Description:FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2003

COMPLETE SPECIFICATION
(SEE SECTION 10 AND RULE 13)

TITLE OF THE INVENTION

SMALL CELL RADIO WITH INTEGRATED SEMI-OMNIDIRECTIONAL ANTENNA

APPLICANT:

Name : Sterlite Technologies Limited

Nationality : Indian

Address : 3rd Floor, Plot No. 3, IFFCO Tower,
Sector – 29, Gurugram, Haryana
122002

The following specification particularly describes the invention and the manner in which it is to be performed:
TECHNICAL FIELD
[0001] The present disclosure relates to radio units, and more specifically relates to a small cell radio with integrated semi-omnidirectional antenna(s).

BACKGROUND
[0002] The increasing demand for high-speed communication and growth of cellular data consumption trends urge faster rollout of Fifth Generation (5G) communication. The increasing need for network capacity and infrastructure requirements are most challenging in 5G deployment. Adding indoor radio unit cells (small cells) can address these challenges in 5G deployments, and the same can also accelerate the rollout of 5G technologies. The indoor small cells can meet the new demands of the 5G cellular communication system while opening a slew of new possibilities. Around 80% of mobile broadband traffic originates from mobile users located indoors, and ensuring good indoor coverage can be challenging, as the higher frequencies used by 5G are more prone to signal propagation limitations than previous generations of mobile technology. To help overcome this and to provide seamless and enhanced 5G experiences to users in indoor environments, it is essential to consider indoor small cells as a deployment option. Some of the prior art references, related to radio unit cells, are given below:
[0003] KR101484034B1 discloses a compact broadband MIMO antenna used for a mobile communication repeater and an indoor base station. The MIMO performance is efficiently realized within the size of a reduced antenna by improving the isolation degree without deteriorating performance between the antennas.
[0004] WO2015120904A1 discloses an omnidirectional antenna arrangement that is scalable from small cell base stations to middle and large cell base stations. The antenna arrangement comprises at least two conductive sheets arranged around at least one ground plane for transmitting radio signals from feeder cables on a transmission frequency band such that the antenna arrangement has a substantially omnidirectional radiation pattern.
[0005] US20120026704A1 discloses a wireless networking adapter that includes an omnidirectional antenna. The wireless networking adapter includes an integrated on-board directional antenna that is adapted to send and receive wireless signals of a first protocol (in one aspect, 2.4 GHz Wi-Fi).
[0006] A non-patent literature entitled “Design of UWB Antenna for the 5G Mobile Communication Applications: A Review” discloses review of Ultra-Wide-Band (UWB) antennas and their role in the future Fifth Generation (5G) mobile networks. The antennas are planar in design and the size is small to provide proper configuration of their geometry to work effectively inside an ultra-wide frequency range in the 5G candidate frequency bands.
[0007] Another non-patent literature entitled “High Gain Triple-Band Metamaterial-Based Antipodal Vivaldi MIMO Antenna for 5G Communications” discloses a miniaturized dual-polarized Multiple Input Multiple Output (MIMO) antenna with high isolation. The antenna design includes four antenna elements (with eight ports) that were laid out orthogonally at the four corners of a mobile printed circuit board (PCB) to be utilized as a MIMO antenna for 5G communications.
[0008] While the prior arts cover various indoor small cells, there is still scope for improvement in terms of operating bandwidth, gain, size, geometry, impedance matching, and feed network design. That is, the existing indoor small cells fail to operate in a wide operating bandwidth while providing high gain and having compact size, simple geometry, enhanced impedance matching and simple and efficient feed network design. Therefore, there is a need to overcome the above stated disadvantages.

OBJECT OF THE DISCLOSURE
[0009] A principal object of the present disclosure is to solve the aforesaid drawbacks and provide a small cell radio with integrated semi-omnidirectional antenna(s).
[0010] Another object of the present disclosure is to provide a semi-omnidirectional antenna for the small cell radio having a simpler, compact and unique three-layer structure, and a unique feeding structure that provide better impedance matching over a wide operating frequency band (3.3 - 3.9 GHz and 4.8 - 4.9 GHz) and a high gain of 8-9 dBi while still fitting into the small cell radio.

SUMMARY
[0011] Accordingly, the present disclosure provides a small cell radio. The small cell radio is composed of / has one or more semi-omnidirectional antennas. The small cell radio comprises one or more antenna elements, wherein each of the one or more antenna elements comprises a ground plane having one or more radiating slots and one or more feeding slots. The one or more radiating slots is one or more pairs of symmetrical radiating slots and each of the one or more radiating slots is separated by a valley in the ground plane, wherein a cross-section length (G2) of each of the one or more radiating slots is more than a cross-section length (G4) of the valley.
[0012] The small cell radio further comprises one or more radiating elements in the one or more radiating slots and one or more feeding elements in the one or more feeding slots, wherein each of the one or more feeding elements is electrically coupled to each of the one or more radiating elements. The one or more feeding elements has a stepped feeding structure for enhanced impedance matching of an antenna element, wherein the impedance is 50 Ohm. Each of the one or more feeding elements is defined by an antenna end and a feed end, wherein the antenna end is defined by an antenna end cross-section area and the feed end is defined by a feed end cross-section area, wherein the antenna end cross-section area is not equal to the feed end cross-section area, and wherein length of the feed end cross-section area of each of the one or more feeding elements increases from the feed end towards the antenna end. Each of the one or more feeding elements has at least two arms such that each arm feeds to exactly one radiating element.
[0013] The small cell radio comprises the one or more antenna elements, wherein each of the one or more antenna elements further comprises a dielectric substrate separating the ground plane and a top plane comprising one or more radiating elements and one or more feeding elements, thereby forming a three-layered antenna.
[0014] These and other aspects herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the invention herein without departing from the spirit thereof.

BRIEF DESCRIPTION OF FIGURES
[0015] The invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the drawings. The invention herein will be better understood from the following description with reference to the drawings, in which:
[0016] FIG. 1 illustrates an antenna element to be used in a small cell radio.
[0017] FIG. 2 illustrates a ground plane of the antenna element of FIG. 1.
[0018] FIG. 3 illustrates a top plane of the antenna element of FIG. 1.
[0019] FIG. 4 illustrates an example small cell radio with integrated four antenna elements.

DETAILED DESCRIPTION
[0020] In the following detailed description of the invention, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be obvious to a person skilled in the art that the invention may be practiced with or without these specific details. In other instances, well known methods, procedures and components have not been described in detail so as not to unnecessarily obscure aspects of the invention.
[0021] Furthermore, it will be clear that the invention is not limited to these alternatives only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without parting from the scope of the invention.
[0022] The accompanying drawings are used to help easily understand various technical features and it should be understood that the alternatives presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings. Although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another.
[0023] The proposed disclosure has utility in the provision of antennas for attachment to or formed on or built into a small cell radio. Now, simultaneous reference is made to FIG. 1 through FIG. 3, in which FIG. 1 illustrates an antenna element (100) to be used in a small cell radio (402); FIG. 2 illustrates a ground plane (102) of the antenna element (100) of FIG. 1; and FIG. 3 illustrates a top plane (128) of the antenna element (100) of FIG. 1.
[0024] The antenna element (100) may also be referred to as an antenna or semi-omnidirectional antenna. Alternatively, the antenna element (100) can be any part of an antenna involved in the reception or transmission of a signal i.e., an antenna element is any part of an antenna active in the reception or transmission of signals. The antenna element (100) comprises the ground plane (102) and top plane (128).
[0025] The ground plane (102) comprises a pair of radiating slots (104a, 104b), a feeding slot (106) (shown in FIG. 2) and a valley (126). The ground plane (102) is made of, but not limited to, copper material on which symmetrical slots (the pair of radiating slots (104a, 104b)) have been cut under a pair of radiating elements (108a, 108b). Each radiating slot of the pair of radiating slots (104a, 104b) is separated by the valley (126) in the ground plane (102), where a cross-section length (G2) of each radiating slot of the pair of radiating slots (104a, 104b) is more than a cross-section length (G4) of the valley (126). The feeding slot (106) is a circular slot (as shown in FIG. 2) made for providing feed to radiating elements through substrate and made by cutting the ground plane (102) in a circular shape.
[0026] The top plane (128) comprises the pair of radiating elements (108a, 108b) and a pair of feeding elements (110a, 110b), wherein the pair of radiating elements (108a, 108b) resides in the pair of radiating slots (104a, 104b), respectively and the pair of feeding elements (110a, 110b) resides in the feeding slot (106). The pair of radiating slots (104a, 104b) is a pair of symmetrical radiating slots. Each of the pair of radiating elements (108a, 108b) is substantially parallel to and vertically displaced from the ground plane (102) by each of the pair of feeding elements (110a, 110b). The pair of feeding elements (110a, 110b) is electrically coupled to the pair of radiating elements (108a, 108b). In general, a feed or feeding element is coupled to an antenna which radiates or receives the radio waves and a radiating element is a basic subdivision of an antenna which is capable of radiating or receiving radio-frequency energy.
[0027] Each feeding element of the pair of feeding elements (110a, 110b) is defined by an antenna end (112a-112b and 112c-112d) and a feed end (114a-114b and 114c-114d). Each antenna end (112a-112b and 112c-112d) is defined by an antenna end cross-section area (116) and each feed end (114a-114b and 114c-114d) is defined by a feed end cross-section area (118), wherein the antenna end cross-section area (116) is not equal to the feed end cross-section area (118). Further, length (R1) of the antenna end cross-section area (116) is greater than length (R11*2 + R9) of the feed end cross-section area (118) with a difference of around 55% and the length of the feed end cross-section area (118) of each feeding element of the pair of feeding elements (110a, 110b) increases from the feed end (114a-114b and 114c-114d) towards the antenna end (112a-112b and 112c-112d).
[0028] Each feeding element of the pair of feeding elements (110a, 110b) has a stepped feeding structure (120) for enhanced impedance matching of the antenna element (100), which is 50 Ohm. The stepped feeding structure (120) is used to energise the antenna element (100) through coupling between the stepped feeding structure (120) and the pair of radiating elements (108a, 108b). The feeding structure increases stepwise from the feed end (114a-114b and 114c-114d) towards the antenna end (112a-112b and 112c-112d), thereby called as the stepped feeding structure (120).
[0029] Each feeding element of the pair of feeding elements (110a, 110b) has at least two arms (122a-122b and 122c-122d) respectively such that each arm (122a, 122b, 122c, 122d) feeds to exactly one radiating element (108a, 108b).
[0030] The antenna element (100) further comprises a dielectric substrate (124) that separates the ground plane (102) and the pair of radiating elements (108a, 108b) and the pair of feeding elements (110a, 110b) thereby forming a three-layered antenna. The dielectric substrate (124) is an Isola I-Speed substrate having a dielectric constant as shown below in Table 1 and Table 5.
[0031] The antenna element (100) has an impedance of 50 Ohm and operates in a frequency band of, but not limited to, 3.3-3.9 GHz and 4.8-4.9 GHz. The antenna element (100) provides 10 dB impedance bandwidth from 3.2-4 GHz. Further, voltage standing wave ratio (VSWR) for the antenna element (100) is less than 1.82 over the operating frequency bands and a peak gain of the antenna element (100) lies between 8 to 9 dBi. Typically, the peak gain or antenna gain describes how much power is transmitted in the direction of peak radiation to that of an isotropic source. VSWR is a different way of representing Return Loss. VSWR refers to the actual voltages generated within a transmission line system, when forwarded and reflected radio waves propagate at the same time. Similarly, return loss of an antenna is a figure of merit that indicates the proportion of radio waves arriving at the antenna input that is rejected as a ratio against those that are accepted. The following tables depict the characteristics of the antenna element (100). Particularly, Table 1 to Table 4 depict characteristics of the antenna element (100) operating in the frequency band of 3.3-3.9 GHz and Table 5 to Table 8 depict characteristics of the antenna element (100) operating in the frequency band of 4.8-4.9 GHz.
S.No. Parameters Details
1 Antenna Type Internal (Integrated PCB based Antenna)
2 Number of Antennas 4 x 4 MIMO
3 Operating Frequency Band 3.3 - 3.9 GHz
4 Return Loss <-10.7 dB
5 VSWR 1.82:1
6 Isolation >27.3 dB
7 Radiation Pattern Semi Omnidirectional
8 Single Antenna Peak Gain ~ 8.8 dBi
9 Radiation Efficiency ~ 80%
10 Polarization Single Linear Polarization
11 Dimension of Each Antenna 85 mm x 30 mm x 0.8 mm
12 Antenna Substrate Isola (?r= 3.64, t= 0.8 mm & tand= 0.006)
Table 1: Characteristics of the antenna element at 3.3 to 3.9 GHz.

Frequency (GHz) Antenna-1 Antenna-2 Antenna-3 Antenna-4
3.3 -15.61 -18.94 -18.79 -16.58
3.4 -18.18 -13.58 -22.78 -19.43
3.5 -11.22 -32.74 -12.1 -10.71
3.6 -16.82 -26.89 -18.12 -14.65
3.7 -16.41 -13.17 -15.84 -15.38
3.8 -25.74 -19.18 -20.38 -24.11
3.9 -21.38 -17.62 -21.03 -24.58
Table 2: Return Loss at different operating frequency.

Frequency (GHz) Antenna-1 Antenna-2 Antenna-3 Antenna-4
3.3 1.4 1.25 1.25 1.34
3.4 1.27 1.51 1.15 1.23
3.5 1.7 1.05 1.66 1.82
3.6 1.35 1.1 1.27 1.46
3.7 1.34 1.56 1.38 1.4
3.8 1.13 1.24 1.2 1.12
3.9 1.21 1.3 1.19 1.12
Table 3: VSWR at different operating frequency.

Frequency (GHz) Antenna-1 Antenna-2 Antenna-3 Antenna-4
3.3 8.51 8.44 8.28 8.12
3.4 8.58 8.54 8.5 8.79
3.5 8.53 8.26 8.17 8.13
3.6 8.77 8.26 8.25 8.08
3.7 8.56 8.94 8.48 8.13
3.8 8.05 8.85 7.56 8.11
3.9 8.64 9.18 8.43 8.18
Table 4: Gain at different operating frequency.

S.No. Parameters Details
1 Antenna Type Internal (Integrated PCB based Antenna)
2 Number of Antennas 4 x 4 MIMO
3 Operating Frequency Band 4.8-4.9 GHz
4 Radiation Pattern Semi Omnidirectional
5 Isolation >22 dB
6 Polarization Single Linear Polarization
7 Single Antenna Peak Gain >9 dB
8 Radiation Efficiency ~ 80%
9 Dimension of Each Antenna 76.90 mm x 27 mm x 0.8 mm
10 Substrate properties Isola (?r= 3.64, t= 0.8 mm & tand= 0.006)
Table 5: Characteristics of the antenna element at 4.8 to 4.9 GHz.

Frequency (GHz) Antenna-1
dB Antenna-2
dB Antenna-3
dB Antenna-4
dB
4.8 -16.67 -12.5 -14.62 -9.88
4.9 -14.67 -12.61 -14.27 -8.47
Table 6: Return Loss at different operating frequency.

Frequency
(GHz) Antenna-1 Antenna-2 Antenna-3 Antenna-4
4.8 1.34 1.62 1.48 1.94
4.9 1.45 1.61 1.48 2.21
Table 7: VSWR at different operating frequency.

Frequency (GHz) Antenna-1
dBi Antenna-2
dBi Antenna-3
dBi Antenna-4
dBi
4.8 9.59 9.45 9.27 9.16
4.9 9.63 9.41 9.29 9.21
Table 8: Gain at different operating frequency.
[0032] The antenna element (100) is an integrated PCB (printed circuit board) based antenna for the small cell radio and is suitable for 4T4R (four transmit and four receive antennas) configuration (as shown in FIG. 4). 4T4R, sometimes referred to as 4x4 MIMO, uses four antennas to establish up to four streams of data with the receiving device. Compared to ordinary single antenna (SISO) networks, 4x4 offers up to a 400% increase in throughput.
[0033] The antenna element (100) fulfils the requirement of high gain and is a compact size antenna to fit inside the form factor of the small cell radio (402). In general, it is difficult to design an antenna element for the small cell radio that can operate in the wide operating frequency band (3.3-3.9 GHz and 4.8-4.9 GHz), with the requirement of high gain and compact size to fit inside the form factor of the small cell radio. The proposed antenna element (100) has a simpler three-layer structure with a unique design that provides a high gain of 8-9 dBi while still fitting into the small cell radio unit, as explained above. Advantageously, unique design and unique feeding structure of the antenna element (100) proposed herein provide better impedance matching over the operating frequency bands as mentioned above, better isolation and a high gain of 8-9 dBi. Typically, impedance relates voltage to current at the input to the antenna element and isolation is a metric for how closely two antennas are coupled, which is measured for antennas on the same PCB.
[0034] Further, the simpler three-layer structure of the antenna element (100) also lowers the cost of PCB fabrication, making it more appealing for cost-constrained applications such as small cell radios. In antenna design, it is difficult to match antenna to 50 Ohm impedance for the wide operating frequency band, however, the present disclosure addresses this problem as well. Moreover, to achieve a return loss (that indicates impedance matching) of better than 10.7 dB, which corresponds to the VSWR value of 1.82, step impedance transformers are employed in the feeding structure (120) that offers enhanced impedance matching for better radiation performance of the antenna element (100).
[0035] Referring to FIG. 2, three slots (radiating slots (104a, 104b) and valley (126)) are cut in the ground plane (102), where the pair of radiating slots (104a, 104b) includes two symmetric slots. For the operating frequency band 3.3-3.9 GHz, each radiating slot has dimensions of 18 mm x 28 mm (G1 x G2) and the valley (126) has dimensions of 18.8 mm x 11 mm (G3 x G4) and for the operating frequency band 4.8-4.9 GHz, each radiating slot has dimensions of 16.24 mm x 24.7 mm (G1 x G2) and the valley (126) has dimensions of 16.2 mm x 8.92 mm (G3 x G4). Referring to FIG. 3, for the operating frequency band 3.3-3.9 GHz, each of the pair of radiating elements (108a, 108b) has dimensions of 9.5 mm x 25.5 mm (R2 x R1) and the stepped feeding structure (120) has a length (R8) of 2.26 mm and similarly, for the operating frequency band 4.8-4.9 GHz, each of the pair of radiating elements (108a, 108b) has dimensions of 7.57 mm x 23 mm (R2 x R1) and the stepped feeding structure (120) has a length (R8) of 2.05 mm.
[0036] It may be noted that the present disclosure is not limited to these dimensions. Variations in dimensions are possible to achieve better performance of the antenna element (100). Further, it may be noted that although a few components have been shown in the form of pairs, however, the components may be varied and be one or more in number depending upon the structure and requirements. Number of each component does not limit the scope of the present disclosure.
[0037] One or more antenna elements (100) forms a small cell radio (402). FIG. 4 illustrates an example small cell radio with integrated four antenna elements (100), i.e., 4T4R small cell radio. FIG. 4 depicts the placement of four antenna elements (100) in an indoor small cell radio (402). The antenna elements (100) are arranged in such a way that a semi-omnidirectional radiation pattern is formed around the small cell radio, thus can be termed as a small cell radio with integrated semi-omnidirectional antenna (400). This ensures the transmission and reception of wireless signals from all the directions providing a consistent coverage around a device or user equipment. The small cell radio can deliver high-quality, secure cellular coverage indoors and outdoors, complementing the macro network to improve coverage, add targeted capacity, and support new services and user experiences. Based on the use case, there are various types of small cells, with varying ranges, power levels, and form factors. With compact and easy to deploy form factors, small cell radios are designed for all site requirements and have a wide variety of mounting options. Similarly, an indoor radio unit is a single board optical to radio interface solution for 5G low power applications. The small cell radio with integrated semi-omnidirectional antenna (400) can be used for improving 5G network coverage and can be cascaded into multiple stages.
[0038] The small cell radio (402) comprises the one or more antenna elements (100), wherein each of the one or more antenna elements (100) comprises the ground plane (102) having one or more radiating slots (104a, 104b) and one or more feeding slots (106). The one or more radiating slots (104a, 104b) is one or more pair of symmetrical radiating slots (104a, 104b) and each of the one or more radiating slots (104a, 104b) is separated by the valley (126) in the ground plane (102).
[0039] The small cell radio (402) further comprises one or more radiating elements (108a, 108b) in the one or more radiating slots (104a, 104b) and one or more feeding elements (110a, 110b) in the one or more feeding slots (106), wherein the one or more feeding elements (110a, 110b) is electrically coupled to the one or more radiating elements (108a, 108b). The one or more feeding elements (110a, 110b) has a stepped feeding structure (120) for enhanced impedance matching of antenna, which is 50 Ohm. Each of the one or more feeding elements (110a, 110b) is defined by the antenna end (112a, 112b, 112c, 112d) and the feed end (114a, 114b, 114c, 114d), wherein the antenna end (112a, 112b, 112c, 112d) is defined by the antenna end cross-section area (116) and the feed end (114a, 114b, 114c, 114d) is defined by the feed end cross-section area (118), wherein the antenna end cross-section area (116) is not equal to the feed end cross-section area (118).
[0040] The small cell radio (402) having the one or more antenna elements (100) further comprises the dielectric substrate (124) separating the ground plane (102) and a top plane (128) having one or more radiating elements (108a, 108b) and one or more feeding elements (110a, 110b), thereby forming a three-layered antenna.
[0041] It may be noted that the small cell radio (402) is formed using one or more antenna elements (100), therefore has the properties, dimensions, characteristics or the like as described in conjunction with FIG. 1 through FIG. 3.
[0042] Advantageously, the small cell radio (402) uses a low-power, short-range wireless transmission system that typically covers small geographical areas or indoor areas. The small cell radio (402) reuses frequencies on a highly dense basis to take full advantage of the available spectrum. They are generally used for handling high data rates for mobile broadband and Internet of Things (IoT) and low-power devices. Typically, they are used to enhance coverage in small areas, especially indoor spaces.
[0043] While the service providers have been using small cells (small cell radios) to enhance coverage of 3G and 4G networks, 5G has heightened the need for a short-range network because 5G use cases demand closer proximity to the location where content is being created. As the 5G rollout gains momentum worldwide, more and more radios are being deployed because 5G demands densification to ensure ultra-high-speed and low-latency services. Densification is not just expensive but also time-consuming. However, small cells are emerging as a technology of choice to boost signals in the indoor areas, especially those with high-density of users, like shopping centers, stadiums and workplaces. Improving indoor coverage is crucial because 80% of mobile broadband traffic originates from mobile users in the indoor environment. 5G especially demands massive number of small cells because signal propagation is more in higher frequencies. Further, the deployment of millimetre wave technologies in urban areas has further enhanced the need for small cells. As a result, more and more 5G small cells will be part of a communications network.
[0044] The various actions, acts, blocks, steps, or the like in the flow chart may be performed in the order presented, in a different order or simultaneously. Further, in some implementations, some of the actions, acts, blocks, steps, or the like may be omitted, added, modified, skipped, or the like without departing from the scope of the invention.
[0045] The embodiments disclosed herein can be implemented using at least one software program running on at least one hardware device and performing network management functions to control the elements.
[0046] It will be apparent to those skilled in the art that other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention. While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope of the invention. It is intended that the specification and examples be considered as exemplary, with the true scope of the invention being indicated by the claims.
[0047] The methods and processes described herein may have fewer or additional steps or states and the steps or states may be performed in a different order. Not all steps or states need to be reached. The methods and processes described herein may be embodied in, and fully or partially automated via, software code modules executed by one or more general purpose computers. The code modules may be stored in any type of computer-readable medium or other computer storage device. Some or all of the methods may alternatively be embodied in whole or in part in specialized computer hardware.
[0048] The results of the disclosed methods may be stored in any type of computer data repository, such as relational databases and flat file systems that use volatile and/or non-volatile memory (e.g., magnetic disk storage, optical storage, EEPROM and/or solid state RAM).
[0049] The various illustrative logical blocks, modules, routines, and algorithm steps described in connection with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. The described functionality can be implemented in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosure.
[0050] Moreover, the various illustrative logical blocks and modules described in connection with the embodiments disclosed herein can be implemented or performed by a machine, such as a general purpose processor device, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components or any combination thereof designed to perform the functions described herein. A general-purpose processor device can be a microprocessor, but in the alternative, the processor device can be a controller, microcontroller, or state machine, combinations of the same, or the like. A processor device can include electrical circuitry configured to process computer-executable instructions. In another embodiment, a processor device includes an FPGA or other programmable device that performs logic operations without processing computer-executable instructions. A processor device can also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Although described herein primarily with respect to digital technology, a processor device may also include primarily analog components. A computing environment can include any type of computer system, including, but not limited to, a computer system based on a microprocessor, a mainframe computer, a digital signal processor, a portable computing device, a device controller, or a computational engine within an appliance, to name a few.
[0051] The elements of a method, process, routine, or algorithm described in connection with the embodiments disclosed herein can be embodied directly in hardware, in a software module executed by a processor device, or in a combination of the two. A software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of a non-transitory computer-readable storage medium. An exemplary storage medium can be coupled to the processor device such that the processor device can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor device. The processor device and the storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In the alternative, the processor device and the storage medium can reside as discrete components in a user terminal.
[0052] Conditional language used herein, such as, among others, "can," "may," "might," "may," “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain alternatives include, while other alternatives do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more alternatives or that one or more alternatives necessarily include logic for deciding, with or without other input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular alternative. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list.
[0053] Disjunctive language such as the phrase “at least one of X, Y, Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain alternatives require at least one of X, at least one of Y, or at least one of Z to each be present.
[0054] While the detailed description has shown, described, and pointed out novel features as applied to various alternatives, it can be understood that various omissions, substitutions, and changes in the form and details of the devices or algorithms illustrated can be made without departing from the scope of the disclosure. As can be recognized, certain alternatives described herein can be embodied within a form that does not provide all of the features and benefits set forth herein, as some features can be used or practiced separately from others
, Claims:CLAIMS

We Claim:
1. A small cell radio (402) comprising:
one or more antenna elements (100), wherein each of the one or more antenna elements (100) comprises a ground plane (102) comprising one or more radiating slots (104a, 104b) and one or more feeding slots (106);
one or more radiating elements (108a, 108b) in the one or more radiating slots (104a, 104b); and
one or more feeding elements (110a, 110b) in the one or more feeding slots (106), wherein each of the one or more feeding elements (110a, 110b) is electrically coupled to each of the one or more radiating elements (108a, 108b), wherein each of the one or more feeding elements (110a, 110b) is defined by an antenna end (112a, 112b, 112c, 112d) and a feed end (114a, 114b, 114c, 114d), wherein the antenna end (112a, 112b, 112c, 112d) is defined by an antenna end cross-section area (116) and the feed end (114a, 114b, 114c, 114d) is defined by a feed end cross-section area (118), wherein the antenna end cross-section area (116) is not equal to the feed end cross-section area (118).

2. The small cell radio (402) as claimed in claim 1, wherein the one or more antenna elements (100) is semi-omnidirectional antennas.

3. The small cell radio (402) as claimed in claim 1, wherein the one or more radiating slots (104a, 104b) is one or more pairs of symmetrical radiating slots.

4. The small cell radio (402) as claimed in claim 1, wherein the one or more feeding elements (110a, 110b) has a stepped feeding structure (120) for enhanced impedance matching of each of the one or more antenna elements (100), wherein the impedance is 50 Ohm.

5. The small cell radio (402) as claimed in claim 1, wherein length (R1) of the antenna end cross-section area (116) is greater than length (R11*2 + R9) of the feed end cross-section area (118) with a difference of around 55%.

6. The small cell radio (402) as claimed in claim 1, wherein length of the feed end cross-section area (118) of each of the one or more feeding elements (110a, 110b) increases from the feed end (114a, 114b, 114c, 114d) towards the antenna end (112a, 112b, 112c, 112d).

7. The small cell radio (402) as claimed in claim 1, wherein each of the one or more feeding elements (110a, 110b) has at least two arms (122a-122b and 122c-122d) such that each arm (122a, 122b, 122c, 122d) feeds to exactly one radiating element (108a, 108b).

8. The small cell radio (402) as claimed in claim 1, wherein each of the one or more antenna elements (100) comprises a dielectric substrate (124) separating the ground plane (102) and a top plane (128) having the one or more radiating elements (108a, 108b) and one or more feeding elements (110a, 110b), thereby forming a three-layered antenna.

9. The small cell radio (402) as claimed in claim 1, wherein each of the one or more radiating slots (104a, 104b) is separated by a valley (126) in the ground plane (102).

10. The small cell radio (402) as claimed in claim 1, wherein a cross-section length (G2) of each of the one or more radiating slots (104a, 104b) is more than a cross-section length (G4) of a valley (126).