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Experimental prototype of microstrip BPF

Microstrip bandpass filter with left transmission zero controlled by parasitic cross coupling

Alexander V. Zakharov, Sergii A. Rozenko, Ludmila S. Pinchuk


A third-order microstrip filter is proposed and studied. It is characterized by a left-handed transmission zero fz, caused by the parasitic cross-coupling between non-adjacent resonators. The filter contains a half-wave middle resonator and two quarter-wave resonators located from different sides, near the open ends of the middle resonator. The coupling between all resonators has magnetic character, and the zero of the filter transfer function fz is located to the left of the center frequency of the passband f0. Such filter is described by a modified coupling matrix, where one of the main coupling coefficients is artificially assigned a minus sign. In the proposed filter design, for a given value of the main coupling coefficients, it is possible to provide different values of the cross-coupling coefficient by appropriately selecting the design parameters. This allows adjusting the zero position of the transmission fz for a given bandwidth of the filter, thereby changing the left slope of the amplitude-frequency characteristic. A sequence of steps is proposed for constructing such a filter. The measured and simulated frequency characteristics of the experimental filter are given.


band pass filter; microstrip line; cross-coupling; zero transmission; coupling matrix

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HONG, J.-S. Microstrip Filters for RF/Microwave Application, 2nd ed. New York: John Wiley & Sons, Inc., 2011.

HONG, J.-S.; LANCASTER, M.J. “Microstrip cross-coupled trisection bandpass filter with asymmetric frequency characteristics,” IEE Proc. Microwaves Antennas Propag., v.146, n.1, p.84-90, 1999. DOI:

ZAKHAROV, A.V.; ROZENKO, S.A. “Duplexer designed on the basis of microstrip filters using high dielectric constant substrates,” J. Commun. Technol. Electron., v.57, n.6, p.649, 2012. DOI:

ZAKHAROV, A.V.; ROZENKO, S.A.; ZAKHAROVA, N.A. “Microstrip bandpass filters on substrates with high permittivities,” J. Commun. Technol. Electron., v.57, n.3, p.342-382, 2012. DOI:

ZHU, F.; HONG, W.; CHEN, J.-X.; WU, K. “Quarter-wavelength stepped-impedance resonator filter with mixed electric and magnetic coupling,” IEEE Microwave Wireless Compon. Lett., v.24, n.2, p.90-92, 2014. DOI:

XU, Z.Q.; WANG, P.; LIAO, J.X.; SHI, Y. “Substrate integrated waveguide filter with mixed coupled modified trisections,” Electron. Lett., v.49, n.7, p.482-483, 2013. DOI:

ZAKHAROV, A.V.; IL’CHENKO, M.E.; TRUBAROV, I.V. “Planar three-resonator bandpass filters with cross coupling,” J. Commun. Technol. Electron., v.62, n.2, p.185, 2017. DOI:

SHEN, W.; WU, L.-S.; SUN, X.-W.; YIN, W.-Y.; MAO, J.-F. “Novel substrate integrated waveguide filters with mixed cross coupling (MCC),” IEEE Microwave Wireless Compon. Lett., v.19, n.11, p.701-703, Nov. 2009. DOI:

KUO, J.-T.; HSU, C.-L.; SHIH, E. “Compact planar quasi-elliptic function filter with inline stepped-impedance resonators,” IEEE Trans. Microwave Theory Tech., v.55, n.8, p.1747-1755, 2007. DOI:

ZAKHAROV, A.; ILCHENKO, M. “Trisection microstrip delay line filter with mixed cross-coupling,” IEEE Microwave Wireless Compon. Lett., v.27, n.12, p.1083-1085, 2017. DOI:

ZAKHAROV, A.V.; ILCHENKO, M.Ye.; TRUBAROV, I.V.; PINCHUK, L.S. “Stripe delay filters,” Radioelectron. Commun. Syst., v.59, n.4, p.173, 2016. DOI:

HSU, C.-L.; YU, C.-H.; KUO, J.-T. “Microstrip trisection filters with quasi-elliptic and flat group delay responses,” Proc. of 4th Int. High Speed Intelligent Communication Forum, 10-11 May 2012, Nanjing, China. IEEE, 2012, p.1-2. DOI:

MAKIMOTO, M.; YAMASHITA, S. Microwave Resonators and Filters for Wireless Communication. Springer Science & Business Media, 2001.

ZAKHAROV, A.V. “Stripline combline filters on substrates designed on high-permittivity ceramic materials,” J. Commun. Technol. Electron., v.58, n.3, p.265, 2013. DOI:

ZAKHAROV, A.V.; ILCHENKO, M.Ye.; PINCHUK, L.S. “Coupling coefficient of quarter-wave resonators as a function of parameters of comb stripline filters,” Radioelectron. Commun. Syst., v.58, n.6, p.284, 2015. DOI:

ATIA, A.; WILLIAMS, A.; NEWCOMB, R. “Narrow-band multi-coupled cavity synthesis,” IEEE Trans. Circuits Systems, v.21, n.5, p.649-655, 1974. DOI:

CAMERON, R.J.; KUDSIA, C.M.; MANSOUR, R.R. Microwave Filters for Communication Systems: Fundamentals, Design, and Applications. John Wiley & Sons, Inc., 2007.

MATTHAEI, G.L.; YOUNG, L.; JONES, E.M.T. Microwave Filters, Impedance-Matching Networks, and Coupling Structures. McGraw-Hill, 1970.

KURZROK, R.M. “General three-resonator filters in waveguide,” IEEE Trans. Microwave Theory Tech., v.14, n.1, p.46-47, 1966. DOI:

RICHARDS, P.I. “Resistor-transmission-line circuits,” Proc. IRE, v.36, n.2, p.217-220, 1948. DOI:

TEMES, G.C.; MITRA, S.K. (eds.), Modern Filter Theory and Design. New York: Wiley, 1973.



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