| 摘要 |
A small radio apparatus such as a pager has a printed circuit loop antenna(12) comprising a generally elongate loop formed by first and second electrical conductors(22,24) interconnected by first and second electrically conductive end portions(18,20). A fixed value high Q capacitance(26) is incorporated into the first end portion(18) and a variable capacitance(30) is incorporated in a tap(28) interconnecting the first and second conductors(22,24) adjacent to, but spaced from, the second end portion(20). The loop antenna may be fabricated from low loss material or may comprise a track or back-to-back tracks on a dielectric substrate. The loop antenna(12) may be connected directly to RF circuitry or may be coupled inductively to the RF circuitry.
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