrip lines and verified by using full-wave analysis based on high-frequency structure simulator (HFSS). The results of the microstrip WPDs have good agreements with the corresponding results obtained by using ideal transmission line sections.

The associated time-consuming procedure and computational burden in realizing WPD through optimization are major disadvantages; needless to mention the substantial increase in optimization time because of the multi-band design. NNs are one of the best candidates in addressing the abovementioned challenges, owing to their ability to process the interrelation between electrical and geometrical/physical characteristics of the WPD in a superfast manner.

The purpose of this paper is to present a monitoring method for a three-coil wireless power transfer (WPT) system, which consists of a transmitting coil (Tx), a relay coil and a movable receiving coil (Rx). Both an ideal resistance and a rectifier bridge load are taken into account.

From the perspective of fundamental component, the equivalent impedance of a rectifier bridge load is well analyzed. On the basis of the circuit model of a three-coil WPT, estimation equations of the variable mutual inductances and load condition are deduced. Multi-frequency input impedance obtained by frequency scans combined with the Newton-Raphson method are used to obtain solutions.

Experimental results indicate that the estimated parameter values are close to each other when different sets of source frequencies are applied. When compared with simulation results, these estimated parameters including both mutual inductances and load resistances are found to be accurate.

Using only the information of input side, the proposed algorithm can estimate the mutual inductances and load resistance regardless of the Rx positions. Estimation is feasible for the system with a rectifier bridge load. The estimated analysis will serve as a key step in load power stabilization for WPT systems.

Purpose of this study is to design a compact gap coupled anchor shape patch antenna for wireless local area network/high performance radio local area network and worldwide interoperability for microwave access applications.

An anchor shape microstrip antenna is conceived, designed, simulated and measured. The anchor shape antenna is transformed to its rectangular equivalent by conserving the patch area. Modeling and simulation of the antenna is performed by Ansys high frequency structure simulator (HFSS) electromagnetic solver based on the concept of finite element method. The simulated results are experimentally verified by using Agilent E5071C vector network analyzer. Theoretical analysis of an electromagnetically gap coupled anchor shape microstrip patch antenna has been performed by obtaining the lumped element equivalent of the transformed antenna.

The proposed antenna has a compact conducting patch of dimension 0.26λ × 0.12λ mm² (λ is calculated at lower resonating frequency of 3.56 GHz) with impedance bandwidths of 100 and 140 MHz and antenna gains of 1.91 and 3.04 dB at lower resonating frequency of 3.56 GHz and upper resonating frequency of 5.4 GHz, with omni-directional radiation pattern.

In literature, one does not encounter anchor shape antenna using the concept of gap coupling and parasitic patches. The design has been optimized for wireless local area network/worldwide interoperability for microwave access applications with a relatively low patch area (291.12 mm²) as compared to other reported antennas for wireless local area network/worldwide interoperability for microwave access applications. Transformed antenna and the actual experimental antenna behavior varies, but the resonant frequencies of the transformed antenna as observed by theoretical analysis and simulated results (by high frequency structure simulator) are reasonably close, and the percentage difference between the resonant frequencies (both at lower and upper bands) is within the permissible limit of 1-2.5 per cent. Results confirm the theoretical proposition of transformation of shapes in antenna design, which allows a designer to adapt the design shape according to the application.

This paper aims to present a triple-band monopole antenna design of 0.2-mm thickness with an overall dimension of 21 × 8 mm² for wireless local area network (WLAN)/worldwide interoperability for microwave access (WiMAX) multiple input and multiple output (MIMO) applications in the laptop computer.

It comprises three monopole radiating elements, namely, strip AD (inverted C), strip EG (inverted J) and strip FI (inverted U) along with two rectangular open-end tuning stubs, namely, “m” and “n” of size 1.5 × 0.9 mm² and 1.8 × 0.9 mm², respectively. The proposed structure is compact, cost-effective and easy to integrate inside the laptop computers.

This structure excites three WLAN (2.4/5.2/5.8 GHz) and three WiMAX (2.3/3.3/5.5 GHz) bands. The proposed antenna array elucidates that it has measured −10dB impedance bandwidth of 11.86 per cent (2.22-2.50) GHz in a lower band (f_l), 6.83 per cent (3.25-3.48) GHz in medium band (f_m) and 16.84 per cent (5.00-5.92) GHz in upper band (f_u). The measured gain and radiation efficiency are above 3.64dBi and 75 per cent, respectively, and isolation better than −20dB. The envelope correlation coefficient (ECC) is less than 0.004. The simulated and measured results are in good concurrence, which confirms the applicability of the proposed antenna array for MIMO applications in the laptop computer.

The proposed antenna is designed without using vias, reactive elements and matching circuits for excitation of WLAN/WiMAX bands in the laptop computers. The design also does not require any additional ground for mounting the antenna. Further, the antenna array, formed by using the same antenna design, does not need additional isolating elements and is designed in such a way that the system ground itself acts as an isolating element. The proposed antenna has a low profile and is ultra-thin, cost-effective and easy to manufacture and can be easily embedded inside the next-generation laptop computers.

The purpose of this paper is to propose a new design strategy to enhance the bandwidth and efficiency of the power amplifier.

To realize the introduced design strategy, a power amplifier was designed using TSMC CMOS 0.18um technology for operating in the Ka-band, i.e. the frequency range of 26.5-40 GHz. To design the power amplifier, first, a power divider (PD) with a very wide bandwidth, i.e. 1-40 GHz, was designed to cover the whole Ka-band. The designed Doherty power amplifier consisted of two different amplification paths called main and auxiliary. To amplify the signal in each of the two pathways, a cascade distributed power amplifier was used. The main reason for combining the distributed structure and cascade structure was to increase the gain and linearity of the power amplifier.

Measurements results for designed power dividers are in good agreement with simulations results. The simulation results for the introduced structure of the power amplifier indicated that the gain of the proposed power amplifier at the frequency of 26-35 GHz was more than 30 dB. The diagram of return loss at the input and output of the power amplifier in the whole Ka-band was less than −8dB. The maximum power-added efficiency (PAE) of the designed power amplifier was 80%. The output P1dB of the introduced structure was 36 dB and the output power of the power amplifier was 36 dBm. Finally, the IP3 value of the power amplifier was about 17 dB.

The strategy presented in this paper is based on the usage of Doherty and distributed structures and a new wideband power divider to benefit from their advantages simultaneously.

The paper aims to present a simple rail‐to‐rail CMOS voltage follower.

The circuit is developed based on a complementary source follower with a common‐source output stage. The circuit is designed using a 0.13 μm CMOS technology, and operates under the supply voltage of 1.5 V. HSPICE is used to verify the circuit performance.

The simulations show output voltage swing of ±0.6 V (300 Ω load) with the total harmonic distortion of 0.55 per cent at the operating frequency of 3 MHz. The bandwidth and power dissipation are 657 MHz and 405 μW, respectively.

A simple rail‐to‐rail CMOS voltage follower is presented.

The purpose of this paper is to investigate of the ultra‐wide band (UWB) characteristics of a conical antenna covered by an electromagnetic band‐gap (EBG) structure composed of alternating high‐ and low‐permittivity dielectric spherical shells.

A finite difference time domain in spherical coordinates is implemented in order to characterize the antenna's performance and waveform fidelity in case an UWB pulse is used. The method of projected effective permittivity is used in order to treat accurately the dielectric interfaces between the dissimilar spherical shells.

The design achieves a very wide impedance bandwidth above 5.5 GHz and presents UWB radiation characteristics and high average gain over the whole bandwidth. The radiation patterns are monopole‐like and their frequency dependence is small in the whole UWB frequency band. A time domain study has shown that the antenna distorts the excitation pulse in a moderate way.

In this paper, a quasi‐planar wideband conical antenna coated on a dielectric EBG structure is proposed for what is believed to be the first time. It is mechanically stable and, relatively easy to build and integrate with the planar circuits.