GB1569768A - Rod antennae assemblies - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO ROD ANTENNAE ASSEMBLIES (71) We, I. M. S. JOH MORAT UND SOIINE GmbH, a German Company of 7929 Eisenbach, German Federal Republic, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to rod antennae of the type formed by a plurality of antenna rods mechanically coupled by screw-threaded elements to extend collinearly with the radiator portions of the individual rods electrically conductively connected.

In such antennae, which in use are frequently exposed to bending loads, and whose rods can be produced from a glass fibre material, it is desirable that the dimensioning, the material and the stability of the screw elements, and the arrangement and fixing of such screw elements on the relevant antenna rod ends are all effectively matched to the maximum load values to which such antennae can be subject, and that a highquality, permanent electrically conductive connection is effectively ensured between the threaded sleeves which engage one another in order to form the rod antenna assembly.

One subject of the present invention is to provide an antenna assembly of the type mentioned in the introduction, in which coupling elements are of a type that can be produced economically but satisfy the requirements regarding their arrangement and fixing on the relevant antenna rod ends, and also satisfy the requirements for stability and reliable electrically conductive contact junctions.

The invention consists in a rod antenna assembly having a plurality of antenna rods, each comprising at least one screw-threaded sleeve-like coupling element engaging a mating screw-threaded bolt-like coupling element of a neighbouring rod, so that the rods are secured collinearly to one another when mutually engaged, to a degree providing sufficient friction, but remain detachable, each said rod having an electrically conductive radiator portion forming part of a central conductor path extending over the length of the entire assembly when the rods are secured together, and at least the sleeve-like coupling element of each rod having its thread produced by cutting, and being arranged coaxially secured on one end of the associated antenna rod.

Advantageously, each said sleeve-like coupling element is produced by cutting from a metallic material to provide an' accurate thread.

However, a synthetic resin-bonded metal powder material can be used for the threaded sleeve-like coupling element if it satisfies the conditions regarding the requisite stability and the electric conductivity for use in such antennae after cutting to form an accurate thread.

The advantage of this type of antenna consists not only in that the production of the screw-threaded coupling elements, in particular of the threaded sleeve-like coupling element, and the arrangement and fixing of the latter at the relevant antenna rod ends is economical, but also in that it is ensured that in operation the mechanical loading of the coupling elements of such antennae can be transferred without damage to the individual highly elastic antenna rods, and thus distributed along the overall antenna assembly.

A further advantage consists in the clearly defined electrically conductive connection which can be designed and executed to a high standard of quality, is durable and can be readily formed as a cut-thread coupling element.

The invention will now be described with reference to the drawings, in which Figure 1 schematically illustrates a first or lower-most antenna rod of an assembly which has the largest outer diameter, with screw threaded coupling elements at its ends; Figure 2 illustrates a second or intermediate antenna rod of the assembly which has a smaller diameter than the first rod, and also has screw-threaded coupling elements arranged at its ends; Figure 3 illustrates a third or terminal antenna rod of an assembly with a screwthreaded coupling element arranged only at one end; Figure 4 schematically illustrates a complete assembly; and Figure 5 is a detail view of the connections at a coupling element.

In the antenna rods illustrated in the Figures, there is a central strand-like radiator portion 1 extending along each rod, and the rods are each fitted over their entire length except for their end-zones with a soft-plastic casing 2 there is encased in a tube of a glass fibre material to form the individual antenna rods 3 of cylindrical cross section. The antenna rods 3 arranged collinearly in series in the illustrated sequence, are detachably screwed to one another to form a rod-antenna as shown in Figure 4.

The antenna rod 3 shown in Figure 1 is provided at the antenna foot with a screwthreaded bolt 6 in which the thread is produced by cutting from a metallic material and is provided with stepped cylindrical bores to fit concentrically on the end of the associated antenna rod 3 which it engages via cylindrical extensions 4 and 5 of the rod 3, and is secured thereon by friction or by means of a glue joint to form a coupling element. At its lower end 10 the rod 3 is provided with a contact plate 9 within an aperture in the threaded bolt 6 via which the radiator portion 1 is electrically conductively connected to the threaded bolt 6 in the embodiment. The threaded bplt 6 can be provided in the region above thread 8 with a tapered centring conical surface 7.

The other end of the antenna rod 3 in Figure 1, which end lies opposite the threaded bolt 6, is provided with an internally threaded sleeve-like coupling element 12 consisting of an electrically conductive material, in particular a metallic material in which a thread has been produced by metal cutting. The threaded sleevelike coupling element 12 is secured by friction or by glue on a thinner extension 11 of cylindrical cross-section forming part of the rod 3.

A thread 15 extends from the end of the rod 3 to a cylindrical guide portion 14 of this coupling element 12, which runs collinearly and concentrically with the threaded portion of the sleeve and has a cylindrical cross-section, and extends up to a final guide portion 13 which runs conically towards the free end of the coupling element, and which is arranged concentrically with the guide 14.

An end 17 of the radiator portion 1 that is at that end of the first antenna rod 3 which carries the sleeve-like coupling element 12 is led through a contact plate 18 to a pot-like contact carrier 16, which is arranged by means of a glue joint on the antenna rod 3. The radiator portion 1 is electrically conductively connected to the contact carrier 16. In the assembly, the threaded sleeve-like coupling element 12 is placed over the contact carrier 16 of the antenna rod 3, arranged against the thinner extension 11 and secured in place by means of a glue joint. A secure electrically conductive connection between the contact carrier 16 and the threaded sleeve-like coupling element 12 is then effected, in particular, by means of a solder connection 19. For this purpose, the threaded sleeve-like coupling element 12 is provided with solder openings or solder break-throughs in the region of the contact' carrier 16.

For arrangement on the antenna rod 3 in Figure 1, the antenna rod 3 in Figure 2 is provided with a threaded bolt-like coupling element 21 which consists of an electrically conductive material and can be secured on an extension 20 of the antenna rod 3, by friction or by glue. A cylindrical guide portion 22 which is arranged concentrically to the threaded portion of the coupling element 21 and a conical guide portion 23 which adjoins the guide 22. At the opposite end of the central antenna rod 3 shown in Figure 2 there is arranged a threaded sleeve-like coupling element 12, which in particular has the same dimensions and the same features 13, 14, 15, 17, 18, 19 as the threaded sleeve-like coupling element 12 shown in Figure 1, for the accommodation, fixing and electrically conductive connection of the upper antenna rod 3 shown in Figure 3, which has a threaded bolt-like coupling element 21 on an antenna rod extension 20, together with a cylindrical guide 22 and an adjoining conical guide portion 23. Both the rods shown in Figure 2 and Figure 3 have their radiator portion 1 connected to the associated electrically conductive threaded components 12 and 21 in Figure 2, or 21 alone in Figure 3. The upper end of the upper rod is sealed by a cap 25.

A plurality of antenna rods assembled collinearly and connected in series to one another via connection elements securely engaged in detachable fashion may be exposed to high alternating bending loads.

For this reason, each actual antenna rod body consists, preferably of a glass fibre material, with a radiator portion embedded in the antenna body. As individual antenna rods are connected to one another by friction in a detachable manner, they are coupled mechanically in a manner to withstand substantially identical loads and as the relevant antenna rods which are to be connected to one another need to be connected in an electrically satisfactorily manner, with a contact resistance that is reliably formed whenever an assembly is put together, therefore in the event of extreme mechanical loads on such antennae, as can occur as a result of any alternating bending load when used on vehicles during assembly and disassembly, and also due to adverse atmospherical influences, the electric connection of the individual antenna rods in the relevant sequence should be such that it is not impaired in respect of its given electric transmission values during normal operation.

In the embodiment described above with reference to Figures 1 to 3, the electrical connection of the radiator portions of the individual antenna rods one to one another is effected directly via the coupling elements of the antenna rods, which for this purpose consist in part or in whole of an electrically conductive material. The connection is effectively completed by a bolt engaging a threaded socket consisting of a conductive material, which act together, when the antenna assembly is screwed together, to engage mechanically and also in an electrically conductive manner with one another. At each end of an antenna rod the radiator portion conductor contained therein is connected to the mating shaped parts of the coupling elements.

However, such an antenna embodiment has the disadvantage that the relatively large-area coupling elements are subject to corrosion and/ or pollution influences, and thus it is not possible to guarantee the required electrical contact resistance values between individual antenna rods, which can result in the fact that, in particular in the event of the increased alternating bending stress that can occur due to overland travel influences, an uncontrollable change can occur in the contact resistance in the coupling elements, thus considerably impairing or even rendering impossible any effective receiving or transmitting conditions.

To positively avoid these problems in the region of the coupling elements in a preferred embodiment of the invention the antenna rods are provided with contact elements which are electrically insulated from the mechanical coupling elements, but which electrically engage with each other when the relevant antenna rods are connected to one another.

In antenna rods with screw-threaded coupling elements, such contact elements can consist of the members of a plug-socket contact device arranged concentrically in the coupling elements, and whose contact elements are each electrically conductively connected to the corresponding radiator portion of the respective antenna rod. As a protection for the electric contact elements, in particular to guard against mechanical damage, the electric contact-plug component can form a unit with a screw threaded sleeve-like coupling element and the electric contact socket component can form a unit with a threaded bolt-like coupling element.

The advantage of such a device consists not only in the fact that a relatively small electric contact device can be equipped to meet all requirements on the electrical connection element extremely economically, as it can be provided, for example, with a non-corrosive contact metal coating of limited area, which is advantageous for such contact devices, but also in that the electric connection of the relevant radiator portion of the individual antenna rods one with one another is rendered independent of any damage to the mechanical coupling elements of the individual antenna rods, and is not exposed to the loads which influence the coupling elements.

Taking the exemplary embodiment illustrated substantially in Figure 4, of a rod antenna composed of three antenna rods securely connected to one another via coupling elements in detachable,there is shown in Figure 5 a sectional view of screw-threaded coupling elements mechanically as described with reference to Figure 1 to 3, but provided with a separate electric contact device for each coupling element.

Figure 4 shows three antenna rods 3 which are connected by means of coupling elements 12 to form a collinear detachable, rod antenna assembly. The coupling elements 12 at the upper end of each rod except the topmost rod are designed mechanically in the same manner as the screw-threaded sleeve-like coupling element of Figure 1, elements, and athreadedbolt- like coupling element 6 is provided at the foot of each antenna rod 3, which can engage with its mating sleeve-like coupling element 12, the lowermost bolt-like coupling element 3, visible in Figure 4 being designed to engage in a stationary antenna assembly base (not shown).

As can be seen in greater detail in Figure 5, the illustrated portions of two neighbouring antenna rods 3 consist of an antenna rod body of a glass fibre material, inside which a radiator portion 1 runs centrally, and which may consist of a flexible stranded wire, each end of which is connected to a related electric contact element 57 or 58 respectively. A sleeve-li8e coupling element 12 having an internally cut threaded portion 50 is provided on the upper end of each rod 3 (except for the uppermost rod) and a bolt-like coupling element 6 having an externally cut thread 59 is provided at the bottom of each rod. The contact elements 57 and 58 are arranged concentrically to the coupling element 12, and, if the coupling elements 12 and 6 are to consist in whole or in part of a metallic material, they are insulated from the latter.

This device ensures that, independently of the influences which can affect the mechanical coupling via elements 12 and 6, the electric connection of the radiator portions between the relevant antenna rods 3 is adequately safeguarded as a result of the special design and arrangement of the contact elements 57 and 58. In particular those contact spots or faces of the contact elements 57 and 58 which engage with one another can be protected against corrosion by a noble metal coating of sufficiently low electric contact resistance, as this can be provided relatively economically, in view of the size of these contact elements 57 and 58. The coupling elements 12 and 6 expediently consist of a synthetic resin material.

The electric contact elements 57 and 58 can consist, in particular, of a cylindrical plug 57 and of a cylindrical socket 58. To provide a mechanical protection of these elements from damage, the contact plug 57 can be arranged within the threaded portion 50 of the of the sleeve-like element 12, and the contact socket 58 can be arranged within the threaded portion 59 of the bolt-like element 6.

WHAT WE CLAIM IS: 1. A rod antenna assembly having a plurality of antenna rods, each comprising at least one screw-threaded sleeve-like coupling element engaging a mating screw-threaded boltlike coupling element of a neighbouring rod, so that the rods are secured collinearly to one another when mutually engaged, to a degree providing sufficient friction, but remain detachable, each said rod having an electrically conductive radiator portion forming part of a central conductor path extending over the length of the entire assembly when the rods are secured together, and at least the sleeve-like coupling element of each rod having its thread produced by cutting, and being arranged coaxially secured on one end of the associated antenna rod.

2. An assembly as claimed in Claim 1, in which each said radiator portion is electrically conductively connected to said or each coupling element of its rod.

3. An assembly as claimed in Claim 1 or Claim 2, in which each said threaded sleevelike coupling element is produced by cutting from a metallic material to provide an accurate thread.

4. An assembly as claimed in Claim 1 or Claim 2, in which each said threaded sleeve-like coupling element is produced by cutting from a synthetic resin-bonded metal powder material to provide an accurate thread.

5. An assembly as claimed in any preceding Claim, in which each threaded sleeve like coupling element is glued onto a corresponding end of an antenna rod and is electrically conductively connected by means of a solder connection to the associated radiator portion of that rod.

6. An assembly as claimed in any preceding Claim, in which an indirect, electrically conductive connection of a threaded sleeve-like portion to its radiator portion is provided by forming the corresponding end of the associated antenna rod with a pot-like contact carrier of electrically conductive material.

7. An assembly as claimed in Claim 1, in which said coupling elements of each rod are insulated electrically from the associated radiator portion, the latter being provided with contact elements electrically insulated from the coupling elements but mutually engaged in electrically conductive fashion when the relevant antenna rods are connected to one another.

8. An assembly as claimed in Claim 7, in which said electric contact elements consist of a contact plug and a mating contact socket.

9. An assembly as claimed in Claim 7 or Claim 8, in which each contact plug is arranged within a screw threaded portion of a sleevelike coupling element, and the mating contact socket is arranged within a screw-threaded portion of a bolt-like coupling element.

10. An assembly as claimed in any one of Claims 7 to 9, in which those contact spots or faces of the electric contact elements which engage with one another are provided with a noble metal contact coating.

11. A rod antenna assembly substantially as described with reference to Figures 1 to 4 or as modified with reference to Figure 5.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. against corrosion by a noble metal coating of sufficiently low electric contact resistance, as this can be provided relatively economically, in view of the size of these contact elements 57 and 58. The coupling elements 12 and 6 expediently consist of a synthetic resin material. The electric contact elements 57 and 58 can consist, in particular, of a cylindrical plug 57 and of a cylindrical socket 58. To provide a mechanical protection of these elements from damage, the contact plug 57 can be arranged within the threaded portion 50 of the of the sleeve-like element 12, and the contact socket 58 can be arranged within the threaded portion 59 of the bolt-like element 6. WHAT WE CLAIM IS:

1. A rod antenna assembly having a plurality of antenna rods, each comprising at least one screw-threaded sleeve-like coupling element engaging a mating screw-threaded boltlike coupling element of a neighbouring rod, so that the rods are secured collinearly to one another when mutually engaged, to a degree providing sufficient friction, but remain detachable, each said rod having an electrically conductive radiator portion forming part of a central conductor path extending over the length of the entire assembly when the rods are secured together, and at least the sleeve-like coupling element of each rod having its thread produced by cutting, and being arranged coaxially secured on one end of the associated antenna rod.

2. An assembly as claimed in Claim 1, in which each said radiator portion is electrically conductively connected to said or each coupling element of its rod.

3. An assembly as claimed in Claim 1 or Claim 2, in which each said threaded sleevelike coupling element is produced by cutting from a metallic material to provide an accurate thread.

4. An assembly as claimed in Claim 1 or Claim 2, in which each said threaded sleeve-like coupling element is produced by cutting from a synthetic resin-bonded metal powder material to provide an accurate thread.

5. An assembly as claimed in any preceding Claim, in which each threaded sleeve like coupling element is glued onto a corresponding end of an antenna rod and is electrically conductively connected by means of a solder connection to the associated radiator portion of that rod.

6. An assembly as claimed in any preceding Claim, in which an indirect, electrically conductive connection of a threaded sleeve-like portion to its radiator portion is provided by forming the corresponding end of the associated antenna rod with a pot-like contact carrier of electrically conductive material.

7. An assembly as claimed in Claim 1, in which said coupling elements of each rod are insulated electrically from the associated radiator portion, the latter being provided with contact elements electrically insulated from the coupling elements but mutually engaged in electrically conductive fashion when the relevant antenna rods are connected to one another.

8. An assembly as claimed in Claim 7, in which said electric contact elements consist of a contact plug and a mating contact socket.

9. An assembly as claimed in Claim 7 or Claim 8, in which each contact plug is arranged within a screw threaded portion of a sleevelike coupling element, and the mating contact socket is arranged within a screw-threaded portion of a bolt-like coupling element.

10. An assembly as claimed in any one of Claims 7 to 9, in which those contact spots or faces of the electric contact elements which engage with one another are provided with a noble metal contact coating.

11. A rod antenna assembly substantially as described with reference to Figures 1 to 4 or as modified with reference to Figure 5.