Antenna structure

An antenna structure includes a housing and a first feed source. The first feed source is electrically coupled to a first radiating portion of the housing and adapted to provide an electric current to the first radiating portion.

FIELD

The subject matter herein generally relates to antenna structures, and more particularly to an antenna structure of a wireless communication device.

BACKGROUND

As electronic devices become smaller, an antenna structure for operating in different communication bands is required to be smaller.

DETAILED DESCRIPTION

FIG. 1andFIG. 2show an embodiment of an antenna structure100applicable in a mobile phone, a personal digital assistant, or other wireless communication device200for sending and receiving wireless signals.

As shown inFIG. 3, the antenna structure100includes a housing11, a first feed source F1, a first matching circuit12, a metal portion13, a second feed source F2, a second matching circuit14, a short circuit portion15, a coupling portion16, and a switching circuit17.

The housing11includes at least a middle frame111, a border frame112, and a backplane113. The middle frame111is substantially rectangular. The middle frame111is made of metal. The border frame112is substantially hollow rectangular and is made of metal. In one embodiment, the border frame112is mounted around a periphery of the middle frame111and is integrally formed with the middle frame111. The border frame112receives a display201mounted opposite the middle frame111. The middle frame111is a metal plate mounted between the display201and the backplane113. The middle frame111supports the display201, provides electromagnetic shielding, and enhances durability of the wireless communication device200.

The backplane113is made of insulating material, such as glass. The backplane113is mounted around a periphery of the border frame112and is substantially parallel to the display201and the middle frame111. In one embodiment, the backplane113, the border frame112, and the middle frame111cooperatively define an accommodating space114. The accommodating space114receives components (not shown) of the wireless communication device200.

The border frame112includes at least an end portion115, a first side portion116, and a second side portion117. In one embodiment, the end portion115is a bottom end of the wireless communication device200. The first side portion116and the second side portion117face each other and are substantially perpendicular to the end portion115.

In one embodiment, the border frame112includes a slot120, a first gap121, and a second gap122. The slot120is substantially U-shaped and is defined in an inner side of the end portion115. In one embodiment, the slot120extends along the end portion115and extends toward the first side portion116and the second side portion117. The slot120insulates the end portion115from the middle frame111.

In one embodiment, the first gap121is located on the first side portion116, and the second gap117is located on the second side portion117. The first gap121is defined in the first side portion116adjacent to a first endpoint E1of the slot120. The second gap122is defined in the second side portion117adjacent to a second endpoint E2of the slot120. The first gap121and the second gap122substantially face each other. The first gap121and the second gap122are connected to the slot120. The slot120, the first gap121, and the second gap122divide the housing11into a first radiating portion A1, a second radiating portion A2, and a third radiating portion A3. In one embodiment, the first radiating portion A1is a portion of the border frame112located between the first gap121and the second gap122. The second radiating portion A2is a portion of the border frame112located between the first gap121and the first endpoint E1. The third radiating portion A3is a portion of the border frame112located between the second gap122and the second endpoint E2.

In one embodiment, the first radiating portion A1is insulated from the middle frame111. An end of the second radiating portion A2adjacent the first endpoint E1and an end of the third radiating portion A3adjacent the second endpoint E2are coupled to the middle frame111. The second radiating portion A2, the third radiating portion A3, and the middle frame111cooperatively form an integrally formed metal frame.

In one embodiment, the border frame112has a thickness D1. The slot120has a width D2. Each of the first gap121and the second gap122has a width D3. D1is greater than or equal to 2*D3. D2is less than or equal to half of D3. In one embodiment, the thickness D1of the border frame112is 2-6 mm, the width D2of the slot120is 0.5-1.5 mm. The width D3of the first gap121and the second gap122is 1-3 mm.

In one embodiment, the slot120, the first gap121, and the second gap122are made of insulating material, such as plastic, rubber, glass, wood, ceramic, or the like.

The wireless communication device200further includes at least one electronic component, such as a first electronic component21, a second electronic component23, and a third electronic component25. The first electronic component21is a universal serial bus (USB) port located within the accommodating space114. The first electronic component21is insulated from the first radiating portion A1by the slot120.

The second electronic component23is a speaker and is mounted on a side of the first electronic component21and is adjacent to the second side portion117. The second electronic component23is spaced 4-10 mm from the slot120. The third electronic component25is a microphone and is mounted within the accommodating space114. The third electronic component25is located between the second electronic component23and the slot120and is adjacent the second gap122. In one embodiment, the third electronic component25is insulated from the first radiating portion A1by the slot120.

In another embodiment, the second electronic component23and the third electronic component25can be mounted in different locations according to requirements.

In one embodiment, the border frame112defines a port123in the end portion115. The port123corresponds to the first electronic component21so that the first electronic component21partially protrudes through the port123. Thus, a USB device can be inserted in the port123to electrically coupled to the first electronic component21.

In one embodiment, the first feed source F1is received within the accommodating space114. One end of the first feed source F1is electrically coupled to a side of the first radiating portion A1adjacent to the first gap121through the first matching circuit12for feeding a current signal to the first radiating portion A1. The first matching circuit12provides a matching impedance between the first feed source F1and the first radiating portion A1.

In one embodiment, the first feed source F1divides the first radiating portion A1into a first radiating section A11and a second radiating section A12. A portion of the border frame112between the first feed source F1and the second gap122is the first radiating section A11. A portion of the border frame112between the first feed source F1and the first gap121is the second radiating section A12. In one embodiment, the first feed source F1is not positioned in the middle of the first radiating portion A1. Thus, a length of the first radiating section A11and a length of the second radiating section A12are not equal.

The metal portion13is made of metal and is mounted within the accommodating space114. One end of the metal portion13is electrically coupled to the second radiating portion A2, and a second end of the metal portion13extends along the slot120.

The second feed source F2and the second matching circuit14are mounted within the accommodating space114. One end of the second feed source F2is electrically coupled to the metal portion13through the second matching circuit14for feeding current signals to the metal portion13. The second matching circuit14provides a matching impedance between the second feed source F2and the metal portion13.

The short circuit portion15is made of metal and is mounted within the accommodating space114. One end of the short circuit portion15is electrically coupled to an end of the second radiating section A12adjacent to the first feed source F1, and a second end of the short circuit portion15is coupled to ground.

The coupling portion16may be an inductor, a capacitor, or a combination of the two. In one embodiment, the coupling portion16is an inductor. One end of the coupling portion16is electrically coupled to an end of the first radiating section A11adjacent to the first electronic component21, and a second end of the coupling portion16is coupled to ground.

FIG. 4shows the switching circuit17. In one embodiment, the switching circuit17is mounted within the accommodating space114and is located between the coupling portion16and the third electronic component25. One end of the switching circuit17extends beyond the slot120to electrically coupled to the first radiating section A11. A second end of the switching circuit17is coupled to ground. The switching circuit17includes a switching unit171and a plurality of switching components173. The switching unit171is electrically coupled to the first radiating section A11. Each switching component173may be an inductor, a capacitor, or a combination of the two. The switching components173are coupled together in parallel. One end of each of the switching components173is electrically coupled to the switching unit171, and a second end of each of the switching components173is coupled to ground. The first radiating portion A1includes a plurality of ground points for coupling to ground, such as through the short circuit portion15, the coupling portion16, or the switching circuit17.

As shown inFIG. 5, when the first feed source F1supplies an electric current, the electric current from the first feed source F1flows through the first matching circuit12and the first radiating section A11in sequence toward the second gap122along a current path P1. Thus, the first radiating section A11forms a planar inverted F-shaped antenna (PIFA) to excite a first resonant mode and generate a radiation signal in a first frequency band.

The electric current from the first feed source F1can also flow through the first matching circuit12and the second radiating section A12toward the first gap121along a current path P2. Thus, the second radiating section A12forms an inverted F-shaped antenna (IFA) to excite a second resonant mode and generate a radiation signal in a second frequency band.

When the second feed source F2supplies an electric current, the electric current from the second feed source F2flows through the second matching circuit14and the metal portion13along a current path P3. Thus, the metal portion13forms a PIFA antenna to excite a third resonant mode and generate a radiation signal in a third frequency band.

In one embodiment, the first resonant mode is a long term evolution advanced (LTE-A) low-frequency band, the second resonant mode is an LTE-A mid-frequency band and LTE-A band40, and the third resonant mode is LTE-A band41. The first frequency band is 700-960 MHz. The second frequency band is 1710-2170 MHz and 2300-2400 MHz. The third frequency band is 2500-2690 MHz.

As shown inFIG. 3, in one embodiment, a portion of the second radiating portion A2has a length L1, and a portion of the third radiating portion A3has a length L2. The length L1and the length L2are 1-10 mm. In one embodiment, the lengths L1and L2enhance radiation efficiency of the antenna structure100.

The coupling portion16enhances impedance matching and bandwidth of the antenna structure100. The coupling portion16enhances the bandwidth of the mid and high-frequency bands to achieve carrier aggregation (CA) requirements.

The first radiating section A11is switched by the switching unit171to electrically couple to different switching components173. Since each switching component173has a different impedance, the switching components173are switched to adjust the LTE-A low-frequency band. In one embodiment, the switching circuit17includes four different switching components173. The four different switching components173are switched to couple to the first radiating section A11to achieve different LTE-A low-frequency bands, such as LTE-A Band17 (704-746 MHz), LTE-A Band13 (746-787 MHz), LTE-A Band 20 (791-862 MHz), and LTE-A Band8 (880-960 MHz).

FIG. 8shows a graph of S11 values of the LTE-A mid-frequency and LTE-A Band40 bands.

FIG. 9shows a graph of total radiation efficiency of the LTE-A mid-frequency and LTE-A Band40 bands.

FIG. 10shows a graph of S11 values of LTE-A Band41.

FIG. 11shows a graph of total radiation efficiency of LTE-A Band41.

As shown inFIGS. 6 and 7, the low-frequency bands of the antenna structure100are excited by the first radiating section A11and switched by the switching circuit17. Thus, the low-frequency bands of the antenna structure100includes LTE-A Band17 (704-746 MHz), LTE-A Band13 (746-787 MHz), LTE-A Band20 (791-862 MHz), and the LTE-A Band8 (880-960 MHz). As shown inFIGS. 8-11, the second radiating section A12excites a portion of the mid-high-frequency bands including 1710-2170 MHz and 2300-2400 MHz, and a portion of the high-frequency bands is excited by the metal portion13including 2500-2690 MHz.

Furthermore, when the antenna structure100operates in LTE-A Band17 (704-746 MHz), LTE-A Band13 (746-787 MHz), LTE-A Band20 (791-862 MHz), and the LTE-A Band8 (880-960 MHz), the LTE-A mid and high-frequency band range is from 1710-2690 MHz. Thus, the switching circuit17adjusts the low-frequency bands and does not affect the mid and high-frequency bands to achieve carrier aggregation requirements of LTE-A.

FIG. 12shows a second embodiment of an antenna structure100afor use in a wireless communication device200a.

The antenna structure100aincludes a middle frame111, a border frame112, a first feed source F1a, a first matching circuit12a, a second feed source F2, a second matching circuit14, a short circuit portion15a, and a switching circuit17a. The wireless communication device200aincludes a first electronic component21, a second electronic component23a, and a third electronic component25a.

The border frame112includes a slot120, a first gap121, and a second gap122. In one embodiment, the first gap121is located on the first side portion116, and the second gap117is located on the second side portion117. The first gap121is defined in the first side portion116adjacent to a first endpoint E1of the slot120. The second gap122is defined in the second side portion117adjacent to a second endpoint E2of the slot120. The first gap121and the second gap122substantially face each other. The first gap121and the second gap122are connected to the slot120. The slot120, the first gap121, and the second gap122divide the housing11into a first radiating portion A1, a second radiating portion A2, and a third radiating portion A3. In one embodiment, the first radiating portion A1is a portion of the border frame112located between the first gap121and the second gap122. The second radiating portion A2is a portion of the border frame112located between the first gap121and the first endpoint E1. The third radiating portion A3is a portion of the border frame112located between the second gap122and the second endpoint E2.

One difference between the antenna structure100aand the antenna structure100is that in the antenna structure100a, a location of the second electronic component23aand the third electronic component25ais different. Specifically, the second electronic component23ais mounted between the first electronic component21and the first gap121and is insulated from the slot120. The third electronic component25aand the second electronic component23aare mounted on a same side of the first electronic component21, and the third electronic component25ais located between the second electronic component23aand the slot120. In one embodiment, the third electronic component25ais located adjacent to the first gap121and is insulated from the first radiating portion A1by the slot120.

Another difference between the antenna structure100aand the antenna structure100is that in the antenna structure100a, a location of the first feed source F1ais different. Specifically, the first feed source F1ais mounted between the first electronic component21and the second gap122and is adjacent to the first electronic component21. One end of the first feed source F1ais electrically coupled to an end of the first radiating portion A1through the first matching circuit12aadjacent to the second gap122for feeding current signals to the first radiating portion A1. The first matching circuit12aprovides a matching impedance between the first feed source F1aand the first radiating portion A1. Another difference between the antenna structure100aand the antenna structure100is that in the antenna structure100a, the metal portion13and the coupling portion16are omitted. One end of the second feed source F2is electrically coupled to an end of the second radiating portion A2adjacent to the first endpoint E1for feeding current signals to the second radiating portion A2. The second matching circuit14provides a matching impedance between the second feed source F2and the second radiating portion A2.

Another difference between the antenna structure100aand the antenna structure100is that the antenna structure100afurther includes a resonance circuit18. One end of the resonance circuit18is electrically coupled to the first radiating portion A1adjacent to the first gap121, and a second end of the resonance circuit18is coupled to ground. Specifically, the resonance circuit18includes a first resonance unit181and a second resonance unit183. One end of the first resonance unit181is electrically coupled to an end of the first radiating portion A1adjacent to the first gap121. A second end of the first resonance unit181is coupled to ground through the second resonance unit183in series.

In one embodiment, the first resonance unit181is an inductor, and the second resonance unit183is a capacitor. In other embodiments, the first resonance unit181and the second resonance unit183may be other electronic components. The resonance circuit18enhances a bandwidth of the high-frequency bands and adjusts a matching impedance of the antenna structure100a.

The antenna structure100afurther includes a third feed source F3and a third matching circuit19. The third feed source F3is mounted between the first feed source F1aand the second gap122. One end of the third feed source F3is electrically coupled to the first radiating portion A1through the third matching circuit19to feed current signals to the first radiating portion A1. The third matching circuit19provides a matching impedance between the third feed source F3and the first radiating portion A1.

The first feed source F1aand the third feed source F3cooperatively divide the first radiating portion A1into a first radiating section A11aand a second radiating section A12a. A portion of the border frame112between the first feed source F1aand the first gap121is the first radiating section A11a, and a portion of the border frame112between the third feed source F3and the second gap122is the second radiating section A12a. In one embodiment, a length of the first radiating section A11ais longer than a length of the second radiating section A12.

Another difference between the antenna structure100aand the antenna structure100is that in the antenna structure100a, a location of the switching circuit17ais different. Specifically, the switching circuit17ais mounted between the first electronic component21and the first gap121. More specifically, the switching circuit17ais mounted between the first electronic component21and the third electronic component25a. One end of the switching circuit17ais electrically coupled to the first radiating section A11a, and a second end of the switching circuit17ais coupled to ground. The switching circuit17aadjusts a bandwidth of the LTE-A low-frequency bands.

Another difference between the antenna structure100aand the antenna structure100is that in the antenna structure100a, a location of the short circuit portion15ais different. Specifically, the short circuit portion15ais mounted between the first electronic component21and the second gap122. More specifically, the short circuit portion15ais mounted between the first feed source F1aand the third feed source F3. One end of the short circuit portion15ais electrically coupled to the first radiating portion A1, and a second end of the short circuit portion15ais coupled to ground.

The antenna structure100afurther includes a switching module19a. The switching module19ais mounted between the third feed source F3and the second gap122adjacent to the second gap122. One end of the switching module19ais electrically coupled to the second radiating section A12a, and a second end of the switching module19ais coupled to ground. The switching module19aadjusts a frequency of the LTE-A mid-frequency bands. A structure of the switching module19ais similar to a structure of the switching circuit17a.

In one embodiment, a width of the slot120between the third feed source F3and the second gap122is greater than a width of the slot120at any other location. Thus, a width of the second radiating section A12ais less than a width of any other portion of the first radiating portion A1, including the first radiating section A11a.

As shown inFIG. 13, when the first feed source F1asupplies an electric current, the electric current from the first feed source F1aflows along a current path P4through the first matching circuit12aand the first radiating section A11atoward the first gap121, and then is coupled to ground through the switching circuit17a. Thus, the first radiating section A11aforms a PIFA antenna to excite a first resonant mode and generate a radiation signal in a first frequency band.

When the second feed source F2supplies an electric current, the electric current from the second feed source F2flows along a current path P5through the second matching circuit14and the second radiating portion A2. Thus, the second radiating portion A2forms a loop antenna to excite a second resonant mode and generate a radiation signal in a second frequency band.

When the third feed source F3supplies an electric current, the electric current from the third feed source F3flows along a current path P6through the third matching circuit19and the second radiating section A12a. Thus, the second radiating section A12aforms a PIFA antenna to excite a third resonant mode and generate a radiation signal in a third frequency band.

In one embodiment, the first resonant mode is a long term evolution advanced (LTE-A) low-frequency band, the second resonant mode is an LTE-A high-frequency band, and the third resonant mode is an LTE-A mid-frequency band. The first frequency band is 700-960 MHz. The second frequency band is 2300-2690 MHz. The third frequency band is 1710-2170 MHz.

FIG. 16shows a graph of S11 values of the LTE-A mid-frequency band. A plotline S161represents S11 values when the switching module19aswitches to a switching component having a capacitance of 0.06 pF and the switching module19aswitches to bandwidth B2and B3(1710-1880 MHz). A plotline S162represents S11 values when the switching module19aswitches to a switching component having an inductance of 140 nH and the switching module19aswitches to bandwidth B1and B2(1850-2170 MHz).

FIG. 17shows a graph of total radiation efficiency of the LTE-A mid-frequency band. A plotline S171represents a total radiation efficiency when the switching module19aswitches to a switching component having a capacitance of 0.06 pF and the switching module19aswitches to bandwidth B2and B3(1710-1880 MHz). A plotline S172represents a total radiation efficiency when the switching module19aswitches to a switching component having an inductance of 140 nH and the switching module19aswitches to bandwidth B1and B2(1850-2170 MHz).

As shown inFIGS. 14-17, the low-frequency mode is excited by the switching circuit17a, and the mid-frequency mode is excited by the switching module19a. Furthermore, the switching module19aswitches the mid-frequency band of the antenna structure100ato LTE-A band2 and LTE-A band3 (1710-1880 MHz), LTE-A band1 and LTE-A band2 (1850-2170 MHz), thereby operating at 1710-2170 MHz.

FIG. 18shows a graph of S11 values of the LTE-A high-frequency band.

FIG. 19shows a graph of total radiation efficiency of the LTE-A high-frequency band.

As shown inFIGS. 14 and 15, the low-frequency bands of the antenna structure100aare excited by the first radiating section A11aand switched by the switching circuit17a. Thus, the low-frequency bands of the antenna structure100includes LTE-A Band17 (704-746 MHz), LTE-A Band13 (746-787 MHz), LTE-A Band20 (791-862 MHz), and the LTE-A Band8 (880-960 MHz). As shown inFIGS. 16-17, the second radiating section A12aexcites the mid-frequency bands including LTE-A 1710-2170 MHz. As shown inFIGS. 18-19, the second radiating portion A2excites the high-frequency bands including LTE-A 2300-2690 MHz.

Furthermore, when the antenna structure100operates in LTE-A Band17 (704-746 MHz), LTE-A Band13 (746-787 MHz), LTE-A Band20 (791-862 MHz), and the LTE-A Band8 (880-960 MHz), the LTE-A mid and high-frequency band range is from 1710-2690 MHz. Thus, the switching circuit17aadjusts the low-frequency bands and does not affect the mid and high-frequency bands to achieve carrier aggregation requirements of LTE-A. Also, the switching module19aadjusts the mid-frequency bands and does not affect the low and high-frequency bands to achieve carrier aggregation requirements of LTE-A.