The invention to which this application relates is an improvement to apparatus for use in receiving and/or transmitting signals from and/or to a satellite. In particular, the improvement relates to the transition between a wave guide channel and data signal processing apparatus which can be provided as integral parts of a Low Noise Block (LNB). The LNB is typically provided mounted with respect to an antenna dish so as to receive data signals which are received from one or more satellites and the signals are then reflected from the antenna dish towards the LNB and in particular to an opening which leads into the waveguide channel. The data signals then pass along the waveguide channel to be separated into different component types and the components are then selectively provided to the data signal processing means. Conventionally, the data signal processing means are provided as part of a printed circuit board and the printed circuit board and waveguide can be provided as an integral unit in a body to form the LNB unit.

The data signals which are received can be provided in circular and/or linear formats. The linear format data signals are provided in two polarity components, horizontal and vertical and the circular format data signals are provided as right and left components. The particular polarity which is used is determined by the satellite provider and the geographical location at which the LNB is to be used and the subsequent processing of the data signals allows video and/ or audio data to be generated from the data signals and then provided to apparatus, such as a display screen and speakers, for use by an end user , said apparatus provided in connection with and downstream from the LNB.

In whichever format of the received data signals, there is a need to be able to separate the components of the received data signals such as, for example, for data signals received with a linear polarity there is a need to separate the horizontal component data signals from the vertical component data signals so as to allow the two different components to be processed by the data signal processing means independently and in the appropriate manner. Conventionally, the two components of data signals enter the waveguide channel together and are then separated within the waveguide channel of the LNB by providing a first probe which extends into the waveguide channel along an axis perpendicular to the longitudinal axis of the channel so as to allow one component of the data signals to be“coupled” by the probe and passed via the first probe to the data signal processing means. A second probe is provided in the channel, downstream of the first probe, which is again perpendicular to the longitudinal axis of the channel and is provided along a second axis which is 90 degrees to the axis of the first probe so as to couple and deflect the second component of the data signals and pass the same, via the second probe, to the data signal processing means. The first and second probes are connected to a PCB on which the data signal processing means are provided, at different locations. In order to ensure that the first component data signals cannot reach the second probe in the waveguide channel, a barrier is provided to extend across the waveguide channel downstream from the first probe and upstream from the second probe so that the barrier, which in one embodiment can be an elongate member which extends across the waveguide channel, lies intermediate the first and second probes and is provided to lie along an axis which is parallel to the axis of the first probe. This means that any first component data signals which go past the first probe are reflected by the bar in the reverse direction back towards the first probe to therefore be coupled by the same and so prevent any first component data signals from reaching the second probe.

While this known form of apparatus performs satisfactorily, the manufacture of the same can be problematic in terms of accurately setting the locations of the respective probes and the barrier with respect to the waveguide channel during the assembly operation. Furthermore, the assembly process requires the body to be drilled into in order to enable the location of the barrier and probes in the waveguide channel and this can cause debris and burrs to be created within the waveguide channel which adversely affect the quality of the data signals and subsequent processing of the same. It is also required that the probes and barrier are placed with a relatively high degree of accuracy in order for the barrier and hence waveguide and probe connections, to operate effectively. Furthermore, these assembly steps all add to the overall assembly time for each LNB and thereby add to the overall cost of manufacture of each LNB and requires additional materials to be used, such as the material to form the barrier, sealant which is required to be used once the barrier and probes have been positioned in the waveguide and also increases the possibility of incorrect operation of the apparatus. A further problem is that the provision of the barrier and the location of the same can allow the ingress of moisture into the waveguide channel during use, which is undesirable.

An aim of the present invention is therefore to provide a transition between a waveguide and data processing means in an LNB which ensures that the performance of the LNB transition is at least maintained in comparison to the conventional apparatus and, preferably, improved. A further aim is to provide the apparatus in a form which allows the assembly and manufacture of the LNB to be simplified and thereby reduce assembly time and cost and therefore provide an opportunity for streamlining of the assembly process.

In a first aspect of the invention, there is provided a Low Noise Block (LNB) including a body in which is defined a waveguide channel through which data signals can pass from an opening in the body at one end of the channel and move towards an opposing rear end of the said waveguide channel, a housing including data signal processing means, connected to first and second probes located so as to extend at least partially into the said waveguide channel at spaced locations along the said waveguide channel and along respective first and second axes which are offset by substantially 90 degrees and perpendicular to the longitudinal axis of the waveguide channel, the first probe located closer to the said opening than the second probe, and said first and second probes respectively transfer first and second components of the data signals to the data signal processing means and wherein in a portion of the said waveguide channel between the first probe and the said rear end of the waveguide channel, the effective width is reduced.

Typically, the said axis along which the width reduces is substantially perpendicular to the said axis of the first probe.

Typically, the length of the axis of the said waveguide channel portion which is perpendicular to the said axis along which the width reduces is substantially constant along the said portion of the channel. Typically, the reduction in width is such that only the second component of the data signals which are required to reach the second probe are able to pass along the waveguide channel portion after the first probe towards the second probe so that the reduction in the width dimension acts as the barrier to prevent the passage of the first component of the data signals which are collected by the first probe, beyond the first probe and act as a separation means to separate the data signals components.

Typically the reduction in the effective width is achieved by shaping the walls of the body which define the waveguide channel portion.

This therefore means that no separate physical barrier component is required to be provided or subsequently inserted in the waveguide channel and so the conventional need for a physical barrier, such as a bar is removed.

In one embodiment, the reduced width of the said portion is achieved by the provision of a profiled wall on one or both, opposing, sides of the waveguide channel so that the reduction in width is asymmetrical or symmetrical.

In one embodiment, the reduction in width is achieved by the provision of one, or a series, of steps which progressively reduce the width of the portion towards the second probe. In one embodiment, the one or more steps are provided on only one side of the waveguide channel portion to provide an asymmetrical reduction or in another embodiment, first and second, typically matching, sets of steps are provided on opposing sides of the waveguide channel to provide a symmetrical reduction.

In one embodiment, the opening into the waveguide channel can be round or elliptical and may include a series of ridges. In one embodiment the waveguide channel, inwardly from the opening, has a substantially square cross-section, a substantially circular cross-section or a rounded corner cross-section from the front end of the waveguide channel towards the start of the portion of the reduced width, and in which portion the cross sectional shape changes to a rectangular cross section. In one embodiment the area of the rectangular cross section reduces gradually or in steps along the said portion towards the rear end of the waveguide channel. In one embodiment, the first and/or second probes protrude from different sides of the waveguide channel into the said channel but do not extend across the channel entirely. Typically, the extent of the protrusion into the channel can be selected to suit particular uses and/or to balance the operation of the waveguide channel, and LNB, accordingly.

Typically the data signal processing means are located on one or more PCB’s to which the first and second probes are connected, and typically the one or more PCB’s are located externally of, and usually to one side of, the waveguide channel.

In one embodiment one of the first or second probes is provided to be linear in form and the other of the first or second probes has a bend and typically the bend is located outside of the waveguide channel.

Typically, it is the second probe which has the 90 degree bend formed therein and the said second probe has a first part and a second part with the said bend located intermediate the first and second parts.

Typically the end of the first probe and a second part of the second probe connect to the one or more PCB’s in the same plane and at spaced locations thereon.

In one embodiment the said first probe and second part of the second probe are substantially parallel.

In one embodiment the said first probe and first part of the second probe which protrudes into the said waveguide channel portion are substantially perpendicular.

In one embodiment the body in which the waveguide channel and the location for the PCB are provided, is formed by casting a metal or a metal alloy and the reduced width portion of the waveguide channel is configured so as to allow the removal of a casting tool from the interior of the waveguide channel through the opening once the housing has been cast. In a further aspect of the invention there is provided a waveguide channel through which data signals can pass from an opening end towards an opposing rear end, said channel including first and second probes which extend at least partially into the waveguide channel at spaced locations therealong, along respective axes offset by substantially 90 degrees and wherein in a portion of the waveguide channel between the location of the first probe and the said rear end, the effective width of the channel with respect of at least one width axis is reduced in a direction towards the said rear end.

Typically the reduction in width commences at a location between the said first and second probes.

Specific embodiments of the invention are now described with reference to the accompanying drawings wherein.

Figures 1A to C illustrate schematically an elevation, plan and end elevation of a conventionally formed waveguide channel of LNB apparatus.

Figures 2A to C illustrate schematically an elevation plan and end elevation of a waveguide channel in accordance with one embodiment of the invention;

Figures 3A to D illustrates views of a waveguide channel of an LNB in accordance with one embodiment of the invention;

Figures 4A-D illustrate a further embodiment of the waveguide channel and probe arrangement in accordance with the invention; and

Figures 5A-D illustrate a further embodiment of the waveguide channel and probe arrangement in accordance with the invention.

Referring firstly to Figures 1A to C, there is illustrated an LNB waveguide channel A in one embodiment of a conventional prior art configuration. In this conventional form, the LNB has a housing B in which a waveguide channel C is formed, passing from an open end D towards a rear end E. The required data signals in the required polarity are received in the open end D and are provided in first and second components such as, for linear polarity data signals, horizontal and vertical components. There is a need to separate the horizontal from the vertical components and so there is provided a first probe F positioned downstream from the open end D and then, downstream from the first probe F there is provided a second probe G as illustrated. The axes along which the first and second probes extend are offset by 90 degrees and thereby allow the first component of the data signals to be collected and passed via the first probe F to data processing means and the data signals for the second component pass towards the second probe G and on to the data processing means for further processing, as the first probe F is effectively invisible to the passage of the data signals of the second component along the waveguide channel.

In order to ensure that data signals of the first component do not reach the second probe G, a bar IT is located intermediate to the first and second probes as indicated and is located in the waveguide channel to pass across the same and extends along an axis parallel to the axis of first probe F. Thus, the bar IT is invisible to the data signals for the second component which can pass along to the second probe G but does act as a deflection means for data signals of the first component which are deflected by the bar IT back towards the first probe F.

In accordance with the invention, these problems are overcome. Figures 2A to C and 3A to D illustrate one embodiment of apparatus in accordance with the invention. In this embodiment there is provided a body 2 which is typically formed by a casting of metal or metal alloy and the body defines therein a waveguide channel 4 which extends from a front end 6 at which received data signals enter the channel and move in a direction towards the rear end 8 along longitudinal axis 10 of the waveguide channel. Also provided in a housing 11 are data signal processing means on one or more printed circuit boards 12 shown in broken lines in Figures 2a-c, on which are provided components which are required for the processing of the received data signals.

As already stated, the LNB will receive, in this embodiment, data signals of a linear configuration and there are two components of the same, a first component being the horizontal polarity data signals and a second component being the vertical polarity data signals. In order for these data signal components to be processed correctly, the same need to be collected and directed towards the appropriate data signal processing means on the PCB 12.

In accordance with the invention, all of the data signals which are capable of being received by the waveguide channel, pass into the opening 6 of the waveguide channel 4 and move there along until the location of the first probe 14 which extends into, but not necessarily across, the waveguide channel 4. The first probe is linear and provided to extend along a first axis 16 and is provided to collect and transfer data signals of one component type and transfer the same along the probe 14 to the PCB to which the first probe end is connected at the location 18.

The second component of the data signals continue to pass along the waveguide channel towards the rear end 8 as the first probe 14 is effectively invisible to the second component data signals. The second probe 20 is located downstream of the first probe 14 and towards the rear end 8 of the waveguide channel and the data signals of the second component are collected by the second probe 20. The first part 22 of the probe 20 which is positioned in the waveguide channel, extends along an axis 24 which is offset to the axis 16 of the first probe by 90 degrees. The second component data signals are passed along the first part of the probe 20 to a 90 degree bend 26 as shown, and then to the second part 28 of the second probe to thereby allow the data signals to pass to the printed circuit board 12 at the required location 30 and in the same plane as the first probe 14. The axes 16 of the first probe and 24 of the first part of the second probe are both perpendicular to each other and to the longitudinal axis 10 of the waveguide channel and, the said axes 16 of the first probe and 31 of the second part of the second probe are substantially parallel.

In order to ensure that the first component data signals do not reach the second probe 20 along the waveguide channel 4 there is provided a reduction in the width along the axis 32 of the waveguide channel in the portion 34 of the waveguide channel between the location of the first probe 14 and the rear end 8 of the waveguide channel and the reduction in width commences at a point 36 between the first and second probes. It should be noted that the length of the channel portion along the axis 38 is substantially constant along the said portion of the waveguide channel and the second probe is located in the said portion 34. The reduction of the width is with respect to only one axis, 32, and that axis is oriented with respect to the first probe so that the reduction in width is effectively invisible to the second component data signals but acts as a barrier to the first component data signals and therefore acts to deflect any of these first component data signals which pass the first probe 14 back towards the first probe when the reduced width stepped 32’ portion is reached. Thus, the reduced portion effectively acts as, and in the same manner as, the bar of a conventional apparatus but as the bar is not required to be provided, the current invention avoids the need for the steps of drilling and inserting a physical barrier such as a bar or any other component into position as the reduced width portion 34 can be formed in the body as part of the casting process and therefore is an integral part of the body.

As illustrated, the reduced width can be achieved by a plurality of stepped portions which are provided so as to reduce the width of the portion in a stepwise manner towards the second probe. Although, in this embodiment, two sets of the step portions are provided, 35,37 on a first wall and 35’, 37’ on the opposing wall of the waveguide channel 4, so as to provide a symmetrical reduction in width, it should be appreciated that the reduction in width could also be achieved by providing stepped portions on only one of the sidewalls in an asymmetrical manner or, furthermore, could be achieved by providing alternative profile shapes along the waveguide channel wall portion 34, with the important requirement being that the width is reduced along axis 32.

Figures 4a-d illustrate a further embodiment of the invention of the wave channel 104 of waveguide in perspective, end elevation, elevation and plan respectively in which there is again shown a waveguide channel 104 in which there are provided first and second probes 114, 120 respectively with the second probe again provided in a reduced width portion 134 located downstream of the larger width portion in which the first probe 114 is located. In this embodiment the reduction in width is achieved by the provision of a series of steps passing progressively inwardly in the direction of the arrow 135 towards the rear end 108 of the waveguide channel. The respective probe entry points 137, 139 are aligned with the centre line or longitudinal axis 110. It is found that in practice the embodiment illustrated here allows the advantages of the invention to be obtained whilst maintaining the required spacing between the first and second probes 114, 120 and allowing the PCB on which the signal processing components are located ( and which is shown in previous embodiments) to be aligned with the waveguide channel and without the need to change the same in comparison to conventional waveguide channel assemblies.

In a yet further embodiment as shown in Figures 5a-d and which use the same reference numerals as in Figures 4a-d, it is possible that at least one of the probes 114, 120, most typically the second probe 120, i.e. the probe positioned downstream from the first probe in the narrower portion 134 of the waveguide channel 104 will include a plurality of bends 136, 138 which are located and are at an angle as necessary in order to allow the entry point 139 of the probe 120 at the waveguide wall to be located at a suitable point on the wall.

It is found that the provision of the assembly in accordance with the invention allows isolation between the signal components to be enhanced as the reduced waveguide width for the portion of the channel creates a waveguide structure that will only support the passage of one component along the reduced width portion and completely cuts off or prevents the passage of the other component along that said portion which can be a considerable part of the length of the waveguide. This is contrary to the conventional apparatus with the bar which only allows the removal of the component over a comparatively small length of the channel i.e. where the isolation bar is present. Thus, this portion is effectively only the width of the isolation bar, so that it only provides a certain amount of attenuation of the unwanted component which is a poor performance when compared to the apparatus of the current invention that provides attenuation of the unwanted component over a considerably longer length of the waveguide channel.

Thus the present invention allows the elimination of the need for the provision of the reflector isolating bar which in turn eliminates the need for accurately drilling the hole into the body to insert the bar, eliminates the need for adhesive sealant to be used to secure the bar and prevents the possibility of moisture ingress into the channel.