M. F. Abd Malek

Impedance modeling for a unit cell of the square loop frequency selective surface at 2.4 GHz

This paper presented an impedance modeling of the Equivalent Circuit (EC) for a unit cell of the square loop Frequency Selective Surface (FSS) structure. The unit cell of the square loop FSS is designed and simulated using the CST Microwave Studio software at 2.4 GHz based on industrial, scientific and medical bands (ISM) standard. The square loop FSS is simulated without FSS, with square FSS and FSS with slot. The investigation has been done on the length of substrate (s), width of substrate (w), length of square FSS (a) and length of slot (b). Imaginary (Im) component of EC has been modeled based on physical parameters of the square loop FSS in wavelength. EC gives a simple alternative method in FSS analyses which are useful for quickly predicting the performance of FSS.

Equilateral triangular microstrip patch antenna with spur lines embedded

This paper presents an equilateral triangular microstrip antenna with spur lines. The proposed antenna, comprising a triangular planar patch element embedded with two spur line slots. The simulation and fabrication process are performed to understand the characteristics of the proposed antenna. The simulation result is compared with the fabricated antenna. The targeting frequency of this antenna is 0.90 GHz (first resonant frequency) and 1.80 GHz (second resonant frequency). The proposed antenna can improve the bandwidth of GSM 1800 up to 100 MHz. It shows the return loss of - 16.176 dB, bandwidth of 33 MHz (0.919 GHz to 0.952 GHz) and a gain of 3.52 dB first resonant frequency. At second frequency, the return loss are - 28.159 dB with a bandwidth of 115 MHz (1.714 GHz to 1.829 GHz) and gain of 3.380 dB.

Reconfigurable beam steer antenna (RBSA) design for WiMAX application

A reconfigurable antenna design for beam steer capability (RBSA) is proposed in this research. The RBSA has successfully achieved beam steer functionality at three angle direction of -42°, -28° and -15°. This is achieved by certain PIN diode configuration. The PIN diode is positioned at the specific location of the RBSA feed network. The proposed antenna consists of an array of three rectangular radiating elements. Aperture coupled feed technique applied in order to reduce the deterioration of power due to the presence of the PIN diode. RBSA has a small dimension of 100 mm × 100 mm that design on Taconic substrate. All designs and simulations have been carried out using CST Microwave Studio. This antenna is potentially useful for Wireless Interoperability Microwave (WiMAX) smart antenna system.

Preliminary study of electromagnetic energy absorption in the head due to the exposure of radio frequency at 900MHz

In this paper, the effects to Specific Absorption Rate (SAR) levels in human head proximity to metal-spectacle when using RF source investigated. The source is from a mobile communications enabled device (MCE) operating in GSM900. A homogenous SAM phantom head and hand model were used to understand the related mechanism with the representative sources of Planar Inverted F antenna (PIFA) at 900MHz. A PIFA inside mobile phone excited in front of the head-worn metallic spectacle. Previous studies have been conducted using dipole in the frontal face. However, human hand holding MCE in the frontal face has not been discussed. The Simulations showed high correlation between the metallic spectacles and powers absorbed in face. All simulations have been done using finite integration in time domain (FIT).

A comparative study on the effect of quasi-block hand model specific absorption rate measurement

A candy bar mobile phone with Planar Inverted-F Antenna (PIFA) operating at 900 MHz and 1800 MHz is simulated with two models of quasi-block hand — homogeneous and inhomogeneous. Maximum Specific Absorption Rate (SAR) is investigated by using Standard Anthropomorphic Model (SAM) hand phantom properties in comparison with the properties of human skin and bone towards the models. Dimension of the quasi-block hand is based on a typical Malaysian hand, while the solid hand properties is as approved by CTIA standards. The simulation results of peak SAR for two conditions are observed and compared between both hands.

Characteristic impedance modelling of circular loop and square loop frequency selective surface (FSS) on hybrid material

An impedance modeling for a unit cell of the circular loop and square loop FSS structure is presented in this paper. The unit cell of the circular loop and square loop FSS are designed and simulated using the CST Microwave Studio software at 2.4 GHz based on industrial, scientific and medical bands (ISM). The design FSS structure consists of FSS structures placed on the FR4 and glass. The reflection (S11) and transmission (S21) of the design FSS structure is analyzed based on the six types of configuration that have been set up. The hybrid material (FR4 and glass) effect the transmission and reflection signal of the FSS. The highest efficiency for circular loop FSS and square loop FSS are 91.4% and 88.1% with a return loss of -25.31 dB and -18.72 dB by using configuration 1. The frequency response of the FSS is shifted to the lower part when the hybrid materials are used. So, the size of the FSS can be reduced by using hybrid materials to achieve the desired frequency response.

Impedance of the unit cell of the frequency selective surface at 2.4 GHz

Equivalent Circuit (EC) method gives a simple alternative method in FSS analyses which are useful for quickly predicting the characteristic of FSS. Impedance of the EC for a unit cell of the design Frequency Selective Surface (FSS) structure is investigated in this paper. The unit cell of the design FSS structure consists of FSS structures placed on the FR4, glass and hybrid (FR4+glass). The square, circle and hexagon FSS structures without and with slot are designed and simulated using the CST Microwave Studio software at 2.4 GHz based on industrial, scientific and medical bands (ISM) standard. The resistance and the reactance of the impedance are depending on the material and shapes. This characteristic impedance can be used to design the advance FSS for similar ISM band.

Investigation of a square loop Frequency Selective Surface (FSS) on hybrid material at 2.4 GHz

The design FSS structure consists of square loop FSS structures placed on the FR4 board and glass. The square loop FSS is designed and simulated by using the CST Microwave Studio software for 2.4 GHz based on industrial, scientific and medical bands (ISM) standard. The reflection (S11) and transmission (S21) of the design FSS structure is analyzed based on the six types of configuration that have been set up. The hybrid material (FR4 board and glass) affects the transmission and reflection of the FSS. The highest efficiency for 2.4 GHz is 73% by using configuration 2.

Optimization of Power Consumption for Centrifugation Process Based on Attenuation Measurements

The main objective of this research is to produce a mathematical model that allows decreasing the electrical power consumption of centrifugation process based on attenuation measurements. The centrifugation time for desired separation efficiency may be measured to determine the power consumed of laboratory centrifuge device. The power consumption is one of several parameters that affect the system reliability and productivity. Attenuation measurements of wave propagated through blood sample during centrifugation process were used indirectly to measure the power consumption of device. A mathematical model for power consumption was derived and used to modify the speed profile of centrifuge controller. The power consumption model derived based on attenuation measurements has successfully save the power consumption of centrifugation process keeping high separation efficiency. 18kW.h monthly for 100 daily time device operation had been saved using the proposed model.

Reduction of Power Consumption for Centrifugation Process Using Separation Efficiency Model

The power consumption, capacity, speed of rotation, separation precision and the centrifugation time are essential technical parameters of the centrifuge device, and hence their reliability may affect the system reliability and productivity. The modified period of velocity profile model (spinning period) which leads to decreasing the power consumption of laboratory centrifuge devices is derived. Based on the centrifugation time model, a fuzzy controller is proposed for the laboratory centrifuge device. The proposed controller design will produce high reliability by selecting various separation efficiencies, evaluating the separation efficiency period precisely, and reduction of separation power consumption. Based on the derived model, a low-cost controller modification leads to a shorter blood test time and lower power consumption while improving the separation efficiency to greater than 95 %.