TECHNICAL FIELD

The disclosure relates to a dual-polarization antenna element comprising first and second conductive structures and first and second antennas.

BACKGROUND

Electronic devices need to support more, complicated and advanced radio signal technologies such as 2G/3G/4G radio standards. For coming 5G radio technology, the frequency range will be expanded from sub-6 GHz to so called millimeter-wave frequency, e.g. above 20 GHz. For millimeter-wave frequencies, an antenna array will be necessary in order to form a radiation beam with higher gain which overcomes the higher path loss in the propagation media. Radiation beam patterns with higher gain result in a narrow beam width, wherefore beam steering techniques such as phased antenna arrays are used to steer the beam in a specific, desired direction.

Furthermore, mobile electronic devices, such as mobile phones and tablets, may be oriented in any arbitrary direction, and therefore such electronic devices need to exhibit an as near full spherical beam coverage as possible. Such coverage is difficult to achieve, i.e. due to the radiation beam being blocked by at least one of a conductive housing, a large display, and/or by the hand of the user holding the device.

Conventionally, a millimeter- wave antenna array is arranged next to the display, such that the display does not interfere with the beam coverage. However, the movement towards very large displays, covering as much as possible of the electronic device, makes the space available for the antenna array very limited, forcing either the size of the antenna array to be significantly reduced, and its performance impaired, or a large part of the display to be inactive. The main radiation beam of the millimeter-wave antenna array is oftentimes directed in the broadside direction, i.e., perpendicular to the display of the electronic device, which radiation may be blocked by both the display and, e.g., a conductive back cover. End-fire antenna arrays, however, can form beams radiating in parallel with the display, thus improving the beam direction coverage. Nevertheless, the electronic device may have a conductive frame surrounding the edges of the electronic device, which may distort the end-fire radiation

SUMMARY

It is an object to provide an improved dual-polarization antenna element. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

According to a first aspect, there is provided a dual-polarization antenna element comprising a first conductive structure, a second conductive structure, a first antenna, and a second antenna, a first main plane of the first conductive structure and a second main plane of the second conductive structure extending at least partially in parallel, the first conductive structure comprising a first aperture having a first configuration, the second conductive structure comprising a second aperture having a second configuration different from the first configuration, the first aperture abutting the second aperture, the first antenna being formed by the first conductive structure, the second conductive structure, and a first antenna feed comprising a first coupling element configured to excite a first electrical field having a first polarization, the first antenna feed extending through the first aperture in a first direction perpendicular to the first main plane and the second main plane, the second antenna being formed by the second conductive structure and a second antenna feed comprising a second coupling element configured to excite a second electrical field having a second polarization, the second antenna feed extending along the second aperture in a second direction parallel to the first main plane and the second main plane.

Such a solution allows dual-polarization, and hence sufficient gain coverage to be achieved in any direction from the electronic device into which the antenna element has been mounted, without negatively affecting, e.g., the mechanical strength of the electronic device and without taking up much volume within the electronic device since the different antennas need neither be interleaved or stacked. This allows the thickness of the antenna element to be significantly reduced compared to prior art solutions. Furthermore, since electrical fields are transmitted directly from the first conductive structure and the second conductive structure, end-fire beamforming is enabled and, hence, full- sphere omnicoverage which is not blocked by, e.g., the frame of the electronic device. Also, dual-polarized radiation allows each individual polarization to be used by an independent data stream to facilitate multiple-input and multiple- output (MIMO) communication.

In a possible implementation form of the first aspect, the first electrical field and the second electrical field may operate at the same operating frequency, facilitating improved performance at the operating frequency.

In a further possible implementation form of the first aspect, the direction of the first electrical field is orthogonal to the direction of the second electrical field. Hence, the transmitted and received signals of the first antenna and the second antenna, which are electromagnetically coupled to the first electrical field and the second electrical field, are isolated from each other, allowing the first antenna and the second antenna to partially share the same space.

In a further possible implementation form of the first aspect, the first configuration of the first aperture is symmetrical in the first main plane about a first axis, and/or the second configuration of the second aperture is symmetrical in the second main plane about a second axis, the first axis extending adjacent to the second axis, or coinciding with the second axis, reducing the volume occupied by the antenna element within the electronic device.

In a further possible implementation form of the first aspect, the second aperture is juxtaposed with the first antenna feed in the first direction, providing an as spatially efficient antenna element as possible.

In a further possible implementation form of the first aspect, the first aperture comprises an open-ended cavity delimited by a closed end wall and side walls, and the second aperture comprises an open-ended slit, the open-ended slit being juxtaposed with the open end of the cavity.

In a further possible implementation form of the first aspect, the first antenna feed extends between the closed end wall and the second conductive structure, and the first coupling element couples the first antenna feed to the second conductive structure by means of one of a galvanic connection and a capacitive connection.

In a further possible implementation form of the first aspect, a largest dimension of the first aperture and a largest dimension of the second aperture are equal and corresponding to a wavelength at minimum frequency within the operating frequency range. This allows the first aperture and the second aperture to work for similar frequencies.

In a further possible implementation form of the first aspect, the first antenna feed excites a first current, in the second antenna, which is out-of-phase with current excited by the second antenna feed, allowing the antennas to operate at the same frequency, within essentially the same space, while still being well isolated from each other.

In a further possible implementation form of the first aspect, the first polarization is vertical polarization and the second polarization is horizontal polarization, facilitating coexistence of different antennas in order to provide two independent communication channels between transmitting and receiving, such that the link is either more robust or faster, allowing higher throughput by MIMO technology.

In a further possible implementation form of the first aspect, the first antenna and the second antenna are configured to generate millimeter-wave frequency radiation.

In a further possible implementation form of the first aspect, the first antenna is an end- fire antenna element having vertical polarization and the second antenna is an end-fire antenna element having horizontal polarization.

In a further possible implementation form of the first aspect, the second conductive structure is a tapered dipole.

In a further possible implementation form of the first aspect, a dimension of the tapered dipole in the second main plane is between 0,35*Amin and 0,65*Amin, Amin being a wavelength at maximum frequency within the operating frequency range, and a dimension of a combination of the tapered dipole and the second aperture in the second main plane is between 0,35*A _max and 0,65*A _max , A _max being a wavelength at minimum frequency within the operating frequency range.

In a further possible implementation form of the first aspect, the first antenna feed comprises a single-monopole feed or a double-folded monopole feed.

In a further possible implementation form of the first aspect, a dimension of the single monopole feed or the double-folded monopole feed in the first direction is between 0,35* Amin and 0,65*A _min , Amin being a wavelength at maximum frequency within the operating frequency range, and a dimension of the first aperture in the first direction is between 0,35*A _max and 0,65*A _max , A _max being a wavelength at minimum frequency within the operating frequency range. According to a second aspect, there is provided a dual-polarization antenna array comprising at least two dual-polarization antenna elements according to the above, the first antennas of the dual-polarization antenna elements forming a first antenna sub-array configured to excite a first electrical field having a first polarization, the second antennas of the dual-polarization antenna elements forming a second antenna sub-array configured to excite a second electrical field having a second polarization. By allowing a first antenna sub-array and a second antenna sub-array to extend within essentially the same the non-conductive volume, two different antenna arrays extend at least partially within the same volume, significantly reducing the space required for antennas within an electronic device.

According to a third aspect, there is provided an electronic device comprising a display, a housing, and at least one dual-polarization antenna array according to the above, the first conductive structure and the second conductive structure of the dual-polarization antenna array being at least one internal component enclosed by the display and the housing, existing components being utilized to provide an electronic device having omnicoverage.

In a possible implementation form of the third aspect, at least one of the first conductive structure and the second conductive structure is a solid or flexible printed circuit board.

In a further possible implementation form of the third aspect, the printed circuit board extends parallel with and/or perpendicular to a main plane of the display and a main plane of the housing, allowing the electrical field of the antenna array to be directed either perpendicular to or parallel with the main plane of the display.

In a further possible implementation form of the third aspect, the housing comprises a back cover and a conductive frame extending between peripheral edges of the display and the back cover, the display being separated from the conductive frame by means of a dielectric gap, the dual-polarization antenna array extending adjacent a face of the display, the dielectric gap allowing the first electrical field and the second electrical field excited by the dual-polarization antenna array to radiate past the conductive frame. This facilitates use of existing components to provide omnicoverage without affecting the assembly reliability or dimensions of the electronic device.

This and other aspects will be apparent from and the embodiments described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the aspects, embodiments and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

Fig. 1 shows a schematic side view of an electronic device in accordance with an embodiment of the present invention;

Fig. 2 shows a schematic top view of the embodiment of Fig. 1;

Fig. 3 shows a schematic cross-sectional side view of an electronic device in accordance with a further embodiment of the present invention;

Fig. 4 shows a partial perspective view of a dual-polarization antenna array in accordance with an embodiment of the present invention;

Fig. 5 shows a partial perspective view of a dual-polarization antenna array in accordance with a further embodiment of the present invention;

Fig. 6 shows a partial perspective view of a dual-polarization antenna element in accordance with an embodiment of the present invention;

Fig. 7 shows a partial perspective view of a dual-polarization antenna element in accordance with an embodiment of the present invention; Fig. 8 shows a partial perspective view of a dual-polarization antenna element in accordance with a further embodiment of the present invention.

DETAILED DESCRIPTION

Figs. 1 and 2 show schematic view of an electronic device 13 comprising a display 14, a housing 15, and at least one dual -polarization antenna array 12 described in more detail further below. The display 14 may cover almost the entire surface area of the front of the electronic device, and also stretch at least partially across the sides of the electronic device 13 towards the rear. The housing 15 may comprise a back cover 15a and a conductive frame 15b extending between peripheral edges of the display 14 and the back cover 15a, the display 14 being separated from the conductive frame 15b by means of a dielectric gap 16. The housing 15 may comprise plastic, glass, ceramic or any other suitable non-conductive material, as well as a conductive material such as aluminum. The dual-polarization antenna array 12 may extend adjacent a face of the display 14, such that a first electrical field FI and a second electrical field F2, which are excited by the dual polarization antenna array 12, can radiate past the conductive frame 15b through the dielectric gap 16.

At least one internal component is enclosed by the display 14 and the housing 15, the internal component being, e.g., a chassis or a solid or flexible printed circuit board (PCB). A solid printed circuit board is shown in Fig. 4, and a flexible printed circuit board is shown in Fig. 5. Such a printed circuit board may extend parallel with and/or perpendicular to a main plane of the display 14 and a main plane of the housing 15. Fig. 3 shows an embodiment which comprises two internal components in the form of one solid printed circuit board extending in parallel with the main plane of the display 14, and one flexible printed circuit board extending both parallel with and perpendicular to the main plane of the display 14, adjacent the edge of the conductive frame 15b and the dielectric gap 16. With such an embodiment, the main radiation beam can be steered towards the broadside direction even if using end-fire antennas. The printed circuit board may also comprise connections to a radio frequency integrated circuit (RFIC). Alternatively, the radio frequency integrated circuit and the printed circuit board are configured as one integral component.

The dual-polarization antenna array 12, shown in Figs. 4 and 5, comprises at least two dual-polarization antenna elements 1 arranged next to each other. Each dual-polarization antenna element 1 comprises a first antenna 4, exciting a first electrical field FI having a first polarization, and a second antenna 5, exciting a second electrical field F2 having a second polarization. The plurality of dual-polarization antenna elements 1 are, as shown in Fig. 4, arranged such that all first antennas 4 of the dual-polarization antenna elements 1 form a first antenna sub-array 12a, configured to excite a first electrical field FI having a first polarization, and such that all second antennas 5 of the dual-polarization antenna elements 1 form a second antenna sub-array 12b, configured to excite a second electrical field F2 having a second polarization.

Figs. 6 and 8 show embodiments of the above-mentioned dual-polarization antenna element 1. The dual-polarization antenna element 1 comprises a first conductive structure 2, a second conductive structure 3, a first antenna 4, and a second antenna 5. The first conductive structure 2 and the second conductive structure 3 are arranged such that a first main plane of the first conductive structure 2 and a second main plane of the second conductive structure 3 extend at least partially in parallel. At least one of the first conductive structure 2 and the second conductive structure 3 may comprise the above- mentioned internal component. In one embodiment, the first conductive structure 2 is a printed circuit board and the second conductive structure 3 comprises two identical and laterally reversed planar sections, as show in Figs. 4, 5, and 8, e.g. in the form of a tapered dipole.

The first conductive structure 2 comprises a first aperture 6 having a first configuration, and the second conductive structure 3 comprises a second aperture 7 having a second configuration which is different from the first configuration. For example, the first aperture 6 may comprise an open-ended conductive cavity, while the second aperture 7 comprises an open-ended slot which separates the two identical and laterally reversed sections. However, other configurations are conceivable.

The first aperture 6 abuts the second aperture 7, such that the first aperture 6 and the second aperture 7 are interconnected.

The first antenna 4, shown detail in Figs. 6 and 7, is formed by the first conductive structure 2, the second conductive structure 3, and a first antenna feed 8 extending through and at least partially across the first aperture 6 in a first direction D1

perpendicular to the first main plane and the second main plane. The first antenna feed 8 may be Y-shaped. The first antenna feed 8 may furthermore comprise a first coupling element 9 which is configured to excite the first electrical field FI having a first polarization.

In one embodiment, the second aperture 7 is juxtaposed with the first antenna feed 8 in the first direction D1.

The second antenna 5, shown in detail in Figs. 5 and 8, is formed by the second conductive structure 3 and a second antenna feed 10 extending across the second aperture 7 in a second direction D2 parallel to the first main plane and the second main plane.

The second antenna feed 10 may comprise a second coupling element 11 configured to excite the second electrical field F2 having a second polarization. The second coupling element 11 may couple the second antenna feed 10 to the second conductive structure 3 by means of a galvanic connection or a capacitive connection.

In one embodiment, the first electrical field FI and the second electrical field F2 operate within the same operating frequency range. A largest dimension of the first aperture 6 and a largest dimension of the second aperture 7 may be equal and correspond to a wavelength at minimum frequency within the operating frequency range. Since the first aperture 6 and the second aperture 7 could work for the same frequency, the largest dimensions of both apertures 6, 7 preferably coincide. The first antenna feed 8 excites in-phase currents in the first antenna 4. The first antenna feed 8 may also excite a current, in the second antenna 5, which is out-of-phase with current excited by the second antenna feed 10. This allows the first antenna 4 and the second antenna 5 to operate at the same frequency, within essentially the same space, while still being well isolated from each other.

The dual-polarization antenna element 1 may generate a first polarization and a second polarization which is orthogonal to the first polarization. The first polarization may be a vertical polarization, and the second polarization may be a horizontal polarization. In one embodiment, the first antenna 4 is an end-fire antenna element having vertical polarization and the second antenna 5 is an end-fire antenna element having horizontal polarization. Furthermore, the first antenna 4 and the second antenna 5 may be configured to generate millimeter- wave frequency radiation.

As shown in Figs. 6 and 7, the first configuration of the first aperture 6 may be symmetrical in the first main plane about a first axis Al. Correspondingly, and as shown in Figs. 5 and 8, the second configuration may be symmetrical in the second main plane about a second axis A2. The first axis Al may extend adjacent to, and parallel with, the second axis A2, or the first axis Al may coincide with the second axis A2.

In one embodiment, shown in Fig. 7, the first aperture 6 comprises an open-ended cavity delimited by a closed end wall 6a and side walls 6b. The cavity may have any suitable shape, e.g. it may be essentially rectangular. The first antenna feed 8 may extend between the closed end wall 6a and the second conductive structure 3, and the first coupling element 9 may couple the first antenna feed 8 to the second conductive structure 3 by means of a galvanic connection or a capacitive connection.

The second aperture 7 may comprise an open-ended slit which is juxtaposed with the open end of the cavity, as shown in Figs. 6 and 8. In one embodiment, the second conductive structure 3 is a tapered dipole. The current induced on the tapered dipole by the first antenna feed 8 may be out-of-phase to the current induced by the second antenna feed 10, providing good isolation between the two co-located antennas 4, 5 of the antenna element 1.

A dimension of the tapered dipole in the second main plane may be between 0,35*Amin and 0,65* Amin, Amin being a wavelength at maximum frequency within the operating frequency range. Furthermore, a dimension of a combination of the tapered dipole and the second aperture 7 in the second main plane may be between 0,35*A _max and 0,65*A _max , Amax being a wavelength at minimum frequency within the operating frequency range.

The first antenna feed 8 may comprise a single-monopole feed or a double-folded monopole feed. The vertical polarization mode defined by the cavity, and the horizontal polarization mode defined by the slot in-phase current, may be used to tune lower resonances. The first antenna feed 8 may be used to tune higher resonances.

A dimension of the single-monopole feed or the double-folded monopole feed in the first direction D1 may be between 0,35*A _min and 0,65*Amin, Amin being a wavelength at maximum frequency within the operating frequency range. Furthermore,

a dimension of the first aperture 6 in the first direction D1 may be between 0,35*A _max and 0,65*A _max , Amx being a wavelength at minimum frequency within the operating frequency range.

The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject- matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article“a” or“an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. The reference signs used in the claims shall not be construed as limiting the scope.