Jawad Yousaf

Design, Analysis, and Equivalent Circuit Modeling of Dual Band PIFA Using a Stub for Performance Enhancement

This work presents a new method for enhancing the performance of a dual band Planer Inverted-F Antenna (PIFA) and its lumped equivalent circuit formulation. The performance of a PIFA in terms of return loss, bandwidth, gain, and efficiency is improved with the addition of the proposed open stub in the radiating element of the PIFA without disturbing the operating resonance frequencies of the antenna. In specific cases, various simulated and fabricated PIFA models illustrate that the return loss, bandwidth, gain, and efficiency values of antennas with longer optimum open stub lengths can be enhanced up to 4.6 dB, 17%, 1.8 dBi, and 12.4% respectively, when compared with models that do not have open stubs. The proposed open stub is small and does not interfere with the surrounding active modules; therefore, this method is extremely attractive from a practical implementation point of view. The second presented work is a simple procedure for the development of a lumped equivalent circuit model of a dual band PIFA using the rational approximation of its frequency domain response. In this method, the PIFA’s measured frequency response is approximated to a rational function using a vector fitting technique and then electrical circuit parameters are extracted from it. The measured results show good agreement with the electrical circuit results. A correlation study between circuit elements and physical open stub lengths in various antenna models is also discussed in detail; this information could be useful for the enhancement of the performance of a PIFA as well as for its systematic design. The computed radiated power obtained using the electrical model is in agreement with the radiated power results obtained through the full wave electromagnetic simulations of the antenna models. The presented approach offers the advantage of saving computation time for full wave EM simulations. In addition, the electrical circuit depicting almost perfect characteristics for return loss and radiated power can be shared with antenna users without sharing the actual antenna structure in cases involving confidentiality limitations.

Analysis of filtering characteristics for coplanar symmetrical meander lines

This paper presents an analysis of the filtering characteristic for a coplanar symmetrical meander lines structure. The effects of geometrical parameters, which are length of vertical and horizontal elements as well as the distance of the gap between two symmetrical lines, on the filtering property of the structure are discussed. A novel direct derivation of the filtering performance of the coplanar configuration based on our proposed circuit model is also addressed. The mentioned analysis could be a useful guidance in the design stage of a uniplanar filter to enhance the signal and power integrity as well as immunity of Integrated circuits.

Analysis of electromagnetic field interference between an antenna and a multiple-noise source using active scattering parameters

This paper proposes an analysis method for electromagnetic field interference between an antenna and adjacent noise sources, using active scattering parameters. Electromagnetic field interference can be analyzed by measurement or simulation of the scattering parameters. In this paper, a multiple-band antenna and a multiple-noise source were designed and fabricated to analyze the electromagnetic field interference between them. The proposed analysis method employs active scattering parameters, whose validity has been verified both experimentally and through simulation.

Efficient circuit and EM model of electrostatic discharge generator

In this work, a new technique for an efficient, simple, and fast equivalent circuit and full wave numerical modeling of the electrostatic discharge (ESD) generator is presented. A novel circuit model of the NoiseKen ESD simulator is proposed based on the frequency domain measurement of the standard waveform calibration setup. The simple full wave electromagnetic model of the same generator, which requires much less computation resources, is also proposed using commercial CST Microwave Studio software. The reliability of the proposed models as an authentic ESD excitation source is validated through an example discharge application. The good agreement between the ESD reference waveform obtained through measurement, circuit model, and 3-D model of the generator is observed.

Effect of ESD generator ground strap configuration on ESD waveform

In this study, an analysis of the effect of the electrostatic discharge (ESD) gun grounding strap on the generated ESD stress waveform is presented. The reference ESD waveform is measured using the standard calibration setup of the IEC 61000-4-2 standard for the different (round, short and long) configurations of the grounding strap. The post processing analysis shows that increasing the length of the simulator ground strap to 3m reduces the variations in the ESD waveform, particularly ringing after the first peak, in comparison with standard reference waveform characteristics.

Novel diagnostic method for a single phase pole-mount transformer using two-port measurement

Diagnosis and maintenance of a power transformer are important because it deals with high power in high voltage, and any failure of previous detection of the malfunction in transformer would cause a disaster in the household customers as well as in the industry. To diagnose a power transformer, Sweep Frequency Response Analyzer (SFRA) has been widely used and been studied for the past years. The SFRA measures the change of a transfer function characteristics of a transformer with some specific terminal conditions, and has been used to check the state of the transformer which could be caused due to aging or to any damage before and after moving, and so on. It, however, uses just one port of the transformer to check the impedance, so the information from the SFRA measurement is limited in principle. This paper suggests a novel way to measure two ports of a power transformer to get the inside information of a transformer. To prove the validity of the proposed method, two-port S-parameters were measured using Vector Network Analyzer (VNA), and the measured S-parameters were converted into the transfer function using proper equations for the comparison of the two measurement data. The comparison of two showed good matching in the range of 20Hz to 2MHz. It suggests that the proposed method could be used to effectively diagnose the power transformers.