Antenna structure

An antenna structure includes a housing, a first feed source, and a second 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. The second feed source is electrically coupled to one of a second radiating portion or a third radiating portion of the housing. The other one of the second radiating portion or the third radiating portion is electrically coupled 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 source12, a first matching circuit13, a second feed source14, and a second matching circuit15.

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 to 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 gap121and the second gap122are located on the end portion115and are spaced apart. The first gap121and the second gap122cut across and cut through the border frame112. The first gap121and the second gap122are connected to the slot120. The slot120, the first gap121, and the second gap122separate 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 located between the first gap121and the second gap122, the second radiating portion A2is a portion of the border frame112located between the first gap121and an endpoint E1of the first side portion116, and the third radiating portion A3is a portion of the border frame112located between the second gap122and an endpoint E2of the second side portion117. In one embodiment, the first radiating portion A1is insulated from the middle frame111. An end of the second radiating portion A2adjacent the endpoint E1and an end of the third radiating portion A3adjacent the endpoint E2are coupled to the middle frame111.

In one embodiment, the border frame112has a thickness D1. The slot120has a width D2. The first gap121and the second gap122have 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 component21may be 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 component23may be a speaker and is mounted corresponding to the first gap121and is spaced 4-10 mm from the slot120. The third electronic component25may be 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 source12and the first matching circuit13are received within the accommodating space114. One end of the first feed source12is electrically coupled to a side of the first radiating portion A1adjacent the second gap122through the first matching circuit13for feeding a current signal to the first radiating portion A1. The first matching circuit13provides a matching impedance between the first feed source12and the first radiating portion A1.

In one embodiment, the first feed source12divides the first radiating portion A1into a first radiating section A11and a second radiating section A12. A portion of the border frame112between the first feed source12and the first gap121is the first radiating section A11. A portion of the border frame112between the first feed source12and the second gap122is the second radiating section A12. In one embodiment, the first feed source12is not positioned in the middle of the first radiating portion A1. Thus, a length of the first radiating section A11may be greater than a length of the second radiating section A12.

In one embodiment, the second feed source14and the second matching circuit15are received within the accommodating space114. One end of the second feed source14is electrically coupled to a side of the second radiating portion A2adjacent the first gap121through the second matching circuit15for feeding a current signal to the second radiating portion A2. The second matching circuit15provides a matching impedance between the second feed source14and the second radiating portion A2.

As shown inFIG. 4, when the first feed source12supplies an electric current, the electric current from the first feed source12flows through the first matching circuit13and the first radiating section A11toward the first gap121in sequence along a current path P1. Thus, the first antenna section A11forms a monopole antenna to excite a first resonant mode and generate a radiation signal in a first frequency band.

The electric current from the first feed source12can also flow through the first matching circuit13, the second radiating section A12, and then coupled to the third radiating portion A3through the second gap122along a current path P2. Thus, the first feed source12, the second radiating section A12, and the third radiating portion A3form a coupled feed antenna to excite a second resonant mode and generate a radiation signal in a second frequency band.

When the second feed source14supplies electric current, the electric current from the second feed source14flows through the second matching circuit15and the second radiating portion A2along a current path P3. Thus, the second radiating portion A2forms a loop 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 mode, the second resonant mode is an LTE-A mid-frequency mode, and the third resonant mode is an LTE-A high-frequency mode. The first frequency band is 700-960 MHz. The second frequency band is 1710-2170 MHz. The third frequency band is 2300-2690 MHz.

In one embodiment, electric current from the first feed source12flows to the first radiating section A11to excite the LTE-A low-frequency mode, and the electric current from the first feed source12flows through the second radiating section A12to couple to the third radiating portion A3to excite the LTE-A mid-frequency mode. Thus, the first radiating portion A1and the third radiating portion A3receive electric current from the first feed source12to excite the LTE-A low and mid-frequency modes which include the frequencies 700-960 MHz and 1710-2170 MHz.

In one embodiment, a portion of the slot120from the endpoint E1and parallel to the first side portion116defines the length L1of 1-10 mm. A portion of the slot120from the endpoint E2and parallel to the second side portion117defines the length L2of 1-10 mm. The lengths L1and L2of the slot120are able to adjust the LTE-A middle and high-frequency modes.

As shown inFIG. 3, the antenna structure100further includes a switching circuit17. The switching circuit17is mounted within the accommodating space114between the first electronic component21and the third electronic component25adjacent to the third electronic component25. One end of the switching circuit17crosses over the slot120and is electrically coupled to a side of the first radiating section A11adjacent the first gap121. Another end of the switching circuit17is coupled to ground.

As shown inFIG. 5, the switching circuit17includes a switching unit171and at least one switching component173. The switching unit171is electrically coupled to the first radiating section A11. The switching component173may be an inductor, a capacitor, or a combination of the two. The switching components173are coupled in parallel. One end of each of the at least one switching component173is electrically coupled to the switching unit171, and the other end is coupled to ground. Thus, the first radiating section A11is switched to electrically coupled to different ones of the switching components173. Since each of the switching components173has a different impedance, the switching components173are switched to adjust the LTE-A low-frequency mode.

In one embodiment, the switching circuit17includes four different switching components173. The four different switching components173are switched to be coupled to the first radiating section A11to achieve different LTE-A low-frequency modes, 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).

The antenna structure100further includes at least one extending portion18. In one embodiment, the antenna structure100includes two extending portions18. The extending portions18are made of metal. One of the two extending portions18is connected to an end of the second radiating section A12adjacent to the second gap122. A second one of the two extending portions18is connected to an end of third radiating portion A3adjacent to the second gap122. The two extending portions18face to each other.

A length and width of the extending portions18can be adjusted according to requirements to adjust an impedance value of the first radiating portion A1, the second radiating portion A2, and the third radiating portion A3. The extending portions18can replace a ground capacitor of the prior art.

FIG. 8shows a graph of S11 values of the LTE-A mid-frequency mode.

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

FIG. 10shows a graph of S11 values of the LTE-A high-frequency mode.

FIG. 11shows a graph of total radiation efficiency of the LTE-A high-frequency mode.

As shown inFIGS. 8-11, when the antenna structure100operates in the 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 mode range is from 1710-2690 MHz). The switching circuit17only adjust the low-frequency mode and does not affect the mid and high-frequency modes.

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 source12, a first matching circuit13, a second feed source14a, a second matching circuit15a, a switching circuit17, and at least one extending portion18a. The wireless communication device200aincludes a first electronic component21, a second electronic component23, and a third electronic component25. The border frame112includes a slot120, a first gap121, and a second gap122. The first gap121and the second gap122cut across and cut through the border frame112. The slot120, the first gap121, and the second gap122separate the housing11into a first radiating portion A1, a second radiating portion A2, and a third radiating portion A3.

The first electronic component21may be a USB port located within the accommodating space114. The first electronic component21is insulated from the first radiating portion A1by the slot120. The second electronic component23may be a speaker and is mounted corresponding to the first gap121and is spaced 4-10 mm from the slot120. The third electronic component25may be 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.

One end of the first feed source12is electrically coupled to a side of the first radiating portion A1adjacent the second gap122through the first matching circuit13for feeding a current signal to the first radiating portion A1. The first matching circuit13provides a matching impedance between the first feed source12and the first radiating portion A1.

One end of the switching circuit17is electrically coupled to a side of the first radiating portion A1adjacent the first gap121. Another end of the switching circuit17is coupled to ground.

A difference between the antenna structure100aand the antenna structure100is that in the antenna structure100a, a location of a second feed source14aand a second matching circuit15ais different. Specifically, as shown inFIG. 13, when the first feed source12supplies the electric current, the electric current from the first feed source12flows through the first matching circuit13and the first radiating portion A1, and then flows toward the first gap121and flows through the switching circuit17to ground along a circuit path P1a. Thus, the first radiating portion A1forms a monopole antenna to excite a first resonant mode and generate a radiation signal in a first frequency band.

Electric current from the first feed source12can also flow along a current path P2athrough the first matching circuit13and the first radiating portion A1, and then couple to the second radiating portion A2through the first gap121. Thus, the first feed source12, the first radiating portion A1, and the second radiating portion A2form a coupled feed antenna to excite a second resonant mode and generate a radiation signal in a second frequency band.

When the second feed source14asupplies electric current, electric current from the second feed source14aflows through the second matching circuit15aand the third radiating portion A3along a current path P3a. Thus, the third radiating portion A3forms a loop 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 mode, the second resonant mode is an LTE-A mid-frequency mode, and the third resonant mode is an LTE-A high-frequency mode. The first frequency band is 700-960 MHz. The second frequency band is 1710-2170 MHz. The third frequency band is 2300-2690 MHz.

Another difference between the antenna structure100aand the antenna structure100is that a location of extending portions18ais different. The antenna structure100aincludes two extending portions18amade of metal. One of the extending portions18ais mounted to the first radiating portion A1adjacent an end of the first gap121, and the other one of the extending portions18ais mounted to the second radiating portion A2adjacent the other end of the first gap121.

A length and width of the extending portions18acan be adjusted according to requirements thereby adjusting an impedance value of the first radiating portion A1, the second radiating portion A2, and the third radiating portion A3. The extending portions18acan replace a ground capacitor of the prior art.

FIG. 16shows a graph of S11 values of the LTE-A mid-frequency mode.

FIG. 17shows a graph of total radiation efficiency of the LTE-A mid-frequency mode.

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

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

As shown inFIGS. 14 and 15, the low-frequency mode is excited by the first radiating portion A1, and the switching circuit17adjusts the low-frequency mode to include the LTE-A Band17, the LTE-A Band13, the LTE-A Band20, and the LTE-A Band8. As shown inFIGS. 16 and 17, the mid-frequency mode is excited by the second radiating portion A2and includes LTE-A 1710-2170 MHz. As shown inFIGS. 18 and 19, the high-frequency mode is excited by the third radiating portion A3and includes LTE-A 2300-2690 MHz.

The switching circuit17only adjusts the low-frequency mode to operate within LTE-A Band17, LTE-A Band13, LTE-A Band20, or LTE-A Band8. The switching circuit17does not affect operation of the mid and high-frequency modes.

FIG. 20shows a third embodiment of an antenna structure100b.

The antenna structure100bincludes a middle frame111, a border frame112, a first feed source12, a first matching circuit13, a second feed source14a, a second matching circuit15a, a switching circuit17, and at least one extending portion18a. The wireless communication device200aincludes a first electronic component21, a second electronic component23, and a third electronic component25.

The border frame112includes a slot120, a first gap121, and a second gap122. The first gap121and the second gap122cut across and cut through the border frame112. The slot120, the first gap121, and the second gap122separate the housing11into a first radiating portion A1, a second radiating portion A2, and a third radiating portion A3.

The first electronic component21may be a USB port located within the accommodating space114. The first electronic component21is insulated from the first radiating portion A1by the slot120. The second electronic component23may be a speaker and is mounted corresponding to the first gap121and is spaced 4-10 mm from the slot120. The third electronic component25may be 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.

One end of the first feed source12is electrically coupled to a side of the first radiating portion A1adjacent the second gap122through the first matching circuit13for feeding a current signal to the first radiating portion A1. The first matching circuit13provides a matching impedance between the first feed source12and the first radiating portion A1.

In one embodiment, the first feed source12divides the first radiating portion A1into a first radiating section A11and a second radiating section A12. A portion of the border frame112between the first feed source12and the first gap121forms the first radiating section A11, and a portion of the border frame112between the first feed source12and the second gap122forms the second radiating section A12. In one embodiment, the first feed source12is not positioned in the middle of the first radiating portion A1. Thus, a length of the first radiating section A11may be greater than a length of the second radiating section A12.

One end of the switching circuit17is electrically coupled to a side of the first radiating section A11adjacent the first gap121. Another end of the switching circuit17is coupled to ground.

A difference between the antenna structure100band the antenna structure100is that in the antenna structure100b, locations of a second feed source14band a second matching circuit15bare different. Specifically, the second feed source14bis not adjacent to the first gap121and is not electrically coupled to the second radiating portion A2. In one embodiment, one end of the second feed source14bis electrically coupled to a side of the third radiating portion A3adjacent to the second gap122through the second matching circuit15bto feed a current signal to the third radiating portion A3. The second matching circuit15bprovides a matching impedance between the second feed source14band the third radiating portion A3.

In one embodiment, the extending portion18are omitted from the antenna structure100b.

As shown inFIG. 21, when the first feed source12supplies electric current, the electric current from the first feed source12flows through the first matching circuit13and the first radiating section A11, and then flows toward the first gap121and flows through the switching circuit17to ground along a circuit path P1b. Thus, the first radiating section A11forms a monopole antenna to excite a first resonant mode and generate a radiation signal in a first frequency band.

Electric current from the first feed source12can also flow along a current path P2bthrough the first matching circuit13and the second radiating section A12, and then to the second gap122to excite a second resonant mode and generate a radiation signal in a second frequency band. In addition, electric current from the first feed source12flows through the first matching circuit13and the first radiating section A11, and then flows to the second radiating portion A2through the first gap121along a path P3bto excite a third resonant mode and generate a radiation signal in a third frequency band.

When the second feed source14bsupplies electric current, the electric current from the second feed source14bflows through the second matching circuit15band the third radiating portion A3along a current path P4b. Thus, the third radiating portion A3forms a loop antenna to excite a fourth resonant mode and generate a radiation signal in a fourth frequency band.

In one embodiment, the first resonant mode is a Long Term Evolution Advanced (LTE-A) low-frequency mode, the second resonant mode is an LTE-A mid-frequency mode, the third resonant mode is an LTE-A high-frequency mode, and the fourth resonant mode is an LTE-A mid-high-frequency mode. The first frequency band is 700-960 MHz. The second frequency band is 1710-2170 MHz. The third frequency band is 2300-2690 MHz. The fourth frequency band is 1710-2170 MHz and 2300-2690 MHz.

The antenna structure100bforms a multiple-input multiple-output (MIMO) antenna structure to excite two groups of LTE-A mid and high-frequency modes. Electric current from the first feed source12flows to the first radiating portion A1and is coupled to the second radiating portion A2to excite a first group of LTE-A low, mid, and high-frequency modes. In addition, electric current from the second feed source14bflows to the third radiating portion A3to excite a second group of LTE-A mid and high-frequency modes. Thus, the first feed source12, the first radiating portion A1, and the second radiating portion A2cooperatively form a first antenna to excite the LTE-A low, mid, and high-frequency modes. The second feed source14band the third radiating portion A3cooperatively form a second antenna to excite a second group of LTE-A mid and high-frequency modes.

FIG. 22shows a graph of scattering values (S11 values) of the LTE-A low-frequency mode. A plotline S221represents S11 values of the first antenna. A plotline S222represents S11 values of the second antenna.

FIG. 23shows a graph of total radiation efficiency of the LTE-A mid and high-frequency modes. A plotline S231represents LTE-A mid and high-frequency mode of the first antenna. A plotline S232represents a total radiation efficiency of the second antenna.

FIG. 24shows a graph of total radiation efficiency of the LTE-A low-frequency mode of the first antenna.

As shown inFIGS. 22-24, the low-frequency mode is excited by the first antenna, and the switching circuit17adjusts the low-frequency mode to include the LTE-A Band17, the LTE-A Band13, the LTE-A Band20, and the LTE-A Band8. The first antenna and the second antenna of the antenna structure100bboth are capable of activating the LTE-A mid and high-frequency modes (1710-2690 MHz).