A Tunable Antenna For Dvb.docx

A tunable antenna for DVB-H applications Abstract—A novel wideband built-in antenna with resonance frequency variability for digital video broadcasting-handheld (DVB-H) is proposed. The tunable antenna consists of two channel matching networks and a spiral-shaped monopole type radiator. Based on the matching networks combined with the switches, wide bandwidth and good radiation gains are obtained. As a demonstration, a wideband tunable antenna is designed and measured. The proposed antenna has an approximately omni directional radiation pattern and its peak gain is 3 dB greater than the required antenna gain covering DVB-H band. These features are suitable for DVB-H applications. Recently, digital video broadcasting-handheld R(DVB-H) in Europe has made it possible to deliver broadcast television or other multimedia services to mobile or handheld devices. The DVB-H system is designed to operate in UHF band (470 to 702 MHz, relative bandwidth %) by considering interoperability with the GSM900 transmitter. From the viewpoint of the external appearance of the mo-bile phone terminal, a built-in antenna has become a global worldwide requirement and is also expected to apply as the antenna to receive the digital terrestrial broadcasting service. However, it is difficult to realize a built-in antenna for UHF band because the wavelength of UHF band is much longer than the length of the mobile phone terminal and the frequency bandwidth of the antenna generally becomes narrow if it is small and built into a mobile phone terminal. Therefore, it is necessary to make a built-in antenna wideband. As a technique for reducing the volume of the antenna, a small meander antenna using magneto dielectric material, which is difficult to fabricate in commercial businesses, was presented in An ear piece cord antenna with a matching network was proposed in and it is consisted of a cable of 1.2 m long and a chip inductor as a RF choke. However, this technique has the disadvantage of requiring a troublesome external ear piece cord for receiving DVB-H broadcasting. In this letter, we propose an internal spiral-shaped monopole-type antenna which is small due to the usage of the boards of the mobile phone terminal and the two parallel matching circuits applied to the antenna element. By electrically controlling single pole double throw (SPDT) switches connected to the input/output port of the matching network, the antenna is expected to have wideband performance . We measured the properties of the proposed antenna and verified its availability through Agilent ADS 2003C.

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Fig. 1. (a) Configuration of proposed antenna. (b) Enlarged view of proposed antenna (all in millimeters). REFERENCES [1]Y. Mano and S. Bae, “A small meander antenna by magneto-dielectric material,” in Proc. IEEE Int. Symp. Microw., Antenna, Propag. EMC Tech. Wireless Commun. Proc., 2005, vol. 1, pp. 63–66. [2]P. Lindberg and A. Kaikkonen, “Earpiece cord antenna for DVB-H reception in wireless terminals,” Electron. Lett., vol. 42, pp. 609–611, 2006. [3] R. V. Garver, “Broad-band diode phase shifters,” IEEE Trans. Microw.Therory Tech., vol. 20, no. 5, pp. 312–323, 1972. [4]DVB-H Implementation Guidelines, ETSI TR 102 377 v1.1.1, 2005, Europ. Telecommun. Standards.