Advances in Radio Science www.adv-radio-sci.net 1684-9965 1684-9973 4 Kleinheubacher Berichte 2005 2006 10.5194/ars-4-25-2006 http://www.adv-radio-sci.net/4/25/2006/ http://www.adv-radio-sci.net/4/25/2006/ars-4-25-2006.html http://www.adv-radio-sci.net/4/25/2006/ars-4-25-2006.pdf 25 32 2006-09-04 Spherical mode analysis of planar frequency-independent multi-arm antennas based on its surface current distribution G. Armbrecht armbrecht@hft.uni-hannover.de O. Klemp H. Eul Universität Hannover, Institut für Hochfrequenztechnik und Funksysteme, Hannover, Germany Deployment in the design of mobile radio terminals focuses on the implementation of multiradio transmission systems, using a multiplicity of different radio standards combined with high-speed data communication over multiple-input multiple-output (MIMO) and multimode diversity techniques. Hence, planar log.-per. four-arm antennas are predistined to meet the requirements of future mobile multiradio RF-frontends and will be introduced and analysed in terms of an efficient spherical mode analysis by means of surface current distribution in order to derive an analytic access to MIMO- and polarisation-diversity performance computation. A remarkable parameter reduction and a faster numerical analysis with respect to conventional techniques may be achieved. The sources in the near-field antenna region are based on the numerical computation of surface currents involving the finite element method (FEM). Relations between the variations of the geometrical antenna parameters and the excitation of discrete spherical modes are presented and will be analysed in detail. Bruning, J H. and Lo, Y T.: Multiple Scattering of EM Waves by Spheres Part I-Multipole Expansion and Ray-Optical Solutions, IEEE Transactions on Antennas and Propagation, 19, 378–390, 1971. Chen, Y. and Simpson, T.: Radiation Pattern Analysis of Arbitrary Wire Antennas Using Spherical Mode Expansions with Vector Coefficients, IEEE Transactions on Antennas and Propagation, 39, 1716–1721, 1991. Chen, Y., Simpson, T L., and Ho, T Q.: Highly efficient technique for solving radiation and scattering problems, IEE Proc.-H, 139, 7–10, 1992. Jensen, M A. and Wallace, J W.: A Review of Antennas and Propagation in MIMO Wireless Communications, 52, 2810–2824, 2004. Klemp, O. and Eul, H.: Radiation Pattern Analysis of Antenna Systems for MIMO and Diversity Configurations, Adv. Radio Scie., 3, 157–165, 2005. Klemp, O., Schultz, M., and Eul, H.: Novel logarithmically periodic planar antennas for broadband polarization diversity reception, Int. J. Electron.\ Commun. (AEUE), 59, 268–277, 2005. Klemp, O., Armbrecht, G., and Eul, H.: Computation of Antenna Pattern Correlation and MIMO Performance by means of Surface Current Distribution and Spherical Wave Theory, Accepted for publication in Adv. Radio Scie., 2006. Ludwig, A C.: Near-Field Far-Field Transformations Using Spherical-Wave Expansions, IEEE Transactions on Antennas and Propagation, 19, 214–220, 1971. Narasimhan, M S., Christopher, S., and Varadarangan, K.: Modal Behavior of Spherical Waves from a Source of EM Radiation with Application to Spherical Scanning, 33, 350–354, 1985. Potter, P D.: Application of Spherical Wave Therory to Cassegrainian-Fed Paraboloids, IEEE Transactions on Antennas and Propagation, 15, 727–736, 1967. Stratton, J A.: Electromagnetic Theory, McGraw Hill, New York, 1941. Werner, D H. and Mittra, R.: Frontiers in Electromagnetics, IEEE Press Series on Microwave Technology and RF, New York, 2000.