6Y. Utsumi. Variational analysis of ridged waveguide modes. IEEE Trans. Microwave Theory Tech. 1985, 33(2): 111-120.
7J P Montgomery. On the complete eigenvalue solution of ridged waveguide. IEEE Trans. Microwave Theory Tech, 1994, 19(6): 547-555.
8D Dasgupta, P K Saha. Eigenvalue spectrum of rectangular waveguide with two symmetrically placed double ridges. IEEE Trans Microwave Theory Tech., 1981, 29(1): 47-51.
9J Bornemann, F Arndt. Modal-S-matrix design of optimum stepped ridged and finned waveguide transformers. IEEE Trans Microwave Theory Tech, 1987,35(6): 561-567.
10S H Hajimowlana, H Djahanshahi, M Kamyab. Determination of cut-off wavelengths of ridged waveguides by modal analysis. Proceeding of the 40th Midwest Symposium on Circuit Systems, 1997, Vol.1: 642 - 645.