BACKGROUND

[0001] Communication devices include slot antennas for the purpose of communication. The slot antennas generally include a long straight slot that operates at predefined harmonic resonance modes to allow the slot antennas to operate in different frequency bands. The different frequency bands allow the communication devices to operate and support different standards of wireless communication. With continuous change and development in the standards of wireless communication, the slot antennas too are modified to support additional frequency bands useful for upgrading to the new standards of wireless communication.

BRIEF DESCRIPTION OF DRAWINGS

[0002] The detailed description is described with reference to the accompanying figures. It should be noted that the description and figures are merely example of the present subject matter and are not meant to represent the subject matter itself.

[0003] Figure 1 illustrates a block diagram of a folded slot antenna, according to an example of the present subject matter.

[0004] Figure 2 illustrates a communication device incorporating a folded slot antenna, according to another example of the present subject matter.

[0005] Figure 3 illustrates a block diagram of a device housing having a folded slot antenna, according to an example of the present subject matter.

[0006] Figure 4 illustrates a block diagram of a folded slot antenna, according to another example of the present subject matter. [0007] Figure 5 illustrates a block diagram of an antenna feed structure of a folded slot antenna, according to another example of the present subject matter.

DETAILED DESCRIPTION

[0008] The subject matter relates to a folded slot antenna. Communication devices generally include slot antennas for communication with other devices, such as communication devices and network devices. The slot antennas generally include a long straight slot that operate at predefined harmonic resonance modes to allow the slot antennas to operate in different frequency bands. The slot antennas support first and third harmonic resonance modes, allowing the slot antennas to operate in a low frequency band (about 704 MHz (megahertz) to 960 MHz) and a high frequency band (about 2500 MHz to 2690 MHz). The slot antennas, however, may not support a second harmonic resonant mode and may thus not operate in a middle frequency band (about 1710 MHz to 2170 MHz).

[0009] Example implementations for a slot antenna that supports the first harmonic resonance mode, the second harmonic resonance mode, and the third harmonic resonance mode are described. As per an example of the present subject matter, the slot antenna is a folded slot antenna. In said example, the folded slot antenna includes a first radiating strip having a first slot, a second radiating strip having a second slot, a third radiating strip having a third slot, and a dielectric disposed between the first radiating strip and the third radiating strip. In one example implementation, one end of the second slot is connected to the first slot and other end of the second slot is connected to the third slot to form a continuous folded slot. The continuous folded slot provides a resonant length appropriate for supporting the second harmonic resonance mode, thus allowing the folded slot antenna to operate in the middle frequency band. Further, the first slot supports operation of the folded slot antenna operate in the low frequency band and the high frequency band. [0010] In one example, the third radiating strip is disposed substantially parallel to the first radiating strip such that a bottom surface of the dielectric is attached to the first radiating strip and a top surface of the dielectric is attached to the third radiating strip. The second radiating strip is disposed substantially perpendicularly between the first radiating strip and the third radiating strip such that one side of the dielectric is attached to the second radiating strip. Further, the dielectric houses an antenna feed structure for the first radiating strip and the third radiating strip.

[0011] In one example implementation of the present subject matter, the first radiating strip includes a first metal layer having the first slot and a first printed circuit board (PCB) attached to the first metal layer on one side and having the antenna feed structure on another side. In one example, the first metal layer may be a back cover of a device housing of a communication device having the folded slot antenna. The second radiating strip includes a second metal layer formed along a first side of the first PCB and a first side of the dielectric. The third radiating strip may include a third metal layer having the third slot and a second PCB attached to the third metal layer on one side and coupled to the dielectric and the antenna feed structure on the other side.

[0012] The present subject matter thus facilitates a slot antenna to operate in the low frequency band, the middle frequency band, and the high frequency band. The first slot is excited in the first harmonic resonance mode and the third harmonic resonance mode to allow the folded slot antenna to operate in the low frequency band and the high frequency band, respectively. The continuous folded slot is excited in the second harmonic resonance mode to allow the folded slot antenna to operate in the middle frequency band. The communication device incorporating the folded slot antenna may thus be able to support different standards of wireless communication. [0013] The present subject matter is further described with reference to Figures 1 to 5. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0014] Figure 1 illustrates a block diagram of a folded slot antenna 102, according to an example implementation of the present subject matter. The folded slot antenna 102 may be implemented in a communication device, such as a desktop computer, a laptop, a smart phone, a personal digital assistant (PDA), a tablet, a notebook, and an all-in-one computer. In one example, the folded slot antenna 102 may be incorporated within a device housing of the communication device.

[0015] In accordance to an example implementation of the present subject matter, the folded slot antenna 102 includes a first radiating strip 104, a second radiating strip 106, and a third radiating strip 108. The first radiating strip 104 includes a first slot 110. The second radiating strip 106 includes a second slot 112. The third radiating strip 108 includes a third slot 114. In one example, one end of the second slot 112 is connected to the first slot 104 and other end of the second slot 112 is connected third slot 114 to form a continuous folded slot. The folded slot antenna 102 further includes a dielectric 116 disposed between the first radiating strip 104 and the third radiating strip 108. The dielectric 116 houses an antenna feed structure 118 for the first radiating strip 104 and the third radiating strip 108.

[0016] The antenna feed structure 118 may provide input feed to the first radiating strip 104 and the third radiating strip 108 to operate the folded slot antenna in predefined frequency bands. In one example, the antenna feed structure 118 may provide input feed to the first radiating strip 104 to excite the first slot 110 to support a first predefined frequency band and a second predefined frequency band. The antenna feed structure 118 may further provide input feed to the second radiating strip 104 to excite the continuous folded slot to support a third predefined frequency band. In one example, the first predefined frequency band is a low frequency band in the range of about 704 MHz (megahertz) to 960 MHz. The second predefined frequency band is a high frequency band in the range of about 2500 MHz to 2690 MHz. The third predefined frequency band is a middle frequency band in the range of about 1710 MHz to 2170 MHz.

[0017] Figure 2 illustrates a communication device 200 incorporating the folded slot antenna 102, according to an example implementation of the present subject matter. In one example, the communication device 200 is depicted as a laptop. As previously described, examples of the communication device 200 may further include, but are not limited to, a desktop computer, a smart phone, a personal digital assistant (PDA), a tablet, a notebook, and an all-in-one computer.

[0018] In one example, the communication device 200 includes a device housing 202. The device housing 202 may support and hold various components, such as a display of the communication device 200. In one example, the folded slot antenna 102 may be disposed on the device housing 202 such that the first radiating strip 104 is disposed on a surface 204 of the device housing 202. The first radiating strip 104 includes the first slot 110 to support the first predefined frequency band and the second predefined frequency band.

[0019] The folded slot antenna 102 may further include the second radiating strip 106 having the second slot 112. In one example, one end of the second slot 112 is connected to the first slot 110. The folded slot antenna 102 also includes the third radiating strip 108 having the third slot 114 connected to other end of the second slot 112. The first slot 110, the second slot 112, and the third slot 114 may thus be connected to form a continuous folded slot for supporting the third predefined frequency band.

[0020] Further, the dielectric 116 may be disposed between the first radiating strip 104 and the third radiating strip 108. As previously described, the dielectric 116 may house the antenna feed structure 118 for the first radiating strip 104 and the third radiating strip 108.

[0021] Figure 3 illustrates a block diagram of a device housing 300 having the folded slot antenna 102, according to an example of the present subject matter. The device housing 300 may support and hold various components, such as a display of a communication device. For instance, the device housing 300 may be the device housing 202 of the communication device 200. The device housing 300 may include a metal cover 302 disposed on one side of a surface, say external surface, of the device housing 300. In one example, the metal cover 302 may be disposed on an external side of an external surface of the device housing 300. For instance, the metal cover 302 may be disposed on an external side of the surface 204 of the device housing 202 as illustrated in the figure 2. In one example, the metal cover 302 may include the first slot 110.

[0022] The device housing 300 may further include a first printed circuit board (PCB) 304 attached to the first slot 110 to form the first radiating strip 104. The device housing 300 further includes the second radiating strip 106 having the second slot 112. In one example, one end of the second slot 112 is connected to the first slot 110. Further, the second slot 112 is perpendicular to the first slot 110. The device housing 300 may further include a second PCB 306 connected to the second radiating strip 106. In one example, a metal layer 308 is attached to the second PCB 306 to form the third radiating strip 108. The metal layer 308 includes the third slot 114 placed parallel to the first slot 110 and perpendicular to the second slot 112. Further, the third slot 114 is connected to other end of the second slot 112 such that the first slot 110, the second slot 112, and the third slot 114 are interconnected to form the continuous folded slot. As previously described, the continuous folded slot supports the third predefined frequency band.

[0023] Figure 4 illustrates a block diagram of the folded slot antenna 102, according to another example implementation of the present subject matter. As previously described, the folded slot antenna 102 may be incorporated within a communication device for wireless communication over multiple predefined frequency bands. In one example, the multiple predefined frequency bands may include, but is not limited to, the low frequency band in the range of about 704 MHz to 960 MHz, the middle frequency band in the range of about 1710 MHz to 2170 MHz, and the high frequency band in the range of about 2500 MHz to 2690 MHz.

[0024] As previously described, the folded slot antenna 102 may include the first radiating strip 104 having the first slot 110, the second radiating strip 106 having the second slot 112, and the third radiating strip 108 having the third slot 114. As illustrated in figure 4, the first radiating strip 104 is placed substantially parallel to the third radiating strip 108, while the second radiating strip 106 is placed substantially perpendicular to the first radiating strip 104 and the third radiating strip 108.

[0025] The folded slot antenna 102 may further include the dielectric 116 disposed between the first radiating strip 104, the second radiating strip 106, and the third radiating strip 1 8. The dielectric 116 may be disposed such that a bottom surface 402 of the dielectric 116 is attached to the first radiating strip 104 and a top surface 404 of the dielectric 116 is attached to the third radiating strip 108. in one example, the dielectric 116 may be a dielectric having a predefined dielectric constant such that the dielectric 116 is able to avoid dielectric loss during operation of the folded slot antenna 102. For instance, the dielectric 116 may be a sponge and a piece of plastic having a dielectric constant of about 2.2.

[0026] In one example, the first radiating strip 104 includes the first PCB 304 attached to the first slot 110 provided on a first metal layer 406. The first metal layer 406, in one example, may be the metal cover 302 disposed on the surface of the device housing 300 of the communication device incorporating the folded slot antenna 102. The first metal layer 406, in another example, may be a part of the metal cover 302. Further, the first slot 110 extends up to a first predetermined resonance length to support the first predefined frequency band and the second predefined frequency band. In one example, the length of the first slot 110 may be equal to 90 millimeters (mm) for supporting the first predefined frequency band and the second predefined frequency band in the communication device 200, such as a laptop and a notebook.

[0027] The first PCB 304 is attached to the first metal layer 406 on one side, covering a substantial length of the first slot 110. In one example, the first PCB has a length of 70 millimeters (mm). Further, the first PCB 304 includes the antenna feed structure 118 on another side, in contact with the bottom surface 402 of the dielectric 116.

[0028] The second strip 106 includes a second metal layer 408 formed along a first side 410 of the first PCB 304 and a first side 412 of the dielectric 116. The second metal layer 408 includes the second slot 112 extending across the entire length of the second strip 106. In one example, the length of the second radiating strip 106 and the second slot 112 on the second metal layer 408 is equal to about 2.5 mm. In one example, the second metal layer 408 may be formed by providing a coating of a metal, such as copper over the first side 410 of the first PCB 304 and the first side 412 of the dielectric 116. In said example, the coating of metal may be etched to form the second slot 112.

[0029] In one example, the third radiating strip 108 includes a third metal layer, say, the metal layer 308 attached to the second PCB 306. As previously described, the third metal layer 308 includes the third slot 114 extending along the length of the third radiating strip 108. In one example, the length of the third radiating strip 108 and the third slot 114 is equal to about 30 mm. The second PCB 306 is attached to the third metal layer 308 on a first side and coupled to the antenna feed structure 118 on a second side, in contact with the top surface 404 of the dielectric 116. In one example, the third metal layer 308 may be formed by providing a coating of a metal, such as copper over the first side of the second PCB 306. In said example, the coating of metal may be etched to form the third slot 114. In another example, a single sheet of metal layer may be used as the third radiating strip 108 in place of the metal layer coated second PCB 306.

[0030] Further, as previously described, one end of the second slot 112 is connected to the first slot 110, while other end of the second slot 112 is connected to the third slot 114. The first slot 110, the second slot 112, and the third slot 114 are thus joined together to form the continuous folded slot. In one example, the length of the continuous folded slot maybe equal to a second predefined resonance length to support the third predefined frequency band. For instance, length of the continuous folded slot may be equal to about 122.5 mm for supporting the third predefined frequency band in the communication device 200, such as a laptop and a notebook.

[0031] The first PCB 304 and the second PCB 306 may be composed of any suitable circuit board material, such as a di-electric material. By way of example, the PCBs could be composed of SR4 material. In other examples, the PCBs may be made of pre-impregnated materials, such as FR-2 (Phenolic cotton paper), FR-3 (Cotton paper and epoxy), and FR-4 (Woven glass and epoxy). Numerous variations of FR-4 may also be used, such as FR-408 and Polydad 370HR.

[0032] Further, as previously described, the first PCB 304 includes the antenna feed structure 118. The antenna feed structure 118 may be housed within the dielectric 116. In one example, the antenna feed structure 118 may be double sided flex printed circuit (FPC) feed lines such that a single antenna feed structure 118 may be used to provide input feed to the first radiating strip 104 and the third radiating strip 108. For instance, the antenna feed structure 118 is connected to the first metal layer 406 to provide a first input feed to the first radiating strip 104 to drive the continuous folded slot at a first frequency and a second frequency. The first input feed provides electric current on the first metal layer 406 causing magnetic current to flow in the first slot 110. The first slot 110 of the continuous folded slot may thus operate in the fundamental first resonant mode and the third resonant mode to support the first predefined frequency band and the second predefined frequency band.

[0033] The antenna feed structure 118 is further coupled to the second PCB 306 to provide a second input feed to the third radiating strip 108 to drive the continuous folded slot at a third frequency. The second input feed provides electric current on the second metal layer 308 causing magnetic current to flow in the continuous folded slot. In one example, the magnetic current may flow in a predefined region within the continuous folded slot. The continuous folded slot may thus operate in the second resonant mode to support the third predefined frequency band.

[0034] Figure 5 illustrates a block diagram 500 of the antenna feed structure 116, according to another example of the present subject matter, as previously described, the antenna feed structure 118 may be double sided FPC feed lines such that a single antenna feed structure 118 may be used to provide input feed to the first radiating strip 104 and the third radiating strip 108. In one example, a first feed line 502 of the antenna feed structure 118 may provide input feed to the first radiating strip 104. A second feed line 504 of the antenna feed structure 118 may provide input feed to the third radiating strip 108. As illustrated, the first feed line 502 and the second feed line 504 may intersect and be joined at a common feed junction 506.

[0035] In one example, the first feed line 502 may include a first lateral feed line 508 and a first longitudinal feed line 510. The first lateral feed line 508 may be of a length of about 20 mm and the first longitudinal feed line 510 may be of a length of about 7 mm. The second feed line 504 may include a second lateral feed line 512 and a second longitudinal feed line 514. The second lateral feed line 512 may be of a length of about 35 mm and the second longitudinal feed line 514 may be of a length of about 5 mm.

[0036] The antenna feed structure 116 may further include an inductor 516 connected to the first metal layer 406. In one example, the inductor 516 may have an inductance of about 5.8 nanohenry (nH).

[0037] Although examples for the present subject matter have been described in language specific to structural features and/or methods, it should be understood that the appended claims are not limited to the specific features or methods described. Rather, the specific features and methods are disclosed and explained as examples of the present subject matter.