Mm-level ultra-thick folded waveguide structures fabricated by UV-LIGA for W-band TWTs

摘要

While the precision CNC milling method is widely used to fabricate relatively large sized folded waveguides (FWGs), especially W-band FWGs, UV-LIGA is considered capable of fabricating small dimensional FWGs, such as those at 220 GHz or above. In this work, an attempt has been made to produce W-band FWG circuits by using UVLIGA for the TWT. The designed FWGs feature a wide side of 1.9 mm, and narrow side 0.3 mm. The UV-LIGA technique was used to fabricate the halves of waveguides with the height of 0.95 mm. The copper FWG halves were then bonded to form completed FWGs, with dimensional accuracy of +/- 2 mu m and + 10 mu m for the height and width, respectively. According to CST calculation results, the dimension error has no obvious effect on the S12-parameters in the range of the operating bandwidth.