“Eigenmodes Analysis of Sectoral Coaxial Ridged Waveguides by Transverse Field-Matching Technique. Part 1. Theory”. Visnyk NTUU KPI Seriia - Radiotekhnika Radioaparatobuduvannia, no. 54, Nov. 2013, pp. 13-23, https://doi.org/10.20535/RADAP.2013.54.13-23.