Design of Millimeter Wave Wideband Transition From Double-ridge Waveguide to Coaxial Line
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Design of Millimeter Wave Wideband Transition From Double-ridge Waveguide to Coaxial Line Yang Zhou & En Li & Gao-Feng Guo & Tao Yang & Lin-Sheng Liu
Received: 5 October 2010 / Accepted: 25 November 2010 / Published online: 7 December 2010 # Springer Science+Business Media, LLC 2010
Abstract In this paper, an improved design method of millimeter wave wideband transition from double-ridge waveguide to coaxial line is introduced. The proposed design is based on the mode conversion theories and impedance matching techniques. The characteristics of the transition in microwave frequencies are analyzed and simulated by full-wave analysis software. According to the simulated results, a couple of transitions are fabricated. The predicted superduper performances have been confirmed experimentally in a wide frequency range of 18~40 GHz. Keywords Millimeter wave . Double-ridge waveguide . Coaxial line to waveguide transition . Mode conversion . Impedance matching
1 Introduction The waveguide to coaxial line transition is a type of passive conversion devices which is widely used in microwave and millimeter wave equipments. The quality of transition directly affects the performance of the systems, so the research about the transition from millimeter wave waveguide to coaxial line is of great significance. The structure shown in Fig 1a is widely used in waveguide to coaxial line transition. The inner coaxial conductor is inserted into the H-plane of the waveguide. This design method Y. Zhou (*) : E. Li : G.-F. Guo : T. Yang : L.-S. Liu School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan 611731, People’s Republic of China e-mail: [email protected] E. Li e-mail: [email protected] G.-F. Guo e-mail: [email protected] T. Yang e-mail: [email protected] L.-S. Liu e-mail: [email protected]
J Infrared Milli Terahz Waves (2011) 32:26–33
(a) Vertical transition
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(b) In-line transition
Fig. 1 The two structures of transition from double-ridge waveguide to coaxial line.
is based on the theory of mode matching [1–3]. Since there is a 90-degree corner between the connection of the coaxial line and waveguide, this structure is inconvenient to be used in cascade systems. Besides, the probe is easily to be broken down when high power is induced to the transformer. Another structure of in-line coaxial to waveguide transition [4, 5] is compared in Fig. 1b. The axis of coaxial lies in the same direction of propagation in the waveguide. This type of transition has good return loss performance and high power capacity. In this paper, the in-line transition structure has been further modified, and an improved design method of millimeter wave wideband transition from double-ridge waveguide to coaxial line is proposed.
2 Design concept In designing the millimeter wave wideband transition from double-ridge waveguide to coaxial line, there are two key problems need to be carefully analyzed firstly, one is the impedance matching for the high impedance of waveguide and low impedance of c
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