An antenna with a multi-layer radiator compring an interposed mathcing element

Abstract

This disclosure provides an antenna, for example, for a base station. The antenna comprises a first radiator and a second radiator of different types, wherein the second radiator is a dual-layer or multi-layer radiator. The disclosure is concerned with making the second radiator transparent to the radiation of the first radiator. The antenna comprises a reflector on which the first and the second radiator are arranged. The first radiator radiates EM waves in a first frequency band, and the second radiator in a second frequency band. The second radiator comprises a matching element arranged between a first and a second radiating element of the second radiator. The matching element is configured to establish a predetermined phase relationship between EM waves of the first radiator scattered by the first radiating element and EM waves of the first radiator scattered by the second radiating element.

Description

[0001] AN ANTENNA WITH A MULTI-LAYER RADIATOR COMPRING AN INTERPOSED M ATHCING ELEMENT

[0002] TECHNICAL FIELD

[0003] The present disclosure provides an antenna, for example, for a base station. The disclosure relates to a scenario, wherein the antenna comprises a first radiator and a second radiator of different types, wherein the second radiator is a dual-layer or multilayer radiator. The disclosure is concerned with making the second radiator transparent to the radiation of the first radiator.

[0004] BACKGROUND

[0005] With the growing demand for a higher integration of antennas with radios, e.g. active antenna systems (AAS), new ways of extending the bandwidth of low profile antennas are needed, without compromising antenna key performance indicators (KPIs). A way to tackle this is to integrate a higher number of antenna arrays in the same enclosure. This integration leads to highly complex systems, and strongly influences the antenna form factor, which is fundamental for commercial field deployment.

[0006] However, the integration usually comes at a cost. Placing together different radiators working at different frequency bands in a small space implies a high level of coupling between the radiators, which may degrade the signal quality of the antenna. Improving the transparency between the radiators for the different frequency bands would lead to an improvement of the antenna radiation pattern shape, and would reduce the intra-system interference.

[0007] To cover the standard operating bands in modem base station antenna systems, while maintaining the same RF performance and with radiators that can be easily integrated with other components, new concepts and / or architectures different from the legacy technology are desired.

[0008] SUMMARY

[0009] The present disclosure and its solutions are further based on the following considerations.

[0010] As shown in FIG. 1, an exemplary antenna 100 with different types of radiators may comprise a first radiator 101, which is configured to radiate electromagnetic (EM) waves in a first frequency band, and a second radiator 102. The second radiator 102 - which is referred to as a dual-layer or multi-layer radiator - comprises at least two radiating elements, namely a first radiating element 103 and a second radiating element 104, which are arranged on a common axis C. Each of these radiating elements 103, 104 is configured to radiate a radio wave in a second frequency band.

[0011] In this exemplary antenna 100, one or more first radiators 101 may be integrated with one or more second radiators 102, for example, in the same enclosure or with a shared reflector as in FIG. 1. However, the second radiators 102 - which are typically low-band (LB) radiators - suffer from an interaction with the first radiators 101 - which are typically high-band (HB) radiators - when employed, for example, in an interleaved configuration. This interaction manifests itself in form of pattern distortion of the radiation of the first radiators 101 for specific frequencies, and is caused by the EM waves of the first radiator 101 being scattered by the first radiating element 103 and the second radiating element 104, and the interference of the scattered EM waves with each other and with the non-scattered EM waves emanating from the first radiator 101.

[0012] For example, in an assembly of multiple HB radiators placed next to multiple LB radiators in an interleaved manner, given the footprint of the LB radiators, the two radiating elements of the LB radiators inevitably protrude into regions of space above the HB radiators. For specific frequency bands, the radiation patterns of the HB radiators thus results distorted due to the presence of the dual-layer LB radiators. In fact, due to the presence of the two layers in each LB radiator, the radiated field of a HB radiator arranged next to the LB radiator is scattered by both layers of the LB radiator, which gives rise to destructive interferences that distort the antenna pattern at specific frequencies.

[0013] In view of this, an objective of this disclosure is to provide an improved antenna. An objective is to provide an antenna design, which enables transparency of a multi-layer radiator at specific frequency bands for other radiators of the antenna. For example, to provide transparency of the second radiator 102 to the frequencies of the first radiator 101 in the scenario of FIG. 1.

[0014] Compared to classical one-layer radiators, due to the higher volume of the dual-layer or multi-layer radiators, it is more challenging to ensure such a transparency at the specific frequency bands, which may be served by other radiators arranged within the same enclosure.

[0015] However, the above-mentioned and other objectives are achieved by the solutions of this disclosure as described in the independent claims. Advantageous implementations are further described in the dependent claims.

[0016] A first aspect of this disclosure provides an antenna comprising: a reflector; a first radiator arranged on the reflector and configured to radiate EM waves in a first frequency band; a second radiator arranged on the reflector and comprising a first radiating element and a second radiating element, which are arranged on a common axis at different distances from the reflector and are respectively configured to radiate EM waves in a second frequency band; wherein the second radiator further comprises a matching element arranged between the first radiating element and the second radiating element; and wherein the matching element is configured to establish a predetermined phase relationship between EM waves of the first radiator scattered by the first radiating element and EM waves of the first radiator scattered by the second radiating element.

[0017] The matching element, which is inserted between the radiating elements of the dual -layer or multi-layer second radiator, is able to make the second radiator (more) transparent at specific frequency bands, for instance, at frequencies in the first frequency band of the first radiator. Thus, an improvement of the antenna pattern shape can be achieved, as well as a reduction of the intra-antenna interference. The antenna of the first aspect thus has a better RF performance than a conventional antenna or the exemplary antenna 100, and allows integrating different radiators (or even arrays of different radiators) on the same reflector. The matching element may be an impedance matching element. The matching element may be a layer or sheet, i.e., may be a matching layer or matching sheet.

[0018] In an implementation form of the first aspect, the antenna further comprises an enclosure, wherein the first radiator and the second radiator are arranged in the enclosure.

[0019] Different radiators or different arrays of radiators can be integrated in the same enclosure, without losing performance due to intra-antenna interference. The intra-antenna interference is reduced by the solution of the matching element.

[0020] In an implementation form of the first aspect, the first frequency band is higher than the second frequency band.

[0021] Accordingly, the first radiators may be HB radiators, and the second radiators may be LB radiators. The two frequency bands may be separated by a frequency gap.

[0022] In an implementation form of the first aspect the predetermined phase relationship is anti-phase or is a non-zero phase difference. Thus, a very good or even absolute transparency at the desired frequency bands may be achieved, or a certain desired antenna pattern may be obtained. The matching element may effect a destructive interference between the scattered EM waves.

[0023] In an implementation form of the first aspect, the matching element is further configured to establish a second predetermined phase relationship between the EM waves of the first radiator scattered by the first radiating element or scattered by the second radiating element and non-scattered EM waves emanating from the first radiator.

[0024] This further improves the transparency of the second radiator at the desired frequency bands.

[0025] In an implementation form of the first aspect, the matching element has a predetermined impedance value or impedance value distribution.

[0026] In an implementation form of the first aspect, the matching element comprises an at least partly conductive layer, which is arranged on the common axis between the first radiating element and the second radiating element of the second radiator.

[0027] In an implementation form of the first aspect, the matching element comprises one or more conductive structures, which are arranged on a substrate layer, and / or a dielectric support layer, and / or a foil.

[0028] The matching element can be fabricated and assembled easily, and may add only little weight to the antenna.

[0029] In an implementation form of the first aspect, the antenna includes multiple second radiators, and the substrate layer and / or the dielectric support layer and / or the foil is arranged between the first and the second radiating element of each second radiator of the multiple second radiators.

[0030] This allows designing a common matching element for more than one or even an array of second radiators, which facilitates fabrication and assembly of the antenna.

[0031] In an implementation form of the first aspect, the matching element comprises a meta-lens.

[0032] A meta-lens may be a very thin lens made up of tiny, engineered structures. A meta-lens is able to interact with EM waves. A meta-lens is able to create a phase shift in the EM waves. The meta-lens can act as the matching element by adjusting the interaction between the electromagnetic waves of the first radiator and the second radiator.

[0033] In an implementation form of the first aspect, the matching element comprises a meta-surface.

[0034] A meta-surface may be a thin, artificial layer composed of small, structured elements designed to manipulate electromagnetic waves in specific ways, such as bending light or shaping waves.

[0035] In an implementation form of the first aspect, the matching element comprises a periodic structure of conductive elements, for example, a periodic arrangement of metal patches.

[0036] In an implementation form of the first aspect, the first radiating element and the second radiating element are arranged concentrically or are arranged with respective center regions on the common axis. In an implementation form of the first aspect, a radiating element of the first radiator and at least one of the first radiating element and the second radiating element of the second radiator are arranged on a second common axis at different distances from the reflector.

[0037] That is, the first and / or the second radiating element of the second radiator may be arranged above (e.g., in transmission direction of) the radiating element of the first radiator. The first radiator may be shadowed by the first and / or second radiating element.

[0038] In an implementation form of the first aspect, the first radiating element and the second radiating element are respectively arranged in a first plane and a second plane parallel to the first plane.

[0039] In an implementation form of the first aspect, the first radiator comprises a radiating element arranged in a third plane parallel to the first plane and the second plane.

[0040] In an implementation form of the first aspect, at least one of the first radiating element and the second radiating element is a dual-polarized radiating element.

[0041] In an implementation form of the first aspect, the antenna comprises an array of first radiators and an array of second radiators, wherein the first radiators are arranged interleaved with the second radiators on the reflector.

[0042] In an implementation form of the first aspect, the second radiator further comprises a feed structure configured to feed a signal to the first radiating element and the second radiating element, and the first radiating element and the second radiating element are respectively configured to radiate the EM waves in the second frequency band in response to the fed signal.

[0043] In an implementation form of the first aspect, the feed structure of the second radiator comprises: a power divider configured to distribute the power of the signal between the first radiating element and the second radiating element; and / or a phase inverter configured to set a quasi-inverted phase between the signal at the first radiating element and the signal at the second radiating element as a phase difference.

[0044] By setting the first phase difference between the two radiating elements, a combined radiation pattern can be achieved, which is more directive than the wave of a simple / single radiating element. The result may be a significant increase in the directivity of the combined radiation pattern of the second radiator. This allows either a miniaturization of a reflector or an increase in coverage and / or an increased signal to interference plus noise ratio (SINR) provided by the antenna. The phase difference, and potentially an amplitude difference as a further degree of freedom, between the feed signals at the two radiating elements, may also be used to improve the front to back and cross-polar discrimination of the antenna.

[0045] In summary of the above aspects and implementation forms, the antenna of this disclosure is designed by interposing a third layer of a suitable impedance (or a suitable impedance distribution) as the matching element between the two radiating element layers / elements of the dual -layer or multi-layer second radiator. The solution can be used, for instance, in an AAS, which means integrating a radio transceiver unit with base station antenna systems.

[0046] A principle behind the solution of this disclosure involves providing an adequate phase shift between the electromagnetic field scattered by the first and the second radiating element of the dual -layer second radiator in a specific frequency band, such that the presence of the second radiator do not interfere with the radiation from other first radiators, which may be arranged in its proximity within the same enclosure and / or on the same reflector. An instance of this scenario can be represented by the combination of LB dual -layer radiators and HB radiators, which are placed closed to each other on the same reflector.

[0047] BRIEF DESCRIPTION OF DRAWINGS

[0048] The above-described aspects and implementation forms are explained in the following description in relation to the enclosed drawings, in which:

[0049] FIG. 1 shows an exemplary antenna, which is useful for understanding a problem solved by this disclosure.

[0050] FIG. 2 shows an antenna according to a solution of this disclosure.

[0051] FIG. 3 shows another antenna according to a solution of this disclosure.

[0052] DETAILED DESCRIPTION OF EMBODIMENTS

[0053] FIG. 2 shows an antenna 200 according to a solution of this disclosure. The antenna 200 may be suitable for a base station of a mobile communication network. For example, the antenna 200 may be suitable for a base station antenna drive system. The antenna 200 may be used in an AAS. The antenna 200 provides an improvement over the exemplary antenna 100 shown in FIG. 1.

[0054] The antenna 200 comprises a reflector 206, which may be configured to reflect radiation that is emitted by the radiators of the antenna 200. The reflector 206 may additionally serve as a ground plane. The reflector 206 may be a ground and / or reflector layer.

[0055] A first radiator 201 and a second radiator 202 are arranged on or above the reflector 206. The two radiators 201, 202 may further be arranged in a common enclosure 207 (indicated by the dotted line as being optional). The first radiator 201 is configured to radiate EM waves in a first frequency band, e.g. a HB, and the second radiator 202 is configured to radiate EM waves in a second frequency band, e.g., a LB. That is, the first frequency band may be higher than the second frequency band, and the two frequency bands may be non-overlapping.

[0056] The second radiator 202 comprises a first radiating element 203 and a second radiating element 204, which are arranged on a common axis A at different distances from the reflector 206. That is, the second radiating element 204 is arranged above the first radiating element 203, wherein above means in a distance from the reflector 206 into a radiating direction of the antenna 200. Both radiating elements 203 and 204 are respectively configured to radiate EM waves in the second frequency band.

[0057] A solution of this disclosure provides that the second radiator 202 further includes a matching element 205, which is arranged between the first radiating element 203 and the second radiating element 204. The matching element 205 may also be arranged on the common axis A. The matching element 205 could be introduced halfway between the first and second radiating element 203, 204. The matching element 205 may be an additional layer of the dual-layer or multi-layer second radiator 202.

[0058] The matching element 205 is configured to establish at least a predetermined phase relationship between EM waves of the first radiator 201, which are scattered by the first radiating element 203, and EM waves of the first radiator 201, which are scattered by the second radiating element 204. The matching element 205 could also be configured to establish a second predetermined phase relationship between the EM waves of the first radiator 201 , which are scattered by the first radiating element 203 , and the non-scattered EM waves emanating from the first radiator 201. The matching element 205 could also be configured to establish a third predetermined phase relationship between EM waves of the first radiator 201 , which are scattered by the second radiating element 204, and non-scattered EM waves emanating from the first radiator 201. In this way, as indicated in FIG. 2, the second radiator 202 may become transparent to the EM waves of the first radiator 201 , unlike in FIG. 1 where the second radiator 102 disturbs the radiation pattern of the first radiator 101. The transparency may be strongest if the scattered EM waves destructively interfere.

[0059] The matching element 205 may exhibit a properly designed impedance value (or impedance value distribution), which is interposed between the top (second) and bottom (first) radiating element 203, 204 of the second radiator 202. In this case it may be referred to as impedance matching element. A properly dimensioned matching element 205 can provide the suitable phase relations of the EM waves radiated by the first radiator 201 and respectively one scattered by one of the two radiating elements 203, 204 and the other one scattered by the other one of the two radiating elements 203, 204.

[0060] The matching element 205 can be realized by a meta-lens, which may be implemented by a variety of techniques (for instance, but not limited to, metal patches or metal grids). The impedance matching layer 205 can also be realized by a meta-surface having meta-structures.

[0061] In one implementation, the matching element 205 is realized by periodic structures, such as metal patches, which are interposed between the first and the second radiating element 203, 204 of the second radiator 202. The periodic structures can be implemented on an RF substrate or even on a simpler dielectric support layer, such as a dielectric foil or sheet. In this case the impedance matching element 205 may be an impedance matching layer. In fact, the dielectric properties do not play a significant role in the effectiveness of this solution, other than supporting the metallization providing the matching element 205. In order to make the antenna more effective, the footprint of the matching element 205 may be at least as large as that of the radiating elements 203, 204 of the second radiator 202, but there is no restriction of the maximum footprint of the matching element 205. For example, a common matching element 205 could be constructed for two or more second radiators 202 arranged next to each other and / or in an array. The common matching element 205 could at least have a common dielectric carrier or support layer, which would span over the area of the two or more second radiators 202.

[0062] For ease of implementation, a metallization of the matching element 205 may be realized on a single-piece foil across the whole array, since the maximum footprint has no restrictions and the impedance values can be modulated across whole area as required.

[0063] FIG. 3 shows an antenna 200 according to a solution of this disclosure, which builds on the antenna 200 shown in FIG. 2. Same elements are labelled with the same reference signs in FIG. 2 and 3, may be implemented likewise, and are not redundantly described.

[0064] The antenna 200 of FIG. 3 includes at least one first HB radiator201, and at least one second LB radiator 202. The antenna 200 may also include at least one third HB radiator 301 as illustrated, which is different from the first HB radiator 201. For example, multiple first HB radiators 201 and / or multiple third HB radiators 301, and multiple second LB radiators 202 can be arranged on the reflector 202. The radiating element of a first HB radiator 201 and the radiating elements 203 , 204 of the second radiator 202 may respectively be arranged on an axis B as illustrated, which means the radiating elements 203, 204 are above the radiating element of the first HB radiator 201. The radiating element of a third HB radiator 301 and the radiating elements 203 , 204 of the second radiator 202 may respectively be arranged on an axis C as illustrated, which means the radiating elements 203, 204 are above the radiating element of the third HB radiator 201 The matching element 205 of the at least one LB radiator 202 may comprise a meta-lens in this example.

[0065] The antenna 200 of FIG. 3 is also shown to have a feed structure 301, which is configured to feed a signal to the first radiating element 203 and the second radiating element 204. The first radiating element 203 and the second radiating element 204 are respectively configured to radiate the EM waves in the second frequency band based on the fed signal. The feed structure 301 may comprise power divider for distributing the power of the signal between the first radiating element 203 and the second radiating element 204. The feed structure 301 may comprise a phase inverter for setting a quasi-inverted phase between the signal at the first radiating element 203 and the signal at the second radiating element 204 as a phase difference.

[0066] For instance, the feed structure 301 may be configured to feed the signal in parallel to the first radiating element 203 and the second radiating element 204. The feed structure 301 may comprise multiple components. A power divider of the feed structure 301 may be used for redirecting power between two or more branches. A phase inverter of the feed structure 301 may set a phase difference of ±180°.

[0067] A power divider of the feed structure 301 could also set a second phase difference, in addition to the first phase difference, between the signal at the first radiating element 203 and the signal at the second radiating element 204. To this end, the power divided may comprise first way or first arm for providing the signal to the first radiating element 203, and a second way or second arm for providing the signal to the second radiating element 204. In this case, the second phase difference may be set by the first way or first arm having a different lengths than the second way or second arm. A total phase difference of 180° ± a may thus be set between the signal at the first radiating element 203 and the signal at the second radiating element 204 The second phase difference may be a = 0°, or may be a > 0°. The power of the signal may be divided equally between the two radiating elements 203, 204, but it can also be divided unequally between them.

[0068] In summary, this disclosure enables the employment of one or more dual-layer or multi-layer radiators (second radiators 202) in an antenna 200 together with other first radiators 201. The coverage efficiency of the antenna can be increased by providing the matching element(s) 205.

[0069] The solutions of the present disclosure can be applied to a base station antenna system. The base station antenna system may include a system composed of the antenna 200, a feeder, a pole, and an antenna adjustment bracket. The antenna 200 can include one or more independent arrays formed by the radiators 201, 202, and a metal reflector 206, wherein frequencies of radiators 201, 202 may be the same or different, and the radiators 201, 202 may be placed above the metal reflector. 206 The arrays may receive or transmit RF signals (generally EM waves) through their respective feeding networks. The feeding network may implement different radiation beam directions, or may be connected to the calibration network to obtain calibration signals required by the system. In addition to a phase shifter network, the feeding network may also include modules such as combiners and filters for expanding performance. The base station antenna 200 may be located in the radome.

[0070] The present disclosure has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed matter, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

CLAIMS1. An antenna (200) comprising: a reflector (206); a first radiator (201) arranged on the reflector (206) and configured to radiate electromagnetic, EM, waves in a first frequency band; a second radiator (202) arranged on the reflector (206) and comprising a first radiating element (203) and a second radiating element (204), which are arranged on a common axis (A) at different distances from the reflector (206) and are respectively configured to radiate EM waves in a second frequency band; wherein the second radiator (202) further comprises a matching element (205) arranged between the first radiating element (203) and the second radiating element (204); and wherein the matching element (205) is configured to establish a predetermined phase relationship between EM waves of the first radiator (201) scattered by the first radiating element (203) and EM waves of the first radiator (201) scattered by the second radiating element (204).

2. The antenna (200) according to claim 1, further comprising an enclosure (207), wherein the first radiator (201) and the second radiator (202) are arranged in the enclosure (207).

3. The antenna (200) according to claim 1 or 2, wherein the first frequency band is higher than the second frequency band.

4. The antenna (200) according to one of the claims 1 to 3, wherein the predetermined phase relationship is anti-phase or is a non-zero phase difference.

5. The antenna (200) according to one of the claims 1 to 4, wherein the matching element (205) is further configured to establish a second predetermined phase relationship between the EM waves of the first radiator (201) scattered by the first radiating element (203) or scattered by the second radiating element (204) and non-scattered EM waves emanating from the first radiator (201).

6. The antenna (200) according to one of the claims 1 to 5, wherein the matching element (205) has a predetermined impedance value or impedance value distribution.

7. The antenna (200) according to one of the claims 1 to 6, wherein the matching element (205) comprises an at least partly conductive layer, which is arranged on the common axis (A) between the first radiating element (203) and the second radiating element (204) of the second radiator (202).

8. The antenna (200) according to one of the claims 1 to 7, wherein the matching element (205) comprises one or more conductive structures, which are arranged on a substrate layer, and / or a dielectric support layer, and / or a foil.

9. The antenna (200) according to claim 8, wherein the antenna (200) includes multiple second radiators (202), and the substrate layer and / or the dielectric support layer and / or the foil is arranged between the first and the second radiating element (203, 204) of each second radiator (202) of the multiple second radiators (202).

10. The antenna (200) according to one of the claims 1 to 9, wherein the matching element (205) comprises a meta-lens.

11. The antenna (200) according to one of the claims 1 to 10, wherein the matching element (205) comprises a metasurface.

12. The antenna (200) according to one of the claims 1 to 11, wherein the matching element (205) comprises a periodic structure of conductive elements, for example, a periodic arrangement of metal patches.

13. The antenna (200) according to one of the claims 1 to 12, wherein the first radiating element (203 ) and the second radiating element (204) are arranged concentrically or are arranged with respective center regions on the common axis (A).

14. The antenna (200) according to one of the claims 1 to 13, wherein a radiating element of the first radiator (202) and at least one of the first radiating element (203) and the second radiating element (204) of the second radiator (202) are arranged on a second common axis (B) at different distances from the reflector (206).

15. The antenna according to one of the claims 1 to 14, wherein the first radiating element (203) and the second radiating element (204) are respectively arranged in a first plane and a second plane parallel to the first plane.

16. The antenna (200) according to claim 15, wherein the first radiator (201) comprises a radiating element arranged in a third plane parallel to the first plane and the second plane.

17. The antenna (200) according to one of the claims 1 to 16, wherein at least one of the first radiating element (203) and the second radiating element (204) is a dual-polarized radiating element.

18. The antenna (200) according to one of the claims 1 to 17, wherein the antenna (200) comprises an array of first radiators (201) and an array of second radiators (202), wherein the first radiators (201) are arranged interleaved with the second radiators (202) on the reflector (206).

19. The antenna (200) according to one of the claims 1 to 18, wherein the second radiator (202) further comprises a feed structure (301) configured to feed a signal to the first radiating element (203) and the second radiating element (204), and the first radiating element (203) and the second radiating element (204) are respectively configured to radiate the EM waves in the second frequency band in response to the fed signal.

20. The antenna (200) according to claim 19, wherein the feed structure (301) of the second radiator (202) comprises: a power divider configured to distribute the power of the signal between the first radiating element (203) and the second radiating element (204); and / or a phase inverter configured to set a quasi-inverted phase between the signal at the first radiating element (203) and the signal at the second radiating element (204) as a phase difference.

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