| 摘要 |
A mobile telephone antenna 49 comprises an electrically insulating substrate 2 which is L-shaped in cross-section, and a driven element 3 formed by an outer electrically conductive layer applied to an inner surface of the substrate 2 and an inner electrically conductive layer 5 applied to the substrate 2 and spaced from the outer layer by an insulating gap. The gap extends to a transmitting edge of the antenna 1 such that two portions of the outer layer are spaced from a portion of the inner layer 5 along the edge by two insulating portions of the substrate 2. The antenna 49 also incorporated an impedance-correcting secondary antenna part 50 comprising an electrically conductive element extending upwardly from the inner layer 5 and constituting an inductive element which is tuned to the frequency of the transmitted radiation. Additionally the antenna 49 incorporates a shielding and reflecting electrically conductive layer, connected to the outer layer, applied to another inner surface of the substrate 2 so as to extend perpendicularly to the outer layer for a distance greater than the distance of the tip of the secondary antenna part 50 from the inner layer 5, and a body of a dielectric material 51 is provided between the shielding layer and the secondary antenna part 50 to contain the electromagnetic field. This shielding layer serves as a field contouring structure which contours the electromagnetic field associated with the antenna so that the transmitted radiation is reflected away from the head of the user. Such an antenna is designed to reduce the level of transmittal radiation in the vicinity of the user's head where such radiation might present a hazard.
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