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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, Dal Ahn, Jae-Ick Choi, Tatsuo Itoh
- Issue Date
- 2004-05
- Citation
- IEEE Transactions on Microwave Theory and Techniques, v.52, no.5, pp.1425-1432
- ISSN
- 0018-9480
- Publisher
- IEEE
- Language
- English
- Type
- Journal Article
- 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 廓, are effectively implemented using microstrip lines with 75- and 50-廓 line widths by incorporating the spiral- and dumbbell-shaped DGSs, respectively.