Sharif Digital Repository

This paper applies the method of decomposition of wavefronts to ray tube tracing model. Energy ray tubes which are emitted from the source are modeled by three rays and the method of decomposition of wavefronts iteratively improves the accuracy of ray tracing. Comparison with applying the method of decomposition of wavefronts to conventional ray tracing is made afterwards. It is observed that by applying the method of decomposition of wavefronts to ray tube model, the accuracy of ray tracing can be improved much more efficiently and the simulation time decreases to almost a half. ©2009 IEEE  

High-quality guided wave devices are key components in integrated millimeter-wave circuits. In this paper, we propose mm-wave planar dielectric waveguides based on thin, anisotropic artificial dielectric layers with very high in-plane permittivity. Waves propagating on such films are surface waves whose field exponentially decays outside the film in the vertical direction, similar to waveguides commonly used in integrated optics. The very high in-plane permittivity of the artificial dielectric layers leads to strong field confinement, and allows the implementation of relatively thin waveguides. This fact, together with the planar structure of these devices, make them highly suitable for... 

To evaluate the performance of distributed mediumaccess control (MAC) layer of emerging ultra wideband (UWB) and 60-GHz millimeter wave (mmWave) wireless personal area networks (WPANs) based on distributed reservation protocol (DRP) of ECMA-368 and ECMA-387 standards, we provide an analytical model for the probability distribution of steady state throughput as a function of the network dimensions size, number of devices, antenna beamwidth, transmission range, bit error rate (BER), antenna disturbance rate (ADR), aggregation length, payload size, and incoming frame rate. Using this model, the optimal payload size is computed as an example of optimization problem.We also propose a formula for... 

We use the 3D vectorial Gaussian beam tracing method to model millimeter wave propagation. We simulate the propagation of Gaussian beams in a large scale environment at 62.4 GHz. First, a known far field pattern of the transmitter antenna is expanded into a set of Gaussian beams. We chose Gabor expansion based method to expanding radiating field into Gaussian beams. Then, a Gaussian beam tracing model considering reflections and transmission is used to represent urban microcell propagation. We use a phase matching method to find reflected Gaussian beam The results of the Gaussian beam tracing simulations including line-of-sight (LOS) and non-Iine-of-sight (NLOS) propagation are compared with... 

In radio channels modelings, the phases and amplitudes of the rays undergo some modifications when they are reflected from or transmitted through a particular material. These reflection and transmission coefficients make use of the electrical properties of the materials, thus, it is essential to know the values of the relative dielectric constant and of the conductivity or the loss tangent of the materials that appear in the propagation environments. In this paper, a theoretical model based on the inter-molecule interactions, has been developed and used to estimate the dielectric parameters of glass. ©2009 IEEE  

A millimeter wave H-plane duplexer using E-plane filters has been designed. T-junction is used for connecting the channel filters compensated by cylindrical post and analyzed by integral contour method. Moreover the junction discontinuity effects have been taken into account. The combination of filters and compensated T-junction allows for low-cost manufacturing. The E-plane filters are analyzed separately, by mode matching method. The scattering parameters of the combination of filters and T-junction are obtained. The diameter and position of the compensating rod and length of T arms are optimized to achieve desired performance. This procedure saves time and memory in computations. The 38... 

Dirac dispersion cones enable remarkable wave phenomena in electronics as well as electromagnetic systems. In this work, the authors experimentally demonstrate for the first time the Dirac leaky wave antennas (DLWAs) at millimetre-wave (mm-wave) frequencies. The demonstrated DLWAs are implemented in the substrate integrated waveguide technology, delivering unprecedented features at high frequencies such as radiation at, and continuous beam scanning through broadside, with ease of fabrication, making these designs well suited for mm-wave applications such as emerging fifth generation and Internet of Things, radar and imaging. It is shown that a planar Dirac photonic crystal can be realised... 

In this paper, an effort has been made to model the 60 GHz wireless channel using a precise yet fast and simple method for short outdoor links that are a possible area for the use of 60 GHz wireless connectivity for high data rate services with dense frequency reuse. Considering the certain properties of this frequency band, it is possible to obtain a simple channel model to replace time consuming ray tracing methods with simpler models by disregarding low power multipath components. The street canyon model has been considered here as a replacement for ray tracing in an urban environment with below rooftop antennas to predict received power along streets and the results have been compared to... 

Channel characterization is an important step in the design of wireless communication systems. While channel sounding procedures are a useful method in determining channel behavior, they also require expensive and time consuming procedures and equipment. Ray tracing has been an important substitute for measurement in deterministic channel modeling and characterization of the wireless channel. Much has been done to improve the precision and efficiency of this method for lower frequency bands (generally below 5 GHz) over the years. Recently, with the worldwide announcement of a broad unlicensed band in the millimeter wave spectrum around 60 GHz, a great amount of attention has been paid to... 

The 3D vectorial Gaussian beam tracing method is used to model a short 62.4-GHz link in a simple urban environment. First the Gabor expansion method with a wide-waisted window function is utilized to expand the known far field pattern of the transmitter antenna into a set of Gaussian beams and then these beams are propagated in space until they impinge on a building wall or ground, on which a phase matching method is used to find the reflected Gaussian beams. We will also concisely introduce a new method to consider 3D GB diffraction when incident on a wedge. Overall coverage map shows the dominant effect of shadowing in the millimeter wave band. Received mean signal power in a line of sight...