WO2020030250A1

WO2020030250A1 - Radio-frequency apparatus and components thereof

Info

Publication number: WO2020030250A1
Application number: PCT/EP2018/071364
Authority: WO
Inventors: Jari Taskila; Timothy Bernhardt; William Wilber
Original assignee: Nokia Shanghai Bell Co. Ltd.; Nokia Solutions And Networks Oy
Priority date: 2018-08-07
Filing date: 2018-08-07
Publication date: 2020-02-13
Also published as: CN117913487A; CN112544011A

Abstract

An apparatus comprising: a conductive housing comprising conductive housing walls that a least partially enclose a cavity; a printed circuit board adjacent the conductive housing walls forming a cover of the cavity that is directly adjacent the cavity; and stress relief features at an interface between the conductive housing walls and the printed circuit board, wherein the combination of at least the conductive housing walls and the printed circuit board creates cavity of a resonant cavity filter.

Description

TITLE

Radio-frequency apparatus and components thereof.

TECHNOLOGICAL FIELD

Embodiments of the present disclosure relate to radio frequency apparatus and components thereof. In particular, at least some relate to higher integration within radio frequency apparatus such as a base station.

BACKGROUND

It is desirable to achieve higher integration within radio frequency apparatus, particularly a base station, that reduces the requirements for screws, coaxial connectors, jumper cables etc.

Other approaches need to be found for saving space and reducing component size.

BRIEF SUMMARY

According to various, but not necessarily all, embodiments there is provided an apparatus comprising:

a conductive housing comprising conductive housing walls that a least partially enclose a cavity;

a printed circuit board adjacent the conductive housing walls forming a cover of the cavity that is directly adjacent the cavity; and

stress relief features at an interface between the conductive housing walls and the printed circuit board,

wherein the combination of at least the conductive housing walls and the printed circuit board creates cavity of a resonant cavity filter.

In at least some examples, the stress relief features are configured to deform to absorb stress.

In at least some examples, the stress relief features are distinct and have spatial separation. In at least some examples, the stress relief features provide distinct connection paths between the printed circuit board and the conductive housing walls and enable relative movement of the connection paths.

In at least some examples, the stress relief features have a repeated pattern.

In at least some examples, the stress relief features are defined by apertures in a substrate of the printed circuit board.

In at least some examples, some or all of the apertures are through-apertures that extend through the substrate and/or or wherein some or all of the apertures are notches that do not extend through the substrate.

In at least some examples, the apertures comprise external apertures that each separately terminate at one point on a perimeter of the printed circuit board and/or wherein the apertures comprise internal apertures that do not terminate at the perimeter of the printed circuit board.

In at least some examples, the internal apertures and external apertures have different sizes.

In at least some examples, the internal apertures and external apertures have different repeat patterns.

In at least some examples, the external apertures are slots.

In at least some examples, the external apertures are straight slots having parallel sides, the parallel sides having a length greater than three times a distance between the parallel sides.

In at least some examples, the straight slots are perpendicular to an edge at a perimeter of the printed circuit board.

In at least some examples, the straight slots are present at all edges of the perimeter. In at least some examples, the apertures comprise multiple parallel first external apertures at a first edge of a perimeter of the printed circuit board and multiple parallel third external apertures at a third edge of the perimeter of the printed circuit board, wherein the first edge opposes the third edge and wherein each first external aperture opposes a corresponding third external aperture and each third external aperture opposes a corresponding first external aperture.

In at least some examples, the apertures comprise regularly spaced internal apertures the internal apertures extend so that they overlap external apertures close to a perimeter of the printed circuit board.

In at least some examples, the apertures comprise external apertures that each separately terminate at one point on a perimeter of the printed circuit board and internal apertures that do not terminate at the perimeter of the printed circuit board, wherein the internal apertures and external apertures are straight slots of different lengths.

In at least some examples, the apertures comprise multiple parallel first external apertures that separately terminate at a first edge of a perimeter of the printed circuit board and multiple parallel third external apertures that separately terminate at a third edge of the perimeter of the printed circuit board, wherein the first edge opposes the third edge and each first external aperture opposes a corresponding third external aperture and each third external aperture opposes a corresponding first external aperture; and

comprise one or more second external apertures that separately terminate at a second edge of the perimeter of the printed circuit board and one or more fourth external apertures that separately terminate at a fourth edge of the perimeter of the printed circuit board, wherein the second edge opposes the fourth edge and each of the one or more second external apertures opposes and is parallel to a corresponding fourth external aperture and each of the one or more fourth external apertures opposes and is parallel to a corresponding second external aperture. In at least some examples, the internal apertures are straight slots having parallel sides, the parallel sides having a length greater than five times a distance between the parallel sides.

In at least some examples, the apertures comprise external apertures that each separately terminate at one point on a perimeter of the printed circuit board and internal apertures that do not terminate at the perimeter of the printed circuit board, wherein the internal apertures and external apertures have different shapes.

In at least some examples, the apertures comprises multiple parallel first external apertures that separately terminate at a first edge of a perimeter of the printed circuit board and multiple parallel third external apertures that separately terminate at a third edge of the perimeter of the printed circuit board, wherein the first edge opposes the third edge and each first external aperture opposes and is parallel to a corresponding third external aperture and each third external aperture opposes and is parallel to a corresponding first external aperture; and

comprise multiple second external apertures that separately terminate at a second edge of the perimeter of the printed circuit board and multiple fourth external apertures that separately terminate at a fourth edge of the perimeter of the printed circuit board, wherein the second edge opposes the fourth edge and each,

wherein each of the second external apertures opposes and is parallel to a corresponding fourth external aperture and each of the fourth external apertures opposes and is parallel to a corresponding second external aperture,

wherein a spacing between the first and third external apertures is the same as a spacing between the second and fourth external apertures.

In at least some examples, the apertures comprise internal apertures that do not terminate at a perimeter of the printed circuit board, wherein the internal apertures are crosses formed by two crossed straight slots having parallel sides.

In at least some examples, the apertures comprise internal apertures that do not terminate at a perimeter of the printed circuit board, wherein the internal apertures are square crosses. In at least some examples, the stress relief features comprise a stress relief element between the housing walls and the printed circuit board.

In at least some examples, the stress relief element comprises multiple distinct supporting pins.

In at least some examples, the stress relief element is conductive.

In at least some examples, the stress relief element directly connects the housing walls and a perimeter of the printed circuit board.

In at least some examples, the stress relief element extends around the whole of a perimeter of the printed circuit board.

In at least some examples, the stress relief element is a comb structure.

conductive housing walls that a least partially enclose a cavity;

stress relief features positioned where the conductive housing walls attaches to a printed circuit board, wherein the combination of the conductive housing walls, the stress relief features and the attached printed circuit board creates an enclosed resonant cavity for a resonant cavity filter.

In at least some examples, the stress relief features comprise a stress relief element for attaching the housing walls to the printed circuit board.

According to various, but not necessarily all, embodiments there is provided

a printed circuit board for use in a resonant cavity filter, comprising:

at least one conductive substrate;

at least one user tunable device for tuning a resonant cavity filter, formed by attaching the printed circuit board to conductive housing walls, that a least partially enclose a cavity, to create an enclosed resonant cavity for the resonant cavity filter, wherein the at least one user tunable device is configured to be varied by a user to tune the resonant cavity filter.

In at least some examples, the PCB comprises stress relief features defined by apertures in a substrate of the printed circuit board.

According to various, but not necessarily all, embodiments there is provided a frequency selective radio-frequency apparatus comprising:

a conductive component;

a printed circuit board adjacent the conductive component; and

stress relief features at an interface between the conductive component and the printed circuit board,

wherein the combination of at least the conductive component and the printed circuit board creates a conductive portion of the frequency selective radio-frequency apparatus.

In at least some examples, the frequency selective radio-frequency component is a cavity filter or an antenna.

According to various, but not necessarily all, embodiments there is provided a conductive component of a frequency selective radio-frequency apparatus comprising:

a conductive stress relief element interface positioned where the conductive component attaches to a printed circuit board,

wherein the combination of the conductive stress relief element, the conductive component and the attached printed circuit board creates a conductive portion of the frequency selective radio-frequency apparatus.

According to various, but not necessarily all, embodiments there is provided a printed circuit board for use in a frequency selective radio-frequency apparatus comprising: at least one conductive substrate;

at least one user tunable apparatus for tuning a frequency selective radio frequency apparatus formed by attaching the printed circuit board to a conductive component of the frequency selective radio-frequency apparatus to form a conductive portion of the frequency selective radio-frequency apparatus, wherein the at least one user tunable device is configured to be varied by a user to control an electrical impedance associated with the conductive portion.

According to various, but not necessarily all, embodiments there is provided examples as claimed in the appended claims.

BRIEF DESCRIPTION

Some example embodiments will now be described with reference to the accompanying drawings in which:

FIG. 1 shows an example embodiment of the subject matter described herein;

FIG. 2 shows another example embodiment of the subject matter described herein; FIG. 3 shows another example embodiment of the subject matter described herein; FIG. 4 shows another example embodiment of the subject matter described herein; FIG. 5 shows another example embodiment of the subject matter described herein; FIG. 6 shows another example embodiment of the subject matter described herein; FIG. 7 shows another example embodiment of the subject matter described herein; FIG. 8 shows another example embodiment of the subject matter described herein; FIG. 9 shows another example embodiment of the subject matter described herein.

DETAILED DESCRIPTION

FIG 1 illustrates an example of an apparatus 100. The apparatus 100 is frequency selective radio-frequency apparatus 100. It is frequency-selective in that it is configured to operate at some frequencies but not at other frequencies. For example, it may have bandpass characteristics at one or more frequency ranges.

The apparatus 100 may, for example, be a filter such as a resonant cavity filter, or an antenna. A resonant cavity filter is a filter with one or more resonant cavities. In some but not necessarily all examples a cavity of a resonant cavity filter can comprise resonators. Examples of resonators include metallic resonators and dielectric resonators.

The apparatus 100 comprises a printed circuit board (PCB) 10, a conductive structure 20; and stress relief features 30 at an interface between the conductive component 20 and the printed circuit board 10. The combination of at least the conductive component 20 and the printed circuit board 10 creates a conductive portion of the frequency selective radio-frequency apparatus 100.

In the example illustrated in FIG 1 , frequency selective radio-frequency apparatus 100 is a resonant cavity filter. The conductive structure 20 is a conductive housing 20 that has conductive housing walls 22 at least partially defining a cavity 24.

The printed circuit board (PCB) 10 provides point-to-point connections in a predetermined arrangement on a common substrate. In some but not necessarily all examples, the PCB 10 is designed to have an effect on circuit operation other than just point to point connection. In some but not necessarily all examples, the PCB 10 comprises active and/or passive components. These components may be embedded in the PCB 10, for example by printing, or mounted on the PCB 10, for example by soldering. A PCB 10 with active and/or passive components may be referred to as a printed circuit board assembly. The PCB 10 mechanically supports and electrically connects the components.

In some but not necessarily all examples, a substrate 12 of the PCB 10 comprises an electrically isolated conductive sheet. The sheet may be formed from metal foil such as copper. Conductive tracks, pads and other features are etched from or onto the sheet. A multi-layer PCB 10 comprises electrically isolated conductive sheets and features of one sheet may be interconnected to features of another sheet.

The substrate 12 therefore provides both electrical connection and mechanical support. The substrate may, for example, comprise a glass-reinforced epoxy laminate such as, for example, FR4, and one or more conductive layers, for example copper layers.

In some but not necessarily all examples, the PCB 10 comprises components of a radio transceiver, for example receiver circuitry and/or transmitter circuitry and/or active antenna circuitry and/or measurement circuitry for measuring transceiver performance. In this illustrated example, the printed circuit board 10 is configured for use in a resonant cavity filter 100, and comprises one or more user-tunable devices 14 for tuning the resonant cavity filter 100.

The resonant cavity filter 100 is formed by attaching the printed circuit board 10 to the conductive housing walls 22 of the housing 20.

The conductive housing walls 22 partially enclose a cavity 24 when the PCB 10 is not attached and enclose the cavity 24 when the PCB 10 is attached. The enclosed cavity 24 is a void filled with dielectric, for example air, and forms a resonant cavity for the resonant cavity filter 100. The PCB 10 forms a cover of the cavity 24.

The one or more user-tunable devices 14 are configured to be varied by a user to tune the resonant cavity filter 100. In some but not necessarily all examples a user-tunable device 14 is a conductive element that extends, by a variable amount, into the resonant cavity 24. In some but not necessarily all examples the user-tunable device 14 is a tuning screw that is rotated in a first sense to move into the resonant cavity 24 and is rotated in a second, opposite, sense to move out of the resonant cavity 24. The PCB 10 forms a tuning cover of the cavity 24

The housing 20 is conductive. It forms with the attached PCB 10 a conductive enclosure for the resonant cavity 24. In some, but not necessarily all examples, the conductivity of the housing 20 arises from using metal, for example aluminum. In some, but not necessarily all examples, the housing 20 is formed from metal, for example, by milling or casting.

The attachment between the PCB 10 and the walls 22 of the housing 20 may be formed in any suitable manner. For example, using soldering or screws.

In some but not necessarily all examples, the PCB 10 is attached to a top of exterior walls 22 of the housing 20 only. The exterior housing walls 22 define an exterior of the housing 20. In some but not necessarily all examples, the housing 20 comprises exterior housing walls 22 defining an exterior of the housing 20 and interior housing walls that extend from the external cavity walls 22 to determine a size and shape of the resonant cavity 24. In some but not necessarily all of these examples, the PCB 10 is attached to the tops of one or more exterior housing walls and/or one or more interior housing walls.

The PCB 10 is attached and supported at a perimeter 16 of the PCB 10, so that the PCB 10 is directly adjacent the resonant cavity 24. The resonant cavity filter 100 is a single assembly having an integrated printed circuit board 10 and housing 20. The PCB 10 has completely replaced the solid metallic cover used to enclose the resonant cavity in current commercially available resonant cavity filters.

FIG 1 illustrate an example of an apparatus 100 comprising: a conductive housing 20 comprising conductive housing walls 22 that a least partially enclose a cavity 24; a printed circuit board 10 adjacent the conductive housing walls 22 forming a cover of the cavity 24 that is directly adjacent the cavity 24; and stress relief features 30 at an interface between the conductive housing walls 22 and the printed circuit board 10, wherein the combination of at least the conductive housing walls 24 and the printed circuit board 10 creates a resonant cavity 24 of a resonant cavity filter 100.

Examples of stress relied features 30 are illustrated in FIGs 2 to 8.

The stress relief features 30 modify the interface between printed circuit board 10 and the housing 20. The stress relief features 30 allow different parts such as the housing 20 and the PCB 10 to expand/contract at different rates without excess stress being generated.

In some but not necessarily all examples the stress relief features 30 are configured to deform to absorb stress and prevent stress propagation.

In the examples illustrated below the stress relief features 30 are distinct and have spatial separation. In the examples illustrated below the stress relief features 30 provide distinct connection paths between the printed circuit board 10 and the conductive housing walls 22 and enable relative movement of the connection paths. In some but not necessarily all examples the stress relief features 30 are conductive and the distinct connection paths provide distinct electrical connection paths.

The combination of the conductive housing walls 24, a conductive substrate 12 of the printed circuit board 10 and the conductive stress relief features 30 creates a conductive enclosure for the resonant cavity 24 of the resonant cavity filter 100.

In the illustrated examples, the stress relief features 30 have a regular, repeated pattern. The pattern of stress relief features has reflection symmetry in a virtual x-axis and has reflection symmetry in a virtual y-axis that is orthogonal to the x-axis.

APERTURES

In the examples illustrated in FIG 2, 3, 4 & 8, the stress relief features 30 are defined by apertures 32 in a substrate 12 of the printed circuit board 10.

In the examples illustrated, the apertures 32 are through-apertures that extend through the substrate 12 from one exterior surface of the PCB 10 to another exterior surface of the PCB 10. However, in other examples, some all or none of the apertures 32 are notches that do not extend all the way through the substrate 12. The notches may, for example, have a U-shaped profile, however other profile shapes are possible. Where the apertures 32 are notches, the notches may, for example, be on one exterior surface of the PCB 10 or may be on two opposing exterior surfaces of the PCB 10.

In some but not necessarily all examples, a stress relief feature 30 defined by a through-aperture 32 has a through-aperture for the purpose of stress-relief and it is not used for the purpose of providing a conductive via or for securing the printed circuit board 10. In some but not necessarily all examples, a stress relief feature 30 defined by a through-aperture 32 has a through-aperture for the purpose of stress-relief only and is otherwise redundant. In the examples illustrated, at least some of the apertures 32 are or comprise slots.

In the examples illustrated in FIG 2, 3, 4 & 8 but not necessarily all examples, the apertures 32 include external apertures 32E that each separately terminate at one point on a perimeter 16 of the printed circuit board 10 and internal apertures 32i that do not terminate at the perimeter 16 of the printed circuit board 10. The internal apertures 32i and external apertures 32E have different sizes (e.g. different lengths or different shapes). Also the internal apertures 32i and external apertures 32E have different repeat patterns. Each repeat pattern has reflection symmetry in the x-axis and the y- axis. In these examples, but not necessarily all examples the internal apertures 32i have the same size. In other examples, the apertures 32 may include only external apertures 32E or only internal apertures 32i_.

In the examples illustrated in in FIG 2, 3, 4 & 8 but not necessarily all examples, the external apertures 32E are slots. The external apertures 32E are elongate, straight slots having parallel sides. The parallel sides have a length greater than three times a distance between the parallel sides. The straight slots are perpendicular to an edge at the perimeter 16 of the printed circuit board 10 .

In these examples, but not necessarily all examples, the straight slots 32E are present at all edges of the perimeter 16 of the PCB 10.

In these examples, but not necessarily all examples, there are multiple parallel first external apertures 32E at a first edge 18i of a perimeter 16 of the printed circuit board 10 and multiple parallel third external apertures 32E at a third edge 18₃ of the perimeter 16 of the printed circuit board 10. The first edge 18₁ opposes the third edge 18₁. Each first external aperture 32E opposes and is aligned with a corresponding third external aperture 32E. Each third external aperture 32E opposes and is aligned with a corresponding first external aperture 32E.

In these examples, the spacing between first external apertures 32E is regular and the same as a regular spacing between the third external apertures 32E. In these examples, but not necessarily all examples, the internal apertures 32i are regularly spaced apart. The internal apertures 32i in this example extend so that they overlap partially external apertures 32E close to the perimeter 16 of the printed circuit board 10.

INTERNAL SLOTS

In the example illustrated in Fig 2, 3 & 8, but not necessarily all examples, the apertures 32 comprise external apertures 32E that each separately terminate at one point on the perimeter 16 of the printed circuit board 10 and internal apertures 32i that do not terminate at the perimeter 16 of the printed circuit board 10. The internal apertures 32i and external apertures 32E are straight slots of different lengths.

In these examples, the apertures 32 comprise multiple parallel first external apertures 32E that separately terminate at the first edge 18i of the perimeter 16 of the printed circuit board 10 and multiple parallel third external apertures 32E that separately terminate at the third edge 183 of the perimeter 16 of the printed circuit board 10. The first edge 181 opposes and is parallel to the third edge 18₃. Each first external aperture 32E opposes and is parallel to and aligned with a corresponding third external aperture 32E and each third external aperture 32E opposes and is parallel to and aligned with a corresponding first external aperture 32E.

The apertures 32 also comprise one or more second external apertures 32E that separately terminate at a second edge 18₂ of the perimeter 16 of the printed circuit board 10 and one or more fourth external apertures 32E that separately terminate at a fourth edge 18₄ of the perimeter 16 of the printed circuit board 10. The second edge 18₂ opposes and is parallel to the fourth edge 18₄. Each of the one or more second external apertures 32E opposes and is parallel to and aligned with a corresponding fourth external aperture 32E and each of the one or more fourth external apertures 32E opposes and is parallel to and aligned with a corresponding second external aperture 32_e.

The internal apertures 32i are straight slots having parallel sides. In these examples, but not necessarily all examples, the parallel sides have a length greater than five times a distance between the parallel sides. In these examples, the straight slots 32 are perpendicular to the first edge 18i and the third edge 1 83or parallel to the second edge 182 and the fourth edge 18₄. Those straight slots that are internal apertures 32i are perpendicular to the edge at which they terminate.

The first external apertures 32E and the third external apertures 32_E are shorter slots, that are parallel and regularly spaced. The internal apertures are 32i are longer slots, that are parallel and regularly spaced. The spacing between the first external apertures 32E (shorter slots), the third external apertures 32E (shorter slots) and the internal apertures 32i (longer slots) is the same, in the same direction. The internal apertures 32i (longer slots) are parallel to and partially overlap the first external apertures 32E (shorter slots) and the third external apertures 32E (shorter slots). The first external apertures 32E (shorter slots) and the third external apertures 32E (shorter slots) are aligned and they alternate with the internal apertures 32i (longer slots). The longer slots are not positioned at a mid-point between the shorter slots.

INTERNAL CROSSES

In the example illustrated in Fig 4, but not necessarily all examples, the apertures 32 comprise external apertures 32E that each separately terminate at one point on a perimeter 16 of the printed circuit board 10 and internal apertures 32i that do not terminate at the perimeter 16 of the printed circuit board 10. The internal apertures 32i and external apertures 32_E have different shapes.

In this example, the apertures 32 comprise multiple parallel first external apertures 32E that separately terminate at a first edge 18₁ of the perimeter 16 of the printed circuit board 1 0 and multiple parallel third external apertures 32_E that separately terminate at a third edge 18₃ of the perimeter 16 of the printed circuit board 10. The first edge 18₁ opposes and is parallel to the third edge 18₃. Each first external aperture 32E opposes and is parallel to and aligned with a corresponding third external aperture 32E and each third external aperture 32E opposes and is parallel to and aligned with a corresponding first external aperture 32E_. The apertures 32 also comprise multiple second external apertures 32E that separately terminate at a second edge 18₂ of the perimeter 16 of the printed circuit board 10 and multiple fourth external apertures 32E that separately terminate at a fourth edge 18₄ of the perimeter 16 of the printed circuit board 10. The second edge 18₂ opposes and is parallel to the fourth edge 18₄ and each of the second external apertures 32E opposes and is parallel to and aligned with a corresponding fourth external aperture 32E and each of the fourth external apertures 32E opposes and is parallel to and aligned with a corresponding second external aperture 32E_.

In this example, the spacing between the first and third external apertures 32E is the same as a spacing between the second and fourth external apertures 32E.

The internal apertures 32i are crosses formed by two crossed straight slots having parallel sides. The parallel sides have a length greater than two times a distance between the parallel sides.

In this example, but not necessarily all examples the internal apertures 32i are of equal size and, in this example, the internal apertures 32i have the same orientation.

In this example, but not necessarily all examples the internal apertures 32i are square crosses. A square-cross has perpendicular arms of equal length. In this example, but not necessarily all examples, one arm of each square-cross is parallel to the first edge 1 8i and the third edge 1 83 and the another arm is parallel to the second edge 1 82 and fourth edge 18₄.

The first external apertures 32E and the third external apertures 32_E are shorter slots, that are parallel and regularly spaced. The second external apertures 32E and the fourth external apertures 32_E are shorter slots, that are parallel and regularly spaced. The internal apertures 32i are crosses that are regularly spaced. The spacing between the first external apertures 32E (shorter slots), the second external apertures 32E (shorter slots), the third external apertures 32E (shorter slots), the fourth external apertures 32E (shorter slots) and the internal apertures are 32E (crosses) is the same. The internal apertures 32i (crosses) partially overlap the external apertures 32 (shorter slots). The first external apertures 32E (shorter slots) and the third external apertures 32E (shorter slots) are aligned and alternate with the internal apertures 32i (crosses). The second external apertures 32E (shorter slots) and the fourth external apertures 32E (shorter slots) are aligned and alternate with the internal apertures 32i (crosses). The crosses are positioned at a mid-point between the shorter slots. In this illustrated example, but not necessarily all examples, the external apertures 32E are arranged in a pattern that has rotational symmetry.

In this illustrated example, but not necessarily all examples, the internal apertures 32i are arranged in a pattern that has rotational symmetry.

In this illustrated example, but not necessarily all examples, the internal apertures 32i have a shape that has rotational symmetry.

STRESS RELIEF ELEMENT

In the example illustrated in Fig 5, 6, 7 & 8, but not necessarily all examples, the stress relief features 30 comprise a stress relief element 50 between the housing walls 22 and the printed circuit board 10. This may be described as a stress relief coupling or stress relief coupling element because it physically couples the housing walls 22 and the printed circuit board 10. In some but not necessarily all examples, the stress relief element is conductive.

In some but not necessarily all examples, the stress relief element 50 connects the housing walls 22 and a perimeter 16 of the printed circuit board 10. The stress relief element 50 can, in some examples, extend around the whole of a perimeter 16 of the printed circuit board 10.

The stress relief element 50 directly connects the housing walls and a perimeter 16 of the printed circuit board 10. There is no intermediary layer between stress relief element 50 and the perimeter 16 of the printed circuit board 10 except perhaps material used to join the stress relief element 50 and the perimeter 16 such as adhesive or solder.

In the examples illustrated in FIG 5, 6 & 7, the stress relief element 50 comprises multiple distinct supporting pins 52. The pins are distinct in that each pin is free- standing and separated from adjacent pins so that each pin can move independently of other pins. The pin height and width can be varied to achieve desired stress relief effects. In the example of FIG 7, the stress relief element 50 is a comb structure. It comprises a continuous part from which extends parallel pins 52. The continuous part is attached to the housing walls 22. The stress relief element 50 forms an interface strip attached to the housing wall before assembly with the PCB 10. After assembly, the interface strip is positioned at the perimeter 16 of the PCB 10.

The stress relief element 50 may, in some examples be soldered in place to the housing and/or the PCB 10.

In the example illustrated in FIG 7 the stress relief features 30 are part of the housing 20 before the PCB 10 is attached. Such an arrangement is also possible in other examples. The housing apparatus 20 consequently comprises: conductive housing walls 22 that a least partially enclose a cavity 24; and stress relief features 30 positioned where the conductive housing walls 22 attach to a printed circuit board 10. The combination of the conductive housing walls 22, the stress relief features 30 and the attached printed circuit board 10 creates an enclosed resonant cavity for a resonant cavity filter 100. The stress relief features 30 may be a stress relief element 50 as previously described with reference to FIGS 5, 6, 7 & 8. The stress relief element 50 extends from the housing wall 22 and is configured for attaching the housing walls 22 to the printed circuit board 10.

The printed circuit board 10 comprises: at least one conductive substrate; at least one user tunable device 14 (not illustrated) for tuning a resonant cavity filter 100, formed by attaching the printed circuit board 10 to the conductive housing walls 22, that at least partially enclose a cavity 24. This combination of PCB 10 and housing 22 including the stress relief features 30, creates an enclosed resonant cavity 24 for the resonant cavity filter 100. The at least one user tunable device 14 is configured to be varied by a user to tune the resonant cavity filter 100. Stress relief features 30 may additionally be defined by apertures 32 in a substrate of the printed circuit board 10 as previously described (see FIG 8, for example).

The stress relief features 30 in the previously described examples of FIGs 1 to 8, reduce the adverse effects arising from different coefficients of thermal expansion between the housing 20 and PCB 10. The stress relied features 30 enable the printed circuit board 10 to be used as a filter cover and enables a new type of housing with printed circuit board 10 as cover, and a new type of printed circuit board 10.

In some, but not necessarily all previously described examples, the PCB 10 can be attached to the housing using solder paste. The combination of the PCB 10 and housing 20 with stress relief features 30 is fused together using the solder paste in a reflow chamber, which may be at a temperature greater than 200°C. The solder, the PCB 10 and housing 20, and in some circumstances the stress relief features 30, form a resonant cavity filter 100 having an homogeneous conductive enclosure of the resonant cavity 24. The stress relief features 30 prevents excessive stress developing in the PCB 10, as a consequence of different coefficients of thermal expansion, as the resonant cavity filter 100 cools.

In the example illustrated in FIG 9, the resonant cavity filter 100 as previously described, is a part of a base transceiver station 200. The filter is low cost and low mass.

The cavity filter 100 may, for example, operate as a diplexer or triplexer.

The cavity filter 100 may, for example, provide components of a passive or active antenna system. An active antenna is an antenna that contains active electronic components such as transistors. These may be provided by the PCB 10.

In the preceding examples a cavity filter 100 was created by combining a housing 20 and a PCB 10, while using stress relief features 30 to control stress. However, in other examples a different frequency selective radio-frequency component 100 may be created, such as an antenna.

The frequency selective radio-frequency apparatus 100 comprises: a conductive component 20; a printed circuit board 10 adjacent the conductive component 20; and stress relief features 30 at an interface between the conductive component 20 and the printed circuit board 10, wherein the combination of at least the conductive component 20 and the printed circuit board 10 creates a conductive portion of the frequency selective radio-frequency apparatus 100. In some examples, but not necessarily all examples, the conductive component of the frequency selective radio-frequency apparatus comprises before attachment to the PCB 10: conductive stress relief element 50 positioned where the conductive component 20 attaches to a printed circuit board 10, wherein the combination of the conductive stress relief element 50, the conductive component 20 and the attached printed circuit board 10 creates a conductive portion of the frequency selective radio- frequency apparatus 100.

In some examples, but not necessarily all examples, the printed circuit board 10 for use in a frequency selective radio-frequency apparatus 100 comprises: at least one conductive substrate 12; at least one user tunable device 14 for tuning a frequency selective radio frequency apparatus 100 formed by attaching the printed circuit board 10 to a conductive component 20 of the frequency selective radio-frequency apparatus 100 to form a conductive portion of the frequency selective radio-frequency apparatus 100, wherein the at least one user tunable device 14 is configured to be varied by a user to control an electrical impedance associated with the conductive portion.

As used in this application, the term‘circuitry’ may refer to one or more or all of the following:

(a) hardware-only circuitry implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable):

(i) a combination of analog and/or digital hardware circuit(s) with software/firmware and

(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions and

(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g. firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit for a mobile apparatus or a similar integrated circuit in a server, a cellular network apparatus, or other computing or network apparatus.

Where a structural feature has been described, it may be replaced by means for performing one or more of the functions of the structural feature whether that function or those functions are explicitly or implicitly described.

The frequency selectivity of frequency selective radio-frequency apparatus 100 means that it is configured to operate in one or more of a plurality of operational resonant frequency bands. For example, the operational frequency bands may include (but are not limited to) Long Term Evolution (LTE) (US) (734 to 746 MHz and 869 to 894 MHz), Long Term Evolution (LTE) (rest of the world) (791 to 821 MHz and 925 to 960 MHz), amplitude modulation (AM) radio (0.535-1.705 MHz); frequency modulation (FM) radio (76-108 MHz); Bluetooth (2400-2483.5 MHz); wireless local area network (WLAN) (2400-2483.5 MHz); hiper local area network (HiperLAN) (5150-5850 MHz); global positioning system (GPS) (1570.42-1580.42 MHz); US - Global system for mobile communications (US-GSM) 850 (824-894 MHz) and 1900 (1850 - 1990 MHz); European global system for mobile communications (EGSM) 900 (880-960 MHz) and 1800 (1710 - 1880 MHz); European wideband code division multiple access (EU- WCDMA) 900 (880-960 MHz); personal communications network (PCN/DCS) 1800 (1710-1880 MHz); US wideband code division multiple access (US-WCDMA) 1700 (transmit: 1710 to 1755 MHz , receive: 21 10 to 2155 MHz) and 1900 (1850-1990 MHz); wideband code division multiple access (WCDMA) 2100 (transmit: 1920-1980 MHz, receive: 21 10-2180 MHz); personal communications service (PCS) 1900 (1850-1990 MHz); time division synchronous code division multiple access (TD-SCDMA) (1900 MHz to 1920 MHz, 2010 MHz to 2025 MHz), ultra wideband (UWB) Lower (3100-4900 MHz); UWB Upper (6000-10600 MHz); digital video broadcasting - handheld (DVB-H) (470-702 MHz); DVB-H US (1670-1675 MHz); digital radio mondiale (DRM) (0.15-30 MHz); worldwide interoperability for microwave access (WiMax) (2300-2400 MHz, 2305-2360 MHz, 2496-2690 MHz, 3300-3400 MHz, 3400-3800 MHz, 5250-5875 MHz); digital audio broadcasting (DAB) (174.928-239.2 MHz, 1452.96- 1490.62 MHz); radio frequency identification low frequency (RFID LF) (0.125-0.134 MHz); radio frequency identification high frequency (RFID HF) (13.56-13.56 MHz); radio frequency identification ultra high frequency (RFID UHF) (433 MHz, 865-956 MHz, 2450 MHz).

An operational frequency band is a frequency range over which an antenna can efficiently operate. It may be defined as a frequency range where the antenna’s return loss (reflection coefficient) is less than an operational threshold dependent upon application.

The term ‘comprise’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising Y indicates that X may comprise only one Y or may comprise more than one Y. If it is intended to use‘comprise’ with an exclusive meaning then it will be made clear in the context by referring to“comprising only one” or by using“consisting”.

In this description, reference has been made to various examples. The description of features or functions in relation to an example indicates that those features or functions are present in that example. The use of the term‘example’ or‘for example’ or‘can’ or ‘may’ in the text denotes, whether explicitly stated or not, that such features or functions are present in at least the described example, whether described as an example or not, and that they can be, but are not necessarily, present in some of or all other examples. Thus‘example’, ‘for example’, ‘can’ or‘may’ refers to a particular instance in a class of examples. A property of the instance can be a property of only that instance or a property of the class or a property of a sub-class of the class that includes some but not all of the instances in the class. It is therefore implicitly disclosed that a feature described with reference to one example but not with reference to another example, can where possible be used in that other example as part of a working combination but does not necessarily have to be used in that other example.

Although embodiments have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the claims.

Features described in the preceding description may be used in combinations other than the combinations explicitly described above. Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

The term ‘a’ or‘the’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising a/the Y indicates that X may comprise only one Y or may comprise more than one Y unless the context clearly indicates the contrary. If it is intended to use‘a’ or‘the’ with an exclusive meaning then it will be made clear in the context. In some circumstances the use of ‘at least one’ or‘one or more’ may be used to emphasis an inclusive meaning but the absence of these terms should not be taken to infer and exclusive meaning.

The presence of a feature (or combination of features) in a claim is a reference to that feature) or combination of features) itself and also to features that achieve substantially the same technical effect (equivalent features). The equivalent features include, for example, features that are variants and achieve substantially the same result in substantially the same way. The equivalent features include, for example, features that perform substantially the same function, in substantially the same way to achieve substantially the same result.

In this description, reference has been made to various examples using adjectives or adjectival phrases to describe characteristics of the examples. Such a description of a characteristic in relation to an example indicates that the characteristic is present in some examples exactly as described and is present in other examples substantially as described.

The use of the term‘example’ or‘for example’ or‘can’ or‘may’ in the text denotes, whether explicitly stated or not, that such features or functions are present in at least the described example, whether described as an example or not, and that they can be, but are not necessarily, present in some of or all other examples. Thus‘example’,‘for example’, ‘can’ or‘may’ refers to a particular instance in a class of examples. A property of the instance can be a property of only that instance or a property of the class or a property of a sub-class of the class that includes some but not all of the instances in the class. It is therefore implicitly disclosed that a feature described with reference to one example but not with reference to another example, can where possible be used in that other example as part of a working combination but does not necessarily have to be used in that other example

Whilst endeavoring in the foregoing specification to draw attention to those features believed to be of importance it should be understood that the Applicant may seek protection via the claims in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not emphasis has been placed thereon.

I/we claim:

Claims

1 . An apparatus comprising:

2. An apparatus as claimed in claim 1 , wherein the stress relief features are configured to deform to absorb stress.

3. An apparatus as claimed in claim 1 or 2, wherein the stress relief features provide distinct connection paths between the printed circuit board and the conductive housing walls and enable relative movement of the connection paths.

4. An apparatus as claimed in any preceding claim, wherein the stress relief features are defined by apertures in a substrate of the printed circuit board.

5. An apparatus as claimed in claim 4, wherein some or all of the apertures are through-apertures that extend through the substrate and/or or wherein some or all of the apertures are notches that do not extend through the substrate.

6. An apparatus as claimed in any of claims 4 or 5, wherein the apertures comprise external apertures that each separately terminate at one point on a perimeter of the printed circuit board and/or wherein the apertures comprise internal apertures that do not terminate at the perimeter of the printed circuit board.

7. An apparatus as claimed in claim 6, wherein the external apertures are straight slots having parallel sides, the parallel sides having a length greater than a distance between the parallel sides.

8. An apparatus as claimed in of claims 4 to 7, comprising multiple parallel first external apertures at a first edge of a perimeter of the printed circuit board and multiple parallel third external apertures at a third edge of the perimeter of the printed circuit board, wherein the first edge opposes the third edge and wherein each first external aperture opposes a corresponding third external aperture and each third external aperture opposes a corresponding first external aperture.

9. An apparatus as claimed in claims 6 to 8 wherein the internal apertures extend so that they overlap external apertures close to a perimeter of the printed circuit board.

10. An apparatus as claimed in any of claims 4 to 9, wherein the apertures comprise external apertures that each separately terminate at one point on a perimeter of the printed circuit board and internal apertures that do not terminate at the perimeter of the printed circuit board, wherein the internal apertures and external apertures are straight slots of different lengths.

1 1 . An apparatus as claimed in any of claims 4 to 10, wherein the apertures comprise comprising multiple parallel first external apertures that separately terminate at a first edge of a perimeter of the printed circuit board and multiple parallel third external apertures that separately terminate at a third edge of the perimeter of the printed circuit board, wherein the first edge opposes the third edge and each first external aperture opposes a corresponding third external aperture and each third external aperture opposes a corresponding first external aperture;

comprising one or more second external apertures that separately terminate at a second edge of the perimeter of the printed circuit board and one or more fourth external apertures that separately terminate at a fourth edge of the perimeter of the printed circuit board, wherein the second edge opposes the fourth edge and each of the one or more second external apertures opposes and is parallel to a corresponding fourth external aperture and each of the one or more fourth external apertures opposes and is parallel to a corresponding second external aperture.

12. An apparatus as claimed in claim 10 or 1 1 , wherein the internal apertures are straight slots having parallel sides, the parallel sides having a length greater than a distance between the parallel sides.

13. An apparatus as claimed in any of claims 4 to 9, wherein the apertures comprise external apertures that each separately terminate at one point on a perimeter of the printed circuit board and internal apertures that do not terminate at the perimeter of the printed circuit board, wherein the internal apertures and external apertures have different shapes.

14. An apparatus as claimed in any of claims 4 to 9, 13 wherein the apertures comprise internal apertures that do not terminate at a perimeter of the printed circuit board, wherein the internal apertures are crosses formed by two crossed straight slots having parallel sides.

15. An apparatus as claimed in any preceding claim, wherein the stress relief features comprise a stress relief element between the housing walls and the printed circuit board.

16. An apparatus as claimed in claim 15, wherein the stress relief element comprises multiple distinct supporting pins.

17. An apparatus as claimed in claim 15 or 16, wherein the stress relief element is conductive.

18. An apparatus as claimed in any of claims 15 to 17, wherein the stress relief element extends around the whole of a perimeter of the printed circuit board.

19. An apparatus comprising:

conductive housing walls that a least partially enclose a cavity;

20. An apparatus as claimed in any preceding claim, wherein the stress relief features comprise a stress relief element for attaching the housing walls to the printed circuit board.