BACKGROUND

[0001] Slot antennas may be used for receiving and transmitting electromagnetic radiation. The slot antennas may convert electric power into electromagnetic waves in response to an applied electric field and associated magnetic field. A slot antenna may include a radiating efement that may radiate the converted electromagnetic waves.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Examples are described In the following detailed description and in reference to the drawings, in which:

[0003] Figure 1 is a schematic representation of an example dual band slot antenna;

[0004] Figure 2 is a schematic representation of an example dual band slot antenna, such as those shown in Figure 1 , with additional details;

[0005] Figure 3 is a schematic representation of an example dual band slot antenna, such as those shown in Figure 1 , in which a C~shaped conductive patch is applied for dual band operation:

[0006] Figure 4 is a schematic representation of an example dual band slot antenna, such as those shown in Figure 1 , in which an inverted C-shaped conductive patch is applied for dual band operation;

[0007] Figure 5 is a schematic representation of an example dual band slot antenna, such as those shown in Figure 1 , in which a conductive patch is divided into a feed trace and a ground trace;

[0008] Figure 8 is a schematic representation of an example dual band slot antenna, such as those shown in Figure 1 , which includes a substantially straight ground trace and an F-shaped feed trace for dual band operation; and

[0009] Figures 7A-7F illustrate an example design comparison of a 2D flexible printed circuit (FPC) antenna and a 3D metal sheet antenna. DETAILED DESCRIPTION

[000103 Slot antennas may be used for receiving and transmitting electromagnetic radiation. Example slot antenna may include two slots, curved slot, wider slot aperture, or integrated with active components on ground plane for duai band operation. Example slot antenna maybe a straight, thin, and passive slot for cosmetic and lower cost scenarios. For example, when using a thin and passive slot antenna design, obtaining a duai wide bandwidth (e.g., 2.4 and 5 GHz bands) may be significantly complex as the s!ot width is directiy proportional to antenna bandwidth.

[000113 The present application discloses techniques to provide a duai band slot antenna that includes a single slot for dual-band operation. The dual band slot antenna may include a ground plane, a dielectric substrate, a conductive patch, a feed trace, a ground trace, a ground point, and a feeding point. A slot may be etched on the ground plane. In one example, the slot may be a straight slot. Further, the dielectric substrate may be p!aced in between the conductive patch and the ground plane. Energy may be coupled to the conductive patch via the feeding point or via feeding and ground points for exciting the slot. In addition, the conductive patch can be divided into a feed trace and a ground trace. Both feed and ground traces may include at least one ground point to make electrical connection with the ground plane for dual band operation. Example dual band slot antenna includes a 2D (two-dimensional) antenna or a 3D (three- dimensional) antenna,

[000123 Figure 1 is a schematic representation of an example dual band slot antenna 100. The dual band slot antenna 100 includes a ground plane 102, a dielectric substrate 104, and a conductive patch 106. The ground plane 102 has a slot 110. The dielectric substrate 104 is disposed/piaced in between the conductive patch 108 and the ground plane 102. Further, a coaxial cable 108 may be fastened (e.g., soldered or joined) on the conductive patch 106 to form a first loop region 112 and a second loop region 114 of different sizes for dual band operation. In the example shown in Figure 1 , the conductive patch 106 is an O- shaped structure and may have at least one feeding point (e.g., feeding point 302 as shown in Figure 3) connected with an inner conductor of coaxial cable 108 and one portion connected with an outer conductor of the coaxial cable 108, in one example, upon soldering of the coaxial cable 108 on the conductive patch 106, two loop structures (e.g., a larger loop region 112 and a smaller loop region 114} placed side by side are formed and the two loops may have different size for dual band operation.

[00013] For example, the larger loop region 112 and the smaller loop region 114 may be able to generate 2.4 GHz and 5-6 GHz frequency bands, respectively. Also, a width and shape of the first loop region 112 and the second loop region 1 14 may be changed such that the conductive patch 106 may be either partially overlapped or fully non-overlapped with the slot 110 for different environments and applications. Energy may be either coupled to the conductive patch 106 via the feeding point or via feeding and ground points for exciting the slot 110.

[000143 Referring now to Figure 2, which illustrates a schematic representation of an example dual band slot antenna 100 with additional details. In one example, the conductive patch 106 may include a protrusion stub 202. The protrusion stub 202 may be protruded into the first loop region 112 (e.g., as shown in Figure 2) and/or the second loop region 114. fn one exampie, the protrusion stub 202 may be overlapped partially or not overlapped with the slot 110 for frequency tuning. In the example, as shown in Figure 2, the protrusion stub 202 Is not overlapped with the slot 110, Similarly, dual band operation frequency can be obtained by different size loop structures (e.g., the larger loop region 112 and the smaller loop region 114) placed side by side.

[0001 S] Figure 3 to Figure 6 illustrate different examples of the dual band slot antenna 100, as shown in Figure 1. These example implementations may be used for frequency tuning for different operating frequencies. For example, Figure 3 is an example of the dual band slot antenna 100, as shown in Figure 1 , in which a C-shaped conductive patch 106 may be applied for dual band operation, in comparison with Figures 1 and 2, one larger loop region 112 can be kept the same for low band operation while smaller loop region 114 can be broken but the dimension of the rest protrusion stubs could still be fine-tuned for high band operation. In one example, the C-shaped conductive patch 106 may be partiatiy overlapped with and fully not overlapped with the slot 110 for frequency tuning. In one example, the C-shaped conductive patch 106 may include a protrusion stub overlapped with the slot 110 for frequency tuning. The C-shaped conductive patch 106 may have no or at least one electrical contact with the ground plane 102. Therefore, energy may be either coupled to the conductive patch 106 via a feeding point 302 or via feeding and ground points for exciting the slot 1 10.

[00016] Figure 4 illustrates another example of the dual band slot antenna 100, as shown in Figure 1 , in which the inverted C-shaped conductive patch 106 is applied for dual band operation. In comparison with Figure 3, one smaller loop region 1 14 may be kept the same for high band operation white larger loop region 1 12 may be broken but the dimension of the rest protrusion stubs could still be fine-tuned for Sow band operation. In one example, the inverted C-shaped conductive patch 106 may be partially overlapped with and further not overlapped with the slot 1 10 for frequency tuning. In one example, the inverted C-shaped conductive patch 106 may include a protrusion stub overlapped with the slot 110 for frequency tuning. The inverted C-shaped conductive patch 106 may have no or at least one electrical contact with the ground plane 102. Therefore, energy may be either coupled to the conductive patch 106 via a feeding point or via feeding and ground points for exciting the slot 1 10.

[00017] Figure 5 illustrates another example of the dual band slot antenna 100 in which conductive patch is divided into a feed trace 504 and a ground trace 502. in the example shown in Figure 5, the feed trace is directly connected with an inner conductor 506 of the coaxial cable 108 for energy transfer and the ground trace 502 is directly connected with an outer conductor 508 of the coaxial cable 108 for assembly stability and grounding consideration. In the example shown in Figure 5, an L-shaped ground trace 502 and a T-shaped feed trace 504 are applied for dual band operation. The T-shaped feed trace 504 may operate as a monopole to excite the dual band slot antenna 100 white the L-shaped ground trace 502 may operate as frequency tuning components. In this example, both the feed trace 504 and the ground trace 502 may be partially overlapped and/or fully not overlapped with the slot 110 for frequency tuning. In one example, both the feed trace 504 and the ground trace 502 may include a protrusion stub overlapped with the slot 1 10 for frequency tuning. Both the feed trace 504 and the ground trace 502 may have no or at least one electrical contact with the ground plane 102. Therefore, energy may be either coupled to the feed trace 504 via a feeding point or via feeding and ground points for exciting the slot 1 10.

[00018] Figure 6 illustrates another example of the dual band slot antenna 100, in which a substantially straight ground trace 602 and an F-shaped feed trace 604 are applied for duai band operation. Even though Figures 5 and 6 describe about the feed trace that includes a T~shape and/or F-shape structure and the ground trace that includes an L-shape and straight line-shape structure, any other structure can be implemented to achieve the duai band operation,

[00019] For example, in slot antenna designs, a significant portion of radio frequency (RF) power may leak away from the siot region in the form of surface wave propagating along the ground plane. When components, such as panel or circuit control board (e.g., metallic objects surrounding the siot), mounted on the same ground plane, this surface wave may be bounded by these metallic objects and transferred into parallel plate wave thereby reducing the radiation intensity significantly. The present subject matter can propose a 3D antenna instead of 2D antenna. This proposed technique may make surface wave propagate through a vertical portion of 3D antenna and radiating outside of bounded metallic objects before it is bounded by metallic objects surrounding the slot thereby largely enhancing radiation intensity. This technique may propose conductive patch or feed/ground traces from 2D (two-dimensional) to 3D (three-dimensional) as shown in Figure 7.

[000203 Figure 7 illustrates an example design comparison of a 2D flexible printed circuit (FPC) antenna and a 3D metal sheet antenna. Figure 7A illustrates a top view of the 2D FPC antenna. In the example shown in Figure 7A, both the feed trace 706 and the ground trace 704 are having ground points 701 A and 701 B, respectively, for making electrical contact with the ground plane 102. The feed trace 706 may include a T-shape and/or F-shape structure and the ground trace 704 may include an L-shape and straight line-shape structure as shown in Figures 5 and 6. Figure 7B shows a side view of 2D FPC antenna.

[00021] Figures 7C and 7D illustrate a side view of the 3D metal sheet antenna. As shown in Figure 7C, both the feed trace 706 and the ground trace 704 are changed to 3D type of antenna for enhancing performance of the antenna and include ground points 701 A and 701 B, respectively, for making electrical contact with the ground plane 102. In the example shown in Figure 7D, ground points 701 A and 701 B (e.g., as shown in Figure 7C) are removed from both the feed trace 706 and the ground trace 704 for electrically coupling energy to the slot 110 on the ground plane 102. [00022] Figures 7E, 7F, and 7G illustrate a side view of the 3D metal sheet antenna with the conductive patch 708 (e.g., such as the conductive patch 106 shown in Figure 1 ). As shown in Figures 7E and 7F, the 3D meta! sheet antenna includes the conductive patch 708 (e.g., without and with ground points 702A and 702B, respectively) for enhancing performance of the antenna. Similarly, a structure shown in Figures 7G can be designed, where the vertical portion of conductive patch 708 can be designed to be across the slot region, in the example shown in Figures 7C to 7G, the conductive patch of the 3D antenna comprises at least a portion (e.g., a substantially vertical metaS rib) that extends outwardly from the dielectric substrate and surrounds at least a side of the slot. In the examples shown in Figures 7C to 7G, the conductive patch 708 can be partitioned into the feed trace 706 and the ground trace 704.

[00023] The 3D structure may not be limited to using a single material, for example metal sheet, but also different materials can be used for combination. For example, PCB can be combined with metal sheet for 3D antenna. Another example for this design can use plastic holder with conductive material on its surface to form 3D antenna.

[00024] it may be noted that the above-described examples of the present solution is for the purpose of illustration only. Although the solution has been described in conjunction with a specific embodiment thereof, numerous modifications may be possible without materially departing from the teachings and advantages of the subject matter described herein. Other substitutions, modifications and changes may be made without departing from the spirit of the present solution. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) may be combined in any combination, except combinations where at least some of such features are mutually exclusive.

[00025] The terms include," "have," and variations thereof, as used herein, have the same meaning as the term "comprise" or appropriate variation thereof. Furthermore, the term "based on," as used herein, means "based at least in part on." Thus, a feature that is described as based on some stimulus can be based on the stimulus or a combination of stimuli including the stimulus.

[000203 The present description has been shown and described with reference to the foregoing examples. It is understood, however, that other forms, detaiis, and exampies can be made without departing from the spirit and scope of the present subject matter that is defined in the foi lowing claims.