Mohd Zarar Mohd Jenu

Analytical and experimental study of the shielding effectiveness of a metallic enclosure with off-centered apertures

An analytical formulation has been developed for the shielding effectiveness of a rectangular enclosure with off-centered apertures. The present analytical formulation has been extended to include modes higher than TE10. The electric shielding may be calculated as a function of frequency, enclosure dimensions, aperture dimensions and position within the enclosure. Measurements conducted in a Gigahertz transverse electromagnetic (GTEM) cell show good agreement with theoretical values

Multimode Consideration in the Analysis of Shielding Effectiveness of a Metallic Enclosure with Off-Centred Apertures

In this paper, an approach to the shielding effectiveness evaluation of a metallic enclosure with off-centered apertures is discussed. It has been previously shown that a simple analytical transmission line formulation gives good predictions of the shielding effectiveness of a metallic enclosure with off-centered apertures. In this work the model is extended to include higher order modes in the transmission line (TL) models. The loading effect of electronic components within the enclosure is modeled by the introduction of losses. The model remains very simple and computationally efficient

A compact flat lens antenna with aperture-coupled patch elements

A compact 7 × 7 flat lens antenna design for X-band applications is presented in this paper. A new design with aperture-coupled E-shaped patch elements at 10 GHz is simulated and analyzed. This antenna design is realized by using two back-to-back printed patches with slotted common ground plane and feed horn antenna. The transmission loss obtained of 2.2 dB is sufficiently low. A 320° transmission phase range for the E-shaped patch unit cell is achieved with less than 1.5 dB of deviation in the transmission loss level.The proposed design uses a simple technique and less manufacturing complexity for transmission phase control.

Fitness monitor system

According to U.S. Department of Health and Human Services, 26% of U.S. adults between the ages of 20 through 74 are overweight. Exercise is a consequential and rewarding strategy to lose body fat and improve ones health. Throughout a large portion of aerobic exercise, a linear relationship exists between heart rate intensity of the exercise and the oxygen consumption (and therefore caloric expenditure). Thus if the heart rate is known, caloric consumption can be reasonably estimated. This paper introduces a new piece of electronic device - fitness monitor system, specially designed for heart rate monitoring and weight management. Its output parameters prefigure ones fitness level and meanwhile give warning if theres health abnormality.

Design and calibration of a wideband TEM-cell for material characterization

A wideband TEM-cell is designed for dielectric measurements to operate over a 50 MHz - 800 MHz frequency range by using transmission/reflection method. This cell is compact, easy to fabricate, and useful for measuring porous samples such as concrete. The classic dielectric measurement setup is usually based on rectangular TE10-mode waveguides which become very large, expensive, and non-practical for lower frequencies. As for a classic coaxial cell, non-uniformity of the electromagnetic field and the difficulty to obtain sample in a toroidal shape for coaxial cells are overcome using the proposed TEM-cell. Wideband matching is performed using a coaxial to waveguide connector based on a tapering technique. A specific calibration is used and the complex permittivity and permeability are calculated from the measured S-parameters. Preliminary experimental results are presented.

Fourth-moment calculation of optical propagation in a turbulent atmosphere with use of the split-step method. I. Plane wave

The split-step method was used to derive the full spatial dependence of the fourth moment of a plane-wave propagating in a two-dimensional turbulent atmosphere with a power-law spectrum for two values of the scattering parameter γk = 0 and 1 [ J. Opt. Soc. Am. A2, 2133 ( 1985)]. The changes in γk were obtained by the use of two different values of the inner scale of turbulence l0 while the operating wavelength and turbulent strength were kept constant. In this way the influence of l0 on the field statistics can be obtained. The results of intensity scintillation index σI2 and covariance function bI are also presented. The agreement of σI2 with the results of the reference cited above especially for γk = 0 is good. We also used the results of bI to study the asymptotic dependence of the characteristic correlation length on ζ, where ζ is the propagation-range scale.

Analytical Solution for Maximum Differential-Mode Radiated Emissions of Microstrip Trace

In this paper, a novel analytical solution was presented for estimating the maximum differential-mode (DM) radiated emission from electrically long PCB traces using transmission-line theory, travelling wave antenna, and far-field magnetic vector potential. The analytical solution was simplified for matched load in which only forward travelling wave was considered. Additionally, a simple expression for predicting maximum DM-RE from electrically short traces was obtained using proper simplifications. The results from the proposed analytical model were then compared to the results obtained from 3-D HFSS full-wave simulation and the measurement performed in a semianechoic chamber. Good agreements within ±3 dB were obtained over a wide range of frequency.

Dual-layer Frequency Selective Surface for wide stop-band applications

This paper presents a dual-layer Frequency Selective Surface (FSS) that exhibits a wide 4.8 GHz stop-band in 7.76-12.57 GHz frequency range. The FSS demonstrates significant 30 dB attenuation that can be effectively used to shield X-band satellite signals and other systems operating in the band. The unit cell consists of two square-loops, each printed as copper, over the opposite surfaces of FR4 can be used in low-profile stop-band applications.

Characterizations of FPGA chip electromagnetic emissions based on GTEM cell measurements

Miniaturized, dense integration and high operating frequencies of FPGAs are factors contributing to electromagnetic emissions. Consequently the radiation issue that used to be discussed at PCB level has shifted to component level. Thus it is of interest and challenging to investigate chip electromagnetic performance. GTEM cell is widely accepted to characterize chip emission and the common measurement practice is mounting the device under test at the GTEM cell body. This paper presents an alternative approach to measure electromagnetic emissions by locating the entire FPGA test board inside the GTEM cell instead of mounting it at the wall of the cell. Before measurements, the FPGA board is properly shielded with metallic enclosure to avoid unintentional contribution from supporting components on the board. During measurements, the shielded FPGA board is arranged in horizontal or vertical positions and for each position the FPGA chip is configured with two different logic circuits. The results have shown a significant impact of FPGA chip positions and IO pins on the electromagnetic emissions.

Shielding effectiveness of concrete with graphite fine powder in between 50MHz to 400MHz

The shielding effectiveness (SE) of building materials is of concern due to the possibility of electromagnetic interference on sensitive equipment located inside the building. The SE of building material could be obtained directly using measurement but it requires expensive and elaborate setup. Alternatively, analytical method is preferable to predict the SE of building material for various conditions regarding the parameters to be evaluated such as thickness, moisture content, percentage of conducting materials added and so forth. Since most of the building materials are non-magnetic, its relative permittivity will be an important parameter for SE calculation. The effective permittivities of the concrete samples between 50 MHz to 400 MHz are measured using a TEM parallel plate. In this work, the SE of concrete samples are compared for various concentrations of graphite fine powder. It is found that a concrete of thickness 20 cm with 12wt% of graphite fine powder is able to provide a maximum of 2.4 dB additional shielding at 360 MHz. It is also observed that reflection loss is the dominant mechanism that contributes on the SE of a concrete with graphite fine powder.