Integrated internal GSM/DCS and WLAN antennas with optimized isolation for a PDA phone

Abstract

other two. Considering that radiation fog has the smallest particlesize distribution, our results should stand for this type of fog as well. Although we do not know the exact particle-size distribution of the fog in the measured link, the upslope fog is similar in formation to the advection fog; therefore, we also believe that, for this type of fog, the performance of the far-IR link should not be worse than those of the other two. Of course, present-day commercial technology still benefits shorter wavelengths, mostly due to the availability of low-cost sources and detectors. However, new technologies can produce competing devices for the far-IR window; thus our results demonstrate that it is worth working in the development of appropriate devices and systems because the optical channel indeed performs better at long wavelengths in most cases. ACKNOWLEDGMENTSThis work was supported by the Research and Development Center of Ericsson Telecomunicações S/A, Brazil, and C. P. Colvero acknowledges scholarship support from the Brazilian Agency CNPq. The authors acknowledge the Brazilian state companies TVE Brasil and Furnas Centrais Elétricas S/A for allowing the installation of the transmitters and receivers within their facilities. INTRODUCTIONDue to the recent successful deployment of wireless local area networks (WLANs) in numerous hotspots, it has become promising to integrate cellular and WLAN networks to provide ubiquitous or seamless data services for users [1, 2]. For this kind of integrated cellular/WLAN network application, it is expected that mobile phones or PDA phones capable of dual-network operation will become popular in the near future. For this promising application, many of the dual-network mobile or PDA phones are generally equipped with two antennas, one for cellular operation and another for WLAN operation. In this case, since there are limited spaces available inside the portable devices, isolation between the two antennas has become a critical issue. However, very little related information is available in the open literature.Recently, a study on the isolation between two promising internal antennas-one GSM/DCS (890 -960 MHz/1710 -1880 MHz) antenna and one 2.4-GHz (2400 -2484 MHz) WLAN antenna [3]-for a dual-network PDA phone has been presented [4]. The results have shown that with the GSM/DCS antenna fixed at the top edge of the system circuit board, optimized or nearoptimized isolation is achieved when the WLAN antenna is placed near the bottom edge of the system circuit board. In this study, the maximum isolation S 21 values over the GSM, DCS, and WLAN bands are less than Ϫ33.6, Ϫ27.9, and Ϫ33.0 dB, respectively, which are quite good for practical applications [4]. However, in this case, the two antennas need to be separated by a relatively large distance. In this paper, we present an isolation study that considers two promising internal GSM/DCS and WLAN antennas printed and integrated on a dielectric substrate. In the study, both of the GSM/DCS and WLAN antennas are printed PIFAs of compact...

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