Wireless handset with improved hearing aid compatibility
View Patent ↗A “candy bar” form factor wireless handset ( 200 ) having an internal antenna ( 222, 306 ) a bottom end of an main internal circuit board ( 208 ) and an auxiliary field shaping conductor ( 226, 502, 1102, 1304 ) at a top end of the main internal circuit board ( 208 ) behind the an earpiece speaker ( 104 ). The field shaping conductor ( 226, 502, 1102, 1304 ) is spaced from a ground plane 304 ) of the main circuit board ( 208 ) but is inductively and capacitively coupled to the ground plane ( 304 ). The field shaping conductor ( 226, 502, 1102, 1304 ) lowers the electric field intensity in front of the earpiece speaker and thereby reduces interference of the wireless handset ( 200 ) with hearing aids.
1. A wireless handset comprising:
a housing comprising a top end and a bottom end, a front side and a rear side;
an antenna counterpoise comprising a printed circuit board disposed in said housing between said front side and said rear side wherein said printed circuit board comprises at least one ground plane;
an earpiece speaker disposed proximate said top end of said housing facing said front side of said housing;
an internal antenna disposed in said housing proximate said bottom end wherein said internal antenna is coupled to the printed circuit board; and
a separate field shaping conductor disposed proximate said top end of said housing in spaced relation from said at least one ground plane, wherein said field shaping conductor is coupled to said at least one ground plane by a bridge conductor that extends across to said printed circuit board;
wherein said bridge conductor is connected to said at least one ground plane through a switch; and
wherein said internal antenna is tuned to a receive band and said separate field shaping conductor is tuned to provide a resonance in a transmit band and wherein said switch is operable to close upon transmission.
2. The wireless handset according to claim 1 wherein said transmit band is lower in frequency relative to said receive band.
3. The wireless handset according to claim 1 wherein said field shaping conductor is disposed proximate said rear side of said housing.
4. The wireless handset according to claim 1 wherein said field shaping conductor has capacitance enhancing portion that bends toward said at least one ground plane.
5. The wireless handset according to claim 1 wherein said field shaping conductor is two-dimensionally extended.
6. The wireless handset according to claim 3 wherein said field shaping conductor comprises sheet metal.
7. The wireless handset according to claim 1 wherein said internal antenna is a folded inverted conformal antenna.
8. The wireless handset according to claim 1 wherein said field shaping conductor is shaped to conform in shape to a portion of said housing.