WO1996019845A1

WO1996019845A1 - Connector for portable telephone

Info

Publication number: WO1996019845A1
Application number: PCT/SE1995/001530
Authority: WO
Inventors: Magnus Marthinsson; Ina Ericsson
Original assignee: Allgon Ab
Priority date: 1994-12-19
Filing date: 1995-12-18
Publication date: 1996-06-27
Also published as: AU4320996A; SE9404411D0; SE9404411L; SE503930C2

Abstract

An antenna connector is used having a ground plane in order to connect an outside antenna with the antenna of a portable telephone via a coaxial cable. The electronic coupling is carried out by means of capacitive electronic coupling between an active member of the cable and the permanent antenna of the telephone. In order to increase the capactive electronic coupling between the active member and the antenna, the active member (5, 15) is screened to the sourroundings at least in one direction from the active member. The screening is carried out by means of a metal plate (12) which is galvanicly connected with the ground plane. The electrical length of the plate is a certain fraction of the wave length of the frequency band of the telephone.

Description

CONNECTOR FOR PORTABLE TELEPHONE

This invention concerns an antenna connector having a ground plane, which connector is used for connecting an antenna at a distance from the portable telephone with the permanent antenna of the portable telephone via a coaxial cable, whereat the transmitting is carried out by means of capacitive electronic coupling between an active member electricly connected to the cable and the permanent antenna.

Connectors of this type are sold on the market and known from US 5 357 262.

The object of this invention is to increase the capacitive electronic coupling between the active member and the permanent antenna, particularly when the ground plane is small in relation to the wave length.

In order to achieve this object the inventin is characterized by the features stated in the enclosed claims.

An embodiment of the invention will be described in the following by refererence to the accompanying drawings.

Fig. 1 is hereby a simplified side view of the upper part of a portable telephone including an antenna connector according to the invention.

Fig. 2 is a view of the active member of the connector viewed from left in fig. 1.

Fig. 3 is a view of the connector from above and without its casing.

Fig. 4 is a view similar to the one according to fig. 1 whereat the active member is of a different design.

Fig. 5 is view of the active member from left in fig. 1. Fig. 6 is a view of the connector from above and without its casing.

Fig. 1 shows strongly simplified the upper part of a portable telephone and its permanent antenna and an antenna connector according to the invention.

The portable telephone 1 includes a helical coil antenna 2 on its upper side, and a radiator may be retractably inserted through the helical coil. The permanent antenna of the portable telephone in the form of the helical antenna 2 and/or radiator operates satisfactory when the portable telephone is on places where it is not screened. When the permanent antenna is screened it is necessary to have an outside antenna, which is connectable to the permanent antenna of the portable telephone.

Said outside antenna is denoted with 3 in the figures and is thus situated on a certain distance from the portable telephone 1. A coaxial cable 4 connects the outside antenna 3 with an active member 5, which for instance can be in the form of a coil or a plate. The active member forms the electrical active part of the connector and is placed closed to the antenna 2 so that capacitive electronic connection is established between the active member 5 and the antenna 2. This means that signals which are received by the outside antenna 3 will be transmitted to the portable telephone via the coaxial cable 4, the active member 5 and the helical antenna 2. Transmission of signals from the portable telephone will be carried out in the opposite direction.

The connector further includes a small ground plane 6, which consists of a plate 7 supporting the active member 5 and which is galvanicly connected to the wrapping of the coaxial cable 4, A second plate 8 is extended obliquely downwards from the plate 7. When the connector is used together with the portable telephone the plate 7 and 8 will be located against or close to the upper side 9 and one of the front sides 10 of the telephone. The antenna connector has preferably a casing of electricly isolating material, this being shown in fig. 1 and fig. 4 in the form of a part 11 of a casing.

It has now been observed that the electronic coupling between the antenna 2 and the active member 5 is sensitive and needs to be increased. This is very much the problem when the ground plane 6 is too small and when the connector is small as has been described above. The coupling factor is now increased according to the invention by that a passive member in the form of an angular metal plate 12 is placed close to the active member 5. According to the shown embodiment the metal plate is galvanicly connected with a plate 7 and is deflected towards the active member so that it screens the active member 5 against the surroundings. The screening effect shall preferably be such that radiation away from the active member 5 and the telephone is screened. The metal plate 12 is thus connected to the ground plane 6, which as said above is galvanicly connected with the conducting wrapping of the coaxial cable.

Fig. 4-6 are similar to fig. 1-3 with the exception that the active member is of a different design. The active member is here a metal plate 15, which is placed standing close to the permanent antenna 2. As can be seen, the plate 15 is connected to the coaxial cable 4 via an unisolated loop 16 having a Z- configuration. This loop forms an impedance match for the coupling between the permanent antenna 2 and the active plate 15. The connector according to this embodiment is otherwise similar to the one according to fig. 1-3, the same references therefore being used in the drawings 4-6.

The electrical length of the metal plate 12 is so chosen that it is a certain fraction of the wave length of the frequency band of the telephone. Thus, the electrical length may be a quarter wave length for the frequencies 824-960 MHz. A high impedance is hereby obtained in the end of the ground plane and the coupling factor is hereby increased in this point. The width of the metal plate can be adapted to the wanted coupling factor and other electrical factors and can be from the diameter of the wire to the width of the active element.

Claims

1. Antenna connector with a ground plane for temporarily connecting an outside antenna with an antenna of a portable telephone via a coaxial cable, whereby the connection is carried out by means of capacitive electronic connection between an active element connected to the cable and the antenna of the telephone, whereat the active member (5; 15) is screened to the surroundings by means of a shield connected with the wrapping of the coaxial cable, c h a r a c t e ¬ r i z e d i n that the shield consists of a metal plate (12) which is galvanicly connected with the ground plane (7, 8) and which has such a location from the ground plane that the radiation of the active member (5; 15) is screened in the direction from the antenna of the telephone, whereat the electrical length of the metal plate is a fraction of the wave length within the operating frequency band.

2. Connector according to claim 1, c h a r a c t e r i z e d i n that the active member consists of a coil (5) .

3. Connector according to claim 1, c h a r a c t e r i z e d i n that the active member consists of a plate (15) .

4. Connector according to claim 1, c h a r a c t e r i z e d i n that the metal plate (12) is curved towards the active member (5; 15) and includes a sector of about 90°.

5. Connector according to claim 1, c h a r a c t e r i z e d i n that the metal plate (12) consist of a passive member.