WO1996005629A1

WO1996005629A1 - Microwave radio antenna/r.f. head mounting arrangements

Info

Publication number: WO1996005629A1
Application number: PCT/GB1995/001957
Authority: WO
Inventors: William Skinner; Michael Anthony Griffiths; David Alexander Cowan
Original assignee: Nera Limited
Priority date: 1994-08-17
Filing date: 1995-08-17
Publication date: 1996-02-22
Also published as: GB2292481A; GB9416636D0; AU3229895A; GB2292481B

Abstract

A microwave radio antenna assembly comprises a radio frequency head (20) which is detachably mounted to an antenna casing (10) and can be attached or detached by an operator using a single hand. The casing (10) is formed with arcuate slots (14), and the radio frequency head (20) comprises studs (26) which engage with the slots (14). The end of each slot (14) is enlarged so that the enlarged heads of the studs (26) can be inserted through the slots when the head (20) is in a particular orientation relative to the casing (10): the head (20) can then be turned to align with the casing (10), the studs (26) sliding along the slots (14). To remove the head (20) from the casing (10), the head (20) is turned such that the studs (26) are aligned with the enlarged ends of the slots (14) such that the head (20) may be removed.

Description

Microwave radio antenna/R.F. head mounting arrangements

This invention relates to mounting arrangements of microwave radio antennas and r.f. heads.

It is known for the radio frequency electronic circuitry of microwave radios to be housed in a head which is detachable from the antenna, so that if a fault develops the r.f. head can be detached and a replacement can be attached instead to the antenna, v/hich itself remains mounted to fixed structure. However, in hitherto known arrangements the means of attachment of the r.f. head to the antenna have been complicated and it has not been easy to detach and re-attach the r.f. head, particularly as the antenna is often mounted in positions where access is difficult.

We have now devised a simple and easy-to-use arrangement of mounting a radio frequency head to a microwave radio antenna.

In accordance with this invention, there is provided a microwave radio antenna assembly which includes a radio frequency head which is detachable from a casing of the antenna by rotating the r.f. head through a predetermined angle relative to the antenna casing, during which rotation studs carried by the r.f. head (or by the antenna casing) slide along guide channels carried by the antenna casing (or by the r.f. head) to a position where the studs can be removed from the guide channels. The secure ent of the r.f. head to the antenna casing is therefore of the bayonet type. Preferably the antenna casing (or the r.f. head) has a circular-section projection which engages in a complementary circular-section socket of the r.f. head (or of the antenna casing) , providing for rotation of the r.f. head relative to the antenna casing. Preferably the projection and complementary socket include respective microwave ports which are in alignment when the r.f. head is in its secured position.

Preferably the guide channels comprise arcuate slots formed in a rear wall of the antenna casing (or in a front wall of the r.f. head), each slot having an enlarged end at which the corresponding stud of the r.f. head (or antenna casing) can be inserted or removed. Preferably the wall portions around the slots are formed on an incline and shoulders of the studs engage the inner sides of these wall portions, so that as the r.f. head is turned into its secured position, the r.f. head is effectively pulled more closely against the antenna casing. Preferably the studs carry elements which are spring-biased inwardly and thus against the wall portions behind the slots. The arrangement in accordance with this invention enables an operator to attach or detach the r.f. head, using a single hand. For this purpose, preferably the r.f. head has a handle at its top: the operator can then hold the r.f. head by gripping this handle in one hand, and can then use this handle to turn the r.f. head relative to the antenna, either for attachment or detachment.

Typically a microwave radio antenna is mounted to fixed structure by means of a mounting bracket arrangement which enables adjustment of the antenna to be made, in respect of one or more of azimuth, elevation and skew (rotation around its longitudinal axis) . Typically each adjustment is made by turning one bracket plate relative to another, about one bolt extending through the two plates, and then tightening another bolt which passes through an arcuate adjustment slot in one of the plates. However it is sometimes difficult to adjust the plates to precisely the required angular position, and sometimes the plates slip as the bolts are tightened. We have now devised an arrangement which overcomes these difficulties.

Thus, also in accordance with this invention, there is provided a bracket arrangement which comprises two overlapping plates having a first bolt passing through them, the two plates being rotatable relative to each other about the first bolt, a second bolt passing through an arcuate slot in a first plate, one plate being formed with an arcuate slot having a toothed edge and the other plate being formed with an aperture located to correspond with said toothed-edge slot.

In use, a tool can be inserted through the aperture to engage between teoth of the toothed slot, and then the tool can be turned to effect fine-adjustment angular movement of the plates relative to each other. The tool can then be held firmly as the bolts are tightened up. Preferably use is made of a tool having a head in the form of a toothed gear wheel, but alternatively a screwdriver may be used.

Embodiments of this invention will now be described by way of examples only and with reference to the accompanying drawings, in which:

FIGURE 1 is a top plan view of a microwave radio antenna having an r.f. head secured to it;

FIGURE 2 is a sectional view of the antenna and r.f. head shown in Figure 1;

FIGURE 3 is an enlarged detail of Figure 2, to show the engagement of a projection of the antenna casing in a socket of the r.f. head to align microwave ports of the projection and socket; FIGURE 4 is a section through the antenna casing on the line IV-IV of Figure 2, to show the bayonet-type fixing arrangement between the r.f. head and antenna casing;

FIGURE 5 is a sectional view showing a detail of the bayonet-type fixing arrangement; and FIGURE 6 is a view of part of a mounting bracket arrangement for the antenna, showing a fine-adjustment facility.

Referring to Figures 1 to 4 of the drawings, there is shown a microwave radio antenna the casing 10 of which has a mounting bracket arrangement 50 which will be described in further detail below. An r.f. head 20 is detachably mounted to the casing 10 and houses the radio frequency electronic circuitry for the antenna. Thus, the casing 10 has a flat rear wall 11 which has a circular-section projection 12 formed with a waveguide port 13 to the antenna. The r.f. head 20 comprises a casing having a flat front wall 21 formed with a circular- section socket 22 having a waveguide port 23. The r.f. head is arranged to attach to the rear of the antenna casing 10 so that (as shown in Figure 3) front wall 21 of the r.f. head lies parallel to but at a small clearance from the rear wall 11 of the casing 10, when the projection 12 of the casing 10 is fully engaged within the socket 22 of the head 20 and the waveguide port 23 of the head aligned with the waveguide port 13 of the antenna: an O-ring 24 forms an environmental seal between the two waveguide ports.

Securement of the r.f. head 20 to the antenna casing 10 is effected by a bayonet-type arrangement, comprising two studs 26 projecting from the front face 21 of the head 20, to engage within respective arcuate slots 14 formed in the rear wall 11 of the casing 10: the slots 14 lie on a circle concentric with the projection 12. An end of each slot 14 is enlarged so that the enlarged heads of the studs can be inserted through the slots when the r.f. head 20 is in a particular orientation relative to the antenna casing 10: the r.f. head 20 can then be turned to align with the casing 10, the studs sliding along the slots 14. In Figure 4, the dotted outline of r.f. head 20 and handle 29 indicate their orientation at the start of engagement: handle 29 is shown in full line at full engagement, the outline of r.f. head 20 being hidden behind the outline of casing 10. As shown in Figure 5, each stud 26 carries a head element 27 which is biassed inwardly from the end 26a of the studs by a spring 28. Portions of the antenna casing wall 11 adjacent each slot are formed, as shown at 11a, to lie inwardly from and at a small angle to the plane of the wall 11, so that as the r.f. head 20 is turned into the secured position, the springs 28 of the two studs are progressively compressed: this has the effect of pulling the r.f. head 20 towards the rear wall of the antenna casing 10, to seat the projection 12 of the casing firmly against the bottom of the socket 22 in the r.f. head 20. Choking grooves 30, shown on projection 12 in Figure 3, reduce the dependency on good contact between the mating faces: the choking grooves may instead be formed in the socket 22. In the example shown, the antenna casing 10 and the r.f. head 20 are generally in the shape of rectangular boxes which are aligned when the r.f. head 20 is secured to the casing 10. A handle 29 is provided on the top of the r.f. head 20 and enables single-handed attachment of the r.f. head 20 to the antenna casing: thus, the operator can simply hold the r.f. head 20 by one hand gripping the handle 29, then bring the r.f. head 20 up to the rear of the antenna casing 10 to engage the projection 12 of the casing 10 in the socket 22 of the head 20, turn the head 20 until its studs 26 will enter the arcuate slots 14 at their enlarged ends, and then turn the head 20 into alignment with the antenna casing 10. A catch or lock mechanism is preferably provided to latch the r.f. head in its secured position: this mechanism may have a release lever conveniently located on the top of the r.f. head 20, so that it can be released by the thumb of the operator's hand when gripping the handle 29.

It will be appreciated that in detaching the r.f. head from the antenna casing, there is relative rotation between the projection 12 of the antenna casing and the socket 22 in the r.f. head: we have found that the corresponding rotation between the 0-ring 24 and the projection 12 effectively breaks a temporary bond which often develops between the O-ring and projection 12 if the r.f. head has remained secured to the antenna casing for an extended period of time.

The mounting bracket arrangement for the microwave antenna is preferably arranged to enable adjustment to be made for azimuth and elevation, and also adjustment around the longitudinal (front-to-rear) axis. An arrangement for the latter adjustment is shown in Figure 4, in that a bracket 51, at the bottom of the antenna casing 10, is pivoted by a bolt 52 to a bracket 53 and a second bolt 54 passes through an arcuate slot in bracket 53: when the correct angular adjustment has been made, the two bolts 52,54 are tightened. For azimuth adjustment, bracket 53 has a branch extending at 90° to that shown in Figure 4, i.e. to lie generally horizontally, and is adjustable relative to the horizontal branch of another bracket, which in turn has a vertical branch adjustable (for elevation adjustment) relative to a vertical plate of a fixed mounting bracket.

Figure 6 shows a preferred form of adjustable engagement between any pair of brackets: this arrangement may be used to provide each of the three adjustments outlined above. It will be seen that the two brackets, which are to be relatively adjusted, comprise respective plates 60,70. One plate, shown here as the lower plate 60, has three circular apertures to receive bolts 61,62,63: the upper plate 70 has one circular aperture to receive bolt 61, and two arcuate apertures to receive bolts 62,63; thus, the plate 70 can be turned around bolt 61 relative to plate 60, and then the three bolts 61,62,63 tightened. One of the plates (e.g. plate 60) is formed with a slot 64 having teeth along one edge, and the other plate is formed with a circular aperture 71 to locate with the slot 64: the toothed slot 64 and the aperture 71 are used to provide fine adjustment for the angular position of one plate relative to the other, and can further be used to hold the plates as the bolts 61,62,63 are tightened, to avoid the plates moving at this time. Thus, a tool having a head in the form of a toothed gear wheel can be inserted through the aperture 71 to engage teeth of the slot 64 and the tool can then be turned in order to urge against these teeth and so effect a fine movement of the plates 60, 70 relative to eachother: then the tool can be held firm whilst the bolts 61, 62, 63 are tightened.

Claims

1) A microwave radio antenna assembly which includes a radio frequency head which is detachable from a casing of the antenna by rotating the radio frequency head through a predetermined angle relative to the antenna casing, during which rotation studs carried by the radio frequency head (or by the antenna casing) slide along guide channels carried by the antenna casing (or by the radio frequency head) to a position where the studs can be removed from the guide channels.

2) A microwave radio antenna assembly as claimed in claim

1, wherein the antenna casing (or the radio frequency head) has a circular-section projection which engages in a complementary circular-section socket of the radio frequency head (or the antenna casing) , the projection and complementary socket providing for rotation of the radio frequency head relative to the antenna casing.

3) A microwave radio antenna assembly as claimed in claim

2, wherein the projection and complementary socket include respective microwave ports which are in alignment when the radio frequency head is in its secured position.

4) A microwave radio antenna assembly as claimed in any preceding claim, wherein the guide channels comprise arcuate slots formed in a rear wall of the antenna casing (or in a front wall of the radio frequency head) , each slot having an enlarged end at which the corresponding stud of the radio frequency head (or antenna casing) can be inserted or removed.

5) A microwave radio antenna assembly as claimed in any preceding claim, wherein the wall portions around the slots are formed on an incline and shoulders of the studs engage the inner sides of these wall portions.

6) A microwave radio antenna assembly as claimed in any preceding claim, wherein the studs carry elements which are spring-biased inwardly and thus against the wall portions behind the slots.

7) A microwave radio antenna assembly as claimed in any preceding claim, wherein the radio frequency head is provided with a handle at its top.

8) A microwave radio antenna assembly substantially as herein described with reference to Figures 1 to 5 of the accompanying drawings.

9) A bracket arrangement which comprises two overlapping plates having a first bolt passing through them, the two plates being rotatable relative to each other about the first bolt, a second bolt passing through an arcuate slot in a first plate, one plate being formed with an arcuate slot having a toothed edge and the other plate being formed with an aperture located to correspond with said toothed-edge slot.

10) A bracket arrangement substantially as herein described with reference to Figure 6 of the accompanying drawings.

11) A microwave radio antenna assembly wich includes a mounting bracket arrangement as claimed in claim 9 or 10.