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Friis transmission equation combined with Finite Difference in Time Domain (FDTD) method has been used to carry out investigation on Specific Absorption Rate (SAR) inside the human head model exposed to a 100 Watt GSM Base Station Antenna (BSA) at GSM-900 band. Maximum local SAR (MLSAR) has been calculated at 925 MHz, keeping distance between head and BSA in the range of 0.5 m to 5.0 m. The human...
Previous enhancements to the FDTD method have facilitated the analysis of structures containing sharp metal edges, such as microstrip, when the edges are aligned with the mesh and also of smooth, arbitrarily curved metal objects. So far, however, there has been little work on the often encountered situation of thin metal patches which are orientated at an angle to the mesh other than for the special...
A wide band planar phased array antenna consisting of 21 by 21 Highly-Coupled Dipole (HCD) elements was designed using a combination of the `AGATE' in-house FDTD based prediction tool and commercial microwave circuit design software. This paper discusses the challenges presented during the manufacture of this array antenna, specifically the impact of practical manufacturing considerations and their...
This paper examines how the SAR in the head is combined when exposed to the field due to multiple sources. The mechanisms when the sources have the same and different frequencies are discussed. FDTD simulation results are included when an anatomically realistic head is excited by various sources including: plane waves, vertically and horizontally orientated dipoles positioned in front and by the side...
Wireless Sensor Networks (WSNs) which utilise IEEE 802.15.4 technology offer the potential for low cost deployment and maintenance compared with conventional wired sensor networks, enabling effective and efficient condition monitoring of aged civil engineering infrastructure. We will address wireless propagation for a below to above ground scenario where one of the wireless nodes is located in a below...
The design steps for a novel cylindrical electronic bandgap antenna in the X-band are given. Simulation results, based on a FDTD modeller are also presented as an aid to designing the physical antenna. The antenna demonstrated high directivity in the H-plane. Measurements on a prototype achieved 54% fractional bandwidth with an average gain of 8 dBi and 17.5 dB front to back ratio in the azimuthal...
An array of four slot antennas backed with substrate integrated waveguide (SIW) cavities is presented for application to multiple input multiple output (MIMO) systems. Two 0.18 ?? spaced antennas are decorrelated by the use of a rat race hybrid. An investigation based on simulations and measurements has been carried out. The impedance matching and the radiation characteristics of these structures...
This paper investigates the possibility of designing and fabricating microwave antennas using metallic nanomaterials. Specifically, we will consider modifying the structure of conventional designs including dipoles, loops and apertures. FDTD simulations are used to examine these modified structures. Due to the prohibitive computational requirements of modelling nanoscale objects on a millimetre scale,...
This paper presents a study of subject-specific radio channels in wireless body area networks (WBANs). The simulation tool is based on a parallel finite-difference time-domain method (FDTD) and is well suited to model radio propagations around complex, inhomogeneous objects including human bodies in WBAN. It is found from our study that radio channel characteristics in WBAN are subject specific when...
This paper examines the effects of metallic semi-rimmed spectacles on the specific absorption rate (SAR) inside the head when illuminated by a frontal dipole source representing a PDA held in front of the face. The frequency considered is 900 MHz. Both children's and adult's spectacles are investigated using the Loughborough SAM (Specific Anthropomorphic Mannequin) head incorporated into a DASY4 robot...
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