RF circuit and antenna optimization using space mapping technique

• Main Author: Abdullah Rasmita
• Other Authors: Arokiaswami Alphones
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Antennas, wave guides, microwaves, radar, radio; DRNTU::Engineering::Computer science and engineering::Computer applications::Computer-aided engineering; DRNTU::Engineering::Computer science and engineering::Computing methodologies::Simulation and modeling; DRNTU::Engineering::Computer science and engineering::Theory of computation::Analysis of algorithms and problem complexity
• Online Access: http://hdl.handle.net/10356/17992
• Institution: Nanyang Technological University

The use of EM simulation in circuit optimization in RF domain is very common. There are some problems with this kind of optimization. Firstly, in many cases EM simulations are expensive process. Another problem is the relationship between circuit response and design variable is not an easy function in many cases. In order to overcome these problems a technique named space mapping (SM) was suggested. This technique has been experimentally proved as effective and efficient technique to do optimization including RF circuit optimization. From large number of SM algorithm variants there are only a few that are designed specially for constrained optimization. In this report some constrained SM algorithms using projection method are investigated. These algorithms are variants of Aggressive Space Mapping (ASM) and Aggressive Output Space Mapping (AOSM) and designed to handle convex constraints. The methods are used to optimize multilayer LTCC bandpass filter. The numerical results shows good convergence rate. All of the constrained SM algorithms designed in this report use equivalent circuit and embedded knowledge in coarse model. Parameter extraction is done using circuit tuning based on physical augmentation. In order to test the efficiency of the tuning method, this tuning method is used to tune multilayer LTCC bandpass filter equivalent circuit. The result shows this tuning algorithm is effective and efficient. This circuit tuning algorithm is a derivative of a modeling algorithm based on physical augmentation. The use of this modeling technique in producing equivalent circuit for antenna is investigated. It is shown experimentally that this modeling algorithm is effective and efficient. Although some of proposed constrained SM algorithms are designed to provide global convergence, the author can not prove the global convergence mathematically. The author can only provide the proof for local convergence of some constrained SM algorithms. Further developments may be done in the direction of finding the mathematical analysis of these SM algorithms, refining the methods especially the AOSM based methods and combining the ASM and AOSM.