A Technique to Identify Electromagnetic Modes in Oversize Waveguides (Short Papers)

• Published in: IEEE transactions on microwave theory and techniques Vol. 32; no. 11; pp. 1493 - 1495
• Main Authors: Carmel, Y., Chu, K.R., Read, M.E., Granatstein, V.L., Faillon, G., Boulanger, P., Kammerer, E., Mourier, G.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.11.1984; Institute of Electrical and Electronics Engineers
• Subjects: Apertures; Applied sciences; Circuit properties; Electric, optical and optoelectronic circuits; Electromagnetic scattering; Electromagnetic waveguides; Electronics; Exact sciences and technology; Frequency; Gyrotrons; Iris; Laboratories; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwave devices; Microwave propagation; Microwave theory and techniques; Visualization; Multimode waveguide; Identification; Gyrotron; Propagation mode; Liquid crystals; Overdimensioned waveguide; Waveguide
• ISSN: 0018-9480
• DOI: 10.1109/TMTT.1984.1132879

There are problems associated with the multimode character of oversize waveguides. This paper reports on a novel, direct way to identify modes in an oversize waveguide by looking at the field map on a liquid crystal sheet inserted in the waveguide. The local temperature change in the liquid crystal due to absorbed microwave energy is translated to a color change in such a way that a map of the Iocal power flow is observed on the sheet. Mode identification is very important in gyrotrons, for example, where the microwave energy generating device is subject to severe problems from mode competition.