استخراج ماتريس تزويج و كاربرد آن در تنظيم و عيب يابي فيلترهاي داراي تزويج چندگانه

چكيده انگليسي :

m esmaeili@ec iut ac ir Date of Submission Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language PersianSupervisor Amir Borji aborji@cc iut ac irAbstract The design of multiple coupled resonator filters MCRF with finite transmission zeros has receivedconsiderable attention in recent years due to their superior selectivity compact size and low insertion losscompared with traditional all pole filters Furthermore real transmission zeros can be placed at desiredfrequencies to completely suppress specific interference signals while complex transmission zeros can besynthesized to equalize the group delay However tuning and design of these filters is a tedious and timeconsuming task even for experienced filter designers The main goal of this research is to develop an efficientCAD tool for synthesis design tuning and diagnosis of MCRF s The thesis is divided into two parts in thefirst part the synthesis of single and dual band filters is addressed and in the second part an efficient methodfor tuning and diagnosis is presented An analytic method is available to synthesize the polynomials for single band filters with arbitrarytransmission zeros while an optimization based approach is adopted for synthesizing the polynomials for dualband filters After calculating the initial coupling matrix from the scattering parameters an eigenvalue basedoptimization technique is applied to reduce the initial coupling matrix to an appropriate form for the desiredfilter topology In the process of tuning physical dimensions of the filter are adjusted so that the desired frequencyresponse is achieved i e the correct values of cross couplings direct couplings input output couplings andresonance frequencies are implemented Therefore an accurate diagnosis technique is required in order toextract the above parameters from the filter response so that the engineer can adjust the physical parameterstowards achieving the desired response In this thesis a robust and efficient model based parameterextraction MBPE technique is utilized to extract the coupling matrix from the filter response The proposedmethod is very fast and robust and can be used with good accuracy for low loss filters After collectingfrequency samples of the filtering function either from measurements post fabrication tuning or fromelectromagnetic simulations during the design process the Cauchy method is used to fit a rational functionto the data In the case of lossy filters the effect of loss is removed by properly shifting the zeros and poles ofthe filtering function thus a lossless model is obtained Finally using the Feldkeller s equation the rationalfunctions for scattering parameters are obtained from which the coupling matrix is extracted In order to test and verify the software package developed in this research and to demonstrate itscapabilities two microwave filters were designed and adjusted numerically For these filters the frequencysamples were obtained from Ansoft HFSS Furthermore the package was used for diagnosis and tuning of afabricated combline bandpass filter for which frequency samples were obtained from measurements Keywords multiple coupled resonator filters MCRF coupling matrix model based parameterextraction method MBPE Cauchy method

اسمعيلي، محبوبه

استخراج ماتريس تزويج و كاربرد آن در تنظيم و عيب يابي فيلترهاي داراي تزويج چندگانه

فيلترهاي MCRF , الگوريتم MBPE , پارامترهاي پراكندگي