IOSR Journal of Electronics and Communication Engineering (IOSR-JECE) e-ISSN: 2278-2834,p- ISSN: 2278-8735.Volume 9, Issue 5, Ver. II (Sep - Oct. 2014), PP 58-66 www.iosrjournals.org www.iosrjournals.org 58 | Page Study of RF Propagation Losses in Homogeneous Brick and Concrete Walls using Analytical Frequency Dependent Models Kedar Nath Sahu 1 , Dr. Challa Dhanunjay Naidu 2 and Dr. K Jaya Sankar 3 1 Professor, Department of Electronics and Communication Engineering, Stanley College of Engineering and Technology for Women, Hyderabad, India. 2 Professor, Department of Electronics and Communication Engineering and Principal of VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad, India. 3 Professor and Head of the Department of Electronics and Communication Engineering, Vasavi College of Engineering, Hyderabad, India. Abstract : The prediction of wall losses is a fundamental aspect in the development of ultra-wideband through- the-wall (TTW) detection systems. Accurate ultra-wideband signal attenuation prediction has always been very difficult due to a broad variety of building materials without the support of a sophisticated model. In this paper, the attenuation of different types of concrete and brick walls are estimated using the electromagnetic characteristics of building materials for frequencies from 1 to 5 GHz by two theoretical models based on the method of general solutions of wave equations using boundary conditions and the impedance transformation method or the method of transmission line analogy. This estimation will enable in the design of any ultra wideband through-the wall radar system. Keywords: brick, concrete, dielectric properties, RF propagation, through-the-wall (TTW), ultra-wideband. I. INTRODUCTION Modeling of radio frequency (RF) propagation of wave through building walls has a significant impact on the development of ultra-wideband (UWB) through-the-wall (TTW) radar systems. The construction of a building wall is usually based on the structural considerations. But the matter of the fact is that, even if the type of elements used to build the wall is known, their influence on electromagnetic waves is difficult to predict. Reflection coefficient, transmission coefficient and signal attenuation are the most dominant factors in the study of propagation of radio signals in any indoor or outdoor environments and are very closely related to the dielectric properties of building materials. This paper describes two analytical techniques such as the method of general solutions of wave equations using boundary conditions and the impedance transformation method (or the method of transmission line analogy) to study the propagation behaviors of some commonly used building wall materials: concrete and brick. Similar wall modeling has been reported in the literature [1] but by using a different approach. Several measurement techniques used to characterize the typical building materials such as brick, concrete, glass, plasterboard, plywood, wood etc. in terms of the frequency dependent dielectric properties , σ etc. have been reported in the literature [2-5]. Using these frequency dependent parameters, the propagation parameters can be estimated. According to the authors of [3], it is not possible to identify a particular trend in the variation of the dielectric parameters, conductivity values with frequency which can be valid for all materials. For some materials the dielectric values are found quite similar at a different frequency and this may be due to the fact that the contributions of multiple internal reflections due to large attenuation inside the wall are neglected. Also as mentioned in [3], when the thickness of the material is not very large as compared to wavelength, multiple reflections greatly impact the transmission and reflection coefficients. Hence the performance of any analytical and theoretical multilayered model in the study of attenuation to the point of its applicability and accuracy depends on whether the attenuation was evaluated including the most important effect of multiple reflections at the several interfaces comprising the model. Both of the models discussed in this paper are valid from a point of view that the effect of multiple successive internal reflections is accounted for. In a theoretical sense, even the general behavior of the dielectric constants is supposed to grow slightly with frequency; it might present some resonant frequencies which are responsible to modify this common trend. Thus, the variation of the dielectric constants with frequency does not necessarily follow the same trend for different materials and depends on the material as well as the polarization used. II. WALL MATERIALS AND THEIR DIELECTRIC PROPERTIES Buildings walls are commonly made up of concrete or brick and can be modeled [5] as a dielectric material having an effective permittivity, and conductivity, constant over the frequency range of interest so