G.M. Aristarkhov1, I.N. Kirillov2, V.V. Kuvshinov3

1, 2 Moscow technical university of communications and informatics (Moscow, Russia)
3 LLC RPE «FLICS» (Moscow, Russia)
1 g.aristarkhov2010@yandex.ru, 2 i.kirillov2009@Gmail.com, 3 info@nppfliks.ru

Planar microstrip filter structures based on half-wavelength resonators are widely used in integrated microwave devices, as they are the most technologically advanced in this class of microwave circuits. Increasing the frequency selectivity of these filters is traditionally achieved by increasing their order (which entails increased dimensions and passband losses) and by creating attenuation poles by cross-coupling non-adjacent resonators. However, the number of attenuation poles formed in existing microstrip filter structures does not exceed the number of resonators, limiting the feasibility of creating more compact, highly selective filters with a small number of resonators.

The purpose of this work is to explore the methods for increasing the frequency selectivity of planar microstrip filters based on structures with a limited number of half-wavelength resonators by creating multiple working attenuation poles.

The feasibility and effectiveness of implementing highly selective filters based on planar multimode structures with a limited number of resonators is demonstrated. The defining element of these structures is the basic unit – a quarter-wavelength lattice section on two coupled microstrip lines with weakened electromagnetic interaction between them in the mid-length region. This section allows for the formation of three working attenuation poles while simultaneously reducing the spectrum of parasitic passbands. It is shown that the proposed three- and four-resonator structures can form up to eight or more working attenuation poles without introducing cross-couplings between non-adjacent resonators. The results of modeling and practical implementation of these filters with various frequency response types are presented, ensuring high frequency selectivity both in local frequency regions and across a wide rejection band up to and including the fourth harmonic.

The proposed design principle and circuit solutions for its implementation based on multimode structures enable the creation of more compact planar filter designs with significantly increased frequency selectivity with a limited number of resonators. The obtained results can be used in the design of filters that have stringent requirements for frequency selectivity and size and weight.

Aristarkhov G.M., Kirillov I.N., Kuvshinov V.V. Highly selective filters based on planar multimode structures with a limited number of resonators. Achieve­ments of modern radioelectronics. 2026. V. 80. № 4. P. 61–71. DOI: https://doi.org/10.18127/j20700784-202604-07 [in Russian]

1. Aleksandrovskij A.A., Belyaev B.A., Leksikov A.A. Sintez i selektivny`e svojstva fil`trov na shpil`kovy`x rezonatorax so shlejfny`mi e`lementami. Radiotexnika i e`lektronika. 2003. T. 48. № 4. S. 398–405.
2. Klimenko D.N. Vy`sokoizbiratel`ny`j mikropoloskovy`j fil`tr na plavno-neregulyarny`x liniyax peredachi. Sovremennaya e`lektronika. 2014. № 3. S. 70-71.
3. Roudz Dzh.D. Teoriya e`lektricheskix fil`trov. M.: Sov. radio. 1980. 240s.
4. Hong J.-S., Lancaster M.J. Microstrip filters for RF/microwave applications. John Wiley&Sons, Inc. MA. 2001. 471p.
5. Lancaster M.J., Hong J.-S. Theory and experiment of novel microstrip slow-wave open-loop resonator filters. IEEE Trans. MTT. 1997. V. 45. № 12. P. 2358–2365.
6. Aristarxov G.M., Cherny`shev V.P. Kosvenny`j sintez mikropoloskovy`x fil`trov na sonapravlenny`x shpilechny`x rezonatorax s polyusami zatuxaniya na konechny`x chastotax. Radiotexnika i e`lektronika. 1987. T. 32. № 6. S. 1168–1175.
7. Aristarxov G.M., Zvezdinov N.V. Vy`sokoizbiratel`ny`e odno- i dvuxrezonatorny`e mikropoloskovy`e fil`try`. Radiotexnika i e`lektronika. 2017. T. 62. № 8. S. 819–824.
8. Aristarkhov G.M., Grebennikov A. and Zvezdinov N.V. High-Selectivity Microstrip Filters Based on Structures With a Limited Number of Hairpin Resonators. IEEE Microwave Magazine. Nov. 2019. V. 20. № 11. P. 22–31.
9. Fil`traciya i spektral`ny`j analiz radiosignalov. Algoritmy`. Struktury`. Ustrojstva / Pod red. Yu.V. Gulyaeva. M.: Radiotexnika. 2020. 504 s.
10. Aristarxov G.M., Kirillov I.N., Kuvshinov V.V., Markovskij A.V. Selektivny`e svojstva dvuxrezonatorny`x struktur i vy`sokoizbiratel`ny`e fil`try` na ix osnove. T-Comm: Telekommunikacii i transport. 2023. T. 17. № 8. S. 21–29.
11. Aristarxov G.M., Kirillov I.N., Korchagin A.I., Kuvshinov V.V. Kompaktny`e vy`sokoizbiratel`ny`e mikropoloskovy`e fil`try` na svernuty`x so­napravlenny`x shpilechny`x rezonatorax. Radiotexnika. 2021. T. 85. № 4. S. 126–137. DOI: https://doi.org/10.18127/j00338486-202104-14