| 摘要 |
According to exemplary embodiments of the present invention, retractable antennas are described for use in two or more frequency hyperbands. The retractable antennas can include a whip antenna, operable when the retractable antenna is extended and a non-uniform helical antenna, operable when the retractable antenna is retracted. For example, retractable antennas can be designed according to the present invention for usage in portable terminals capable of operating both at 800 MHz and at 1900 MHz. Tuning for the whip antenna is accomplished using a matching circuit. Tuning to both resonance frequencies for the non-uniform helical antenna can be accomplished by varying parameters of the helical structure including, for example, the pitch angle, coil diameter, length and number and spacing of the coil turns. |
