Design of the Novel Arbitrary Dual-Band Branch-Line Coupler Applied to Dual-Band Dual-Sense Circularly Polarized Antenna

• Main Authors: Wu, Chao-Lin, 伍昭霖
• Other Authors: Chen, Fu-Chiarng
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/20399620222513048246

碩士 === 國立交通大學 === 電信工程研究所 === 102 === A design of the novel dual-band branch-line coupler applied to dual-band dual-sense circularly polarized antenna is presented in this thesis. The resonant frequency of the dual-band branch-line coupler is designed at 2.55 GHz and 3.5 GHz. Different from the conventional branch-line coupler, the concept of composite right left handed transmission line is used in this thesis by inserting open stubs and the lump elements of capacitors and inductors in the branch. In order to have a dual-band circuit, there are exact parameter values which obtained by the steps of even-odd mode analysis method. The circuit can be operated at arbitrary dual-frequency which is decided by designer. It is importance to have the properties of dual-band and producing the condition of circular polarization of the patch antenna. Especially, the novel dual-band branch-line coupler is most important because of equally power amplitude and ninety phase difference between two output ports. Also, the patch antenna is etched four slots and fed by L-shaped capacitive coupling probes so that it can produce circular polarization and more symmetry as same as the branch-line coupler. Finally, the whole configuration is combined with the circuit and the patch antenna to obtain the dual-band dual-sense circularly polarized antenna.