U.S. Philips Corporation

Nxp B.v.

Roger Hill

Kevin Robert Boyle

Peter Johan Massey

Robert J Cox

Philip J Connor

A wireless terminal comprises a ground conductor () and a transceiver coupled to an antenna feed, the antenna feed being coupled directly to the ground conductor (). In one embodiment the ground conductor is a conducting case (). The coupling may be via a parallel plate capacitor () formed by a plate () and a surface () of the case (). The case () acts as an efficient, wideband radiator, eliminating the need for a separate antenna. In a modification of this embodiment a slot () is provided to increase the resistance of the case () as seen by the transceiver, thereby increasing the radiating bandwidth of the terminal.

Wireless terminal

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.

Radio apparatus

A loop antenna (10) is provided with feed means (12,14) and a variable capacitor (C1) to adjust a first resonant frequency of the antenna (10). A reactive network (C2,L2,X) is included which permits the antenna to provide a further resonant frequency. The reactive network comprises a series-resonant circuit (L2,C2) in parallel with a further reactive element (X). The resonant frequency of the series-resonant circuit is arranged to be substantially equal to the first resonant frequency of the antenna as tuned by the capacitor (C1). The reactance (X) thus has no effect at this frequency. Another resonant frequency for the antenna may be adjusted by altering the reactance (X). The arrangement may be extended to provide further resonant frequencies.

Growing community of inventors

Horley, United Kingdom

Roger Hill