Research: Acoustics, electromagnetics, waveguide filters and components

Research interest

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

Thesis

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

Papers

2001

Acta Acustica

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

Presentations

1997	Ustaoset 1997	Presentation 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]
1998	Ustaoset 1998	Presentation 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]
1999	Matlab Seminar 1999	J. 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]
1999	1999 IEEE Ultrasonics Symposium	J. 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]
2000	Ustaoset 2000	Presentation 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]
2002	2002 IEEE MTT-S International Microwave Symposium	Design Procedure for Waveguide Filters with Cross-Couplings, Jan Kocbach and Kjetil Folgerų, Nera ASA, Nera Research, N-5020 Bergen [Link]
2002	2002 IEEE MTT-S International Microwave Symposium	The use of CAD tools in filter design for telecommunication applications (part of Workshop), J. Kocbach & K. Folgerų, Nera ASA, Nera Research, N-5020 Bergen, NORWAY. [Link]
2003	33rd European Microwave Conference 2003	Yield-driven Design of Direct-coupled Waveguide Filters with Minimum Use of Full Wave EM Solvers, K. Folgerų & 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. Folgerų (NERA Research, Norway), T. Kjųde, M. Jansson (NERA Networks, Norway) [Available on request]
2004	CNES International Workshop on Microwave Filters	A Low-cost Polymer Waveguide Filter for DVB-RCS Satellite Terminals, Wheatley E., Folgerų K., Kocbach J., Pettersen T., Kopperud A, [Available on request]
2005	Ansoft Converge 2005	Use of HFSS as integral part of efficient design environment for waveguide components, J. Kocbach, K. Folgerų [Link]

Reports

1999	ONACS report	J. 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]
1999	FEMP report	J. 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

1999	Mode shapes of PZT-5A disks	Frequency 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]
1999	Mode shapes of BaTiO3 disks	Frequency 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]
1999	Mode shapes of PbTiO3 disks	Frequency 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]
1999	PZT5A disk with front layer	Eigenmodes of a PZT-5A disk with a cork front layer with varying thickness vibrating in vacuum. Made for the IEEE 1999 Ultrasonics Symposium. [Link]
2000	Movie of radiated sound field	Movie 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]