Analysis of groove NRD waveguide bend using the coupled-mode theory

In this paper, the propagation characteristics of the dominant mode in GNRD guide bend are analysed employing the coupled-mode theory. The curves of bending loss vs. The groove depth or width, radius of curvature and frequency are given, which caused by the mode conversion of the operatingLSM ₁₁ ^x mode to the parasiticLSE ₁₁ ^x mode. It is found that the groove depth has a great influence upon the bending loss than the other parameters. According to the theoretical results, appropriate sizes of groove and radius of curvature should be chosen in designing a GNRD bend structure.