Arrangement for connecting additional antenna to radio device
View Patent ↗An arrangement for connecting an additional antenna to a portable radio device (RD) having an internal planar antenna. Energy for the additional antenna is taken from the near field of the planar antenna, the coupling elements being provided by conductors ( 311, 312 ) located outside the covering of the radio device and following the conductive branches (B 1 , B 2 ) of the radiating plane (RPL) of the planar antenna. The arrangement further comprises a conductive plate ( 320 ) located in front of and parallel to the ground plane (GND) in the radio device to take energy from the field of the ground plane. The inner conductor of the cable ( 330 ) for the additional antenna is galvanically connected to the conductors placed over the planar antenna, and the sheath is galvanically connected to the conductive plate ( 320 ) near the connection point of the inner conductor.
1. An arrangement for connecting an additional antenna to a radio device which has a ground plane and an internal planar antenna with a radiating plane, which arrangement comprises a first coupling part for providing coupling with the internal antenna, a second coupling part for providing coupling with the ground plane and an intermediate cable for the additional antenna, the second coupling part comprising a conductive plate galvanically isolated from the radio device, which plate, when the arrangement is in use, is substantially parallel to the ground plane of the radio device and in front thereof in the direction of the normal of the ground plane in order to take energy from the radio frequency field of the ground plane, wherein
the first coupling part comprises at least one coupling conductor galvanically isolated from the radio device, which conductor, when the arrangement is in use, follows a conductive branch of the radiating plane of the internal antenna being located over said conductive branch for most of the length thereof, to take energy from the near field of the internal antenna, and
a first conductor of the intermediate cable is in galvanic contact with said coupling conductor, and a second conductor of the intermediate cable is in galvanic contact with said conductive plate near the connection point of the first conductor.
2. An arrangement according to claim 1 , the number of said coupling conductors being two, which coupling conductors, when the arrangement is in use, follow the different conductive branches of the radiating plane of the internal antenna and which are galvanically interconnected near the connection point of the first conductor of the intermediate cable.
3. An arrangement according to claim 2 , said coupling conductors being rigid conductive wires and having a first point and a second point such that when the arrangement is in use, the distances of the first and second points from the radiating plane are substantially different.
4. An arrangement according to claim 1 , said at least one coupling conductor being a rigid conductive wire.
5. An arrangement according to claim 1 , said at least one coupling conductor being a conductive strip on a surface of a dielectric plate.
6. An arrangement according to claim 1 , said conductive plate comprising bent portions which are arranged to face the side surfaces of the radio device.
7. An arrangement according to claim 1 , the intermediate cable being coaxial whereby the first conductor thereof is an inner conductor and the second conductor is an outer conductor.
8. An arrangement according to claim 7 , the outer conductor of the intermediate cable being connected to said conductive plate by a conductive crimp joint.
9. An arrangement according to claim 1 , being mechanically a part in a device fabricated primarily for hands-free operation, in which a radio device is to be inserted.