| Summary: | 碩士 === 國立彰化師範大學 === 電子工程學系 === 104 === The main objective of this thesis is the study and design of balanced wideband filtering planar inverted-F antenna (PIFA) and balanced ultra-wideband (UWB) open-slot antenna with a 5-GHz notched band. For the first work, the integrated design of a balanced wideband filter and a PIFA is performed. The balanced wideband filter is constructed using parallel coupled-line resonators and the antenna is designed in inverted-F configuration. The improvement of the differential-mode (DM) passband selectivity and upper stopband rejection, as well as the increase of the common-mode (CM) rejection level are investigated. For the second circuit, the balanced UWB open-slot antenna is fed with a differential microstrip line which intersects the antenna at the position a quarter-wavelength away from the shorted end of the open-slot to achieve strong coupling. In addation, a 5-GHz notched band is implemented to avoid the interference with signals of the 5.2- and 5.8-GHz WLAN bands.
Besides the design and investigation of the above balanced wideband/UWB antennas, this thesis also proposes a novel approach of measuring balanced antennas using conventional two-port antenna measurement systems. The formulas needed to convert the S parameters of the standard single-port antenna to those of the balanced antenna will be derived. The proposed approach will be validated by practical example circuits. The approximated balanced antenna measurement method is expected to be useful to researchers who own only a two-port antenna measurement system. It can not only provide an easy and convenient way for measuring balanced antennas, but also help save the cost needed for building a balanced antenna measurement system. This could be the biggest contribution of this thesis.
Keywords—balanced wideband bandpass filter, balanced wideband PIFA, ultra-wideband (UWB), passband selectivity, common-mode suppression
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