| Summary: | 碩士 === 國立臺北科技大學 === 電腦與通訊研究所 === 94 === In this thesis, three topics are presented including the equiangular spiral antenna with planar microstrip line feed, ultra-wideband CBCPW broadside coupled band-pass filter, and wide band planar parallel-connected balun as well as the coupled-mode analysis. These planar microwave components are studied theoretically and experimentally.
First, the tapered microstrip-to-coplanar strip line feeding structure is incorporated into the equiangular spiral antenna to obtain broad impedance matching bandwidth and significant size reduction. The planar equiangular spiral antenna possesses 140% impedance bandwidth from 2.75 to 17 GHz, 132% axial ratio radiation bandwidth and an 3.5 dBi averaged antenna gain. This equiangular spiral antenna fed by microstrip
line is convenient to integrate with other microwave components.
Second, the UWB band-pass filter combining the CBCPW structure and the hairpin resonator possesses not only 2 dB insertion loss within the passband but also two transmission zeros located in the higher and lower frequency regions of the passband. The group delay within the passband varies between 0.18 and 0.6 ns, which represents that smooth group delay will avoid pulse signal dispersion in time domain.
Third, a wide-band balun is implemented by CPW structure. The unbalanced input impedance is 50 ohm and balance output impedance is 100 ohm. Bandwidth of back-to-back structure is larger than –0.7 dB from 100 MHz to 4 GHz. The size of the balun structure is only 8 mm*20 mm. Beside, normal mode parameter equations are used to investigate the three-line coupled structure.
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