A. D. Poligina1, Yu. P. Salomatov2
1 JSC «NPP «Radiosvyaz» (Krasnoyarsk, Russia)
1, 2 Siberian Federal University (Krasnoyarsk, Russia)

1 anastasia0711@mail.ru, 2 ysalomatov@sfu-kras.ru

The development of millimeter-wave systems requires the creation of hybrid devices that combine the integrated advantages of planar SIW and gap-waveguide technologies, offering ultra-low losses and the ability to provide contactless coupling. The key element of such devices is the transition between these disparate environments. Existing compact gap-waveguide transitions have a narrow bandwidth (3–5%), while broadband solutions based on smooth transformers are excessively large.

The aim of this work is to develop and analyze a compact, broadband SIW-to-gap-waveguide transition for the 41…47 GHz range, eliminating these drawbacks through the use of a combined reactive compensation scheme in the slot region.

This article presents the design, physical principles of operation, and analysis of a broadband SIW-to-gap-waveguide transition designed for millimeter-wave systems (41…47 GHz). The transition is implemented using a common metal wall with an offset longitudinal slot, which ensures efficient coupling of the magnetic fields of two dissimilar waveguide structures. To expand the matching bandwidth, a combined compensation is employed: a metallized hole in the SIW serves as a shunt inductor, and two rectangular protrusions are symmetrically installed in the gap-waveguide cavity, functioning as impedance transformers. Each physical principle underlying the operation of the transition elements has been analyzed in detail: the equivalence of the gap to the magnetic current, the formation of a suppression band in the gap structure, and reactance compensation using lumped elements. Full-wave simulation results confirm excellent performance: the reflection coefficient (S11) is below minus 18 dB and the transmission coefficient (S21) is above minus 0,2 dB across the entire target band. The proposed transition is a ready-made unit for constructing hybrid antenna systems requiring efficient coupling of planar circuits with low-loss transmission lines.

Poligina A.D., Salomatov Yu.P. Compact broadband SIW – gap-waveguide transition with reactive compensation for the frequency range of 41…47 GHz. Antennas. 2026. № 2. P. 71–77. DOI: https://doi.org/10.18127/j03209601-202602-07 (in Russian)

1. Rappaport T.S. et al. Millimeter wave mobile communications for 5G cellular: It will work! IEEE Access. 2013. V. 1. P. 335–349. DOI: 10.1109/ACCESS.2013.2260813.
2. Deslandes D., Wu K. Integrated microstrip and rectangular waveguide in planar form. IEEE Microwave Wireless Components Letters. 2001. V. 11. № 2. P. 68–70. DOI: 10.1109/7260.914305.
3. Kildal P.-S., Alfonso E., Valero-Nogueira A. et al. Local metamaterial-based waveguides in gaps between parallel metal plates. IEEE Antennas Wireless Propagation Letters. 2009. V. 8. P. 84–87. DOI: 10.1109/LAWP.2008.2011147.
4. Rajo-Iglesias E., Ferrando-Rocher M., Zaman A.U. Gap waveguide technology for millimeter-wave antenna systems. IEEE Communications Magazine. 2018. V. 56. № 7. P. 14–20. DOI: 10.1109/MCOM.2018.1700998.
5. Pérez-Escudero J.M., Torres-García A.E., Gonzalo R. et al. A gap waveguide-based compact rectangular waveguide to a packaged microstrip inline transition. Applied Science. 2020. V. 10. P. 4979.
6. Li L., Chen X., Khazaka R. et al. A transition from substrate integrated waveguide (SIW) to rectangular waveguide. 2009 Asia Pacific Microwave Conference. Singapore. 2009. P. 2605–2608. DOI: 10.1109/APMC.2009.5385245.
7. Li Y., Luk K.-M. A broadband V-band rectangular waveguide to substrate integrated waveguide transition. IEEE Microwave and Wireless Components Letters. 2014. V. 24. № 9. P. 590–592. DOI: 10.1109/LMWC.2014.2325217.
8. Rezaee M., Zaman A.U., Kildal P.-S. V-band groove gap waveguide diplexer. 2015 9th European Conference on Antennas and Propagation (EuCAP). Lisbon, Portugal. 2015. P. 1–4.
9. Dansran B., Xu S., Heo J. et al. Design of a broadband transition from a coaxial cable to a reduced-height rectangular waveguide. Applied Science. 2023. V. 13. P. 11265.
10. Zaman A.U., Kildal P.S. GAP waveguides. In Chen Z., Liu D., Nakano H., Qing X., Zwick T. (Eds.) Handbook of antenna technologies. Springer, Singapore. 2016.
11. Ghorbani S., Razavi S.A., Ostovarzadeh M.H. et al. Development of a center fed slot array antenna with very low side lobes using ridge gap waveguide (RGW) technology. International Journal of Electronics and Communications. 2020. V. 125. P. 153385.
12. Auda H., Harrington R.F. Inductive posts and diaphragms of arbitrary shape and number in a rectangular waveguide. IEEE Transactions on Microwave Theory and Techniques. 1984. V. 32. № 6. P. 606–613. DOI: 10.1109/TMTT.1984.1132736.