Wide band with W-band stepped septum OMT polarizer

• Main Authors: Yen-Lin Chen, 陳彥麟
• Other Authors: Tzi-Hong Chiueh
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/48426631407659216829

碩士 === 國立臺灣大學 === 物理研究所 === 96 === The septum OMT (orthomode transducer) is a three-port waveguide polarizer used to transform the orthogonal linear polarization into purely left and right hand circular polarization. In the design, we use the Ansoft HFSS (High Frequency Structure Simulator) to simulate this model. the W-band OMT will be produced and used in the NTU-Array project. We will discuss two kind of W-band OMT designs with square and circular cross-section. The extreme bandwidth of stepped septum OMT nowadays is about 17% because its resonance resulting from the septum. In our design, we make use the band division to avoid the resonance and increase the bandwidth to 36.6% (78-113GHz). We focus on the magnitude of two input polarization because of possible leakage from I to Q experiment. We do optimization to lower the return loss to -20dB, we also try to make the phase difference as close to as possible to preserve the quality of OMT polarizer.