MXPA96004663A

MXPA96004663A - Retrac antenna system

Info

Publication number: MXPA96004663A
Application number: MXPA/A/1996/004663A
Authority: MX
Inventors: Elliott Michael; Martiskainen Matti
Original assignee: Galtronics Ltd
Priority date: 1995-10-10
Filing date: 1996-10-08
Publication date: 1998-04-01

Abstract

The present invention relates to a retractable antenna system, characterized in that it comprises: an electrical device, a rod antenna mounted to the electrical device and movable towards an extended position or a retracted position with respect to the electrical device, an electric coil carried by a end of the rod and movable antenna with it towards the extended and retracted positions, and a coil antenna carried by the electrical device, such as to be electromagnetically coupled to the electrical coil in the retracted position of the rod antenna and the electric coil The coil antenna is operative to radiate or receive energy only when it is coupled electromagnetically with the electrical coil, when the electrical coil is in the retracted position

Description

RETRACTABLE ANTENNA SYSTEM FIELD AND BACKGROUND OF THE INVENTION The present invention relates to a retractable antenna system for electrical devices. The invention is particularly useful with respect to the retractable antenna system described in our U.S. patent. No. 5,204,687, and in the co-pending application of the US. Serial No. 08 / 485,992 filed July 6, 1995, and therefore is described below with respect to these antenna systems. The above-mentioned co-pending patent and application describe retractable antenna systems for electrical devices, particularly cordless telephones, these antenna systems include a rod antenna (sometimes referred to as a whip antenna), and a coil antenna carried by the outer end of the antenna. the rod antenna. The rod antenna is movable to any of a retracted position within the housing, wherein substantially only the coiled antenna is externally disposed to the housing, or to an externally extended position of the housing, wherein substantially the entire coil antenna and coil antenna they are arranged externally to the housing. In the preferred embodiments described therein, the rod antenna and the coiled antenna are pre-tuned to the same frequency, so that REF: 23296 that in the extended position of the antenna system, the rod antenna is activated for use in long distance operation, and in the retracted position of the antenna system, the coiled antenna is activated for use in short distance operation. In these constructions, the coiled antenna that is transported at the outer end of the rod antenna is of substantial mass. Therefore, when the rod antenna is in its extended position, the long length of the rod antenna, together with the substantial mass of the antenna wound on the outer end of the rod antenna, causes the rod antenna to be becomes very flexible, that is, it flexes or vibrates easily with substantial displacement magnitudes. This can be very disturbing for the user transporting the electrical device assembly and connected antenna; Even more, it can also result in rupture of the rod antenna. OBJECTIVES AND BRIEF SUMARY PE? INVENTION It is an object of the present invention to provide a retractable antenna system having advantages in the above aspects, and particularly one that decreases the flexibility of the antenna system in the extended position of the rod antenna.

In accordance with the present invention, there is provided a retractable antenna system for an electrical device, comprising: a rod antenna movably mounted in the electrical device in an extended position or a retracted position with respect to the electrical device; an electric coil carried at one end of the rod antenna and movable to the extended and retracted positions, and a coil antenna carried by the electrical device to be electromagnetically coupled with the electric coil in the retracted position of the rod antenna and the electric coil According to additional features in the preferred embodiment described, the electrical device is mounted within a housing having an opening, through which the rod antenna moves to its extended and retracted positions, with respect to the housing. The rod antenna has an outer end external to the housing and an inner end inside the housing. The electrical coil is transported at the outer end of the rod antenna and the coil antenna is mounted in the housing on its outer side coaxial with the opening. As will be more particularly described below, the above features of the present invention substantially reduce the mass at the outer end of the antenna rod and therefore substantially reduce the flexibility of the antenna system in its extended position. Reduced antenna interference has also been observed in some constructions of the novel retractable antenna system. Additional features and advantages of the invention will be apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS The invention herein is described by way of example only with reference to the accompanying drawings, wherein: Figure 1 illustrates a form of a retractable antenna system constructed in accordance with the present invention, the antenna system is illustrated in its retracted position; Figure 2 is a partial sectional view of the antenna system of Figure 1, illustrating the antenna system in its retracted position; Figure 3 is a partial sectional view of the antenna system of Figure 1, illustrating the antenna system in its extended position; and Figures 4 and 5 are views corresponding to Figure 1, but illustrating two variations in the structure of the effective antenna system in the retracted position of the rod antenna. DESCRIPTION OF PREFERRED EMBODIMENTS Figures 1-3 illustrate an electrical device that includes an electrical circuit, indicated schematically by block 2, circumscribed within a housing 4 and connected by an electrical terminal 6 to a retractable antenna system, generally designated 10, constructed in accordance with the present invention. The electrical device can for example be a telephone transceiver in a cordless telephone, wherein the antenna system 10 moves to its retracted position (Figures 1 and 2) for short range operation, and its extended position (Figure 3) for long range operation. The housing 4 also includes an electrical contact 8 which is grounded and which is coupled by a part of the antenna in its retracted position in one case, as will be described more particularly below. As seen more particularly in Figures 2 and 3, the housing 4 is formed with an opening 12, which fixedly receives a metal sleeve 14 of the retractable antenna system 10. The terminal 6 of the electrical circuit 2 is electrically connected to the metal sleeve 14. The sleeve 14 in turn includes an inner metal sleeve 16 constituting an electrical contact fixed to the housing 4. As described below, the contact 16 is selectively coupled by a second electrical contact carried by the inner end of the antenna assembly 10 in the extended position of that antenna, or a third electrical contact carried by the antenna assembly in the retracted position of that assembly.

The retractable antenna system 10 includes a rod antenna, generally designated 20, mounted coaxially within the opening 12 of the housing 4, to be circumscribed by the metal sleeve 14 and the electrical contact 16 carried by the housing. The rod antenna 20 includes a metal rod 22 circumscribed by an insulating sheath 24 for the entire length of the metal rod, except for its inner end which is circumscribed and engaged by a metal sleeve 26. The metal sleeve 26 in this way it constitutes the second electrical contact mentioned above, which is coupled by the fixed electrical contact 16, carried by the housing 4 in the extended position of the rod antenna as illustrated in Figure 3. The outer end of the insulating liner 24 of the rod antenna 20 is reduced in diameter, as illustrated at 28, to receive a coil assembly, generally designated 30, carried on the upper end of the rod antenna 20. The coil assembly 30 includes an electrical coil 32 , also completely insulated by an insulating jacket 34. The lower end of the coil assembly 30, includes a metal sleeve 36 electrically connected by a metal collar 37 to the coil 32. The outer end of coil assembly 30 terminates in an enlarged cover 38, formed with a flattened bottom surface. As will be more particularly described below, the metal sleeve 36 constitutes the third electrical contact connected to the coil 32 and engages the electrical contact 16 of the housing 4 in the retracted position of the antenna assembly. The antenna assembly 10 further includes a coil antenna, generally designated 40, fixedly mounted to the housing 4 by the metal sleeve 14, coaxial with the opening 12 in the housing. The coil antenna 40 includes an electrical coil 42 embedded in the dielectric material 44, formed with a reduced diameter base 46 at its lower end to connect to the metal sleeve 14, and further formed with an axial passage 48, to receive the assembly of coil 30 of the rod antenna 20. As illustrated in Figures 1 and 2, the coil antenna 40 is thus fixed to the housing 4 for circumscribing, and for electro-magnetically coupling to, the electrical coil 32 carried on the the upper end of the rod antenna 20 in the retracted position of the rod antenna. The upper end of the coil antenna 40 is crushed in order to be able to engage by the flattened bottom surface of the cover 38 at the outer end of the coil assembly 30 in the retracted position of the rod antenna, as illustrated in the Figures 1 and 2. The antenna assembly illustrated in Figures 1-3 operates as follows: When the electrical device 2 circumscribed within the housing 4 is to be used for short-range operation, the rod antenna 20 moves to its retracted position as illustrated in Figures 1 and 2. In this retracted position, the antenna rod 20 is circumscribed substantially completely inside the housing 4 except for its coil assembly 30, which is externally exposed to the coaxial housing within the coil antenna 40, fixed to the housing. In this retracted position of the antenna assembly, the electrical ground contact 8 couples the electrical contact 26 to the inner end of the rod antenna 20, thereby grounding the metal rod 22 and rendering the rod antenna ineffective. On the other hand, in this retracted position of the antenna assembly, the electric coil 32 is connected by its collar 37 and its electrical contact 36 to the electrical contact 16 carried by the housing 4; also, the electric coil 32 is now aligned with the fixed coil antenna 40, to be electromagnetically coupled with that antenna, thereby allowing the antenna coil 42 to radiate or receive energy. When the electrical device 2 is to be used for long range operation, the rod antenna 20 moves to its extended position as illustrated in Figure 3. In this position, the electrical contact 16 now couples the metal sleeve 26 to the inner end of the rod antenna 20, which in this way electrically connects circuit 2 through terminal 6 to metal rod 22 and makes that rod effective to radiate or receive energy. In this extended position of the antenna assembly, the electrical coil 32 is electrically isolated by the upper end of the liner 24 of the rod 22, thereby electrically disconnecting the electrical coil 32 from the metal rod 22. In some applications, however it may also be convenient to include the electric coil 32 as part of the rod antenna 22 in the extended position of the antenna assembly, in which case the electric coil 32 will be electrically connected to the metal rod 22. In this way it will be seen that since the electric coil 32 is used only to feed the coil antenna 40 in the retracted position of the antenna assembly, the electric coil 32 can be made of relatively small diameter wire and can include a relatively thin insulating shell, such that its mass would be substantially less than that if the electric coil will also be used to radiate or receive energy. Accordingly, the mass at the upper end of the rod antenna is substantially reduced, thereby also substantially reducing the flexibility of the rod antenna in its extended position. In addition, the coil antenna 40 fixed to the housing 4 and receiving the rod antenna 20, provides additional support to the rod antenna in its extended position, thereby further reducing its flexibility. As illustrated in Figure 1, the rod antenna can be deactivated from use in its retracted position by engaging its metal contact 26 with the ground contact 8 carried within the housing 4 when the electrical coil 32 is electrically connected in contact 16. Fig. 4 illustrates another assembly for doing this, wherein the housing 4 is provided with an electrical shield tube illustrated at 50, circumscribing the rod antenna 20 in its retracted position. Figure 5 illustrates a further alternative, wherein the housing is provided with a coaxial metal tube 52 circumscribing the rod antenna 20 in its retracted position and forming a transmission line coaxial with it. While the invention has been described with respect to several preferred embodiments, it will be appreciated that these are set forth simply for purposes of example, and that many other variations, modifications and applications of the invention can be made.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates. Having described the invention as above, the content of the following is claimed as property:

Claims

CLAIMS 1. A retractable antenna system for use with an electrical device, the antenna system comprising: a rod antenna mounted on the electrical device and mobile to an extended position or a retracted position with respect to the electrical device, - a coil electric carried by one end of the rod antenna and movable with it to the extended and retracted positions; and a coil antenna carried by the electrical device, for electromagnetically coupling with the electrical coil in the retracted position of the rod antenna and the electrical coil, characterized in that the coil antenna is operative to radiate; or to receive energy only when it is coupled electromagnetically with the electric coil, when the electric coil is in the retracted position. The antenna system according to claim 1, characterized in that the rod antenna has an outer end that carries a cover that engages the coil antenna in the retracted position of the rod antenna. The antenna system according to any of claims 1 or 2, characterized in that the electrical device is housed within a housing having an opening through which the rod antenna moves to its extended and retracted positions with with respect to the housing, the rod antenna has an outer end externally to the housing and an inner end inside the housing; the electric coil is transported on the outer end of the rod antenna, - the coil antenna is mounted in the housing on its outer side coaxial with the opening. The antenna system according to any of the preceding claims, characterized in that the system further comprises: a first electrical contact fixed to the housing adjacent the opening, - a second electrical contact carried by and electrically connected to the rod antenna and which is engaged by the first electrical contact in the extended position of the rod antenna; and a third electrical contact carried by the rod antenna, electrically connected to the electrical coil and coupled by the first electrical contact in the retracted position of the rod antenna. 5. The antenna system according to any of the preceding claims, characterized in that the rod antenna includes a metal rod circumscribed by an insulating sheath, the electric coil being electrically isolated from the metal rod. The antenna system according to any of the preceding claims, characterized in that the third electrical contact is in the form of a metal sleeve located between the insulating sheath and the electrical coil and electrically connected to the electrical coil. The antenna system according to any of the preceding claims, characterized in that the electrical coil is covered by an insulating layer and a lid is conveyed at its outer end which is coupled with the coil antenna in the retracted position of the antenna of rod. The antenna system according to any of the preceding claims, characterized in that the housing includes an additional electrical contact connected to ground and which engages with the second electrical contact in the retracted position of the rod antenna. The antenna system according to any of the preceding claims, characterized in that the housing includes an electrical shielding tube circumscribing the rod antenna in the retracted position of the rod antenna. The antenna system according to any of the preceding claims, characterized in that the housing includes a coaxial metal tube circumscribing the rod antenna in the retracted position of the rod antenna and forming a transmission line coaxial with it. . 11. Apparatus according to any of the preceding claims, characterized in that it also includes an electrical device that transmits and receives through the antenna system.