A multi-layer antenna arrangement is provided that includes a first layer having a conductive radiating element configured to have multiple overlapping resonant modes that define a first frequency range. The multi-layer antenna arrangement also includes a second layer having at least a portion of a ground plane for the conductive radiating element. The multi-layer antenna arrangement additionally includes a third layer, between the first layer and the second layer, that has a conductive resonator configured to provide a stop band within the first frequency range.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to European Application No. 19172157.0, filed May 2, 2019, the entire contents of which are incorporated herein by reference.

TECHNOLOGICAL FIELD

Embodiments of the present invention relate to a multi-band antenna arrangement. Some embodiments of the present disclosure relate to a multi-band antenna arrangement suitable for use in 5G telecommunications.

BACKGROUND

Telecommunication standards specify operational frequency bands. It is therefore desirable for a transceiver to be multi-band and operate in multiple different operational frequency bands.

While, in some examples, it may be possible to use an antenna arrangement that has a single wide operational bandwidth that covers simultaneously multiple different operational frequency bands, this can be undesirable as there can then be insufficient isolation between communications in the different operational frequency bands causing interference.

BRIEF SUMMARY

According to various, but not necessarily all, embodiments there is provided multi-layer antenna arrangement comprising: a first layer comprising a conductive radiating element configured to have multiple overlapping resonant modes that define a first frequency range; a second layer comprising at least a portion of a ground plane for the conductive radiating element; and a third layer, between the first layer and the second layer, comprising a conductive resonator configured to provide a stop band within the first frequency range.

In some but not necessarily all examples, the first, second and third layers are integrated as a single component.

In some but not necessarily all examples, the first frequency range is greater than 24 GHz.

In some but not necessarily all examples, the conductive radiating element is a slotted patch antenna.

In some but not necessarily all examples, a fundamental dipole mode of the slotted patch antenna is responsible for a first resonance mode and two slot modes are responsible for a second and a third resonance mode, wherein a length of the conductive radiating element determines the fundamental dipole mode.

In some but not necessarily all examples, the conductive radiating element comprises stepped straight slots, each slot comprising a thinner straight central section and a wider straight peripheral section.

In some but not necessarily all examples, a total length of each slot determines a second one of the multiple resonant modes.

In some but not necessarily all examples, dimensions of the wider straight peripheral portion determine a third one of the multiple resonant modes.

In some but not necessarily all examples, the resonator, in the third layer, is configured to operate as a reflector for stop band frequencies.

In some but not necessarily all examples, the conductive resonator comprises multiple microstrip resonators, placed under respective slots of the conductive radiating element.

In some but not necessarily all examples, the microstrip resonators are curved.

In some but not necessarily all examples, the multi-layer antenna arrangement comprises a symmetrical crossed slot arrangement in the conductive radiating element.

In some but not necessarily all examples, the second layer is a lifted ground plane to enhance the gain in higher frequency bands and the multi-layer antenna arrangement further comprises a fourth layer, below the second layer comprising a main ground plane for the conductive radiating element.

In some but not necessarily all examples, the multi-layer antenna arrangement is directly connected to amplification circuitry without an intervening bandstop filter component.

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

DETAILED DESCRIPTION

FIG. 1illustrates an example of a multi-layer antenna arrangement10. As illustrated inFIG. 2C, the multi-layer antenna arrangement10is a multi-band antenna that has two isolated resonant modes721,722. Each resonant mode721,722has an associated operational frequency band.

The multi-layer antenna arrangement10comprises a first layer L1comprising a conductive radiating element20configured to have multiple overlapping resonant modes52that define a first frequency range F; a second layer L2comprising at least a portion of a ground plane40for the conductive radiating element20; and a third layer L3, between the first layer L2and the second layer L2, comprising a conductive resonator30configured to provide a stop band S within the first frequency range F.

FIG. 2Aschematically illustrates a frequency response50of the reflection parameter S11for each of the multiple overlapping resonant modes52. In this example, the conductive radiating element20is configured to have multiple overlapping resonant modes521,522,523.

Each of the resonant modes521,522,523of the conductive radiating element20has an associated operational frequency band. The associated operational frequency bands of the multiple resonant modes52overlap.

The overlap is sufficient to define a combined operational frequency band, as illustrated inFIG. 2B, that has a bandwidth equal to the first frequency range F.

As illustrated inFIG. 2B, the conductive resonator30is configured to have a frequency response62that provides a stop band S within the first frequency range F.

FIG. 2Cillustrates a frequency response70of the reflection parameter S11for the combination of the conductive radiating element20and the conductive resonator30in the multi-layer antenna arrangement10.

The frequency response70has a first operational band721and a second operational band722that are isolated by a stop band S. The reflection parameter S11is less than a threshold value T in the first operational band721and the second operational band722and is more than a threshold value T in the stop band S. The stop band S splits the first frequency range F into two distinct operational frequency bands721,722. The stop band S reduces cross-talk (interference) between the operational frequency bands721,722.

As illustrated inFIG. 3, in some, but not necessarily all examples, the multi-layer antenna arrangement10is a single integrated component100. The first layer L1comprising the conductive radiating element20, the second layer L2comprising at least a portion of the ground plane40and the third layer L3comprising the conductive resonator30are each integrated within the single component100. In this example, dielectric material102interconnects the first layer L1and the third layer L3and dielectric material102interconnects the third layer L3and the second layer L2. The dielectric material may be any suitable dielectric material, in some but not necessarily all examples it can be a solid dielectric material. The third layer L3is embedded within the component100.

The dielectric material102between the first layer L1and the third layer L3and/or the dielectric material102between the third layer L3and the second layer L2could be “mostly air” with physically small (relative to the area between L1/L3or L2/L3) pillars between each layer used for mechanical support. Such supports will have a much smaller effect on the dielectric constant.

One or more of the layers L1, L2could be supported by a dielectric layer below L2or above L1leaving mostly air between L1& L3and/or between L3& L2. In this case small pillars could be used again to support L3relative to either L1and/or L2.

FIG. 4illustrates an example of a first layer L1of the multi-layer antenna arrangement10. The first layer L1comprises the conductive radiating element20. The conductive radiating element20is configured to have multiple overlapping resonant modes52that define a first frequency range F.

In this example, but not necessarily all examples, the conductive radiating element20is a slotted patch antenna22. A slotted patch antenna22is a patch24that comprises slots23. The patch24is formed from a continuous portion of conductive material and is typically a planar two-dimensional conductive sheet. The slots23are areas within the patch24where the conductive material has been removed or is not present.

A fundamental dipole mode of the slotted patch antenna22is responsible for a first resonance mode521and two slot modes are responsible for a second resonance mode522and a third resonance mode523. A length L* of the conductive radiating element20determines the fundamental dipole mode. The resonant wavelength for a fundamental dipole mode is twice the electrical length equivalent to the physical length L*.

In this example, but not necessarily all examples, the conductive radiating element20comprises stepped straight slots23. Each stepped straight slot23comprises a thinner straight central section25and a step to a wider straight peripheral section27.

In the example illustrated, a first slot231and a second slot232are joined. The first slot231and the second slot232both extend along an axis of symmetry AA of the slotted patch antenna22. The slotted patch antenna22has reflection symmetry in the line AA, in this example.

The first slot231comprises a thinner straight central section251and a wider straight peripheral section271. Both the thinner straight central section251and the wider straight peripheral section271have reflection symmetry in the line AA. The total length of the first slot231is L1*. The thinner straight central section251has a length L2* and a width W2. The wider peripheral section271has a length L3*=L1*−L2* and a width W3.

The second slot232comprises a thinner straight central section252and a wider straight peripheral section272. Both the thinner straight central section252and the wider strip peripheral section272have reflection symmetry in the line AA. The thinner straight central section252of the second slot232is interconnected to the thinner straight central section251of the first slot231. The second slot232has a total length L1*. The thinner straight central section252has a length L2* and a width W2. The wider peripheral section272has a length L3*=L1*−L2* and a width W3.

The total length L1* of each slot23determines a second one522of the multiple resonant modes52. The resonant wavelength for the second resonant mode522is twice the electrical length equivalent to the physical length L1*.

The dimensions, for example the length L3* and width W3of the wider straight peripheral section27, determine a third one523of the multiple resonant modes52.

FIG. 5illustrates an example of the conductive resonator30in the third layer L3. The conductive resonator30is configured to provide a stop band S within the first frequency range F. The conductive resonator30in the third layer L3can be a conductive element32within a dielectric (or a dielectric slot in a conductive element, according to Babinet's principle). The conductive resonator30in the third layer L3can be a planar, two-dimensional conductive resonator30.

In the example illustrated, but not necessarily all examples, the conductive element32is configured to operate as a reflector for the stop band frequencies S.

In this example, but not necessarily all examples, the conductive resonator30comprises multiple micro strip resonators32nplaced under respective slots27nof the conductive radiating element20. Each resonator32ncan be placed under any part of the respective slot27n, for example, each resonator32ncan be placed under a widest portion of the respective slot27n.

In this example, but not necessarily all examples, the micro strip resonators32are elongate, that is narrower than they are long, and curved, that is not-straight.

FIG. 6illustrates another example of a multi-layer antenna arrangement10. The previous description of multi-layer antenna arrangement10and components of such an arrangement10is also relevant to this example.

The multi-layer antenna arrangement10comprises a first layer L1comprising a conductive radiating element20configured to have multiple overlapping resonant modes52(seeFIG. 8A) that define a first frequency range F; a second layer L2comprising at least a portion of a ground plane40for the conductive radiating element20; and a third layer L3, between the first layer L1and the second layer L2, comprising a conductive resonator30configured to provide a stop band S within the first frequency range F (seeFIG. 8A).

In this example, the ground plane40comprises two parts40A,40B. The second layer L2comprises a lifted ground plane40A to enhance the gain in higher frequency bands and the multi-layer antenna arrangement10further comprises a fourth layer L4, below the second layer L2, comprising a main ground plane40B for the conductive radiating element20. The ground plane40for the conductive radiating element20is therefore a split ground plane comprising non-overlapping portions40A,40B. The portion40A directly under the conductive radiating element20is lifted so that the gap between the conductive radiating element20and the ground plane40is less directly under the conductive radiating element20than outside the perimeter of the conductive radiating element20.

The multi-layer antenna arrangement10additionally comprises a fifth layer L5comprising a feed lines42and a sixth layer L6comprising a ground44for the feed lines42. The fourth layer L4is directly under but separated from the second layer L2and the fifth layer L5is between and separated from the fourth layer L4and the sixth layer L6.

FIGS. 7A, 7B, 7C and 7Dillustrate examples of the first layer L1, the third layer L3, the second layer L2and the fifth layer L5respectively. Referring toFIG. 7A, the conductive radiating element20is a planar slotted patch antenna22. The conductive radiating element20comprises a symmetrical crossed-slot arrangement within the conductive radiating element20. The symmetrical crossed-slot arrangement is comprised of two stepped straight slots23as described in relation toFIG. 4that are orthogonal to each other and overlap.

The crossed-slot arrangement comprises a first slot231, a second slot232, a third slot233and a fourth slot234. The first slot231and the second slot232are aligned along a first line. The third slot233and the fourth slot234are aligned along a second line, that is orthogonal to the first line. The crossed-slot arrangement enables two orthogonal polarizations for the multi-layer antenna arrangement10.

Each stepped straight slot23comprises a thinner straight central section25and a step to a wider straight peripheral section27.

In the example illustrated, a first slot231, a second slot232, a third slot233and a fourth slot234are joined to form a cross. The first slot231and the second slot232both extend along the first direction which is an axis of symmetry of the slotted patch antenna22. The slotted patch antenna22has reflection symmetry in the first direction, in this example. The third slot233and the fourth slot234both extend along the second direction which is another axis of symmetry of the slotted patch antenna22. The slotted patch antenna22has reflection symmetry in the second direction, in this example. The second direction is orthogonal to the first direction.

The first slot231comprises a thinner straight central section251and a wider straight peripheral section271. Both the thinner straight central section251and the wider straight peripheral section272have reflection symmetry in the first line. The total length of the first slot231is L1*. The thinner straight central section251has a length L2* and a width W2. The wider peripheral section271has a length L3*=L1*−L2* and a width W3.

The second slot232comprises a thinner straight central section252and a wider straight peripheral section272. Both the thinner straight central section252and the wider strip peripheral section272have reflection symmetry in the first line. The thinner straight central section252of the second slot232is interconnected to the thinner straight central section251of the first slot231. The second slot232has a total length L1*. The thinner straight central section252has a length L2* and a width W2. The wider peripheral section272has a length L3*=L1*−L2* and a width W3.

The third slot233comprises a thinner straight central section253and a wider straight peripheral section273. Both the thinner straight central section253and the wider straight peripheral section273have reflection symmetry in the second line. The total length of the third slot233is L1*. The thinner straight central section253has a length L2* and a width W2. The wider peripheral section27has a length L3*=L1*−L2* and a width W3.

The fourth slot234comprises a thinner straight central section254and a wider straight peripheral section274. Both the thinner straight central section254and the wider strip peripheral section274have reflection symmetry in the second line. The thinner straight central section254of the fourth slot234is interconnected to the thinner straight central section254of the third slot233. The fourth slot234has a total length L1*. The thinner straight central section254has a length L2* and a width W2. The wider peripheral section274has a length L3*=L1*−L2* and a width W3.

The planar conductive radiating element20has 90° rotational symmetry within the plane of the first layer L1.

The conductive radiating element20is a slotted patch antenna22that has directional gain. The conductive radiating element20is planar.

The patch24of the planar conductive radiating element20is fed via feed lines35. The feed lines35are vertically arranged and extend through the second layer L2and the third layer L3and to contact the patch24of the planar conductive radiating element20. The lifted ground portion40A in the second layer L2comprises apertures41through which the vertical feed lines35extend (seeFIG. 7C). In this example, the vertical feed lines35make galvanic contact with the patch24of the planar conductive radiating element20.

The conductive resonator30in the third layer L3, is illustrated inFIG. 7B. In this example, the conductive resonator30comprises multiple elongate conductive elements32each of which is a microstrip resonator. Each microstrip resonator32nis placed under a respective slot27nof the planar conductive radiating element20. The microstrip resonators32are curved in that they are not a straight line. They have a cruciform form. Each elongate conductive element32traces a substantial portion of a perimeter of a cross. The shape could also be described as a meandering form, series-connected C-shaped or U-shaped conductive portions.

The conductive resonator30, in the third layer L3, is configured to operate as a reflector for stop band frequencies S. The resonator30represents an impedance discontinuity/mismatch for propagating currents at the stop band frequency. The propagating current is reflected back from the location of the resonator30in the arrangement10. This can be considered to be an impedance mismatch at the antenna input port.

The conductive resonator30operates as a band stop filter integrated within the arrangement10. The total length of the resonator30determines the center frequency of the band notch filter. The width of the resonator30, the distance between the patch22and the resonator30and the location of the resonator30under the slot23(along the slot end) together define a width of the stop band S.

FIG. 7Cillustrates an example of a lifted ground plane40A in the second layer L2. The lifted ground plane40A is configured to enhance the gain in higher frequency bands. The lifted ground plane enhances the gain in the higher frequencies so that the gain over both of the operational frequency bands721,722will be flat (seeFIG. 8B).

FIG. 7Dillustrates an example of feed lines42which are mounted over a ground44for the feed lines42. The illustrated horizontal feed lines42interconnect with the vertically extending feed lines35also illustrated in theFIG. 7D. The feed lines42/35are used to differentially feed the slotted patch antenna22. A differential feed arrangement is one in which a structure is excited by two signals which have the same amplitude but a 180° difference in phase. Thus, the feed signal is fed to a position intermediate of the first slot231and the third slot233is 180° out of phase with the signal fed to a position intermediate of the second slot232and the fourth slot234. Likewise, a signal that is fed to a position intermediate of the first slot231and the fourth slot234is 180° out of phase with the signal fed to the position intermediate of the second slot232and the third slot233.

The multi-layer antenna arrangement10may be formed as a single component in which the multiple layers L1to L6are integrated within the single component. In some, but not necessarily all examples, the different layers may be separated using dielectric material.

FIG. 8Aschematically illustrates a frequency response50of the reflection parameter S11associated with the conductive radiating element20(without the conductive resonator30) and a frequency response70of the reflection parameter S11associated with the conductive radiating element20(with the conductive resonator30). The frequency response70of the reflection parameter S11is the frequency response of the multi-layer antenna arrangement10.

The conductive radiating element20is configured to have multiple overlapping resonant modes521,522,523. Each of the resonant modes521,522523of the conductive radiating element20has an associated operational frequency band. The associated operational frequency bands of the multiple resonant modes52overlap and the overlap is sufficient to define a combined operational frequency band, as illustrated inFIG. 8A, that has a bandwidth equal to the first frequency range F.

The conductive resonator30is configured to have a frequency response that provides a stop band S within the first frequency range F.

The frequency response70has a first operational band721and a second operational band722that are isolated by the stop band S. The reflection parameter S11is less than a threshold value T in the first operational band721and the second operational band722and is more than a threshold value T in the stop band S. The stop band S splits the first frequency range F into two distinct operational frequency bands721,722. The stop band S reduces cross-talk (interference) between the operational frequency bands721,722.

As previously described, the first layer L1comprising a conductive radiating element20is configured to have multiple overlapping resonant modes52that define a first frequency range F. The third layer L3, between the first layer L1and the second layer L2, comprises a conductive resonator30configured to provide a stop band S within the frequency range F.

The frequency selective attenuation provided by the conductive resonator30in the third layer L3can be observed fromFIG. 8B.

FIG. 9Aschematically illustrates a frequency response50of the reflection parameter S11associated with the conductive radiating element20(without the conductive resonator30) andFIG. 9Bschematically illustrates a frequency response70of the reflection parameter S11associated with the conductive radiating element20(with the conductive resonator30). The frequency response70of the reflection parameter S11is the frequency response of the multi-layer antenna arrangement10.

As can be observed fromFIG. 9A, a fundamental dipole mode of the slotted patch antenna22is responsible for a first resonance mode521and two slot modes are responsible for a second resonance mode522and a third resonance mode523.

A length L* of the conductive radiating element20determines the fundamental dipole mode that provides the first resonance mode521. The resonant wavelength for the first resonant mode521is twice the electrical length equivalent to the physical length L*.

A width and length of the stepped slots23determine the second resonant mode522and the third resonant mode523.

The total length L1* of each slot23determines a second one522of the multiple resonant modes52. The resonant wavelength for the second resonant mode522is twice the electrical length equivalent to the physical length L1*.

The dimensions L3*, W3of the wider strip peripheral section27of the slot23determine a third one523of the multiple resonant modes52. The wider strip peripheral section27operates as a λ/4 resonator. The resonant wavelength for the second resonant mode521is four times the electrical length equivalent to the physical length L3*.

In this example, the first frequency range F is greater than 24 GHz. For example, the first frequency range can be within 24 to 86 GHz.

InFIG. 9B, if the operational bandwidth is defined by a threshold −10 dB for the reflection parameter S11, the first operational band721is 24.25 to 29.5 GHz and the second operational band722is 37 to 40 GHz.

FIG. 10illustrates an example of a transceiver system200comprising the multi-layer antenna arrangement10. The transceiver system comprises a receiver system and a transmitter system. In this example, the multi-layer antenna arrangement10is directly connected to amplification circuitry202without an intervening band stop filter component. The absence of the band stop filter component is indicated by reference206in the receiver system and the transmitter system.

The transceiver system200may be used in a base station or a mobile station. It may, for example, be suitable for use in 5G telecommunications.

In a receiver only implementation, the receiver system is present but the transmitter system is not. In a transmitter only implementation, the transmitter system is present but the receiver system is not.

The transceiver system200and/or the multi-layer antenna arrangement10have several advantages including compact size, good inter-band rejection, a constant radiation pattern shape for dual band and dual polarization, flat gain performance over desired operation bands, ease of fabrication and freedom of resonator design by adjusting the geometry of four individual resonators32.

In each of the preceding examples, the first slot231and the second slot232or the first slot231, the second slot232, the third slot233and the fourth slot234can each comprise a thinner straight central section251, a wider straight intermediate section and an even wider straight peripheral section271. The thinner straight central section251, the wider straight intermediate section and the even wider straight peripheral section have reflection symmetry in the first line. The total length of the first slot231is L1*. The thinner straight central section251has a length L2* and a width W2.

In each of the preceding examples, additional conductive layers may be present forming a stacked patch configuration.

An operational resonant mode (operational band or bandwidth) is a frequency range over which an antenna can efficiently operate. An operational resonant mode (operational band) may be defined as where the absolute value of the return loss S11of the antenna arrangement is greater than an operational threshold T.

As used here ‘module’ refers to a unit or apparatus that excludes certain parts/components that would be added by an end manufacturer or a user. The antenna arrangement10can be a module.

The above described examples find application as enabling components of: automotive systems; telecommunication systems; electronic systems including consumer electronic products; distributed computing systems; media systems for generating or rendering media content including audio, visual and audio visual content and mixed, mediated, virtual and/or augmented reality; personal systems including personal health systems or personal fitness systems; navigation systems; user interfaces also known as human machine interfaces; networks including cellular, non-cellular, and optical networks; ad-hoc networks; the internet; the internet of things; virtualized networks; and related software and services.