GB2337364A

GB2337364A - Antenna and radio unit with a ratchet coupling arrangement

Info

Publication number: GB2337364A
Application number: GB9810347A
Authority: GB
Inventors: Barry Norman Mitchell; Paul Masser; Nicholas Cantillon Fletcher
Original assignee: Motorola Ltd
Current assignee: Motorola Solutions UK Ltd
Priority date: 1998-05-15
Filing date: 1998-05-15
Publication date: 1999-11-17
Anticipated expiration: 2018-05-15
Also published as: GB2337364B; GB9810347D0

Abstract

An antenna 12 comprises a ratchet arrangement 14 which is suitable for coupling with a complementary ratchet arrangement 34 of a radio unit, such that the antenna 12 is not readily removable from the radio unit. The ratchet arrangement 14 may be formed as an inner portion of an antenna sheath with a skirt 16 which conceals the ratchet arrangement 14. A spigot 20 may extend from the end of the antenna 12 into the radio unit with a left handed threaded portion which may be engaged with a left hand threaded member of the radio unit. The spigot 20 may include a recess for receiving a wide diameter circlip to secure the antenna to the radio unit. The antenna 12 is arranged such that a special tool and/or disassembly of the radio unit will be required to release the antenna 12 from the radio unit 14.

Description

1 ANTENNA AND RADIO UNIT

Field of the Invention

2337364 This invention relates to an antenna. The invention is applicable to, but not limited to, radio equipment requiring non-removable antennas.

Backeround of the Invention In radio equipment, transmission and reception of signals is performed via electromagnetic radiating components, for example dipole antennas.

Antennas are typically designed with a screw thread at one end of the antenna for screwably mounting to radio units, the radio unit having a complementary screw thread. With such an arrangement they antenna can be easily and readily attached to and dismantled from the radio unit. This is particularly useful when attaching measurement equipment to the radio unit ' via the screw thread, to determine radio performance characteristics of the radio unit. The use of a screw thread to attach the antenna to the radio unit also facilitates the easy replacement of such a vulnerable component.

However, this ease of attachment and subsequent dismantling of an antenna from a radio unit has disadvantages. It is very easy for a user to either knowingly, or by mistake, connect the wrong form of antenna to a radio unit. Such an antenna may be designed for different operating frequencies than that of the radio unit, and will subsequently prevent the radio unit from operating correctly, when that antenna is connected. The screwthread arrangement also makes it very easy for the antenna and the radio unit to be tampered with.

Consequently, new European legislation being proposed by some countries for European adoption, stipulate specification and performance requirements of the antenna and antenna coupling arrangement that suggest that a non-removable design of an antenna will be required. In particular, it is likely that at least the antenna will only be able to be removed by using special tools or by a part-disassembly of the radio unit.

This invention seeks to provide an antenna that mitigates at least some of the above mentioned disadvantages.

2 Summary of the ILivention

According to a first aspect of the present invention there is provided An antenna having a distal end and a proximal end for coupling to a radio unit, the antenna characterised by a ratchet arrangement at the proximal end for coupling to a complementary ratchet arrangement of a radio unit such that unauthorised users of the radio unit are prevented from removing the antenna from the radio unit. The provision of the ratchet arrangement ensures that the antenna is substantially non-removable when attached to a radio unit.

Preferably the ratchet arrangement comprises at least one projection circumferentially disposed about the proximal end of the antenna. In this manner, the at least one projection abuts against a corresponding projection in the radio unit to prevent removal of the antenna from the radio unit. In addition, the antenna further comprising a substantially coaxial spigot extending from the proximal end of the antenna, for retaining the antenna to a radio unit housing. The advantage of such an arrangement is that the skirt hides the ratchet coupling arrangement attaching the antenna to the radio unit from the user, thereby preventing unauthorised users from determining the mechanism used for securing the antenna to the radio unit.

In the preferred embodiment of the invention, the antenna further comprises a substantially coaxial spigot extending from the proximal end of the antenna, for retaining the antenna to a radio unit housing. Preferably an extended region of the spigot at the proximal end includes a screw threaded portion, for engaging a threaded portion in the radio unit and further retaining the antenna thereto and the spigot has a reduced diameter region at the proximal end for engaging a retaining clip to retain the antenna to the radio unit. In this manner, additional fixing arrangements are provided to further increase the mechanical coupling of the antenna to the radib unit so as to substantially prevent removal of the antenna from the radio unit by unauthorised users.

In a second aspect of the present invention, a radio unit is provided having an antenna according to the first aspect of the present invention. Preferably, the radio unit has a corresponding complementary ratchet arrangement for securing the antenna to the radio unit.

3 Advantageously, the invention described herein has the ability to take into account the varying degrees of performance of the fit if the antenna to the radio unit.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the drawings.

Brief Description of the Drawings

FIG. 1 shows a side view of an antenna attaching arrangement according to a preferred embodiment of the invention; and FIG. 2 shows a plan view of the antenna attaching arrangement 15 according to the preferred embodiment of the invention.

Detailed Description of the Drawings

Referring first to FIG. 1, a side view of an antenna attaching arrangement 10 is shown, according to a preferred embodiment of the invention. The antenna attaching arrangement 10 includes an antenna 12, having a ratchet mechanism 14 at one end (a proximal end) of the antenna for coupling to the radio unit housing 18. In the preferred embodiment of the invention, the ratchet mechanism 14 is part of an internal portion of an antenna sheath, with an antenna skirt 16 extending along an external portion of the antenna sheath.

In such a manner, the antenna skirt 16 hides from view the ratchet mechanism 14 when the antenna 12 is coupled to the radio unit housing 18.

This prevents non-authorised users from determining how the antenna is connected to the radio unit and thus prevents them tampering with the connection.

In the preferred embodiment of the invention, the antenna attaching arrangement 10 also includes an extending inner portion 20 (spigot) for inserting into the radio unit housing. Internal to the radio unit housing 18, a securing nut 22 is mounted on a printed circuit board 24 for providing an internal screw-fit arrangement to the antenna. The inner portion 20 of the 4 antenna 12 includes a smaller diameter region that extends through the securing nut 22. The inner portion 20 is threaded so as to mechanically couple with the thread on the securing nut 22. To further increase the nonremovable nature of the antenna, a reverse thread is used, i.e. a left handed thread. This will be hidden from the outside by the antenna skirt 16, in addition to the ratchet mechanism.

A retaining circlip (TM) is also attached to the smaller diameter region, once the inner portion 20 is inserted through the securing nut, the retaining circlip having a diameter extending beyond the securing nut 22, to further prevent removal of the antenna 12 from the radio unit housing 18. In this manner, a number of securing arrangements are used to firmly secure the antenna to the radio unit housing in a non-removable arrangement.

Referring now to FIG. 2, a plan view of an antenna mount of a radio unit, according to the preferred embodiment of the invention, is shown. The antenna mount includes a ratchet mechanism 34 for coupling to the corresponding complementary ratchet mechanism 14 of the antenna.

A particular advantage of using a ratchet mechanism is that no additional components are required to fixedly attach the antenna to the radio unit. Furthermore, the securing arrangement is further enhanced by provision of a skirt on the outside of the antenna, thereby hiding the ratchet mechanism from view, a screw thread arrangement of a spigot and a reducing cross section of the spigot for attachment thereto of a wide diameter circlip.

Thus, an antenna is provided that is, to all intent and purpose, nonremovable to unauthorised users. A number of features have been included in the antenna design to further prevent dismantling of an antenna from a radio unit, thereby dissuading unauthorised users from tampering with the antenna. In particular, the arrangement is such that the antenna can only effectively be removed by using special tools or by a part-disassembly of the radio unit.

Claims

1. An antenna having a distal end and a proximal end for coupling to a radio unit, the antenna characterised by a ratchet arrangement at the proximal end for coupling to a complementary ratchet arrangement of a radio unit such that unauthorised users of the radio unit are prevented from removing the antenna from the radio unit.

2. An antenna according to claim 1, wherein the ratchet arrangement comprises at least one projection circumferentially disposed about the proximal end of the antenna.

3. An antenna according to claims 1 or 2, wherein the antenna comprises a sheath for covering the ratchet arrangement.

4. An antenna according to claims 1, 2 or 3, the antenna further comprising a substantially coaxial spigot extending from the proximal end of the antenna, for retaining the antenna to a radio unit housing.

5. An antenna according to claim 4, wherein an extended region of the spigot at the proximal end includes a screw threaded portion, for engaging a threaded portion in the radio unit and further retaining the antenna thereto.

6. An antenna according to claims 4 or 5, wherein the spigot has a reduced diameter region at the proximal end for engaging a retaining clip to retain the antenna to the radio unit.

7. A radio unit having an antenna according to any of the preceding claims.

8. A radio unit according to claim 7, the radio unit comprising a corresponding complementary ratchet arrangement for securing the antenna to the radio unit.

9. An antenna fixing arrangement substantially as herein before described with reference to, or as illustrated by, FIG. 1 or FIG. 2 of the drawings.