A four-pole elliptic function compact bandpass filter is designed by using interdigital hairpin resonator and step-impedance hairpin resonator. The miniaturized band-pass filter is also implemented using high permittivity dielectric substrate. The full-wave simulator IE3D is used to design the compact hairpin resonator, and to calculate the coupling coefficient of the basic coupling strictures. The responses of the fabricated filters using Al2O3(εr = 9.7, Q×f = 350000 GHz) and 0.6Sm(Co1/2Ti1/2)O3-0.4CaTiO3 (εr=37, Q×f = 43000 GHz) dielectric substrates are designed at a center frequency of 2 GHz. The size of the compact hairpin filter using 0.6Sm(Co1/2Ti1/2)O3-0.4CaTiO3 ceramic substrate, as compared to that of a compact hairpin filter using Al2O3 ceramic substrate, is reduced in size by 45%. The compact size and good agreement have been obtained between simulations and implementation results.
2. Cohn, S. B., "Parallel-coupled transmission line resonator filters," IRE Trans. Microwave Theory Tech., 223-231, 1958.
3. Caspi, S. and J. Adelman, "Design of combline and interdigital filter with tapped-line input," IEEE Trans. Microwave Theory Tech., Vol. 36, 759-763, 1988.
4. Matthaei, G. L., "Comb-line bandpass filter of narrow or moderate bandwidth," IEEE Trans. Microwave Theory Tech., Vol. 6, 82-91, 1963.
5. Gysel, U. H., "New theory and design for hairpin-line filters," IEEE Trans. Microwave Theory Tech., Vol. 22, 523-531, 1974.
6. Kwon, K. H., S. M. Han, S. NaHm, M. H. Kim, and Y. S. Kim, "Compact hairpin-shaped duplexer using a BMT Substrate with high dielectric constant," Microwave Opt. Tech. Lett., Vol. 41, No. 4, 251-253, 2004.
7. Cristal, E. G. and S. Frankel, "Hairpin-line and hybrid hairpin-line/half-wave parallel-coupled-line filters," IEEE Trans. Microwave Theory Tech., Vol. 20, 719-728, 1972.
8. Hong, J. S. and M. J. Lancaster, "Cross-coupled microstrip hairpin-resonator filters," IEEE Trans. Microwave Theory Tech., Vol. 46, 118-122, 1998.
9. Matthaei, G. L., N. O. Fenzi, R. J. Forse, and S. M. Rohlfing, "Hairpin-comb filters for HTS and other narrow-band applications," IEEE Trans. Microwave Theory Tech., Vol. 45, 1226-1231, 1997.
10. Sagawa, M., K. Takahashi, and M. Makimoto, "Miniaturized hairpin resonator filters and their application to receiver front-end MIC's," IEEE Trans. Microwave Theory Tech., Vol. 37, 1991-1997, 1989.
11. Yabuki, H., M. Sagawa, and M. Makimoto, Voltage controlled push-push oscillators using miniaturized hairpin resonators, IEEE MTT-S Int. Microwave Symp. Dig., 1175-1178, 1991.
12. Levy, R., "Filters with single transmission zeros at real or imaginary frequencies," IEEE Trans. Microwave Tech., Vol. 24, 172-181, 1976.
13. Kurzok, R. M., "General four-resonator filters at microwave frequencies," IEEE Trans. Microwave Tech., Vol. 14, 295-296, 1966.
14. Hsu, C. H., Microwave dielectric properties and mixture behavior of Sm(Co1/2Ti1/2)O3-CaTiO3 ceramic system, Proceedings of 11th International Conference and Exhibition of the European Ceramic Society, June 21-25, 2008.
15. Lee, S. Y. and C. M. Tsai, "New cross-coupled filter design using improved hairpin resonators," IEEE Trans. Microw. Tech., Vol. 48, No. 12, 2482-2490, Dec. 2000.
16. Yabuki, H., Y. Endo, M. Sagawa, and M. Makimoto, Miniaturized hairpin resonators and their application to push-push oscillators, Proc. the 3rd Asia-Pacific Microwave Conf., 263-266, 1990.
17. Hong, J. S. and M. J. Lancaster, Microstrip Filters for RF/Microwave Applications, Wiley, New York, 2001.
18. Zeland Software, Inc., IE3D 6.0, New York, 1999.