| 摘要 |
A dual-band glass-mounted antenna system includes a dual-band through-the-glass coupler, a matching section, and a dual-band collinear antenna element. The coupler has a portion which is secured to an interior surface of the glass, and a portion which is secured to the exterior surface of the glass at a position opposite the interior portion. Co-planer transmission line circuitry in the interior and exterior portions of the coupler cooperatively form a four-conductor transmission line operating in the "coupled microstrip line odd mode," thereby achieving coupling of RF energy through the glass window material in two disparate frequency bands. The transmission line characteristics are selected to achieve efficient coupling and desired impedance characteristics in the cellular and PCS frequency bands. The dual-band antenna element includes upper and lower radiator sections separated by a phasing coil. A sleeve choke assembly positioned at an intermediate location in the upper radiator section is on the order of one quarter wavelength at PCS frequencies. At PCS frequencies, the choke virtually eliminates current flow beyond the base of the choke, effectively establishing a half-wave radiating section between the top of the phasing coil and the base of the choke. At cellular frequencies, the choke has little effect, and therefore the entire upper radiator section acts as a half-wave radiator. The phasing coil advantageously achieves broadband, "in-phase" radiation conditions between the upper and lower collinear radiator sections at both cellular and PCS frequencies.
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