| 摘要 |
An antenna can efficiently radiate at both the lower cell phone frequency band of about 850 MHz and the higher cell phone frequency band of about 1920 MHz that are in current use. The antenna includes a vertical conductor with an upper portion (32) of a length that is about ½ wavelength at the lower frequency to effectively radiate at that frequency. An upper PRD (phase reversal device) (40) located along the upper conductor portion divides it into top and bottom parts (60, 70) each of about ½ wavelength at the higher frequency, the PRD providing a 180° phase reversal at the higher frequency without affecting the lower frequency. A lower conductor portion (34) includes a coil (80) that produces a phase reversal at the lower frequency, a lower PRD (82), and a short straight conductor part (84). A lower conductor part (90) extends through the lower PRD (82) and connects through a mount member (130) to a coaxial feed.
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