PERFORMANCE OF THE GENERALIZED MULTIPOLE TECHNIQUE (GMT/MMP) IN ANTENNA DESIGN AND OPTIMIZATION

摘要

During the last decade, the generalized multipole technique (GMT) has been extensively studied, improved and applied to many electromagnetics problems such as bioelectromagnetics, optics, waveguides and electromagnetic compatibility (EMC), but little has been reported towards utilizing this method for antenna design and optimization. On the other hand, the few published examples of simple dipoles and helices in the close vicinity of lossy scatterers have suggested the potential significance of GMT for antenna design purposes. In this paper, the applicability of the GMT based 3D multiple multipole (3D MMP) code for simulation of wire antenna has been investigated. To evaluate the advantages and limitations of 3D MMP, several basic types of wire antenna configurations were simulated. These were linear and linear array, helical, and physically constrained low profile antennas. To validate the method's performance, we calculated radiation patterns, impedance, return loss, reflection coefficient, VSWR, and compared them to available results from experiments and/or results published by others using different techniques. This investigation showed several conceptual advantages of this technique for antenna simulations. Furthermore, the thin-wire expansion in combination with multipoles and roof top functions provides a great degree of flexibility in modeling. The most recently implemented expansion, "line multipoles," extends the code's efficiency to non-thin-wire configurations (e.g., helix with small ratio of pitch to wire diameter). Critical issues of modeling are the feedpoint and wire tip area, matching point locations and segment length-to- diameter ratio. Symmetries are used where possible to minimize computation time without loss of generality as any antenna element may easily be assembled in non- symmetrical configurations with the block-iterative solver. In order to achieve better confidence on more complex configurations, extensive studies were performed to increase efficiency and stability of modeling and will be discussed. In addition, the numerical validation techniques were extended to satisfy the special requirements of antenna simulations. These studies demonstrate the potential of GMT/MMP for use in analysis, synthesis and optimization of antennas. [Vol. 9, No. 3 (1994), Special Issue on Generalized Multipole Technique (GMT), pp 79-89]