Dayang Azra Awang Mat

Biological Effect of 900MHz and 1800MHz Mobile Phones in SAR Weight

In recent years, the public concern on human biological effect of mobile phone is increasing due to the widely used of mobile phones by public including the children. As a consequences, a safety guidelines have been established by the various public organization such as World Health Organization (WHO) and International Commission on Non-Ionization Radiation Protection (ICNIRP). The main objective of this paper is to investigate and study on the human biological effect that may cause by the used of 900MHz and 1800MHz mobile phones. For the purpose of the assessment, Finite-Difference Time Domain (FDTD) is used to simulate the modeling of mobile phone attached to human head in order to obtain the Specific Absorption Rate (SAR) value of mobile phones that absorbed into human head. The minimum SAR value stated by International Commission on Non-Ionization Radiation Protection (ICNIRP) is 2W/kg. When the limit is exceeds, it may produces adverse human health effects that contibute to reverse cell membrane polarity, alter brain waves and damage DNA. This leads to cancer and memory loss. However, mobile phones are designed with low power and operate at high frequency, resulted in lower SAR value comparing to 2W/kg that stated by ICNIRP. Other temporary biological or potential human health effects that may produce by mobile phones are heating, headache, fuzziness, fatigue and nausea. By the way, further studies or researches are needed in order to draw more complete picture of health risks that may cause by the used of mobile phones.

Human health implication of 900MHz and 1800MHz mobile phones

In recent years, there has been increasing public concern about the health implication of Electromagnetic (EM) wave exposures due to the mobile phone. For this reason, various public organizations in the world have been established safety guidelines. This paper focused on the investigation or study of human health effect that cause by the used of 900MHz and 1800MHz mobile phones. For the purpose of the assessment, Finite-Difference Time Domain (FDTD) is used to find the Specific Absorption Rate (SAR) value of mobile phones that absorbed into human head. The minimum SAR value stated by International Commission on Non-Ionization Radiation Protection (ICNIRP) is 4W/kg. When the limit is exceeds, it produces human health effects where it can caused reverse cell membrane polarity, alter brain waves and brain chemistry and damage DNA. This leads to cancer and memory loss. However, mobile phones are designed with low power and operate at high frequency where the value of SAR is lower than the limit that stated by ICNIRP. Other temporary biological or potential human health effects produce by mobile phones are heating, headache, fuzziness, fatigue and nausea. By the way, further studies or researches are needed in order to draw more complete picture of health risks that cause by the use of mobile phones.

Low-loss 60 GHz patterned ground shield CPW transmission line

This paper describes the slow wave structure design below the metallization plane to reduce dielectric loss of the silicon substrates. Three types of structure, floating strips with shield strip length (SL) = shield strip spacing (SS)=10µm and 5µm, and patterned ground with SL=SS=5µm have been designed for coplanar waveguide (CPW) transmission line using 0.18µm CMOS TSMC technology. These structures act to prevent the penetration of the electric field into the silicon substrate. It shows that at frequency of 60GHz, patterned ground shield resulted lower attenuation loss, approximately 60% lower compare to conventional CPW with the increase of quality factor to 16.006. The patterned structure exhibit the attenuation loss of 0.731dB/mm. The wavelength of the design is 980µm at 60GHz.

Electromagnetic radiation towards adult human head from 900MHz handheld mobile phone

Electromagnetic radiation produce by mobile phone and the relationship with the humans health is not a new issue nowadays. Since the used of mobile phone had increased rapidly over the past few years, people are becoming more concern with their health when dealing with the so-called electromagnetic radiation. This type of radiation would leads to heating of body tissue at specific rate called the thermal radiation. Thermal radiation depends on the frequency of the energy, the power density of the radio frequency field that strikes the body and the polarization of wave. This paper will discuss on the result collected from the thermal radiation generated by handheld mobile phone with frequency of 900 MHz towards adult human head. The analysis is conducted in a laboratory with average of 45 minutes talking hour with two different types of mobile phone, internal and external antenna. The results show an increased of heat especially at the place near the ear skull after 45 minutes of operation. When comparing both different types of mobile phone, mobile phone with external antenna produce more heat compared to mobile phone with internal antenna.

Low power, low group delay MB-OFDM UWB CMOS power amplifier using current-reused technique

This paper presents a low power and low group delay for multiband orthogonal frequency division multiplexing (MB-OFDM) ultra wideband (UWB) power amplifier (PA) for 3.1–7.5 GHz is proposed. The proposed PA employs a common gate with current-reused structure to provide wideband input matching, low group delay and low power consumption. The simulation results shows that the proposed PA design has an average gain of 11.4 dB with flatness of ±0.8 dB, while maintaining bandwidth of 2.6 to 8.3 GHz. An input return loss (S11) less than −11.1 dB and output return loss (S22) less than −10.5 dB, respectively are obtained. The PA design achieves the phase linearity (i.e. group delay) of ±67.1 ps and only consuming 14.5 mW power from 1.2 V supply voltage. A good output 1-dB compression point OP1dB of 0.5 dBm is obtained.

Visualization and Analytical Measurement of Electromagnetic Radiation from Handheld Mobile Phones

Mobile communication is where signal is transferred via electromagnetic wave through radio frequency and microwave signals. This signal produced electromagnetic radiation in the form of thermal radiation that consists of harmful ionizing radiation and harmless non-ionizing radiation. When using mobile phone, electromagnetic wave is transferred to the body in the form of thermal radiation that might cause health problems especially at the place near ear skull region for a certain period of time (talking time or operation time). In this analysis, the simulation and experimental analysis are carried out to examine the effect of electromagnetic radiation towards design phantom (dry phantom), water molecules and human volunteer when using the mobile phone for 45 minutes talking hour. This analysis is conducted in an anechoic chamber. Simulation is done using MATLAB’s software to show the radiation produced by the mobile phone. In the experimental analysis, thermal imaging technique is used to monitor and capture temperature distribution towards design phantom and human head. Two different design of mobile phone are used with internal (built-in) and external monopole antenna serving two different GSM frequencies GSM 900 and GSM 1800. The results show that mobile phones produced electromagnetic radiation (thermal) towards human head with high radiation produced by mobile phone with external antenna serving for GSM 900 MHz.

900MHz and 1800MHz mobile phone effect towards adult head in SAR distribution and SAR in weight

The investigation on the effect of mobile phone towards adult head in Specific Absorption Rate (SAR) Distribution and SAR in Weight is presented in this paper. Finite Different Time-Domain (FDTD) was used to construct adult head modeling with the attachment of monopole antenna and also to do a simulation in obtaining the SAR Distribution and SAR in Weight either 1g or 10g weight value, respectively. From the simulation, the results show that the values of both SAR are small and do not exceed 4W/kg stated by International Commission on Non-Ionizing Radiation Protection (ICNIRP), National Council on Radiation Protection and Measurement (NCRP) and Institute of Electrical and Electronics Engineers (IEEE). The simulation covered 900MHz and 1800MHz frequency with 0.6W radiated power.

Integration of Image Segmentation Method in Inverse Scattering for Brain Tumour Detection

This paper presents a microwave imaging for brain tumour detection utilizing ForwardBackward Time-Stepping (FBTS) inverse scattering technique. This technique is applied to solve electromagnetic scattered signals. It is proven that this technique is able to detect the presence of tumour in the breast. The application is now extended to brain imaging. Two types of results are presented in this paper; FBTS and FBTS integrated with image segmentation as a pre-processing step to form a focusing reconstruction. The results show that the latter technique has improved the reconstructions compared to the primary technique. Integration of the image segmentation step helps to reduce the variation of the estimated dielectric properties of the head tissues. It is also found that the optimal frequency used for microwave brain imaging is at 2 GHz and able to detect a tumour as small as 5 mm in diameter. The numerical simulations show that the integration of image segmentation with FBTS has the potential to provide useful quantitative information on the head internal composition.

Iterative refinement in inverse scattering technique with median filter

This paper presents a preliminary study of integrating median filter in Forward-Backward Time-Stepping (FBTS) algorithm for single object detection. A two dimensional (2D) homogeneous numerical phantom image with significant contrast was utilized to represent an unknown object. Mean Squared Error (MSE) was used to evaluate the efficiency of the proposed technique in eliminating artifacts that exists in the reconstructed image due to strong nonlinearity and ill-posedness of inverse scattering method in FBTS method. Preliminary results shown that MSE of median filtered FBTS was significantly lower than FBTS.

Design of Integrated Open Loop Resonator Bandpass Filter Antenna for 2.4GHz Applications

This paper presented the design of integrated filter antenna for 2.4GHz microwave applications. Open loop resonator bandpass filter is designed to increase the bandwidth of the antenna by producing the range of frequencies that can be accepted by the antenna structure. Direct connection between the filter structure and antenna may cause impedance mismatch and deteriorates the performance of both antenna and filter. Thus, by integrating both filter and antenna into a single module, the overall performance can be improved and increase the efficiency of the system with improved bandwidth. The design used FR4 with dielectric constant of εr = 4.7 with substrate thickness of 1.6mm. It is shown that the simulation result for the proposed integrated filter antenna produce return loss, S11=-20.009dB, gain of radiation pattern is 3.36dB and an increase of bandwidth to approximately 3.74% compare to the single structure antenna.