AU596830B2

AU596830B2 - Electrical cable termination means

Info

Publication number: AU596830B2
Application number: AU70164/87A
Authority: AU
Inventors: Terrence Shane O'Meara
Original assignee: R H O ANTENNAS Pty Ltd
Current assignee: RF Industries Pty Ltd
Priority date: 1986-07-04
Filing date: 1987-03-18
Publication date: 1990-05-17
Anticipated expiration: 2007-03-18
Also published as: AU7016487A

Description

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44048* 4 8 COMMONWEALTH OF AUSTRALIA Patents Act 1952 IS WJQt[o RHO ANTENNAS PTY, LTD.

(Patent Application No, PH 06780) COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED:- "ELECTRICAL CABLE TERMINATION MEANS" ihe following statement is a full description of this invention, including the best method of performing it known to us:- This invention relates to electrical cable termination means.

This invention has particular but not exclusive reference to cable termination means for connecting co-axial feed cable to radio antennas and quick-disconnect plugs and the like. For illustrative purposes this invention will be described hereinafter with respect to its application to radio antennas. However the cable termination means of this invention may be used in other electrical applications, 0 especially where the transmission cf alternating current signals is required.

o 0o Most radio transmitters and some receivers utilise co-axial cable for connections between the electronic o components and the antenna, Co-axial cable consists of a 0 00 ccntral conductor which joins the electrically active parts o the radio and antenna, atr insulating sheath which envelops the central conductor, an outer cylindrical braided conductor o0 which is normally connected to ground in order to shield the central conductor from electrical interference and an outer insulating sheath which insulates and protects the outer braided conductor. For normal electrical function, the central conductor and the outer conductor must be connected to a pair of electrical terminals at each end of the cable. The termination of co-axial cable is an involved process, as it is necessary to strip the outer protective shield, the outer 3 conductor, and the inner insulation before the inner conductor is exposed for joining to its connections by soldering, welding, or clamping. The outer braided conductor must then be joined to its connections, and the outer sheath of the cable must be clamped by some means to resist tensile loads on the cable.

As used hereinafter, the term "sheath" is to be taken to include both insulating sheaths such as the outer plastic skin of a two-conductor coaxial cable and a shielding sheath of conductive material.

This invention aims to alleviate the abovementioned disadvantages and to provide cable termination means and radio antennas incorporating same which will be reliable and efficient in use. Other objects and advantages of this invention will hereinafter become apparent.

With the foregoing and other objects in view, this invention in one aspect resides broadly in cable termination means for terminating a cable, said cable comprising a plurality of co-axial, sheathed connectors, said cable termination means including an insulating body supporting a plurality of electrical terminals and cable support means on said body for supporting said cable, wherein at least one of said sheathed conductors is held in capacitive relationship 025 with one said terminal and at least one other of said sheathed conductors is connected with anot-her of said terminals. The said other cable may be operatively connected to said other terminal by being held in capacitive relationship therewith but preferably the conductor of said 30 other cable is fixed to said other cable is fixed to said o

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o other terminal in conductive relationship therewith. For this purpose said other terminal may be provided with a spring i i clip or a screw clamp or other retention means adapted to engage about the conductor. The retention means may be in the form of a threaded aperture into which the conductor may be screwed.

In the preferred form, the cable termination means is adapted for terminating co-axial cable and the support means may be a clamp associated with the insulating body and adapted to engage about the inner or outer sheathed conductor to hold the cable in its operative position. Preferably however, the support means is constituted by the retention means which secures the outer braided conductor of the co-axial cable to said other terminal.

It is also preferred that the cable termination means be associated with a base mounting of an antenna assembly wherein the central conductor of the co-axial cable complete with its insulating sheath is disposed within a cavity in o said one terminal whereby electrical signals at radio frequency are passed between the central conductor and said Sone terminal by capacitive action with said insulating sheath forming the dielectric.

In another aspect this invention resides broadly in a base mounting assembly for an antenna assembly, said base mounting assembly being of the type having a metallic mounting base interconnected by an insulating housing to an antenna mounting and a coil supported within said housing and r connected at opposite ends to said mounting base and said antenna mounting, characterised in that said mounting base and said antenna mounting constitute the terminals of cable termination means as defined above. The antenna mounting may be formed of metal and have a socket therein in which the lower end of a whip aerial may be supported and the mounting base may have a downwardly projecting threaded stem to enable it to be bolted to a supporting bracket or surface.

In yet another aspect, this invention resides broadly S in a gutter supporting assembly for supporting a voltage fed or capacitively coupled radio antenna assembly and including:a lower mounting formed of plastics material and adapted for clamping to the rain gutter of a motor vehicle or other such projecting flange; an upper mounting formed of plastics ,5 material and pivotally connected to said lower mounting and locking means for maintaining said upper and lower mountings 0 o 0 in a selected pivotal relationship. The lower mounting is preferably in the form of a channel having a pair of spaced o threaded fasteners fitted to one of the opposed flanges, the latter being more flexible than said rain gutter so that any distortion necessary to produce clamping engagement between one said opposed flanges and said rain gutter will occur within said channel. Preferably the pivotal connection between said upper and lower mountings permits the antenna to Sbe adjusted to a vertical orientation, regardless of the

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-6inclination of the said rain gutter. It is also preferred that said locking means include a locking screw threaded into one mounting and engageable with the other said mounting.

In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate typical embodiments of the invention, wherein:- FIG 1 is a perspective view of a typical antenna assembly; i FIG 2 is a cross-sectional view of the antenna base mounting assembly illustrated with the cable terminated o therein, and FIG 3 is a view of a cable end prepareJ for termination.

S'105 As illustrated in FIG 1, the antenna assembly "0 includes a gutter bracket 11 formed of plastics material and connected rigidly to a base mounting assembly 12 of a voltage S fed antenna 13. The latter is formed to a length suitable for the application.

0 0 The prepared end of a co-axial cable 14 is terminated in the base mounting assembly 12 which is formed with a lower threaded metal stem 15 bolted to the upper pivotable mounting 16 of the gutter bracket 11. The lower channel shaped clamping part 17 of the gutter bracket 1 1 is provided with clamping screws 18 in its upper flange 19 which are adapted to be advanced into clamping engagement with a vehicle's gutter.

A mounting lug 20 extends away from the base of the clamping part 17 and it engages 21 with the forked base 22 of the upper mounting 16 for pivotal movement about the pivot pin 21. A locking screw 23 supported in the upper mounting 16 may be screwed into locking engagement with the lug 20 to hold the parts of the gutter bracket 11 in a selected pivotal co relationship.

The cylindrical body 24 of the base mounting assembly 0oon; 12 is formed of a plastics insulating material and it holds the lower metal stem 15 and the upper metal antenna mount S in spaced relationship. The antenna 13 is retained in a socket 26 in the top wall of the mount 25 by a grub screw 27 and a socket 27 in the base wall of the mount 25 closely S".I accommodates the upper end 29 of the sheathed inner core 30 of o00 the co-axxal cable 14. The length of the exposed inner insulated core 30 is so formed that a small gap is left between the end of the insulated core 30 and the adjacent end 0 04 S of socket 27 as that electrical contact between the inner conductor and the mount 25 is prevented. A coil 31 passes concentrically through the cavity 32 within the cylindrical body 24 and connects with the antenna mount 25 and the stem The coil 31 extends about the exposed inner core 30 of the co-axial cable and of course the coil may be formed to suit particular applications.

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1 -8- As illustrated in FIG 3, the end of a co-axial cable 14 is prepared for termination by stripping a length of the outer insulating sheath 33, cutting the outer braided conductor 34 short and folding it back over the outer insulating sheath 33.

The inner insulating sheath 35 4s exposed by this process but the inner conductor shown in dotted outline at 36 remains within the inner insulating sheath 35. The exposed braided conductor 34 is threadedly engaged within the thr-eded bore 37 such that the co-axial cable 14 is secured in the 3ase o"O mounting assembly with the inner core 30 projecting upwardly o into the socket 28 in the antenna mount 25 to form a capacitor therewith.

In use, the co-axial cable may be easily installed by simply screwing the prepared end of the cable into the base mounting assembly, the socket 28 in which the inner core is received and he threaded bore 37 being in axial alignment for s4 this purpose. Furthermore, at any stage the co-axial cable can be removed and connected to another antenna without the 0 o° need to disconnected or form soldered joints and the like, To"2 Thus such terminations with antennas or other plugs or the like can be performed without the need for special tools.

It will of course be realised that the above has been given only by way of illustrative example of the present invention and that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is defined in the appended claims.

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Claims

1. Cable termination means for terminating a cable, said cable comprising a plurality of co-axial, sheathed conductors, said cable termination means including an insulating body supporting a plurality of electrical terminals and cable support means on said body for supporting said cable, wherein at least one of said sheathed conductors is held in capacitive relationship with one said terminal and at least one other of said sheathed conductors is connected with another of said terminals.

2. A cable termination ineans according to claim 1 wherein said cable is sheathed co-axial cable having an insulated inner conductor co-axial with an outer conductor. 3, Cable utwmination means according to Claim 1 and adapted for terminating a co-axial cable, wherein said other terminal is adapted to interlock with the exposed outer conductor of said co-axial cable so as to form an electrically conductive 4 connection between said outer conductor and said other terminal and hold the inner sheathed conductor of said co- o axial cable in its capacitive relationSh.p with said one terminal.

4. Cable termination means according to Claim 2, wherein said one terminal is provided with a receiving passage in which the end portion of said sheathed inner conductor may be closely accommodated. i pc n 11 Cable termination means according to Claim 2 or claim 3, wherein said other terminal is apertured to permit said sheathed inner cable to pass therethrough and to engage tightly about said outer conductor.

6. Cable termination means according to Claim 4, wherein said receiving passage and the aperture of said aperture terminal are substantially co-axial.

7. Cable termination means according to Claim 5, wherein said aperture is internally threaded. .o 8. A radio antenna mounting assembly of the type having an antenna mounting base interconnected by a non-conductive housing to an antenna mounting and a coil supported within said housing and connected at opposite ends to said mounting base and said antenna mounting, characterised in that said antenna mounting and said mounting base constitute said i terminals of cable termination means as defined in any one of i the preceding claims, o. 9. A radio antenna assembly according to Claim 7, where said housing is tubular and said coil is supported co-axially within said tubular housing. Cable termination means sibstantially as hereinb' described with reference to the accompanying draw reS rr 1 i III-~ 12

11. A radio antenna substantially as hereinbefore described with reference to the accompanying drawings. DATED THIS Seventeenth DAY OF November, 1989. RHO ANTENNAS PTY. LTD. BY PIZZEY COMPANY PATENT ATTORNEYS aoi. o h i I O (I (1 n o o n o B Q ii "j o, c