TECHNICAL FIELD

The present disclosure relates generally to the field of wireless communication; and more specifically, to an antenna device which features very low side lobe radiation (e.g. reduced undesired radiation lobes) and suitable for use in next generation wireless communication system.

BACKGROUND

With evolution of wireless communication technologies, such as fifth generation (5G) technology, long term evolution (LTE) advanced, LTE advanced pro (e.g. 4.5G) technology, or an upcoming sixth generation (6G), an antenna device (or an antenna arrray) with enhanced radiation characteristics is required. The quality of radiation characteristics (i.e. radiation patterns) can be enhanced by reducing undesired radiation lobes (e.g. side lobes). The reduction of undesired radiation lobes decreases interference to other cells as well as to other systems (e.g. satellites). Moreover, the reduction of undesired radiation lobes reduces the electromagnetic field (EMF) and hence, electromagnetic interference (EMI) to other frequencies in the electromagnetic spectrum. Typically, used non-overlapping arrays (e.g. phased antenna arrays) have high grating lobes (i.e. side lobes), particularly when the nonoverlapping arrays are composed of contiguous sub-arrays (i.e. sub-arrays those are adjacent to each other) with a large space in between and therefore, electrical steering also takes place among the contiguous sub-arrays.

Currently, certain attempts have been made to reduce the grating lobes (i.e. side lobes) radiations such as a conventional overlapped arrays (or overlapped antenna arrays). The conventional overlapped antenna arrays eliminate the grating lobes (i.e. side lobes) partially and are cost-intensive to implement. Typically, the conventional overlapped antenna arrays are employed either by use of a conventional resistive network or a conventional non- resistive network. The conventional resistive network make use of Wilkinson power combiners in order to share input signals with contiguous radiating elements (or radiators) and hence, realize overlapping of sub-arrays. Therefore, the conventional overlapped antenna arrays when employed by use of the conventional resistive network are somewhat simple and cost effective, however, possess high losses due to the presence of resistive elements of the Wilkinson power combiners, hence, are less preferred. In another example, the conventional overlapped antenna arrays may employ the conventional non-resistive network, which make use of cascades of 180-degree directional couplers in oder to share input signals with contiguous radiating elements (or radiators), and hence realize overlapping of sub-arrays. The conventional non-resistive network have relatively more complex layout and lower losses in comparison to the conventional resistive network. Moreover, the conventional non-resistive network do not radiate a sub-array beam which is selective enough to cut-out the grating lobes (i.e. side lobes) significantly within a beam scanning range appropriate for the fifth generation (5G) technology. Thus, there exists a technical problem of an inefficient antenna device (or antenna array) that manifests reduced efficiency, high losses and inadequate reduction of the grating lobes (i.e. side lobes), therefore, is not desirable with reduced efficiency (or non-optimal) for use in the wireless communication technologies such as 4.5G, 5G, and the like.

Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks associated with the conventional antenna device (or antenna arrays).

SUMMARY

The present disclosure seeks to provide an antenna device (or antenna arrays) which features very low side lobe radiation and is suitable for use in next generation wireless communication technologies such as 4.5G or 5G technology. The present disclosure seeks to provide a solution to the existing problem of an inefficient antenna device (or antenna array) that manifests reduced efficiency, high losses and inadequate reduction of the grating lobes (i.e. side lobes). An aim of the present disclosure is to provide a solution that overcomes at least partially the problems encountered in prior art, and provides an improved antenna device (or antenna array) with an improved efficiency, low losses and with significant reduction of the grating lobes (i.e. side lobes) therefore, is suitable for use in the next generation wireless communication technologies such as 4.5G technology or 5G technology. The object of the present disclosure is achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.

In one aspect, the present disclosure provides an antenna device comprising one or more power dividers, each configured to receive an input signal and output three intermediate signals. The antenna device further comprises three or more beamforming matrices, BFMs, each configured to receive one or more intermediate signals and output three feed signals, wherein each power divider is configured to output the three intermediate signals to three adjacent BFMs. The antenna device further comprises an array of radiators, including one sub-array for each beamforming matrix, BFM, wherein each sub-array comprises three radiators and the three radiators of each sub-array are arranged to receive the three feed signals from a respective BFM.

The antenna device of the present disclosure provides an array of overlapped sub-arrays which significantly alleviates the grating lobes (i.e. side lobes), or reduces undesired radiation lobes that cause interference to other cells, or systems. Each sub-array radiates a flat-topped beam whose beamwidth is determined by scanning range. The radiated flattopped beam is such that it cuts out the grating lobes of the array factor and thus, significantly reduces the side lobe level (SLL) even when the flat-topped beam is scanned. In this way, the disclosed antenna device features very low side lobe radiation along with the predefined scanning range (approximately 0° - 15° off-axis). Moreover, the disclosed antenna device possesses relatively lower losses in comparison to the conventional resistive networks because of the use of transmission lines in a feeding network of the device instead of passive components (e.g. resistors). The disclosed antenna device presents a reduced complexity as compared to a conventional antenna device which uses overlapped-array feeding networks. Since, the disclosed antenna device features very low side lobe radiation and low losses therefore, the disclosed antenna device is suitable for use in next generation wireless communication technologies such as 4.5G technology or 5G technology.

In an implementation form, each beam forming matrix, BFM includes a plurality of internal lines. The BFM further includes a plurality of 90-degree couplers arranged to connect each one of the internal lines to another one of the internal lines. The BFM further includes one or more delay lines on each internal line.

The disclosed antenna device makes use of 90-degree couplers and a specific arrangement of the BFM ports which result in a more uniform phase distribution feeding to each subarray of radiators related to each beam forming matrix (BFM) in comparison to the conventional overlapped arrays which use 180-degree couplers and produces anon-uniform phase distribution.

In a further implementation form, each beam forming matrix, BFM includes an input delay line on each internal line, and an output delay line on each internal line; wherein the plurality of 90-degree couplers are arranged between the input and output delay lines.

The beam forming matrix (BFM) of the disclosed antenna device possesses an innovative selection of the delay lines on each internal line and thereby offers a steeper rejection of the grating lobes and hence, very low side lobe levels (approximately below -15dB).

In a further implementation form, a first internal line and a second internal line are connected with a 1:2 90 degree-coupler, and the second internal line and a third internal line are connected with two 1:1 90-degree couplers and wherein the 1:2 90-degree coupler is arranged between the two 1:1 90-degree couplers.

The disclosed antenna device produces an enhanced uniform phase distribution because of interconnections between the internal lines and the 90-degree directional couplers.

In a further implementation form, the third internal line includes an additional delay line arranged between the two 1:1 90-degree couplers.

By virtue of the additional delay line, the disclosed antenna device provides steeper rejection of grating lobes and hence, significantly reduces the side lobe level (SLL).

In a further implementation form, first, second and third feed signals from each BFM are provided respectively to second, third and first radiators in the corresponding sub-array.

Because of such internal connections, the sub-array radiation pattern of the disclosed antenna device can be made more selective towards grating lobes. In a further implementation form, the number of power dividers is between 2 and 6.

In an example, four power dividers can be used depending on a use case. In another example, six power dividers can also be used.

In a further implementation form, each BFM receives between 1 and 3 intermediate signals.

Each beam forming matrix (BFM) receives minimum 1 and maximum 3 intermediate signals in order to get interconnected to other BFM in a specific interleaved fashion.

In a further implementation form, each input signal is provided from an input port through a user-defined phase shifter.

By use of the input port, beam steering of the disclosed antenna device can be performed.

In a further implementation form, the aforesaid antenna device is formed in a three-layer structure; wherein a first layer includes the one or more power dividers, a second layer includes the three of more BFMs, and a third later includes a feed arrangement providing the feed signals to the array of radiators.

The disclosed antenna device can be implemented by use of the three-layer structure of transmission lines to compose the feeding network. The three-layer structure can be realized by use of a typical printed circuit board (PCB) technology.

In a further implementation form, the antenna device further comprises a second plurality of power dividers and a second plurality of BFMs; wherein each radiator in the radiator array is a dual-polarised radiator configured to receive a first feed signal from one of the first plurality of BFMs and a second feed signal from the one of the second plurality of BFMs.

The disclosed antenna device can be designed and implemented with a duplicity of the power dividers and the BFMs by virtue of the dual-polarized radiators in the radiator array.

It has to be noted that all devices, elements, circuitry, units and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof. It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.

Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations construed in conjunction with the appended claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.

Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:

FIG. 1 A is an illustration of an antenna device, in accordance with an embodiment of the present disclosure;

FIG. IB is a circuit diagram of a beam forming matrix (BFM), in accordance with an embodiment of the present disclosure;

FIG. 1C is an illustration of internal interconnections of an antenna device, in accordance with another embodiment of the present disclosure; FIG. 2 is a graphical representation that illustrates normalized radiation pattern of an antenna device, in accordance with an embodiment of the present disclosure;

FIG. 3 is a graphical representation that illustrates normalized radiation pattern of an antenna device, in accordance with another embodiment of the present disclosure;

FIG. 4A is a graphical representation that illustrates feeding amplitudes of sub-array elements of an antenna device, in accordance with another embodiment of the present disclosure;

FIG. 4B is a graphical representation that illustrates feeding phases of sub-array elements of an antenna device, in accordance with another embodiment of the present disclosure;

FIG. 5 A is a graphical representation that illustrates normalized radiation pattern of an antenna device, in accordance with an embodiment of the present disclosure;

FIG. 5B is a graphical representation that illustrates normalized radiation pattern of an antenna device, in accordance with an embodiment of the present disclosure;

FIG. 6A is a graphical representation that illustrates feeding amplitudes of sub-array elements of an antenna device, in accordance with an embodiment of the present disclosure;

FIG. 6B is a graphical representation that illustrates feeding amplitudes of sub-array elements of an antenna device, in accordance with an embodiment of the present disclosure;

FIG. 7A is an illustration of an antenna device, in accordance with an embodiment of the present disclosure;

FIG. 7B is a graphical representation that illustrates the radiation pattern corresponding to an implementation of the antenna device (of FIG. 7A) with 18 elements, in accordance with an embodiment of the present disclosure;

FIG. 7C is an illustration of an antenna device, in accordance with another embodiment of the present disclosure; FIG. 7D is a graphical representation that illustrates the radiation pattern corresponding to an implementation of the antenna device (of FIG. 7C) with 12 elements in accordance with another embodiment of the present disclosure; and

FIG. 8 is a three-layer network of an antenna device, in accordance with an embodiment of the present disclosure.

In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the nonunderlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

DETAILED DESCRIPTION OF EMBODIMENTS

The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.

FIG. 1 A is an illustration of an antenna device, in accordance with an embodiment of the present disclosure. With reference to FIG. 1A, there is shown an antenna device 100A. The antenna device 100A includes one or more phase shifters such as a first phase shifter 102A, a second phase shifter 102B, a third phase shifter 102C and a fourth phase shifter 102D, one or more power dividers such as a first power divider 104A, a second power divider 104B, a third power divider 104C and a fourth power divider 104D, one or more beam forming matrices (BFM) such as a first beam forming matrix (BFM) 106A, a second BFM 106B, a third BFM 106C, a fourth BFM 106D, a fifth BFM 106E and a sixth BFM 106F and an array of radiators 108. The antenna device 100A further includes one or more input signals such as a first input signal 110A, a second input signal HOB, a third input signal HOC and a fourth input signal HOD, one or more intermediate signals such as a first intermediate signal H2A, a second intermediate signal 112B and a third intermediate signal 112C as output from the first power divider 104A, a first intermediate signal 114A, a second intermediate signal 114B and a third intermediate signal 114C as output from the second power divider 104B and similarly, up to intermediate signals 118A, 118B and 118C as output from the fourth power divider 104D. The antenna device 100A further includes one or more feed signals such as a first feed signal 120A, a second feed signal 120B and a third feed signal 120C as ouput from the first beam forming matrix (BFM) 106A, a first feed signal 122A, a second feed signal 122B and a third feed signal 122C as ouput from the second beam forming matrix (BFM) 106B and similarly, up to feed signals 130A, 130B, 130C from the sixth BFM 106F. The array of radiators 108 includes one or more sub-arrays such as a first sub-array 132, a second sub-array 134, a third sub-array 136, a fourth sub-array 138, a fifth sub-array 140 and a sixth sub-array 142. The array of radiators 108 and the associated sub-arrays are represented by dashed rectangular boxes, which is used for illustration purpose only and do not form a part of circuitry.

In operation, each of the first phase shifter 102A, the second phase shifter 102B, the third phase shifter 102C and the fourth phase shifter 102D includes suitable logic, circuitry, and/or interfaces that is configured to provide the first input signal 110A, the second input signal HOB, the third input signal HOC and the fourth input signal HOD to the first power divider 104A, the second power divider 104B, the third power divider 104C and the fourth power divider 104D, respectively. Each of the first input signal 110A, the second input signal HOB, the third input signal HOC and the fourth input signal HOD has a phase shift which is introduced by the first phase shifter 102A, the second phase shifter 102B, the third phase shifter 102C and the fourth phase shifter 102D, respectively.

Each of the first power divider 104A, the second power divider 104B, the third power divider 104C and the fourth power divider 104D is configured to receive the first input signal 110A, the second input signal HOB, the third input signal HOC and the fourth input signal HOD, respectively and output three intermediate signals. The first power divider 104A receives the first input signal 110A and provides three intermediate signals in output such as the first intermediate signal 112A, the second intermediate signal 112B and the third intermediate signal H2C. The three intermediate signals are provided to three adjacent beam forming matrices (BFM) such as the first intermediate signal 112A, the second intermediate signal 112B and the third intermediate signal 112C is provided to the first BFM 106A, the second BFM 106B and to the third BFM 106C, respectively. Similarly, the second power divider 104B receives the second input signal HOB and provides three intermediate signals in output such as the first intermediate signal 114A, the second intermediate signal 114B and the third intermediate signal 114C to the second BFM 106B, the third BFM 106C and the fourth BFM 106D, respectively. Similarly, the third power divider 104C and the fourth power divider 104D receives the third input signal HOC and the fourth input signal HOD, respectively and provides 116A, 116B, 116C and 118A, 118B, 118C intermediate signals in output, respectively.

Each of the first beam forming matrix (BFM) 106A, the second BFM 106B, the third BFM 106C, the fourth BFM 106D, the fifth BFM 106E and the sixth BFM 106F is configured to receive one or more intermediate signals and output three feed signals. Generally, a beam forming matrix (BFM) is used to feed an antenna array (or array of radiators) such as the array of radiators 108 and to control the direction of a beam or beams of radio transmission. The three feed signals are used to feed the radiators of the array of radiators 108. The first beam forming matrix (BFM) 106A receives one intermediate signal such as the first intermediate signal 112A from the first power divider 104A and provides three feed signals such as the first feed signal 120A, the second feed signal 120B and the third feed signal 120C. The second beam forming matrix (BFM) 106B receives two intermediate signals such as the second intermediate signal 112B from the first power divider 104A and the first intermediate signal 114A from the second power divider 104B and provides three feed signals such as the first feed signal 122A, the second feed signal 122B and the third feed signal 122C. The third beam forming matrix (BFM) 106C receives three intermediate signals such as the third intermediate signal 112C from the first power divider 104A, the second intermediate signal 114B from the second power divider 104B and the first intermediate signal 116A from the third power divider 104C and provides three feed signals such as the first feed signal 124A, the second feed signal 124B and the third feed signal 124C. Similarly, each of the fourth beam forming matrix (BFM) 106D and the fifth beam forming matrix (BFM) 106E receive three intermediate signals and provides 126A, 126B, 126C and 128A, 128B, 128C as feed signals, respectively. The sixth beam forming matrix (BFM) 106F receives one intermediate signal such as the third intermediate signal 118C from the fourth power divider 104D and provides three feed signals 130A, 130B and 130C as output. In this embodiment, 6 beam forming matrices are used. In another embodiment, 3 beam forming matrices may be used. The structure of a beam forming matrix (BFM) is further described in detail, for example, in FIG. IB.

The array of radiators 108 includes one sub-array for each beam forming matrix (BFM) such as the first sub-array 132, the second sub-array 134, the third sub-array 136, the fourth subarray 138, the fifth sub-array 140 and the sixth sub-array 142 for the first beam forming matrix (BFM) 106A, the second BFM 106B, the third BFM 106C, the fourth BFM 106D, the fifth BFM 106E and the sixth BFM 106F, respectively. Each sub-array comprises three radiators and the three radiators of each sub-array are arranged to receive the three feed signals from a respective BFM. The first sub-array 132 includes three radiators such as a first radiator 132A, a second radiator 132B and a third radiator 132C which are configured to radiate the three feed signals such as the first feed signal 120A, the second feed signal 120B and the third feed signal 120C, respectively, which are received from the first beam forming matrix (BFM) 106A. Similarly, the second sub-array 134 includes three radiators such as a first radiator 134A, a second radiator 134B and a third radiator 134C which are configured to radiate the three feed signals such as the first feed signal 122A, the second feed signal 122B and the third feed signal 122C, respectively, received from the second beam forming matrix (BFM) 106B. In the same way, the third sub-array 136, the fourth subarray 138, the fifth sub-array 140 and the sixth sub-array 142 operate. The sixth sub-array 142 includes three radiators such as a first radiator 142A, a second radiator 142B and a third radiator 142C which are configured to radiate the three feed signals such as the first feed signal 130A, the second feed signal 130B and the third feed signal 130C, respectively, received from the sixth beam forming matrix (BFM) 106F.

In accordance with an embodiment, first, second and third feed signals from each BFM are provided respectively to second, third and first radiators in the corresponding sub-array. For example, the first feed signal 120A, the second feed signal 120B and the third feed signal 120C, from the first beam forming matrix (BFM) 106A is provided to the second radiator 132B, the third radiator 132C and to the first radiator 132A, respectively, of the first subarray 132 for radiation. The internal connections of the feed signals from each BFM to the radiators in the corresponding sub-array is further described in detail, for example, in FIG. 1C. In accordance with an embodiment, the number of power dividers is between 2 and 6. In this embodiment, the number of power dividers is 4 such as the first power divider 104A, the second power divider 104B, the third power divider 104C and the fourth power divider 104D. It is to be understood by one of skill in the art that the number of power dividers may vary. For example, in a case where edge antenna elements (or radiators) are not cut-off, then 6 power dividers may be used.

In accordance with an embodiment, each beam forming matrix receives between 1 and 3 intermediate signals. For example, the first beam forming matrix (BFM) 106A receives one intermediate signal (i.e. 112A), the second beam forming matrix (BFM) 106A receives two intermediate signals (i.e. 112B and 114A) and the third beam forming matrix (BFM) 106C receives three intermediate signals (i.e. 112C, 114B and 116A). Therefore, each beam forming matrix (BFM) receives minimum 1 intermediate signal and maximum 3 intermediate signals.

In accordance with an embodiment, each input signal is provided from an input port through a user-defined phase shifter. Each input signal such as the first input signal 110A, the second input signal HOB, the third input signal HOC and the fourth input signal HOD are provided from the input port through the user-defined phase shifter such as the first phase shifter 102A, the second phase shifter 102B, the third phase shifter 102C, and the fourth phase shifter 102D, respectively.

In accordance with an embodiment, the antenna device 100A is formed in a three layer structure, wherein, a first layer includes the one or more power dividers, a second layer includes the three of more BFMs, and a third layer includes a feed arrangement providing the feed signals to the array of radiators 108. The two or more power dividers such as the first power divider 104A, the second power divider 104B, the third power divider 104C and the fourth power divider 104D together constitute the first layer of the antenna device 100A. Each of the first BFM 106A, the second BFM 106B, the third BFM 106C, the fourth BFM 106D, the fifth BFM 106E and the sixth BFM 106F constitutes the second layer of the antenna device 100A. The feed arrangement of providing the feed signals from each BFM to the corresponding sub-array of the array of radiators 108 constitutes the third layer of the antenna device 100A. The three layer structure of the antenna device 100A is further described in detail, for example, in FIG. 8.

In accordance with an embodiment, the antenna device 100A further comprises a second plurality of power dividers and a second plurality of BFMs, wherein, each radiator in the radiator array 108 is a dual-polarised radiator configured to receive a first feed signal from one of the first plurality of BFMs and a second feed signal from the one of the second plurality of BFMs. In a case, the antenna device 100A comprises the second plurality of power dividers and the second plurality of BFMs. For such a case, each radiator in the radiator array 108 function as the dual-polarised radiator and that is configured to receive the first feed signal from the first plurality of BFMs and the second feed signal from the one of the second plurality of BFMs.

In another embodiment, the antenna device 100A is used in a reciprocal way. In such an embodiment, each of the first power divider 104A, the second power divider 104B, the third power divider 104C and the fourth power divider 104D is configured to receive the three intermediate signals and transmits the first output signal 110A, the second output signal HOB, the third output signal HOC and the fourth output signal HOD, respectively. Alternatively stated, each of the first power divider 104A, the second power divider 104B, the third power divider 104C and the fourth power divider 104D is used reciprocally. For example, the first power divider 104A receives three intermediate signals such as the first intermediate signal 112A, the second intermediate signal 112B and the third intermediate signal 112C and provides the first output signal 110A in output. Similarly, the second power divider 104B, the third power divider 104C and the fourth power divider 104D operates in the reciprocal manner.

Thus, the antenna device 100A significantly alleviates the grating lobes (i.e. side lobes) by use of the array of radiators 108 (or array of overlapped sub-arrays). Each sub-array radiates a flat-topped beam whose beamwidth is determined by scanning range. The radiated flat- topped beam is such that it cuts out the grating lobes of the array factor and thus, significantly reduces the side lobe level (SLL) even when the flat-topped beam is scanned. This is further described in more detail, for example, in FIG. 2. In this way, the antenna device 100A features very low side lobe radiation along with the predefined scanning range (approximately 0° - 15° off-axis). Moreover, the antenna device 100A possesses relatively lower losses in comparison to a conventional antenna device (which is implemented by use of resistive networks) because of the use of metal and dielectrics in a feeding network of the device 100A instead of passive components (e.g. resistors). Since, the antenna device 100A features very low side lobe radiation and low losses therefore, the antenna device 100A is suitable for use in next generation wireless communication technologies, such as 4.5G technology or 5 G technology.

FIG. IB is a circuit diagram of a beam forming matrix (BFM), in accordance with an embodiment of the present disclosure. FIG. IB is described in conjunction with elements from FIG. 1A. With reference to FIG. IB there is shown a circuit architecture 100B of a beam forming matrix (BFM) such as the third beam forming matrix (BFM) 106C of FIG. 1A. The reason behind considering the third BFM 106C over the first BFM 106A and the second BFM 106B is that the third BFM 106C receives three intermediate signals whereas the first BFM 106A and the second BFM 106B receive one and two intermediate signals, respectively. The third BFM 106C includes three intermediate signals such as the third intermediate signal 112C from the first power divider 104A, the second intermediate signal 114B from the second power divider 104B and the first intermediate signal 116A from the third power divider 104C of FIG. 1A, (also represented by Pl, P2 and P3), respectively. The third BFM 106C further includes a plurality of internal lines such as a first internal line 144A, a second internal line 144B and a third internal line 144C. The third BFM 106C further includes three input delay lines such as a first input delay line 146A, a second input delay line 146B and a third input delay line 146C. The third BFM 106C further includes three output delay lines such as a first output delay line 148A, a second output delay line 148B and a third output delay line 148C. The third BFM 106C further includes three 90- degree directional couplers such as a first directional coupler 150A, a second directional coupler 150B and a third directional coupler 150C. The third BFM 106C further includes an additional delay line 152.

The third beam forming matrix (BFM) 106C is configured to receive three intermediate signals such as the third intermediate signal 112C from the first power divider 104A, the second intermediate signal 114B from the second power divider 104B and the first intermediate signal 116A from the third power divider 104C of FIG. 1A, (i.e. Pl, P2 and P3), respectively and provides three feed signals in the output. The three feed signals are used to feed the third sub-array 136 of the array of radiators 108 which in turn feed the three radiators such as the first radiator 136A, the second radiator 136B and the third radiator 136C, respectively.

Each of the three input delay lines such as the first input delay line 146A, the second input delay line 146B and the third input delay line 146C is used to introduce a specific delay in the respective intermediate signals. Similarly, each of the three output delay lines such as the first output delay line 148A, the second output delay line 148B and the third output delay line 148C is used to introduce a specific delay in the respective feed signals at output end.

Each of the three 90-degree directional couplers such as the first 90-degree directional coupler 150A, the second 90-degree directional coupler 150B and the third 90-degree directional coupler 150C is arranged to connect each one of the internal lines to another one of the internal lines. Generally, a 90-degree directional coupler is a four-port passive device and used to equally split an input signal into two output signals which have equal amplitudes and a phase difference of 90 degree from each other. Additionally, the 90-degree directional coupler is used to combine two input signals which are 90-degree apart from each other. The first 90-degree directional coupler 150A is a 1 :2 directional coupler whereas the second 150B and the third 90-degree directional coupler 150C are 1: 1 directional couplers. Each of the three 90-degree directional couplers is generally referred as a quadrature coupler.

In accordance with an embodiment, each BFM includes an input delay line on each internal line, and an output delay line on each internal line; wherein the plurality of 90-degree couplers are arranged between the input and output delay lines. The three input delay lines such as the first input delay line 146A, the second input delay line 146B and the third input delay line 146C are arranged on the first internal line 144A, the second internal line 144B and the third internal line 144C, respectively. Similarly, the three output delay lines such as the first output delay line 148A, the second output delay line 148B and the third output delay line 148C are arranged on the first internal line 144A, the second internal line 144B and the third internal line 144C, respectively. Each of the first 90-degree directional coupler 150A, the second 90-degree directional coupler 150B and the third 90-degree directional coupler 150C is arranged between the input and output delay lines. In accordance with an embodiment, the first internal line 144A and the second internal line 144B are connected with the 1 :290 degree-coupler 150A, and the second internal line 144B and the third internal line 144C are connected with two 1:1 90-degree couplers (i.e. the second 90-degree directional coupler 150B and the third 90-degree directional coupler 150C, respectively). The 1:2 90-degree coupler 150A is arranged between the two 1:1 90-degree couplers. Because of interconnections between the internal lines, the 90-degree directional couplers and the input/ output delay lines, the antenna device 100A offers a steeper rejection of the grating lobes and hence, provides very low side lobe levels (approximately below - 15dB).

In accordance with an embodiment, the third internal line 144C includes the additional delay line 152 arranged between the two 1:1 90-degree couplers (i.e. the second 90-degree directional coupler 150B and the third 90-degree directional coupler 150C, respectively). The additional delay line 152 is used to introduce a certain delay in an output of the second 90-degree directional coupler 150B and to provide the delayed output as an input to the third 90-degree directional coupler 150C.

FIG. 1C is an illustration of internal interconnections of an antenna device, in accordance with another embodiment of the present disclosure. FIG. 1C is described in conjunction with elements from FIGs. 1A and IB. With reference to FIG. 1C there is shown a circuit architecture 100C which illustrates internal interconnections of an antenna device such as the antenna device 100A (of FIG. 1A). The antenna device 100A includes an initial feeding stage 154, a beam forming network (BFN) 156, and an array of radiators 158.

The initial feeding stage 154 includes intermediate signals which are provided by one or more power dividers which corresponds to one of the first power divider 104A, the second power divider 104B, the third power divider 104C and the fourth power divider 104D of FIG. 1 A. In this embodiment, only one power divider is used to provide intermediate signals to three adjacent beam forming matrices (BFMs). The power divider is configured to receive an input signal which has a definite phase shift introduced by use of a user-defined phase shifter. In another embodiment, more than one power dividers may also be used.

The beam forming network (BFN) 156 includes three beam forming networks (BFNs) such as a first beam forming network 156A, a second beam forming network 156B and a third beam forming network 156C (also represented by BFN1, BFN2, and BFN3, respectively). Each of the first BFN (i.e. BFN1) 156A, the second BFN (i.e. BFN2) 156B and the third BFN (BFN3) 156C is configured to receive their respective intermediate signals from the initial feeding stage 154 and to provide feed signals to the array of radiators 158. Each of the first BFN (i.e. BFN1) 156A, the second BFN (i.e. BFN2) 156B and the third BFN (BFN3) 156C comprises 90-degree directional couplers and delay lines to provide feed signals. The feed signals are provided in groups of three signals such as a first feed signal, a second feed signal and a third feed signal from their respective beam forming networks. The feed signals are of different amplitudes and have a uniform phase distribution which is advantageous over a conventional antenna array where 180-degree directional couplers are used which produce a different phase distribution. The amplitudes and phase distribution of feed signals are described in detail, for example, in FIGs. 4A and 4B, respectively. In this embodiment only 3 beam forming networks (or beam forming matrices) are used. In another embodiment 6 beam forming networks (or beam forming matrices) may also be used.

The array of radiators 158 include sets of three radiators which together compose a subarray. The array of radiators 158 includes three sub-arrays such as a first sub-array 158A, a second sub-array 158B and a third sub-array 158C. Each of the first sub-array 158A, the second sub-array 158B and the third sub-array 158C corresponds to one of the six sub-arrays of the array of radiators 108 of FIG. 1A. Each of the first sub-array 158A, the second subarray 158B and the third sub-array 158C includes three radiators such as a first radiator, a second radiator and a third radiator. In this way, the array of radiators 158 includes 9 radiators, represented by 1A, 2A, 3A, 4A, 5 A, 6A, 7A, 8A and 9A, respectively. The array of radiators 158 produce a sub-array pattern with a flat-topped beam as described in detail, for example, in FIG. 3.

In accordance with an embodiment, the first, the second and the third feed signals from each BFN (e.g. 156A) are provided respectively to the second radiator (represented by 2A), the third radiator (represented by 3A) and the first radiator (represented by 1A) in the corresponding sub-array 158A of the array of radiators 158. Similarly, the first, the second and the third feed signals from the second BFN (i.e. BFN2) 156B are radiated by the 5 A, 6A and 4A radiators, respectively. FIG. 2 is a graphical representation that illustrates normalized radiation pattern of an antenna device, in accordance with an embodiment of the present disclosure. FIG. 2 is described in conjunction with elements from FIGs. 1A, IB, and 1C. With reference to FIG. 2, there is shown a graphical representation 200 that illustrates normalized radiation pattern of an antenna device such as the antenna device 100A (of FIG. 1A). The graphical representation 200 includes an X-axis 202A that represents off axis angle in degree and a Y-axis 202B that represents radiated power measured in decibels (dB).

In the graphical representation 200, a plurality of radiation patterns 204 represents an ideal sub-array pattern. The antenna device 100A includes overlapped sub-arrays of radiators (i.e. sub-arrays of the array of radiators 108) and beam forming matrices (i.e. 106A, 106B, 106C, 106D, 106E and 106F). The beam forming matrices (or beam forming networks) are used to create a current distribution of radiators of the sub-arrays (i.e. sub-arrays of the array of radiators 108) close to a sine distribution, if possible. Such current distribution of the radiators of the sub-arrays radiate ideally flat-topped beams 204A, 204B, 204C and 204D as represented in the plurality of radiation patterns 204. The beamwidth of each flat-topped beam is dictated by a scanning range. The flat-topped beams 204A, 204B, 204C and 204D are such that they cut out grating lobes (or side lobes level) from a scan region (or the beam scanning range i.e. approximately 0° - 15° off-axis) and hence, avoid scan losses. The flat- topped beams 204A, 204B, 204C and 204D are selective enough to cut out the grating lobes (or side lobes level) and therefore, enables the antenna device 100A compatible with next generation wireless communication technologies, for example, fifth generation (5G) wireless communication technology.

FIG. 3 is a graphical representation that illustrates normalized radiation pattern of an antenna device, in accordance with another embodiment of the present disclosure. FIG. 3 is described in conjunction with elements from FIGs. 1A, IB, and 1C. With reference to FIG. 3, there is shown a graphical representation 300 that illustrates normalized radiation pattern of an antenna device such as the antenna device 100A (of FIG. 1A) and having the internal interconnections according to the FIG. 1C. The graphical representation 300 includes an X- axis 302A that represents off axis angle in degree and a Y-axis 302B that represents radiated power measured in decibels (dB). In the graphical representation 300, a first line 304 represents a sub-array pattern with a flattopped beam which is radiated by the antenna device 100A having the internal interconnections which has been described in detail, for example, in FIG. 1C. A second line 306 represents a sub-array pattern which is radiated by a conventional antenna device. The sub-array pattern with the flat-topped beam 304 is relatively narrower over the sub-array pattern 306 of the conventional antenna device. This indicates that the antenna device 100A has steeper roll-off which further leads to greater selectivity.

FIG. 4A is a graphical representation that illustrates feeding amplitudes of sub-array elements of an antenna device, in accordance with another embodiment of the present disclosure. FIG. 4A is described in conjunction with elements form FIGs. 1A, IB, and 1C. With reference to FIG. 4A, there is shown a graphical representation 400A that illustrates feeding amplitudes of sub-array elements of an antenna device such as the antenna device 100A (of FIG. 1A). The graphical representation 400A includes an X-axis 402A that represents sub-array element index and a Y-axis 402B that represents a linear scale.

In the graphical representation 400A, a first line 404A represents feeding amplitudes to subarray elements (i.e. the three radiators of each sub-array comprised by the array of radiators 108 of FIG. 1A) at a frequency of 3.30 giaghertz (GHz) when 7 elements (or radiators) are excited in phase. A second line 404B (also denoted by a dashed line) represents feeding amplitudes to sub-array elements (i.e. the three radiators of each sub-array comprised by the array of radiators 108 of FIG. 1 A) at a frequency of 3.30 GHz when 5 elements (or radiators) are excited in phase. A third line 406A and a fourth line 406B (also denoted by a dashed line) represent feeding amplitudes to sub-array elements (i.e. the three radiators of each subarray comprised by the array of radiators 108 of FIG. 1 A) at a frequency of 3.55 GHz when 7 and 5 elements (or radiators) are excited in phase, respectively. Similarly, a fifth line 408A and a sixth line 408B (also denoted by a dashed line) represent feeding amplitudes to subarray elements (i.e. the three radiators of each sub-array comprised by the array of radiators 108 of FIG. 1A) at a frequency of 3.80 GHz when 7 and 5 elements (or radiators) are excited in phase, respectively. A sub-array pattern can be made more selective if more radiating elements (or radiators) of a sub-array are excited in phase. Therefore, the first line 404A, the third line 406A and the fifth line 408A has relatively more selectivity by virtue of the 7 elements (or radiators) over the second line 404B, the fourth line 406B and the sixth line 408B which are obtained when 5 elements (or radiators) are excited in phase. The excitation of more elements (i.e. 7) or radiators can be obtained by reordering output ports (even if this shifts the maximum power output to the right edge of the triplet (i.e. sub-array)) and adjusting the length of the lines (i.e. the internal lines) connecting the directional couplers with the input and the output delay lines in each beam forming matrix (BFM).

FIG. 4B is a graphical representation that illustrates feeding phases to sub-array elements of an antenna device, in accordance with another embodiment of the present disclosure. FIG. 4B is described in conjunction with elements form FIGs. 1 A, IB, 1C, and 4A. With reference to FIG. 4B, there is shown a graphical representation 400B that illustrates feeding phases of sub-array elements of an antenna device such as the antenna device 100A (of FIG. 1A). The graphical representation 400B includes an X-axis 410A that represents sub-array element index and a Y-axis 410B that represents phase in degree (DEG.).

In the graphical representation 400B, a first line 412A represents feeding phases to sub-array elements (i.e. the three radiators of each sub-array comprised by the array of radiators 108 of FIG. 1A) at a frequency of 3.30 giaghertz (GHz) when 7 elements (or radiators) are excited in phase. A second line 412B (also denoted by a dashed line) represents feeding phases to sub-array elements (i.e. the three radiators of each sub-array comprised by the array of radiators 108 of FIG. 1A) at a frequency of 3.30 GHz when 5 elements (or radiators) are excited in phase. A third line 414A and a fourth line 414B (also denoted by a dashed line) represent feeding phases to sub-array elements (i.e. the three radiators of each sub-array comprised by the array of radiators 108 of FIG. 1 A) at a frequency of 3.55 GHz when 7 and 5 elements (or radiators) are excited in phase, respectively. Similarly, a fifth line 416A and a sixth line 416B (also denoted by a dashed line) represent feeding phases to sub-array elements (i.e. the three radiators of each sub-array comprised by the array of radiators 108 of FIG. 1A) at a frequency of 3.80 GHz when 7 and 5 elements (or radiators) are excited in phase, respectively. In the antenna device 100A, internal interconnections are modified and the input and the output delay lines are added in order to achieve a phase distribution as uniform as possible. In the antenna device 100A, 90-degree directional couplers are used (i.e. the first 90-degree directional coupler 150A, the second 90-degree directional coupler 150B and the third 90-degree directional coupler 150C) to achieve the uniform phase distribution which is advantageous over the conventional antenna device which uses 180- degree directional couplers and produces a different phase distribution.

FIG. 5 A is a graphical representation that illustrates normalized radiation pattern of an antenna device, in accordance with an embodiment of the present disclosure. FIG. 5 A is described in conjunction with elements from FIGs. 1A, IB, 1C, and 2. With reference to FIG. 5 A, there is shown a graphical representation 500A that illustrates normalized radiation pattern of an antenna device such as the antenna device 100A (of FIG. 1A). The graphical representation 500A includes an X-axis 502A that represents off axis angle in degree and a Y-axis 502B that represents radiated power measured in decibels (dB).

The graphical representation 500A is for the antenna device 100A (of FIG. 1A) that comprises an ideal feeding network which feeds 18 ideal dipoles (or radiators). The 18 ideal dipoles (or radiators) are perfectly matched and non-interacting. In the graphical representation 500A, a first line 504 represents that side lobe level (SLL) is below -15dB in all scanning conditions of interest. The normalized radiation pattern (or sub-array pattern) radiated by the ideal feeding network as presented in the graphical representation 500A has an undesired side lobe 506 around -50° off-axis.

FIG. 5B is a graphical representation that illustrates normalized radiation pattern of an antenna device, in accordance with an embodiment of the present disclosure. FIG. 5B is described in conjunction with elements from FIGs. 1A, IB, 1C, 2, and 5 A. With reference to FIG. 5B, there is shown a graphical representation 500B that illustrates normalized radiation pattern of an antenna device such as the antenna device 100A (of FIG. 1A). The graphical representation 500B includes an X-axis 508A that represents off axis angle in degree and a Y-axis 508B that represents radiated power measured in decibels (dB).

In the graphical representation 500B, a first line 510 represents the factor of the radiation pattern that corresponds to the effect of overlapping the feeding of the sub-arrays. The undesired side lobes represented by the first line 510 are located on mimima of the radiation pattern of the array factor (i.e. the antenna device 100A) and hence, do not increase the side lobe level (SLL) of the final array (i.e. the antenna device 100A). FIG. 6A is a graphical representation that illustrates feeding amplitudes of sub-array elements of an antenna device, in accordance with another embodiment of the present disclosure. FIG. 6A is described in conjunction with elements form FIGs. 1A, IB, 1C, and 4A. With reference to FIG. 6A, there is shown a graphical representation 600A that illustrates feeding amplitudes of sub-array elements of an antenna device such as the antenna device 100A (of FIG. 1A). The graphical representation 600A includes an X-axis 602A that represents sub-array element index and a Y-axis 602B that represents sub-array element feeding amplitudes.

In the graphical representation 600A, a plurality of lines 604 represents feeding amplitudes to sub-array elements (i.e. the three radiators of each sub-array comprised by the array of radiators 108 of FIG. 1A) at different frequencies, for example, 3.30 GHz, 3.55 GHz and 3.80 GHz. When sub-array feeding amplitudes represented by the plurality of lines 604 are integrated (or summed up), feeding amplitudes of different values are obtained, that is described in detail, for example, in FIG. 6B.

FIG. 6B is a graphical representation that illustrates feeding amplitudes of sub-array elements of an antenna device, in accordance with another embodiment of the present disclosure. FIG. 6B is described in conjunction with elements form FIGs. 1A, IB, 1C, 4A, and 6A. With reference to FIG. 6B, there is shown a graphical representation 600B that illustrates feeding amplitudes of sub-array elements of an antenna device such as the antenna device 100A (of FIG. 1A). The graphical representation 600B includes an X-axis 606A that represents sub-array element index and a Y-axis 606B that represents sub-array element feeding amplitudes.

In the graphical representation 600B, a plurality of lines 608 represents feeding amplitudes to sub-array elements (i.e. the three radiators of each sub-array comprised by the array of radiators 108 of FIG. 1A) at different frequencies, for example, 3.30 GHz, 3.55 GHz and 3.80 GHz. The feeding amplitudes represented by a first section 610 and a second section 612 are very low (in magnitude) and related to side sub-arrays those are located on edges of the array of radiators 108 (of FIG. 1 A), hence, these side sub-arrays can be removed in order to shorten the antenna length (i.e. length of the antenna device 100A) with low impact on electrical parameters. The effects of removing the side sub-arrays are described in detail, for example, in FIGs. 7C and 7D.

FIG. 7 A is an illustration of an antenna device, in accordance with an embodiment of the present disclosure. FIG. 7A is described in conjunction with elements from FIGs. 1A, IB, and 1C. With reference to FIG. 7A, there is shown an antenna device 700A. The antenna device 700A corresponds to the antenna device 100A (of FIG. 1 A). The antenna device 700A includes an array of radiators 702.

The array of radiators 702 corresponds to the array of radiators 108 of FIG. 1A and includes 18 antenna elements (or radiators). The 18 antenna elements (or radiators) are fed in sets of three (composing a sub-array) or multiples of three by means of beam forming matrices (BFMs) which have been described in detail, for example, in FIGs. 1A and IB. The 18 antenna elements (or radiators) lead to the antenna device 700A of length 846 millimetre (mm).

FIG. 7B is a graphical representation that illustrates the radiation pattern corresponding to an implementation of the antenna device (of FIG. 7A) with 18 elements, in accordance with an embodiment of the present disclosure. FIG. 7B is described in conjunction with elements form FIGs. 1A, IB, 1C, and 7A. With reference to FIG. 7B, there is shown a graphical representation 700B that illustrates the radiation pattern corresponding to an implementation of the antenna device (of FIG. 7A) with 18 elements such as the antenna device 700A. The graphical representation 700B includes an X-axis 704A that represents phase (or Theta) in degree and a Y-axis 704B that represents gain in decibels (dB).

The graphical representation 700B includes a square section 706 which indicates a side lobe level (SLL) of -13.8 dB of the antenna device 700A.

FIG. 7C is an illustration of an antenna device, in accordance with another embodiment of the present disclosure. FIG. 7C is described in conjunction with elements from FIGs. 1A, IB, 1C, 6A, 6B, 7A, and 7B. With reference to FIG. 7C, there is shown an antenna device 700C. The antenna device 700C includes an array of radiators 708. The array of radiators 708 includes side sub-arrays which are represented by dashed rectangular boxes 708A and 708B. The dashed rectangular boxes are used for illustration purpose only and do not form a part of circuitry.

The antenna device 700C corresponds to the antenna device 700A except a difference. The difference is that, the antenna device 700C has less number of antenna elements (or radiators). In the antenna device 700C, 708A and 708B represent side sub-arrays of the array of radiators 708. The side sub-arrays 708A and 708B are located on edges of the array of radiators 708 and have very low feeding amplitudes. Therefore, the side sub-arrays 708A and 708B are removed from the array of radiators 708 in order to reduce the number of antenna elements (or radiators) from 18 (of the antenna device 700A) to 12 antenna elements (or radiators). Since, each sub-array includes 3 antenna elements (or radiators), therefore, total of 6 antenna elements (or radiators) are removed in the antenna device 700C. Thus, the array of radiators 708 of the antenna device 700C includes 12 antenna elements (or radiators). The 12 antenna elements (or radiators) lead to the antenna device 700C of length 564 millimetre (mm). The impact of reducing the antenna elements (or radiators) is further described in detail, for example, in FIG. 7D.

FIG. 7D is a graphical representation that illustrates the radiation pattern corresponding to an implementation of the antenna device (of FIG. 7C) with 12 elements, in accordance with an embodiment of the present disclosure. FIG. 7D is described in conjunction with elements form FIGs. 1A, IB, 1C, 6A, 6B, 7A, 7B, and 7C. With reference to FIG. 7D, there is shown a graphical representation 700D that illustrates the radiation pattern corresponding to an implementation of the antenna device (of FIG. 7C) with 12 elements such as the antenna device 700C. The graphical representation 700D includes an X-axis 710A that represents phase (or Theta) in degree and a Y-axis 710B that represents gain in decibels (dB).

The graphical representation 700D includes a square section 712 which indicates a side lobe level (SLL) of -14.0 dB of the antenna device 700C. The difference in the side lobe level (SLL) of the antenna device 700A and the antenna device 700C i.e. ASLL < 0.3dB at all frequencies and steer. Therefore, the removal of the side sub-arrays (i.e. 708A and 708B of FIG. 7C) in the antenna device 700C have very low impact on electrical parameters, however, significantly reduce the antenna length by 282 millimetre (mm). FIG. 8 is a three-layer network of an antenna device, in accordance with an embodiment of the present disclosure. FIG. 8 is described in conjunction with elements from FIGs. 1A, IB, 1C, 7A, and 7C. With reference to FIG. 8, there is shown a design 800 of a three-layer network of an antenna device such as the antenna device 100A of FIG. 1A. The design 800 includes a power divider network 802 (also denoted by PWD) in a first layer, a beam forming network 804 (also denoted by BFN) in a second layer, and a feed network 806 (also denoted by OUT) in a third layer, respectively.

The design 800 is a three-layer network an antenna device such as the antenna device 100A of FIG. 1A and can be implemented by use of a stripline technology with no occurrence of line crossings. The design 800 can be realized by use of atypical printed circuit board (PCB) technology.

The power divider network 802 (i.e. PWD) include input ports to provide an initial feeding stage to the beam forming network 804 (i.e. BFN). The input ports to the initial feeding stage are control points and are accessible to an operator of the antenna device 100A in order to perform beam steering.

The beam forming network 804 (i.e. BFN) includes three or more beam forming matrices (BFMs) which are interconnected by the initial feeding stage in a specific interleaved fashion, so that a signal from such initial feeding stage is distributed over three adjacent BFMs. Each beam forming matrix is configured to provide three feed signals.

The feed network 806 include feed signals having feeding amplitudes and feeding phases for all radiators in each sub-array. The feed signals are radiated by radiators (or antenna elements) of an array of radiators 808. The array of radiators 808 include radiating elements in sets of three which together make a sub-array that has been described in detail, for example, in FIG. 1A.

Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. The word "exemplary" is used herein to mean "serving as an example, instance or illustration". Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and/or to exclude the incorporation of features from other embodiments. The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments". It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as suitable in any other described embodiment of the disclosure.