Abstract	Network Synthesis using modern methods based on transformed variables will be presented. This automatically solves the previously difficult approximation problem, and simplifies the theory to such an extent that it can no longer be considered as a difficult topic. Examples to be presented include cross coupled filters, physically asymmetric filters, such as singly-terminated structures, and other new realizations. The process of equivalent circuit elements extarction using electromagnetic simulations is described. This process allows very fast optimization of synthesized practical filters to yield precise responses. The synthesis of different physical filter configurations using various transmission media and topologies such as dual mode, dielectric resonator, coaxial cavity (combline), and ridge waveguide filters are discussed. Equivalent circuits of components (e.g. T-junctions) used in multiplexrs realizations are described.
Organizer 1	Kawthar A. Zaki University of Maryland, EE Department College Park, MD 20742; USA kzaki@ieee.org tel: 301-405-3674 fax: 301-314-9281
Organizer 2	Ralph Levy R. Levy Associates 1897 Caminito Velasco, La Jolla, CA 92037; USA r.levy@ieee.org tel: 619-459-6752 fax: 619-459-6752
Sponsor	MTT-8 Filters and Passive Components
Technical level	Tutorial and Advanced
Day/ time	Sunday, 11 June 2000, 8:00 AM to 5:00 PM
Room	Hynes Convention Center Room 210
Speakers	Coupled Resonators Prototype Synthesis, H. Clark Bell, HF Plus Direct Synthesis of Cross-Coupled Filters, Ralph Levy, Levy Associates Multiple Coupled Resonator Filters Synthesis by Optimization, Ali E. Atia, Orbital Sciences Corporation The Art and Science of Selecting Physical Filter Configuration for a Given Transfer Function, Wai-Cheung Tang, Com Dev Ltd. Equivalent Circuits: How to Obtain Them and Use Them, Arthur A. Oliner, Polytechnic University, Brooklyn, New York Techniques for Obtaining Equivalent Circuits for Discontinuities in Planar Microwave Circuits, George Matthaei, University of California, Santa Barbara Derivation of circuit element models from EM simulation, Ralph Levy, Levy Associates Further Discussion of Any Topics of Interest to the Audience, K. A. Zaki, University of Maryland

Coupled Resonator Prototype Synthesis, H. Clark Bell

1. Normalized lowpass prototype

2. Approximation of specification

2.1 Equiripple passband

2.2 Iterative approximation

3. Realization of prototypes

3.1 Symmetric prototype

3.2 Orthonormal transformations

4. Synthesis examples

Direct Synthesis of Cross-Coupled Filters, Ralph Levy

1. Quick revision of transformed variable synthesis and approximation theory

2. Extension to commensurate distributed networks

2.1 Richards' theorem

2.2 The unit element

3. Formation of the transfer (ABCD) matrix in the transformed variable

4. Transfer matrix of singly-terminated networks

5. Synthesis of cross-coupled filters in canonic form

6. Direct synthesis of cascaded-quadruplet (CQ) and cascaded-trisection (CT) filters without matrix rotation operations

Multiple Coupled Resonator Filters Synthesis by Optimization, Ali E. Atia

1. Classical CAD of filters by optimization and its associated difficulties.

2. Classical design of filters by synthesis and its limitation in the resulting topologies.

3. Desired non standard topologies for practical packaging of filters

4. Solution of the approximation problem and critical natural frequencies (zeros and poles) of the desired transfer function.

5. Circuit model and the general topology matrix.

6. Defining an error function from the response at the zeros and poles of the network.

7. Coupling matrix optimization to obtain the desired zeros and poles.

8. Examples of multiple coupled resonator filters design by optimization:

- Three pole asymmetric filters with transmission zeros below or above the pass bad

- Five pole filters with asymmetric response

- Six pole filter with an unusual topology

The Art and Science of Selecting Physical Filter Configuration for a Given Transfer Function, Wai-Cheung Tang

1. Selection of proper realization technology to complement filter synthesis

1.1 Enhance the achievable performance

1.2 Simplify the tuning characteristics of the filter

2. Filter realization technologies and corresponding coupling options

2.1 Dual mode filters

2.2 Dielectric resonator filters

2.3 Co-axial cavity filters

3. Practical implementation examples and design options of different filter topologies.

Equivalent Circuits: How to Obtain Them and Use Them, Arthur A. Oliner

1. Review of general properties of equivalent circuits

1.1 Pictorial aspects

1.2 Capacitive and inductive nature, and relation to higher-order modes

1.3 Analytical dependences

2. Stored-power concept and techniques

2.1 Physical insights

2.2 Relation to variational expressions

2.3 Applications to various structures to illustrate the versatility and usefulness

3. Two other methods for obtaining equivalent circuit parameters quickly

3.1 Small-aperture and small-obstacle theory

3.2 Babinet's principle

4. Using equivalent circuits where they are appropriate

4.1 Periodic structures and their stop-band properties

4.2 Properties of resonant cavities

4.3 Guided-wave behavior for structures with discontinuities in their cross sections

Techniques for Obtaining Equivalent Circuits for Discontinuities in Planar Microwave Circuits, George Matthaei

1. Fundamentals of anticipating what form of equivalent circuit a given discontinuity will have.

2. Selected circuit examples having equivalent circuits with increasing complexity

3. Methods for obtaining extremely accurate field solutions when using certain kinds of software.

4. Results of an extensive computer study of a filter designed using an array of parallel-coupled microstrip lines & comparison with measured data.

4.1 Effects of evanescent fields of the dominant housing mode

4.2 A method of correcting for this in CAD programs.

4.3 Effect of housing modes on the apparent fringing capacitances seen at the ends of the lines.

4.4 Situations where there is significant coupling between evanescent modes and transmission lines and how to include in some CAD programs.

Derivation of circuit element models from EM simulation, Ralph Levy

1. Advantages and disadvantages of the scattering matrix representation

2. Derivation of equivalent circuits from the impedance or admittance matrices

3. Examples:

3.1 Stripline step junction

3.2 Aperture coupling from a waveguide into a cavity supporting two modes

4. Derivation of impedance matrices for interacting discontinuities

5. Example: Theory of the short slot narrow wall coupler

Further Discussion of Any Topics of Interest to the Audience, K. A. Zaki