TECHNICAL FIELD

The present disclosure relates generally to an antenna for radiating radio waves, and more particularly to an antenna apparatus that is configured to radiate radio beams with a high gain and in a wide angular range in one (horizontal or vertical) plane, thereby providing high-gain wide-angle beam scanning in that plane.

BACKGROUND

A self-organizing network (SON) is a self-healing network configured to dynamically reconfigure itself to optimize its performance as a physical environment or network conditions dynamically change. The SON may be used, for example, in mobile radio access networks (RANs), such as radio access networks of fifth generation (5G) communication systems. The multipoint-to-multipoint (mesh) SON providing Internet access may be implemented using, for example, at least one wireless customer premises equipment (CPE), such as a wireless router, switch, and the like, so that a home, office or the like is connected to a fixed network node (e.g., a base station or gNB) via one or more wireless CPEs.

However, for the SON to operate properly, a high gain and a wide scan range in a horizontal plane should be provided. In most real-life environments, each wireless CPE needs to cover more than a hemisphere in space, and at least 120° in the horizontal plane. Especially for the 5G communication systems, there is a need for a wireless CPE having a high-effective isotropic radiated power (EIRP) omnicoverage millimeter-wave (mmWave) link connection.

Given the above, one possible way could consist in arranging multiple independent antennas in a wireless CPE such that they cover corresponding spatial regions by themselves. For example, the wireless CPE may have four such antennas, with each antenna covering a 90° sector. However, such antenna arrangement may provide vertical scanning within the angular range of ±45° and horizontal scanning within the angular range of ±45°, which is not sufficient for some SON applications. Furthermore, each of such independent antennas needs an own mmWave module, thereby causing additional costs and increasing the overall CPE size.

Another possible way could consist in using a lens antenna in a wireless CPE, base station or gNB. The lens antenna is a known antenna type that uses a shaped piece of microwave- transparent material to bend and focus radio waves by means of refraction. However, the existing lens antenna structures are too large for use in communication devices. Furthermore, the existing lens antenna structures are not used for beam tilting, and typically deal with fixed beams.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure.

It is an objective of the present disclosure to provide a technical solution that enables high- gain wide-angle beam scanning for an antenna in one (horizontal or vertical) plane.

The objective above is achieved by the features of the independent claim in the appended claims. Further embodiments and examples are apparent from the dependent claims, the detailed description and the accompanying drawings.

According to a first aspect, an antenna apparatus is provided. The antenna apparatus comprises an array of radiators configured to radiate a radio beam. The antenna apparatus further comprises a refractive device having an optical axis that passes through the array of radiators. The refractive device is configured to widen the radio beam in a first geometric plane and to narrow the radio beam in a second geometric plane. The first geometric plane and the second geometric plane are mutually orthogonal and intersect in the optical axis. The first geometric plane and the second geometric plane are referred to herein briefly as a first plane and a second plane, respectively. By widening the radio beam in the first plane, it is possible to provide beam forming and beam scanning in the first plane in the angular range of up to ±80°. At the same time, by reducing the width of the radio beam in the second plane, it is possible to provide a gain improvement for the antenna apparatus up to +3 dB. Given this, a reduced number of similar antenna apparatuses is needed to achieve a similar or better result (in terms of the gain and scan range) compared to the prior art antennas currently used in wireless CPEs.

In one embodiment of the first aspect, the refractive device is or comprises a lens that is concave in the first plane and convex in the second plane. In addition to the above-mentioned improvements in the gain and scan range, such a dual-profile lens may also reduce side lobes and grating lobes in a radiation pattern of the antenna apparatus. Furthermore, the dual-profile lens provides a significant reduction in the total height (e.g., 12 mm) of the whole apparatus structure, thereby enabling its installation in communication devices. The lens may be a simple lens (i.e. a singlet lens) or a composite lens, e.g. a doublet lens. A simple lens can be robust and can be easy to manufacture.

In one embodiment of the first aspect, the antenna apparatus further comprises a first reflector and a second reflector arranged on opposite sides of the first plane and facing each other across a space between the array of radiators and the refractive device. By using the first and second reflectors, it is possible to additionally increase the boresight gain and beam scanning gain of the antenna apparatus. Furthermore, the first and second reflectors may reduce the grating lobes and the side lobes in the radiation pattern of the antenna apparatus.

In one embodiment of the first aspect, the antenna apparatus further comprises a third reflector and a fourth reflector arranged on opposite sides of the second plane near two opposite edge regions of the array of radiators. By using the third and fourth reflectors, it is possible to increase the beam scanning gain of the antenna apparatus, as well as increase the gain of the radiated radio beam. Furthermore, the third and fourth reflectors may reduce the grating lobes and the side lobes in the radiation pattern of the antenna apparatus.

In one embodiment of the first aspect, the third reflector and the fourth reflector each extend away from the array of radiators. By implementing the third and fourth reflectors in this way, it is possible to increase an aperture in the boresight direction of the antenna apparatus and the gain of the radiated radio beam. Furthermore, the third and fourth reflectors thus implemented may reduce a beam ripple and the side lobes in the radiation pattern of the antenna apparatus more efficiently.

In one embodiment of the first aspect, the third reflector and the fourth reflector are arranged outside a three-dimensional angular sector that is defined as follows. The sector has a vertex provided by a central axis of the array of radiators, an angle bisector provided by a half-plane of the second plane, and a central angle of at least 140 degrees. The half-plane of the second plane extends from the vertex through the refractive device. The third and fourth reflectors thus arranged may increase the aperture in the boresight direction of the antenna apparatus and the gain of the radiated radio beam. Furthermore, the third and fourth reflectors thus implemented may reduce the beam ripple and the grating lobes in the radiation pattern of the antenna apparatus more efficiently.

In one embodiment of the first aspect, the third reflector and the fourth reflector are configured to deflect the radio beam in directions away from the first reflector and the second reflector, while the first reflector and the second reflector are configured to form an aperture for the radio beam. In this embodiment, the refractive device covers the radiating aperture, and there is an air gap between the array of radiators and the refractive device. The air gap decreases in a direction away from a center of the array of radiators toward said two opposite edge regions of the array of radiators. By configuring the antenna apparatus in this way, it is possible to increase the scan range in the first plane even more. Moreover, such a configuration of the antenna apparatus may allow reducing the side lobes and the grating lobes in the radiation pattern of the antenna apparatus more efficiently. On top of that, such a confirmation of the antenna apparatus allows reducing the total height of the antenna apparatus even more, thereby making the antenna apparatus more compact.

In one embodiment of the first aspect, the at least one air gap increases in a direction from the center of the array of radiators toward two opposite edge regions of the array of radiators that are located on opposite sides of the first plane. This may provide more efficient narrowing of the radio beam in the second plane, thereby increasing the boresight gain of the antenna apparatus even more.

In one embodiment of the first aspect, the aperture gradually expands in a direction away from the array of radiators towards the refractive device. This gradually increasing aperture may allow increasing the boresight gain of the antenna apparatus and the gain of the radiated radio beam. Furthermore, such an aperture may reduce the grating lobes in the radiation pattern of the antenna apparatus more efficiently, as well as provide more efficient widening of the radio beam in the first plane.

In one embodiment of the first aspect, the aperture formed by the first reflector and the second reflector is shaped as a truncated cone or as a horn. With this aperture shape or, in other words, with this arrangement of the first and second reflectors, the widening of the radio beam in the first plane occurs more efficiently.

In one embodiment of the first aspect, each of the first reflector, the second reflector, the third reflector and the fourth reflector comprises a layer of conductive material on a substrate. This may allow one to minimize the usage of conductive material in the manufacture of the reflectors.

In one embodiment of the first aspect, the array of radiators extends in a plane perpendicular to the optical axis. The refractive device with such an optical axis may focus the radio beam mainly towards a normal direction relative to the array of radiators.

In one embodiment of the first aspect, the radio beam has a vacuum wavelength shorter than 10 cm. The antenna apparatus radiating such a radio beam may be used in a variety of applications (e.g., wireless communications, road obstacle detection, etc.).

In one embodiment of the first aspect, at least one of the third reflector and the fourth reflector is flush with or arranged lower than the array of radiators. In this embodiment, the array of radiators is arranged below the refractive device. The third and fourth reflectors thus arranged may form an aperture for travelling waves in the left and right directions from the array of radiators, thereby increasing the aperture and, as a result, increasing the scan range in the first plane of the antenna apparatus and the gain of the radiated radio beam. Furthermore, such an arrangement of the third and fourth reflectors may allow reducing the grating lobes in the radiation pattern of the antenna apparatus more efficiently.

In one embodiment of the first aspect, the refractive device is made of at least one low-loss radio-frequency material. Such materials provide a low loss tangent, thereby minimizing the dissipation of the radio beam from the array of radiators. In other words, such materials allow the radio beam to remain focused into a desired direction.

Other features and advantages of the present disclosure will be apparent upon reading the following detailed description and reviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is explained below with reference to the accompanying drawings in which:

FIG. 1 shows a schematic top view of a wireless CPE typically used in a conventional SON;

FIG. 2 shows a schematic perspective view of an antenna apparatus in accordance with a first exemplary embodiment;

FIGs. 3A-3C show different schematic views of a refractive device in accordance with one exemplary embodiment;

FIG. 4 shows a cutaway perspective view of an antenna apparatus in accordance with a second exemplary embodiment;

FIG. 5 shows a cutaway perspective view of an antenna apparatus in accordance with a third exemplary embodiment;

FIG. 6 shows an exploded perspective view of an antenna apparatus in accordance with a fourth exemplary embodiment;

FIGs. 7A and 7B shows differential sectional views of the antenna apparatus shown in FIG. 6;

FIGs. 8A and 8B show an electric field distribution in the antenna apparatus shown in FIG. 6 in the absence and presence of a third reflector and a fourth reflector, respectively; FIGs. 9A and 9B show an electric field distribution in the antenna apparatus shown in FIG. 6 in the absence and presence of a first reflector and a second reflector, respectively;

FIGs. 10A-10D show how the presence of a dual-profile lens allows reducing the so-called grating lobes;

FIG. 11 shows dependencies of a radio beam gain on a scanning angle in one plane for different antenna apparatuses.

DETAILED DESCRIPTION

Various embodiments of the present disclosure are further described in more detail with reference to the accompanying drawings. However, the present disclosure may be embodied in many other forms and should not be construed as limited to any certain structure or function discussed in the following description. In contrast, these embodiments are provided to make the description of the present disclosure detailed and complete.

According to the detailed description, it will be apparent to the ones skilled in the art that the scope of the present disclosure encompasses any embodiment thereof, which is disclosed herein, irrespective of whether this embodiment is implemented independently or in concert with any other embodiment of the present disclosure. For example, the apparatus disclosed herein may be implemented in practice by using any numbers of the embodiments provided herein. Furthermore, it should be understood that any embodiment of the present disclosure may be implemented using one or more of the features presented in the appended claims.

The word “exemplary” is used herein in the meaning of “used as an illustration”. Unless otherwise stated, any embodiment described herein as “exemplary” should not be construed as preferable or having an advantage over other embodiments.

Any positioning terminology, such as “left”, “right”, “top”, “bottom”, “above” “below”, “upper”, “lower”, “horizontal”, “vertical”, etc., may be used herein for convenience to describe one element’s or feature's relationship to one or more other elements or features in accordance with the figures. It should be apparent that the positioning terminology is intended to encompass different orientations of the apparatus disclosed herein, in addition to the orientation(s) depicted in the figures. As an example, if one imaginatively rotates the apparatus in the figures 90 degrees clockwise, elements or features described as “left” and “right” relative to other elements or features would then be oriented, respectively, “above” and “below” the other elements or features. Therefore, the positioning terminology used herein should not be construed as any limitation of the invention. Although the numerative terminology, such as “first”, “second”, “third”, “fourth”, etc., may be used herein to describe various embodiments and features, it should be understood that these embodiments and features should not be limited by this numerative terminology. This numerative terminology is used herein only to distinguish one feature or embodiment from another feature or embodiment. For example, a first plane and a second plane which are discussed below could be renamed a second plane and a first plane, respectively, without departing from the teachings of the invention.

As used in the embodiments disclosed herein, an antenna apparatus may refer to an apparatus configured to radiate and receive radio beams. The radio beams may refer to a type of electromagnetic radiation that occurs in the so-called centimeter-wave (cm-wave) and millimeter-wave (mm-wave) bands. The radio beams have been used, for example, in wireless communications, such as point-to-point communications, intersatellite links, and point-to- multipoint communications, etc. However, the application of the radio beams is not limited to wireless communications only, and they may be also used, for example, for (air, ground or marine) vehicle navigation and control, road obstacle detection, etc. For this reason, the antenna apparatus according to the embodiments disclosed herein may be used in the same use scenarios as the radio beams. More specifically, the antenna apparatus may be implemented as part of a user equipment (UE) that may refer to a CPE, a mobile device, a mobile station, a terminal, a subscriber unit, a mobile phone, a cellular phone, a smart phone, a cordless phone, a personal digital assistant (PDA), a wireless communication device, a desktop computer, a laptop computer, a tablet computer, a single-board computer (SBC) (e.g., a Raspberry Pi device), a gaming device, a netbook, a smartbook, an ultrabook, a medical device or medical equipment, a biometric sensor, a wearable device (e.g., a smartwatch, smart glasses, a smart wrist band, etc.), an entertainment device (e.g., an audio player, a video player, etc.), a vehicular component or sensor (e.g., a driver-assistance system), a smart meter/sensor, an unmanned vehicle (e.g., an industrial robot, a quadcopter, etc.) and its component (e.g., a self-driving car computer), industrial manufacturing equipment, a global positioning system (GPS) device, an Internet-of-Things (loT) device, an Industrial loT (HoT) device, a machine-type communication (MTC) device, a group of Massive loT (MIoT) or Massive MTC (mMTC) devices/sensors, or any other suitable device that uses the radio waves for operation. In some embodiments, the UE may refer to at least two collocated and interconnected UEs thus defined.

FIG. 1 shows a schematic top view of a wireless CPE 100 typically used in a conventional SON. The SON may be a RAN in which the CPE 100 communicates with a base station, for example. The CPE 100 may be implemented, for example, as a wireless router. As shown in FIG. 1 , the CPE 100 comprises four Antenna-in-Package (AIP) modules 102-1 , 102-2, 102-3, 102-4. Each of the AIP modules 102-1 , 102-2, 102-3, 102-4 covers a 90° sector, i.e. has a scan range up to 90°. There may be more than four AIP modules in the CPE 100, if required. The CPE 100 suffers from at least the following disadvantages: the scan range is only ±45° in the vertical plane, and the scan range is only ±45° in the horizontal plane, and each of the AIP modules 102-1 , 102-2, 102-3, 102-4 needs its own module for generating a radio wave (e.g., in a mm-wave band).

The CPE 100 could be enhanced by using lens antennas instead of the AIP modules 102-1 , 102-2, 102-3, 102-4. However, the existing lens antennas are too large for use in CPEs like the CPE 100. Furthermore, the existing lens antennas are not used for beam tilting (which may be required to optimize the SON operation), and typically deals with fixed beams.

The exemplary embodiments disclosed herein provide a technical solution that allows mitigating or even eliminating the above-sounded drawbacks peculiar to the prior art. In particular, the exemplary embodiments disclosed herein provide an antenna apparatus that is configured to radiate a radio beam with a high gain and in a wide angular range in one (horizontal or vertical) plane, thereby providing high-gain wide-angle beam scanning in that plane. To achieve this, the antenna apparatus is provided with a refractive device that is configured to widen the radio beam in a first plane and to narrow the radio beam in a second plane perpendicular to the first plane. In some embodiments, the gain and scan range of the antenna apparatus may be improved by using reflectors properly arranged around an array of radiators included in the antenna apparatus.

FIG. 2 shows a schematic perspective view of an antenna apparatus 200 in accordance with a first exemplary embodiment. As noted earlier, the antenna apparatus 200 may be implemented as part of a UE. The UE may, e.g., be a CPE, such as the CPE 100 shown in FIG. 1. As shown in FIG. 2, the antenna apparatus 200 comprises an array 202 of radiators (schematically shown as two light-gray lines) configured to radiate a radio beam, and a refractive device 204 having an optical axis 206 that passes through the array 202 of radiators. The refractive device 204 is arranged such that it is in the path of the radio beam radiated by the array 202 of radiators. The refractive device 204 is configured to widen the radio beam in a first plane 208 (i.e. to widen the beamforming angular range of the radio beam), thereby increasing the scan range of the antenna apparatus 200 in the first plane 208. The refractive device 204 is further configured to narrow the radio beam in a second plane 210, thereby increasing the gain of the antenna apparatus 200 in the second plane 210. The first plane 208 and the second plane 210 are mutually orthogonal and intersect in the optical axis 206. As used in the embodiments disclosed herein, the term “array of radiators” should be construed as encompassing not only radiators themselves (or, in other words, antenna elements) but also a substrate or support which carries the radiators, as well as wires (e.g., in the form of conductive tracks) connected the radiators to a signal generator or processor (not shown) that is external relative to the antenna apparatus 100 (at the same time, both the antenna apparatus 200 and the signal generator or processor may be included in the same CPE). It should be also noted that the number, shape and arrangement of the constructive elements constituting the antenna apparatus 200, which are shown in FIG. 2, are not intended to be any limitation of the present disclosure, but merely used to provide a general idea of how the constructive elements may be implemented within the antenna apparatus 200. For example, the number of rows and columns of radiators in the array 202 of radiators 202 may vary depending on particular applications, as well as the refractive device 204 may be arranged such that its optical axis 206 is not perpendicular to the array 202 of radiators.

In one embodiment, the refractive device 204 may be assembled (e.g., glued) from pieces or layers of different low-loss radio-frequency materials such that it provides the above-mentioned widening and narrowing of the radio beam passing therethrough. Such a multipiece or multilayer composite structure may improve mechanical parameters, such as strength, weight, robustness from environmental impacts. Furthermore, the multipiece or multilayer composite structure may improve visual appearance and reduce production costs. The refractive device 204 may additionally include fiberglass, polyurethane foams, polycarbonate, polystyrene, acrylonitrile butadiene styrene, glass, and their composites.

In another embodiment, the refractive device 204 may be made of a single low-loss radiofrequency material (e.g., by means of molding, casting, etc.), and the above-mentioned widening and narrowing of the radio beam passing therethrough may be achieved by selecting a certain profile of the refractive device 204.

FIGs. 3A-3C show different schematic views of a refractive device 300 in accordance with one exemplary embodiment. More specifically, FIG. 3A shows a schematic perspective view of the refractive device 300, FIG. 3B shows a schematic sectional view of the refractive device 300 which is taken along a contour line 302 in FIG. 3A (i.e. a longitudinal section of the refractive device 300), and FIG. 3C shows a schematic sectional view of the refractive device 300 which is taken along a contour line 304 in FIG. 3A (i.e. a cross-section of the refractive device 300). The refractive device 300 may be used in the antenna apparatus 200 instead of the refractive device 204. As shown in FIGs. 3A-3C, the refractive device 300 is a dual-profile lens made of a single low-loss radio-frequency material. To provide the above-mentioned widening and narrowing of the radio beam, the refractive device 300 should be arranged in the antenna apparatus 200 such that it is concave (like in FIG. 3B) in the first plane 208 and convex (like in FIG. 3C) in the second plane 210. FIG. 4 shows a cutaway perspective view of an antenna apparatus 400 in accordance with a second exemplary embodiment. As noted earlier, the antenna apparatus 400 may be implemented as part of a UE (like the CPE 100 in FIG. 1). Similar to the antenna apparatus 200, the antenna apparatus 400 comprises an array 402 of radiators configured to radiate a radio beam, and a refractive device 404 having an optical axis 406 that passes through the array 402 of radiators. The refractive device 404 is arranged such that it is in the path of the radio beam radiated by the array 402 of radiators. The refractive device 404 is configured to widen the radio beam in a first plane 408 and to narrow the radio beam in a second plane 408. The first plane 408 and the second plane 410 are mutually orthogonal and intersect in the optical axis 406. In the example, the refractive device 404 is a dual-profile lens. In FIG. 4, the first plane 408 and the second plane 410 delimit a cutaway that reveals the profile (i.e. thickness) of the dual-profile lens. Unlike the antenna apparatus 200, the antenna apparatus 400 additionally comprises a first reflector 412 and a second reflector 414 which are arranged on opposite sides of the first plane 408 and face each other across a space between the array 402 of radiators and the refractive device 404. Furthermore, the antenna apparatus 400 additionally comprises a third reflector 416 and a fourth reflector 418 arranged on opposite sides of the second plane 410 near two opposite edge regions of the array 402 of radiators. The first reflector 412, the second reflector 414, the third reflector 416, and the fourth reflector 418 together form a conductive structure around the array 402 of radiators. This conductive structure may serve different purposes. For example, the first reflector 412 and second reflector 414 may additionally improve the gain of the antenna apparatus 400, while the third reflector 416 and fourth reflector 418 may improve scan range by reducing grating lobes in the radiation pattern of the antenna apparatus 400. Although the first reflector 412, the second reflector 414, the third reflector 416, and the fourth reflector 418 are shown as continuous walls, one or more of them may be implemented as a mesh wall, if required and depending on particular applications. The antenna apparatus 400 may optionally comprise a rigid structure 420 which uses as a support for the array 402 of radiators and each of the first reflector 412, the second reflector414, the third reflector 416, and the fourth reflector 418. The rigid structure 420 may additionally function as a heat sink for the array 420 of radiators.

As also follows from FIG. 4, the third reflector 416 and the fourth reflector 418 each extend away from the array 402 of radiators at a lower level than the array 402 of arrays. In another embodiment, the third reflector 416 and/or the fourth reflector 418 may be flush with the array 402 of radiators. In general, the third reflector 416 and the fourth reflector 418 may extend substantially parallel to the plane of the array 402 of radiators.

In one embodiment, the third reflector 416 and the fourth reflector 418 may be arranged around the array 402 of radiators such that they are outside an imaginary three-dimensional angular sector (not represented in the figure) that is defined by a vertex provided by a central axis of the array 402 of radiators, an angle bisector provided by the half-plane 410 of the second plane (the half-plane 410 extends from the vertex through the refractive device 404), and a central angle of at least 140 degrees, preferably at least 160 degrees. In the shown example, the central angle of the three-dimensional angular sector is approximately 180 degrees. The third reflector 416 and the further reflector 418 contribute to confining the radio beam to a wide but limited angular range in the first plane 408 and to feeding the radio wave from the array 402 of radiators to the refractive device 404.

As for the first reflector 412 and the second reflector 414, they may extend upwards at an angle relative to the plane of the array 402 of radiators. Moreover, the first reflector 412 and the second reflector 414 extend from the array 402 of radiators such that the radiation aperture formed by them gradually expands in a direction from the array 402 of radiators towards free space (through the refractive device 404). In some embodiments, this radiation aperture formed by the first reflector 412 and the second reflector 414 may be in the form of a truncated cone or horn (e.g., with a central angle greater than 90°).

In one embodiment, each of the first reflector 412, the second reflector 414, the third reflector 416 and the fourth reflector 418 may be fully made of a conductive material having reflective properties (e.g., metal). In another embodiment, each of the first reflector 412, the second reflector 414, the third reflector 416 and the fourth reflector 418 may comprise a substrate and a layer of conductive material provided on the substrate. The conductive material should have reflective properties. By so doing, it is possible to make the antenna apparatus 400 less expensive in terms of conductive material consumption.

FIG. 5 shows a cutaway perspective view of an antenna apparatus 500 in accordance with a third exemplary embodiment. As noted earlier, the antenna apparatus 500 may be implemented as part of a UE (like the CPE 100 in FIG. 1). Similar to the antenna apparatus 200, the antenna apparatus 500 comprises an array 502 of radiators configured to radiate a radio beam, and a refractive device 504 having an optical axis 506 that passes through the array 502 of radiators. The refractive device 504 is arranged such that it is in the path of the radio beam radiated by the array 502 of radiators. The refractive device 504 is configured to widen the radio beam in a first plane 508 (i.e. the beamforming angular range of the radio beam in the first plane 508), thereby increasing the scan range of the antenna apparatus 500 in the first plane 508. The refractive device 504 is further configured to narrow the radio beam in a second plane 510 (i.e. narrow the beamforming angular range of the radio beam in the second plane 510), thereby increasing the gain of the antenna apparatus 500 in the second plane 510. The first plane 508 and the second plane 510 are mutually orthogonal and intersect in the optical axis 506. In the example, the first plane 508 and the second plane 510 delimits a cutaway that reveals the profile (i.e. thickness) of the dual-profile lens. Unlike the antenna apparatus 200 but similar to the antenna apparatus 400, the antenna apparatus 500 additionally comprises a first reflector 512 and a second reflector 514 which are arranged on opposite sides of the first plane 508 and face each other across a space between the array 502 of radiators and the refractive device 504. Furthermore, the antenna apparatus 500 additionally comprises a third reflector 516 and a fourth reflector (not shown in FIG. 5) arranged on opposite sides of the second plane 510 near two opposite edge regions of the array 502 of radiators. The first reflector 512, the second reflector 514, the third reflector 516, and the fourth reflector together form a conductive structure around the array 502 of radiators. This conductive structure may serve the same purposes as the conductive structure shown in FIG. 4. In general, the first reflector 512, the second reflector 514, the third reflector 516, and the fourth reflector may be implemented in the same or similar way as the first reflector 412, the second reflector 414, the third reflector 416, and the fourth reflector 418, respectively. Furthermore, the antenna apparatus 500 may optionally comprise a rigid structure 518 that serves the same purposes as the rigid structure 420.

At the same time, the antenna apparatus 500 differs from the antenna apparatus 400 in that the refractive device 504 (unlike the refractive device 404) is implemented as a lens cap that is installed on top ends of the first reflector 512 and the second reflector 514, thereby covering the radiation aperture formed by the first reflector 512 and the second reflector 514. To make such an installation possible, the refractive device 504 may comprise several protrusions 520. The protrusions 520 may have such a shape that allows them to tightly clasp the top ends of the first reflector 512 and the second reflector 514, thereby firmly securing the refractive device 504 on the first reflector 512 and the second reflector 514. However, any other ways of installation, such, for example, as gluing, mounting by using fasteners, etc., are also possible.

FIG. 6 shows an exploded perspective view of an antenna apparatus 600 in accordance with a fourth exemplary embodiment. As noted earlier, the antenna apparatus 600 may be implemented as part of a UE (like the CPE 100 in FIG. 1). Similar to the antenna apparatus 200, the antenna apparatus 600 comprises an array 602 of radiators configured to radiate a radio beam, and a refractive device 604 having an optical axis 606 that passes through the array 602 of radiators when the antenna apparatus 600 in the assembled condition. More specifically, the refractive device 604 should be installed above the array 602 of radiators such that axes A-A’ and B-B’ of the refractive device 604 are aligned with corresponding axes A-A’ and B-B’ of the array 602 of radiators. With this installation, the refractive device 604 is in the path of the radio beam radiated by the array 602 of radiators. The refractive device 604 is configured to widen the radio beam in a first plane (i.e. widen the beamforming angular range of the radio beam in the first plane) and to narrow the radio beam in a second plane (i.e. narrow the beamforming angular range of the radio beam in the second plane). The first plane is intended to pass along the axis A-A’ and perpendicular to the array 602 of radiators, while the second plane is intended to pass along the axis B-B’ and perpendicular to the array 602 of radiators. The first plane and the second plane are mutually orthogonal and intersect in the optical axis 606. Unlike the antenna apparatus 200 but similar to the antenna apparatuses 400 and 500, the antenna apparatus 500 additionally comprises a first reflector 608 and a second reflector 610 which are arranged on opposite sides of the first plane and face each other across a space between the array 602 of radiators and the refractive device 604. As follows from FIG. 6, the first reflector 608 and the second reflector 610 have a trapezoidal cross-section. Furthermore, the antenna apparatus 600 comprises a third reflector 612 and a fourth reflector 614 arranged on opposite sides of the second plane near two opposite edge regions of the array 602 of radiators. The first reflector 608, the second reflector 610, the third reflector 612, and the fourth reflector 614 together form a conductive structure around the array 602 of radiators. This conductive structure may serve the same purposes as the conductive structures shown in FIGs. 4 and 5. In general, the first reflector 608, the second reflector 610, the third reflector 612, and the fourth reflector 614 may be implemented in the same or similar way as the first reflector 412, the second reflector 414, the third reflector 416, and the fourth reflector 418, respectively.

FIGs. 7A and 7B shows differential sectional views of the antenna apparatus 600. More specifically, FIG. 7A is a sectional view obtained by cutting the antenna apparatus 600 with the first plane (i.e. along the axis A-A’), while FIG. 7B is a sectional view obtained by cutting the antenna apparatus 600 with the second plane (i.e. along the axis B-B’). As can be seen, the refractive device 604 is implemented as a dual-profile lens (like the refractive device 300, 404 or 504) that has a divergent (concave) profile in the first plane or, in other words, along the axis A-A’ (see FIG. 7A), and a convergent (convex) profile in the second plane or, in other words, along the axis B-B’ (see FIG. 7B).

As follows from FIG. 7A, the divergent profile is implemented in the first plane such that a lens thickness h increases and an air gap R between the array 602 of radiators and the refractive device 604 decreases in a direction from the center of the array 602 of radiators toward two opposite edge regions of the array 602 of radiators which are located on opposite sides of the second plane (i.e. to the left and to the right from the center of the array 602 of radiators in FIG. 7A). In other words, the refractive device 604 is aspheric in the first plane, i.e. an effective radius coming from the center of the array 602 of radiators to the refractive device 604 is angular-dependent, R(cp), where (p is the angle relative to the normal to the array 602 of radiators (in FIG. 7A, this normal coincides with the optical axis 606). Thus, the lens thickness h increases from a normal direction (see hi) towards a horizontal direction (see h2). The divergent profile in the first plane (i.e. along the axis A-A’) allows an increase in the scan range of up to ±70°. At the same time, the gain of the antenna apparatus 600 is stabilized.

Relative to FIG. 7B, the convergent profile is implemented in the second plane such that the lens thickness h reduces and the air gap R increases in a direction from the center of the array 602 of radiators toward two opposite edge regions of the array 602 of radiators that are located on the opposite sides of the first plane (i.e. to the left and to the right from the center of the array 602 of radiators in FIG. 7B). The convergent profile in the second plane allows the gain of the antenna apparatus 600 to be improved. In some embodiments, the gain may be improved back to the same level as without the dual-profile lens 604. The first reflector 608, the second reflector 610, and the convergent profile in the second plane together provide a 2.5 dB gain improvement. In addition, the convergent profile reduces side lobes, and focuses the radio beam in the normal direction relative to the array 602 of radiators. In some other embodiments, the gain may be improved even to a higher level as compared to the situation without the dual-profile lens 604.

Having the dual-profile refractive device 604, it is possible to tilt a radio beam even more (compared to a single-profile lens), thus making it possible to tilt energy even more, thereby increasing the scan range. At the same time, the combination of the refractive device 604 and the conductive structure constituted by the first reflector 608, the second reflector 610, the third reflector 612, and the fourth reflector 614 allows additionally improving this beam tilting capability. This is also true for the combination of the refractive device and the conductive structure which are shown in FIG. 4 or FIG. 5.

The presence of the conductive structure (like the one shown in any of FIGs. 4-6) allows forming the so-called travelling wave. By combining the conductive structure with the refractive device (like the one shown in any of FIGs. 3-6), it is possible to cause the travelling wave to propagate along the refractive device and radiate towards the free space at a tilted direction.

FIGs. 8A and 8B show an electric field distribution in the antenna apparatus 600 in the absence and presence of the third reflector 612 and the fourth reflector 614, respectively. More specifically, the electric field distribution is shown in the first plane (i.e. along the axis A-A’). As can be seen, the third reflector 612 and the fourth reflector 614 significantly improve the propagation of the travelling wave along the refractive device 604 towards the free space (see the dashed areas in FIGs. 8A and 8B). It should be noted that similar results may be obtained for the antenna apparatuses 400 and 500.

FIGs. 9A and 9B show an electric field distribution in the antenna apparatus 600 in the absence and presence of the first reflector 608 and the second reflector 610, respectively. More specifically, the electric field distribution is shown in the second plane (i.e. along the axis B- B’). As can be seen, the first reflector 608 and the second reflector 610 significantly mitigate parasitic surface waves and reduce side-lobes (see the dashed areas in FIGs. 9A and 9B). It should be noted that similar results may be obtained for the antenna apparatuses 400 and 500.

In yet other words, the conductive structure allows controlling the beam shaping and beam tilting capabilities of the antenna apparatus 400, 500, or 600, so that with a suitable conductive structure, stable dual-polarization beam tilting may be achieved. Thus, the conductive structure improves the uniformity of the beam coverage for a certain angular range. Without the conductive structure, the beam stability would be degraded, resulting in parasitic beam ripples, blind angles, and various disruptions of the radio beam. In turn, the beam ripples are reduced by using the conductive structure, thus improving the scan range.

FIGs. 10A-10D show how the presence of a dual-profile lens allows reducing the so-called grating lobes. A grating lobe is a known problem in the field of antenna arrays, and it may be reduced by using any of the antenna apparatuses 400, 500, and 600. The grating lobes are caused by the spatial aliasing effect of electromagnetic (EM) waves constructively interfering at an undesired direction. That direction is defined by the periodicity (pitch) of radiators or antenna elements in an array. Non-uniform gaps between each radiator and the inner surface of the dual profile lens (like the one shown in FIG. 3, for example) cause local distortions of the EM waves radiated by each radiator. As a result, conditions for constructive interference are not met, the grating lobes are reduced, and EM energy is redirected towards intended spatial directions. FIGs. 10A and 10B show a change in a radiation pattern in the absence and presence of the dual-profile lens, respectively, while FIGs. 10C and 10D show a change in an electric field distribution in the absence and presence of the dual-profile lens, respectively. One can easily see that the presence of the dual-profile lens significantly reducing the grating lobes.

FIG. 11 shows dependencies of a gain on a scanning angle in one plane for different antenna apparatuses. More specifically, FIG. 11 shows scan ranges of the different antenna apparatuses in a horizontal plane (which may correspond to the above-described first plane). A short-dashed curve is obtained by using a conventional AIP module like the one shown in FIG. 1 (i.e. the AIP module without any dual-profile lens and conductive structure). A long- dashed curve corresponds to an antenna apparatus having a conventional single-profile deflection lens and a conductive structure like the one shown in FIG. 6 (for convenience, this antenna apparatus is further referred to as the maximum scan range structure). A thin solid curve corresponds to an antenna apparatus having a conventional single-profile deflection lens but without any conductive structure (i.e. no reflectors around an array of radiators). A bold solid curve corresponds to the antenna apparatus 600. As can be seen, the antenna apparatus 600 allows increasing the scan range from +/-4O ⁰ provided by the conventional AIP module (see the short-dashed curve) to +/-55 ⁰ (see the bold solid curve) at 13.6 dBi, and even to +/- 70° provided by the maximum scan range structure (see the long-dashed curve), as shown in Fig. 11 by using the vertical straight lines. The antenna apparatus 600 provides the same gain but a wider tilted beam as compared to the conventional AIP module without any dual-profile lens and conductive structure. Furthermore, the gain at the tilted beam direction of -55° is improved by 2.4 dBi: from 11.2 dBi to 13.6 dBi, as shown in Fig. 11 by using the horizontal straight lines. Although the exemplary embodiments of the present disclosure are described herein, it should be noted that any various changes and modifications could be made in the embodiments of the present disclosure, without departing from the scope of legal protection which is defined by the appended claims. In the appended claims, the word “comprising” does not exclude other elements or operations, 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 measures cannot be used to advantage.