Mutual coupling between monopoles on F-4 aircraft at transition frequencies: A comparison between MoM and MoM/UTD hybrid method at UHF band

In this paper, the analysis of mutual coupling between monopole antennas mounted on the aircraft at UHF band is presented. The Method of Moments (MoM) and hybridized MoM with Uniform Geometrical Theory of Diffraction (UTD) method (MoM/UTD) are used to calculate the coupling in 225 MHz-400 MHz frequency range. Numerical results with MoM and MoM/UTD are performed and the reliability of these methods is discussed based on the measurement results

Heat analysis of biological tissue exposed to microwave by using thermal wave model of bio-heat transfer (TWMBT)

Thermal analyses of biological tissues exposed to microwaves were studied by using thermal wave model of bio-heat transfer (TWMBT). As a model, skin stratified as three layers with various thermal physical properties were simulated and thermal wave model of bio-heat transfer equations were solved by using finite difference method. Finally, the thermal variations were simulated in the cross section of the model. Comparative studies on the traditional Pennes' equations and thermal wave model of bio-heat transfer were performed and evaluated. Furthermore, temperature variations in the skin exposed to microwave were predicted depending on blood perfusion rate, thermal conductivity, frequency and power density of microwave, and exposure time. Thermal wave model of bio-heat transfer gives lower heat rise predictions than that of Pennes' equation, initially. When it approaches to steady state, it overlaps with the Pennes' equation. (C) 2007 Elsevier Ltd and ISBI. All rights reserved

A simulation study of the cloud propagation model

Propagation through a sparse distribution of lossy particles in a cloud is investigated. Using a discrete modelling technique, a mathematical model to aid in the interpretation of the interaction data obtained by electromagnetic probing of mixed ice crystals and waterdrop clouds is developed. Such clouds can contain many possible crystal forms, most notably thin long cylinders and flat plate crystals. The present work is a simulation of the theoretical aspects of this problem. The attenuation, phase, bistatic scattering patterns and emissivity are computed for waves of selected polarizations passing through clouds with specified sizes, shape and distributions. The results are compared with the literature and good agreement is obtained

Electromagnetic Radiation Interaction and Pollution Measurements

Electromagnetic waves caused from base stations, which are rapidly increasing due to the opportunities provided by modern technology, create an undesired effective electromagnetic pollution in the environment. Mobile phones, as an important electromagnetic radiation source in the human body, are deliberately preferred devices for their use. However, those who live near base stations are exposed to electromagnetic radiation outside of personal preference and often are unaware of this effect. Especially, in districts with high populations such as Kadikoy, possible negative effects should be systematically examined by independent measurement institutions. In this study, the results of the 3-year project entitled "Determination of Electromagnetic Radiation from Base Stations at Istanbul Kadikoy and Determination of Exposure Levels" are discussed in comparison with national and international limits

Electromagnetic Radiation Interaction and Pollution Measurements

Electromagnetic waves caused from base stations, which are rapidly increasing due to the opportunities provided by modern technology, create an undesired effective electromagnetic pollution in the environment. Mobile phones, as an important electromagnetic radiation source in the human body, are deliberately preferred devices for their use. However, those who live near base stations are exposed to electromagnetic radiation outside of personal preference and often are unaware of this effect. Especially, in districts with high populations such as Kadikoy, possible negative effects should be systematically examined by independent measurement institutions. In this study, the results of the 3-year project entitled "Determination of Electromagnetic Radiation from Base Stations at Istanbul Kadikoy and Determination of Exposure Levels" are discussed in comparison with national and international limits

Plasma density measurements of confined capacitively coupled plasma by microwave interferometer and ion energy distribution function methods

Measurements of hydrogen plasma density, are made in a symmetric single frequency confined capacitively coupled plasma (C-CCP) RF system. Comparison is made between density measured by microwave interferometer (MWI) and electrode wall ion density gathered from Ion Energy Distribution Function (IEDF) responses. Ion number density at electrode wall is obtained by two methods as IEDF integration method and IEDF splitting method. Both methods were compared with MWI and a linear relation is obtained between both methods and MWI. It is demonstrated that electrode wall surface density obtained by IEDF splitting and IEDF integral methods are about 50,000 times less than the bulk plasma density, and integral method reads more data than splitting method. The three different measurement results are compared and they are in good qualitative agreement; the deviation in ratio of bulk plasma density measured by MWI to number density at the electrode wall resolved from ion energy distribution function is greatest at highest pressure or electrode voltages/powers. The reasons for deviations are explained by analysis of the potential drop across the presheath decreases with respect to increased applied power

DETECTION OF P- AND S-WAVE ARRIVAL TIMES USING THE DISCRETE WAVELET TRANSFORM IN REAL SEISMOGRAMS

In this study, a novel solution based on discrete wavelet transform is introduced to determine P- and S-wave arrival times. An algorithm is developed based on changes in frequencies and energy in high frequency bands. Firstly, the earthquake seismogram is divided into a series of windows of 256 samples in length, neighboring windows overlapping by 128 samples. Next, each window is decomposed to its high frequency and low frequency components using discrete wavelet transforms. After that, energies of these components are calculated. As a result of these calculations, we have found that energy variations in high frequency bands are effective to calculate the P- and S-wave arrival times. P- and S-wave arrival times are determined using the frequency components with the highest energy level and first refraction directions in the interested window. In this study, 200 earthquakes with approximately 1000 real-time records were investigated using the proposed method

Achieving Frequency Synchronization by GPS Disciplined Reference Signal

A method for achieving frequency synchronization between two distantly positioned high frequency oscillators is presented. The method is based on using GPS disciplined 10 MHz reference sine waves and phase locked dielectric resonator oscillators. In order to be able to measure the frequency difference between high frequency sources precisely, frequency down-conversion by a mixer is implemented. The presented method enables the usage of frequency sources at various locations to work in sync with each other, which is essential for accurate frequency measurements and radar applications

DESIGN AND IMPLEMENTATION OF CAN / CAN, CAN 1 ETHERNET AND CAN/ATM BRIDGES

The Controller Area Network (CAN) is a high performance and highly reliable advanced serial cornmunication protocol which effıciently supports distributed real-time control systems at high speed, low cost, and a very high level data security. The CAN was originally developed as an automotive standard for a serial interface between electronic control units, but in a short time, it has become a desirable, cheap solution for networks in industrial environments. The fast growth of the CAN in industrial applications results some potential problems such as the size of the area that the devices, controlled by the CAN, are distributed and the communication between the CAN and the existing network systems (such as Ethernet or ATM). One of the solutions to these problems is to use bridges. However, the characteristics of the CAN creates problems, when CAN segments are connected by a bridge, since CAN frames do not contain any information related to destination address, source address, or LAN number that are used by traditional address-hased bridges for routing decisions. Thus, new bridges (suitable for the CAN protocol features) must be designed to overcome the problems. The objective of this paper is not only to investigate the characteristics of bridged CAN systems and to give a bridge proposal to connect CAN segments, but also to design and implement bridges that connect the CAN and existing LAN s and provide communication between them

Measurement of Electromagnetic Radiation around Wind Turbines

The number of wind energy plants in energy production is rapidly increasing in many countries of the world. In recent years, as an alternative energy source, it has been observed that wind energy installations have been established in various regions of our country. Wind turbines are sometimes discussed with the concern that the electromagnetic fields around them can cause health problems. In this study, ELF electromagnetic field levels are given, obtained around the 16.2 km long transmission line which enables the energy generated in 50 wind energy energy central turbines operating in Izmir-Karaburun locality to be transported to the 380kV Karaburun Havza GIS TM transformer center. The results are obtained in magnetic field and electric field. And they are evaluated for electromagnetic pollution in terms of environment and human health