Multifunctional microstrip transmission lines integrated with defected ground structure for RF front-end application |
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Authors: | Younkyu Chung Seong-Sik Jeon Shinho Kim Ahn D. Jae-Ick Choi Itoh T. |
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Affiliation: | Dept. of Electr. Eng., Univ. of California, Los Angeles, CA, USA; |
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Abstract: | This paper presents multifunctional microstrip transmission lines for designing a high port-isolation dual-frequency orthogonally polarized rectangular patch antenna and the antenna-integrated power amplifier. The proposed lines were realized through the integration of defected ground structures (DGSs) with conventional microstrip lines. A spiral-shaped DGS-integrated microstrip line enhances the port isolation of the antenna, while feeding the 2.0-GHz excitation to the antenna and filtering out the 2.5-GHz receiving signal from the other port. High-order harmonic signal suppression of the power amplifier at the 2.5-GHz port was accomplished by the dumbbell-shaped DGS, thereby improving the efficiency of the amplifier. Measurements show an improvement of 20 dB in port isolation and 3% in power-added efficiency relative to an identical RF front-end, but integrated with a conventional patch antenna. An image impedance of the DGS-integrated microstrip lines can be controlled by the integrated DGS geometries. Relatively high-impedances lines, i.e., 150 and 100 /spl Omega/, are effectively implemented using microstrip lines with 75- and 50-/spl Omega/ linewidths by incorporating the spiral- and dumbbell-shaped DGSs, respectively. |
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