This paper presents the design and fabrication of HE11 miter bend along with a TM11 to HE11 mode converter and corrugated up-taper, which are the integral parts of a transmission line system (TLS) that carries 200 kW microwave power at 42 GHz from Gyrotron to plasma or calorimetric dummy load. It has a hybrid (HE11) mode. The HE11 mode transmission loss in miter bend is derived using mode-matching techniques and gap loss theory. The gap length (L) in a waveguide of diameter (D = 2a) at a wavelength (λ) for the predicted loss (D ≥ λ) is approximately 1.7[Lλ/2a2]3/2 dB. The HE11 miter bend design incorporates a demountable cooling assembly with a flat mirror. The design and optimization of the proposed miter bend were carried out using CST-microwave studio software. Finally, HE11 miter bend was fabricated along with integrated assembly. The proposed HE11 miter bend with mode converter and corrugated up-taper gives the transmission efficiency of 95.64%.
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