S.G. Vesnin1, S.I. Gorbunov2, A.A. Blinnikov3, D.A. Frolov4

1,3 Center for Microwave Diagnostics Development (Moscow, Russia)

2,4 National Research University Moscow Power Engineering Institute (Moscow, Russia)

1 vesnin47@gmail.com, 2 colzon@yandex.ru, 3 andrey@alexeyevich.ru, 4 FrolovDanA@mpei.ru

Traditional microstrip bandpass filters operating in the Ku-band suffer from high dissipative losses. The skin effect and radiation losses severely limit standard printed circuit board performance at these frequencies. Thus, there is an urgent need to develop highly selective printed devices with low insertion losses. This work aims to develop such printed bandpass filters for Ku-band applications using Substrate Integrated Waveguide (SIW) technology, effectively bridging the gap between planar circuits and bulky rectangular waveguides. The design process involved mathematical synthesis and electrodynamic modeling methods in specialized simulation software. The structures were excited using waveguide ports to ensure the highest accuracy in extracting scattering parameters. The proposed filter topologies utilize transverse slots in the top metal cover of the SIW cavity, creating transmission zeros and enhancing out-of-band rejection. A T-shaped equivalent circuit of the slotted SIW resonator was developed alongside empirical formulas for calculating its frequency-dependent impedances. The filters were designed on a domestic alumina ceramic substrate ("VK-100") with an exceptionally low dielectric loss tangent and minimal surface roughness, which is critical for the Ku-band. Topologies for third- to sixth-order bandpass SIW filters were synthesized. The theoretical models demonstrated excellent selectivity; the fifth-order SIW filter with a 2.4% fractional bandwidth exhibited a shape factor of 3.76 at the 50 dB level, with passband dissipative losses restricted to 2.47 dB. To validate this concept, a third-order SIW filter prototype was fabricated and tested. Experimental measurements showed outstanding agreement with computational models. After de-embedding the 0.5 dB losses from SMA connectors, the inherent dissipative insertion losses were 0.6 dB. This corresponds to an unloaded quality factor of approximately 380, significantly outperforming conventional hairpin microstrip filters. The measured frequency response closely followed the simulated data, confirming the equivalent circuit's validity. A slight passband narrowing at higher frequencies was attributed to the initial via hole spacing. Ultimately, the developed SIW structures demonstrate significant superiority in dissipative losses and selectivity. Their planar design allows seamless monolithic integration with other microwave components, leveraging standard batch manufacturing technologies to drastically reduce overall size and production costs for advanced Ku-band transceiver equipment.

Vesnin S.G., Gorbunov S.I., Blinnikov A.A., Frolov D.A. Ku-band bandpass SIW filters with transverse slots // Nanotechnology development and applications-XXI Ce. 2026. V. 18. № 3. P. 31−44. DOI: https://doi.org/10.18127/j22250980-202603-03

1. Bozzi M., Georgiadis A., Wu K. Review of substrate-integrated waveguide circuits and antennas. IET Microwaves, Antennas & Propagation. 2011. V. 5. № 8. P. 909–920. DOI: 10.1049/iet-map.2010.0463.
2. Deslandes D., Wu K. Single-substrate integration technique of planar circuits and waveguide filters. IEEE Transactions on Microwave Theory and Techniques. 2003. V. 51. № 2. P. 593–596. DOI: 10.1109/TMTT.2002.807820.
3. Chen X.P., Wu K. Substrate integrated waveguide filter: Basic design rules and fundamental structure features. IEEE Microwave Magazine. 2014. V. 15. № 5. P. 108–116. DOI: 10.1109/MMM.2014.2321263.
4. Rhbanou A., Sabbane M., Bri S. Design of dual-mode substrate integrated waveguide band-pass filters. Circuits and Systems. 2015. V. 6. № 12. P. 257–267. DOI: 10.4236/cs.2015.612026.
5. Smajevic A. Substrate Integrated Waveguide (SIW) and Superconducting Filters. Master's thesis. University of Waterloo. 2022.
6. Huang L. Novel substrate integrated waveguide filters and circuits. PhD thesis. University of Leeds. 2013.
7. Moitra S., Bhattacharjee A. K., Mukhopadhyay A. K., Kundu J., Mondal B. Substrate integrated waveguide (SIW) filter using stepped-inductive posts for Ku-band applications. Third International Conference on Computational Intelligence and Information Technology (CIIT 2013). 2013. P. 398−401. DOI: 10.1049/cp.2013.2619.
8. Rhbanou A., Bri S. Design of Substrate Integrated Waveguide Pass Filter at [33–75] GHz Band. International Journal of Engineering and Technology. 2014. V. 6. № 6. P. 2815−2825.
9. He Y., Ma Z.H., Wang M., Huang J., Chen X. Design of a Dual-Mode SIW Bandpass Filter with Multi-Transmission Zeros. IEEE Access. 2025. V. 13. P. 65552−65565. DOI: 10.1109/ACCESS.2025.3556252.
10. Chen X.P., Wu K. Substrate integrated waveguide filters: Design techniques and structure innovations. IEEE Microwave Magazine. 2014. V. 15. № 6. P. 121−133. DOI: 10.1109/MMM.2014.2332886.
11. Namanathan P., Nagarajan G. Realization of dual-mode, high-selectivity SIW cavity bandpass filter by perturbing circular shape vias. Applied Physics A. 2022. V. 128. № 9. P. 773. DOI: 10.1007/s00339-022-05918-x.
12. Iqbal A., Tiang J.J., Wong S.K., Alibakhshikenari M., Falcone F., Limiti E. Miniaturization trends in substrate integrated waveguide (SIW) filters: A review. IEEE Access. 2020. V. 8. P. 223287−223305. DOI: 10.1109/ACCESS.2020.3044088.
13. Liu H., Yang L., Cai B., Wu L., Cheng Y., Chen F., Luo H., Li X. Compact and miniaturized wideband bandpass filter based on substrate integrated waveguide and microstrip line. Journal of Applied Physics. 2024. V. 135. № 24. P. 244501. DOI: 10.1063/5.0216293.
14. Ding Y., Wu K. Miniaturized hybrid ring circuits using T-type folded substrate integrated waveguide (TFSIW). 2009 IEEE MTT-S International Microwave Symposium Digest. 2009. P. 705−708. DOI: 10.1109/MWSYM.2009.5165794.
15. Chien H.Y., Shen T.M., Huang T.Y., Wang W.H., Wu R.B. Miniaturized bandpass filters with double-folded substrate integrated waveguide resonators in LTCC. IEEE Transactions on Microwave Theory and Techniques. 2009. V. 57. № 7. P. 1774−1782. DOI: 10.1109/TMTT.2009.2022591.
16. Huang X. Design of miniaturized SIW filter loaded with improved CSRR structures. Electronics. 2023. V. 12. № 18. P. 3789. DOI 10.3390/electronics12183789.
17. Zelyah E.V., Fel'dshtejn A.L., YAvich L.R., Brilon V.S. Miniatyurnye ustrojstva UVCH i OVCH diapazonov na otrezkah linij. M.: Radio i svyaz'. 1989. 112 s. (In Russian).