Communications: radio wave antennas – Antennas – Plural separate diverse type
Patent
1996-03-05
1997-09-30
Le, Hoanganh T.
Communications: radio wave antennas
Antennas
Plural separate diverse type
343702, 343715, H01Q 124, H01Q 132
Patent
active
056730535
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an antenna coupling device for coupling, substantially inductively, a first antenna, e.g., situated in a vehicle and, e.g., incorporated in a hand-portable telephone, to a second antenna.
Specifically, the invention relates to an antenna coupling device for coupling inductively a first antenna, situated in a screened place, to a second antenna, working under better transmission and reception conditions. Such an antenna coupling device may be used, e.g., when travelling in a vehicle for applying onto a helical antenna of a hand-portable telephone, which is not provided with means for a galvanical connection to an external antenna. The telephone may hereby be coupled inductively via an RF coupling means and a coaxial cable to an external antenna for achieving better antenna performance.
An antenna coupling device of this kind is disclosed in U.S. Pat. No. 4 220 955, which describes a device for coupling inductively an antenna, which is incorporated in a "transceiver", to an external antenna. The coupling device comprises a shielded housing intended to be threaded onto the antenna and containing an helical antenna in the form of a coil for the inductive coupling.
An isolated sleeve with an open end carries the coil, the one end of which is connected to the center conductor of a transmission line, which leads to an external device, and the second end of which is open. The coil and the sleeve are surrounded by a conductive housing, which is coupled to the shield of the transmission line.
The above antenna coupling device is distinguished by the use of a helical antenna, i.e. a coil with one open end, for the inductive coupling. Further, the diameter of the coil is small in relation to the transferred wavelengths. This means that the helical antenna is functioning in "normal mode". Such is also the case for the helical antenna built in the "transceiver". Hereby the short range radiation fields of the electromagnetic radiation of the two antennas correspond, which is one of the conditions for satisfactory inductive coupling, when the antennas have the same geometrical orientation and are situated close to each other.
In order to achieve satisfactory inductive coupling in this prior art antenna coupling device, the helical antenna must also be provided with a relatively large number of turns, in respect to its required diameter and total wire length, and the turns must be distributed spaciously, i.e. the helical antenna shall have a large axial elongation.
If the helical antenna is to be compressed axially through a more compact winding this may to some extent be compensated by a greater number of turns, which requires a more complicated design and creates difficulties in achieving the same efficiency.
SUMMARY OF THE INVENTION
The object of the invention is to achieve an antenna coupling device that overcomes as far as possible the above mentioned drawbacks and that fulfills the demands of a high degree of coupling, simple and compact design, and uncomplicated operating.
A loop antenna has other features than a helical antenna. The loop antenna works by both its ends, or poles, being galvanically coupled. Hereby it presents another radiation pattern or field. However, in the immediate proximity of antennas of the different types, i.e. within the short range fields, the radiation patterns are approximately the same. This enables a loop antenna to be designed to give excellent inductive coupling to a helical antenna, provided that these have the same geometrical orientation and that the loop antenna preferably surrounds the helical antenna.
Further, it is advantageous to use a loop antenna, since it gives a high degree of efficiency for the inductive coupling with a very simple design. An electrically well-dimensioned loop antenna including a well-tuned impedance matching unit may in one single turn give a degree of efficiency of 50-70%. Hereby the loop antenna may be given an exceptionally small size and an easily adapted design. With this solution it is also
REFERENCES:
patent: 2202368 (1940-05-01), Berndt
patent: 2953782 (1960-09-01), Byatt
patent: 3882506 (1975-05-01), Mori et al.
patent: 4220955 (1980-09-01), Frye
patent: 4407000 (1983-09-01), Sasaki et al.
patent: 5099252 (1992-03-01), Bryant et al.
patent: 5181043 (1993-01-01), Cooper
patent: 5274388 (1993-12-01), Ishizaki et al.
patent: 5300936 (1994-04-01), Izadian
patent: 5357262 (1994-10-01), Blaese
Allgon AB
Le Hoanganh T.
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