Download (.pdf) Average- Instantaneous, Unimodal and Multimodal Scattering Responses in Spatial Gaussian Channels
Submitted to IEEE Transactions on Wireless Communications, March 2012
In this paper the long standing problem of a heavy tailed power azimuth spectrum and the associated scattering... more In this paper the long standing problem of a heavy tailed power azimuth spectrum and the associated scattering mechanism that triggers its observance is undertaken using the geometry-based stochastic approach that was initially developed in [1], and is further extended herein. More specifically, the unimodal power azimuth spectrum (PAS) and joint power angular scattering response (PASR) are derived under the 2-D Gaussian scattering model. The developed methodology concentrates on two-dimensional (2-D) propagation and therefore provides theoretical insights for the azimuthal domain. At first, it is formally shown that a Gaussian scatter distribution in 2-D space gives rise to an angular power spectrum that may be well modeled by the Gaussian function; under the assumption of free space propagation. Numerical results are presented for higher path-loss exponents, where it is shown that heavier tailed functions such as the Lorentzian and Laplacian functions provide good fits to the derived spectrum. To complement earlier research works in this area, the geometry-based stochastic model developed in [1] is extended in order to express the instantaneous multimodal PASR, which significantly contributes to the estimated correlation statistics as shown in the paper. The 2-D spatial channel model developed herein, allows the distance from the observation point to vary, which enhances the validity of the derived PAS and PASR. Statistical results are provided for various distances from the observation point in order to facilitate any potential practical use of the derived 2-D model. Finally, an analytical expression for the correlation experienced between two antenna patterns is derived under the proposed model. The correlation function is expanded in a series of cylindrical harmonics and the correlation experienced is estimated, which reveals the impact of the instantaneous PASR and average PAS on the correlation function.
A Three- Dimensional Angular Scattering Response Including Path Powers
To Appear in IEEE Transactions on Wireless Communications
Coupled Vertical Monopole Antennas in the Presence of a Lossy Half-Space: Self- and Mutual- Admittances/Impedances
Co-authored with Predrag D. Rancic, presented at International Conference on Electromagnetics in Advanced Applications ICEAA 2007.
Unknown current distribution (UCD), self-and mutual-admittances/impedances and grounding impedances of coupled... more Unknown current distribution (UCD), self-and mutual-admittances/impedances and grounding impedances of coupled vertical monopole antennas (CVMAs) in the presence of lossy ground are determined in this paper. The ground is treated as a linear, isotropic and homogenous lossy half-space (LHS) of known electrical parameters. Influence of the LHS, expressed by the Sommerfeld's integral kernel (SIK), is modelled in a new, simple and efficient way. Afterwards, numerically solving the system of integral equations of Hallen's type (SIE-H), UCDs along antenna conductors are obtained. For this purpose, the method of moments (MoM) is applied assuming the unknown current distribution in a polynomial form.
EM Far-Field of Vertical Dipole Antenna above Real Ground: Two-Image Approximation (TIA) of Sommerfeld's Integral
Co-authored with Predrag D. Rancic, presented at the Second European Conference on Antennas and Propagation EuCAP 2007.
EM radiation field of the vertical dipole antenna (VDA) placed above linear, isotropic and homogeneous lossy-half... more EM radiation field of the vertical dipole antenna (VDA) placed above linear, isotropic and homogeneous lossy-half space (LHS) is determined in this paper. The influence of the LHS, expressed by the Sommerfeld's integral kernel (SIK), is modelled using a new two-image approximation (TIA), which was presented by the authors at the previous EuCAP 2006 Conference when the near-field of the VDA was modelled in order to determine the unknown current distribution (UCD) along antenna conductors. In this paper, it will be shown that the proposed TIA model has the same good characteristics in the far-field zone as it does in the near-field.
Far-field of cooupled vertical mast antennas: Sinusoidal current approximation
presented at 3rd European Conference on Antennas and Propagation, 2009. EuCAP 2009.
Radiation field of coupled vertical monopole antennas (CVMAs) placed above linear, isotropic and homogeneous... more Radiation field of coupled vertical monopole antennas (CVMAs) placed above linear, isotropic and homogeneous lossy-half space (LHS) is determined in this paper. The influence of real ground on radiation characteristics of the CVMAs is modelled in two ways. The first one considers an application of a well known plane wave reflection coefficient (Wait's) model, and the second one a new, so-called TIA (two-image approximation) model, which was proposed at previous EuCAP Conferences. Field patterns obtained applying the two models will be compared for various values of electrical parameters of the ground, as well as for different geometries of the CVMAs.
Two shifted coupled asymmetrical vertical dipole antennas above a lossy half-space
Co-authored with Predrag D. Rancic, presented at 7th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services, 2005.
The unknown current distributions (UCDs) along a system of two coupled asymmetrical vertical dipole antennas... more The unknown current distributions (UCDs) along a system of two coupled asymmetrical vertical dipole antennas arbitrarily placed above a lossy half-space, are determined in this paper. Antennas are fed by two ideal voltage generators of voltages U1 and U2. The UCDs are determined by numerical solving of system of integral equations of Hallen's type (SIE-H) using the point-matching method and the polynomial current approximation. The SIE-H was solved in the so-called symmetrical and asymmetrical working regimes, and afterwards, self- and mutual- admittances/impedances were determined. The influence of the semi-conducting medium, expressed by the Sommerfeld's integral kernel (SIK), was modelled in a very simple, general and accurate way.
Field pattern of the vertical dipole antenna above a Lossy half-space
Co-authored with Predrag D. Rancic, published in SERBIAN JOURNAL OF ELECTRICAL ENGINEERING, Vol. 2, No. 2, 2005, pp. 125-136
The field pattern of the vertical dipole antenna (VDA) placed above a homogenous and isotropic medium is determined in... more The field pattern of the vertical dipole antenna (VDA) placed above a homogenous and isotropic medium is determined in this paper. The unknown current distribution (UCD) on the antenna is evaluated by solving the system of integral equations of Hallen’s type (SIE-H) using a point-matching method (MoM) and a polynomial current approximation. The influence of the lossy half-space, expressed by the Sommerfeld’s integral kernel (SIK), was modelled with a new, very simple and accurate approximate expression. In the surroundings of the antenna, this expression is valid for all positions of the antenna conductors, as well as all possible combinations of the electrical parameters of the ground. A certain number of numerical results were compared to the corresponding ones from the references.
Vertical dipole antenna above a lossy half-space: Efficient and accurate two-image approximation for the Sommerfeld's integral
Co-authored with Predrag D. Rancic, presented at First European Conference on Antennas and Propagation EuCAP 2006.
A new, simple and general model for near field numerical calculation of the Sommerfeld's integral kernel (SIK) that... more A new, simple and general model for near field numerical calculation of the Sommerfeld's integral kernel (SIK) that corresponds to introduction of two fictitious images is proposed in this paper. Applying this model, the unknown current distribution (UCD) and input impedance of the vertical dipole antenna (VDA) placed above linear, isotropic and homogenous lossy half-space are determined. For this purpose, the system of integral equations of Hallen's type (SIE-H) is used, which was numerically solved using the point-matching method and assuming the UCD in a polynomial form.
Vertical Ground-Based Antenna with Reinforced Concrete Foundation as Counterpoise
Co-authored with Predrag D. Rancic, presented at the Second European Conference on Antennas and Propagation EuCAP 2007.
Unknown current distribution (UCD), antenna input admittance/impedance and grounding impedance of the vertical... more Unknown current distribution (UCD), antenna input admittance/impedance and grounding impedance of the vertical monopole antenna (VMA), fed by an ideal voltage generator, are determined in this paper. A model of a small semi-spherical ground electrode is adopted as an antenna counterpoise, while surrounding soil is treated as a linear, isotropic and homogeneous lossy half-space (LHS). The UCD is determined numerically solving the system of integral equations of Hallen's type (SIE-H) using the point-matching method (PMM) and applying an entire domain polynomial current approximation. Special attention was paid to accurate modelling of LHS influence, which is expressed by the Sommerfeld's integral kernel (SIK).
Vertical linear antennas in the presence of a lossy half-space: An improved approximate model
Co-authored with Predrag D. Rancic, published in AEU - International Journal of Electronics and Communications, Volume 60, Issue 5, 2 May 2006, Pages 376-386
The unknown current distribution (UCD) and the input impedance/admittance of the vertical dipole previous... more The unknown current distribution (UCD) and the input impedance/admittance of the vertical dipole previous termantennanext term (VDA) in the previous termpresencenext term of the homogeneous and isotropic previous termlossynext termprevious termhalfnext term-previous termspacenext term are determined in this paper. The moment method (MoM) with an entire domain polynomial current approximation for numerical approach to the system of integral equations of Hallen's type (SIE-H) is applied for solving of this problem. The influence of the finite ground conductivity, expressed by the Sommerfeld's integral kernel (SIK), is modelled in previous termanext term new simple way without limitations for the refraction index. This previous termmodelnext term gives output numerical results of enviable accuracy.
Horizontal linear antennas above a lossy half-space: A new model for the Sommerfeld's integral kernel
Co-authored with Predrag D. Rancic, published in AEU - International Journal of Electronics and Communications, Volume 65, Issue 10, October 2011, Pages 879-887
Unknown current distribution (UCD) and input impedance/admittance of a horizontal dipole antenna (HDA) placed above a... more Unknown current distribution (UCD) and input impedance/admittance of a horizontal dipole antenna (HDA) placed above a homogenous and isotropic lossy half-space (LHS) will be determined in this paper. Integrals of Sommerfeld's type, which occur in potential expressions, will be solved approximately applying a new simple, very accurate and efficient model. Firstly, the accuracy of the proposed model for the Sommerfeld's integral kernel (SIK) is going to be verified, comparing the obtained results with corresponding ones of other authors. In order to illustrate validity of the proposed method, the system of integral equations of Hallen's type (SIE-H) will be numerically solved using the point-matching method (PMM), assuming the polynomial approximation for the current along the antenna conductors. Results obtained for the current distribution and input impedance of the observed HDA will be graphically illustrated and, also, compared with corresponding ones of other authors.
Simple Numerical Approach in Analysis of Horizontal Dipole Antennas Above Lossy Half-Space
Co-authored with Slavoljub Aleksić, published in IJES - International Journal of Emerging Sciences (selected paper from the 10th International Conference on Applied Electromagnetics PES 2011, Niš, Serbia, September 25-29), Vol. 1, No. 4, pp. 586-596, 2011. ISSN 2222-4254
A Two-Dimensional Geometry-Based Stochastic Model
K. Mammasis and P. Santi, IEEE Transactions on Wireless Communications, vol. 11, no. 1, pp. 38-43, Nov 2011.
Spatial fading correlation model using mixtures of von Mises Fisher distributions
K. Mammasis and R. Stewart, J. S. Thompson, IEEE Transactions on Wireless Communications, vol. 8, no. 4, pp. 2046-2055, April 2009.
The Fisher Bingham Spatial Correlation Model for Multielement Antenna Systems
K. Mammasis and R. W. Stewart, IEEE Transactions on Vehicular Technology, vol. 58, no. 5, pp. 2130-2136, June 2009.
Three-dimensional channel modelling using spherical statistics for smart antennas
K. Mammasis, R. W. Stewart, E. Pfann, and G. Freeland, IET Electronics Letters, vol. 44, no. 2, 2008.
The FB5 Distribution and its Application in Wireless Communications
K. Mammasis and R. W. Stewart, in Proc. International ITG Workshop on Smart Antennas, 26-27 Feb. 2008, pp. 375-381.