Research: Acoustics, electromagnetics, waveguide filters and components

Research interest (updated 2005)

I have taken a Ph.D. in hydroacustics, and have worked on electromagnetical problems at Nera for five years between 2001 and 2006. I am currently again doing research related to hydroacoustical problems.

My research interests include

  • Simulation tools for acustical and electromagnetical structures - with special emphasis on the Finite Element Method
  • Design of waveguide filters and components
  • Design of antenna components
  • Piezoelectric transducers, including radiation problems
I am especially interested in methods to speed up and automate design processes by effective use of simulation tools and helper applications.

Publications and Presentations (updated 2005)

Thesis

1996M.Sc. ThesisFEM of piezoelectric disks / Endelig element modellering av piezoelektriske skiver, Norwegian, (HTML/Postscript)
[Link]
2000Ph.D. ThesisFinite Element Modeling of Ultrasonic Piezoelectric Transducers. Influence of geometry and material parameters on vibration, response functions and radiated field [Additional info]
[Link]

Papers

2001Acta AcusticaResonance Frequency Spectra with Convergence Tests of Piezoceramic Disks using the Finite Element Method, J. Kocbach, P. Lunde and M. Vestrheim, 2001.
[Link]

Presentations

1997Ustaoset 1997Presentation held at 20th Scandinavian Symposium on Physical Acoustics, Ustaoset, 1997. "FEM-ANALYSIS OF PIEZOELECTRIC DISKS - METHOD AND TESTING". This link points to the abstract.
[Link]
1998Ustaoset 1998Presentation held at 21th Scandinavian Symposium on Physical Acoustics, Ustaoset, 1998. "Piezoceramic disks with a front layer - Comparisons of FEM with experimental data." This link points to the abstract and slides.
[Link]
1999Matlab Seminar 1999J. Kocbach and M. Kaltenbacher, "ONACS - Object oriented Numerical Analysis of Coupled Systems using MATLAB," in Seminarunterlagen S53, Matlab-Seminar (ARGESIM, c/o EDV-Zentrum TU Wien, Wiedner HStr. 8-10, A-1040 Wien, 1999
[Link]
19991999 IEEE Ultrasonics SymposiumJ. Kocbach, P. Lunde and M. Vestrheim, "FE Simulations of Piezoceramic Disks with a Front Layer of Varying Thickness," Proc. of 1999 IEEE International Ultrasonics Symposium, 1999.
[Link]
2000Ustaoset 2000Presentation held at 23rd Scandinavian Symposium on Physical Acoustics, Ustaoset, 2000. " FE Modeling of Piezoceramic Disks including Radiation into a Fluid Medium". This link points to the abstract and slides.
[Link]
20022002 IEEE MTT-S International Microwave SymposiumDesign Procedure for Waveguide Filters with Cross-Couplings, Jan Kocbach and Kjetil Folgerø, Nera ASA, Nera Research, N-5020 Bergen
[Link]
20022002 IEEE MTT-S International Microwave SymposiumThe use of CAD tools in filter design for telecommunication applications (part of Workshop), J. Kocbach & K. Folgerø, Nera ASA, Nera Research, N-5020 Bergen, NORWAY.
[Link]
200333rd European Microwave Conference 2003Yield-driven Design of Direct-coupled Waveguide Filters with Minimum Use of Full Wave EM Solvers, K. Folgerø & J. Kocbach, Nera ASA, Nera Research, N-5020 Bergen, NORWAY.
[Available on request]
2004 PIERS 2004 Progress In Electromagnetic Research Symposium Tunable dielectric resonator filters for radio link applications, J. Kocbach, K. Folgerø (NERA Research, Norway), T. Kjøde, M. Jansson (NERA Networks, Norway)
[Available on request]
2004CNES International Workshop on Microwave FiltersA Low-cost Polymer Waveguide Filter for DVB-RCS Satellite Terminals, Wheatley E., Folgerø K., Kocbach J., Pettersen T., Kopperud A,
[Available on request]
2005Ansoft Converge 2005Use of HFSS as integral part of efficient design environment for waveguide components, J. Kocbach, K. Folgerø
[Link]

Reports

1999ONACS reportJ. Kocbach, "ONACS - Object oriented Numerical Analysis of Coupled Systems using MATLAB," Technical report, Institute of Measurement Technology, Johannes Kepler University Linz, Austria, 1999, 21 p.
[Link]
1999FEMP reportJ. Kocbach, P. Lunde and M. Vestrheim, "FEMP - Finite Element Modeling of Piezoelectric Structures. Theory and Verification for Piezoceramic Disks," Scientific/Technical report no. 1999-07, Department of Physics, University of Bergen, Bergen, Norway, 1999, 100 p.
[Link]
2001-Several internal NERA-reports.No abstracts/titles/articles given.

Demonstrations

1999Mode shapes of PZT-5A disksFrequency spectrum of PZT-5A disks with varying diameter/thickness ratio. Click on the figure to see how the mode shapes vary with diameter/thickness ratio. Made in conjuntion with the article "Resonance Frequency Spectra with Convergence Tests of Piezoceramic Disks using the Finite Element Method" submitted to Acustica.
[Link]
1999Mode shapes of BaTiO3 disksFrequency spectrum of BaTiO3 disks with varying diameter/thickness ratio. Click on the figure to see how the mode shapes vary with diameter/thickness ratio. Made in conjuntion with the article "Resonance Frequency Spectra with Convergence Tests of Piezoceramic Disks using the Finite Element Method" submitted to Acustica.
[Link]
1999Mode shapes of PbTiO3 disksFrequency spectrum of PbTiO3 disks with varying diameter/thickness ratio. Click on the figure to see how the mode shapes vary with diameter/thickness ratio. Made in conjuntion with the article "Resonance Frequency Spectra with Convergence Tests of Piezoceramic Disks using the Finite Element Method" submitted to Acustica.
[Link]
1999PZT5A disk with front layerEigenmodes of a PZT-5A disk with a cork front layer with varying thickness vibrating in vacuum. Made for the IEEE 1999 Ultrasonics Symposium.
[Link]
2000Movie of radiated sound fieldMovie of sound field radiated from a PZT-5A disk with diameter/thickness ratio of 5 for some selected modes. Made for the Ustaoset-2000 meeting. See abstract/slides for further explanations.
[Link]

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