CN204375947U - A kind of multiple frequency broad band plane antenna for mobile phone - Google Patents

Abstract

The utility model provides a multi-frequency broadband planar mobile phone antenna, comprising: a metal ground, a dielectric plate arranged above the metal ground, and a metal antenna piece attached to the surface of the medium plate, the metal antenna piece includes a first radiation unit, The second radiating unit, the third radiating unit, the fourth radiating unit, the fifth radiating unit, the sixth radiating unit, the first connection part connecting the first radiating unit, the second radiating unit, the third radiating unit, and the fourth radiating unit , the second connecting part connecting the fifth radiating unit and the metal ground, the third connecting part connecting the sixth radiating unit and the metal ground, and a 50-ohm microstrip feeder connected to the first connecting part. The multi-frequency broadband planar mobile phone antenna of the utility model adopts bending radiation branches, multi-branch technology and double-strip line coupling structure to achieve the purpose of miniaturization, multi-frequency and broadband, and has realized all LTE/WWAN/WLAN/WiMAX Coverage of the communication frequency band.

Description

A multi-band broadband planar mobile phone antenna

technical field

The utility model relates to a mobile phone antenna technology, in particular to a multi-frequency broadband planar mobile phone antenna.

Background technique

In the past 30 years, mobile communication has developed rapidly, and has experienced technological innovations from generation to generation, from the "big brother" of the first generation of mobile communication, to the GSM digital mobile phone of the second generation of mobile communication, to the third generation of mobile communication Mobile multimedia mobile phones, and finally 4G multifunctional smart phones, handheld communication devices are developing towards smaller, thinner and lighter, and can receive and transmit images, voices and data anytime and anywhere, which requires handheld communication terminals It can support multiple network technologies and work in multiple frequency bands at the same time. As an important part of mobile phones, antennas also need to meet the above requirements. Therefore, miniaturization, multi-frequency, broadband and planarization have become the development trend of mobile phone antennas, and colleagues have also become current research hotspots. The popularity of ultra-thin Internet entertainment smart phones has put forward higher requirements for the coverage of 2G/3G/4G frequency bands of mobile phone antennas. It is necessary to design a system that can cover all existing communication channels (including LTE three frequency bands LTE700/2300/2500, WWAN Five frequency bands GSM850/900/1800/1900/UMTS, WLAN three frequency bands 2.4/5.2/5.8GHz, WiMAX three frequency bands 2.5/3.5/5.5GHz) planar mobile phone antenna has become an urgent need.

In recent years, with the continuous development of theory and technology, various forms of multi-frequency antennas have been continuously proposed, but there are two shortcomings in the existing mobile phone antennas: on the one hand, the existing multi-frequency antennas only cover part of the communication frequency bands, not It can realize the coverage of all frequency bands of 2G/3G/4G; on the other hand, in order to realize the miniaturization of the antenna, many mobile phone antennas are designed as a three-dimensional structure, which does not conform to the development trend of ultra-thin mobile phones.

Utility model content

The purpose of the utility model is to overcome the shortcomings and deficiencies of the prior art, and provide a multi-frequency broadband planar mobile phone antenna. The purpose of modernization and broadbandization, thus realizing the coverage of all communication frequency bands of LTE/WWAN/WLAN/WiMAX, conforms to the development trend of ultra-thin mobile phones.

The purpose of this utility model is achieved through the following technical solutions: a multi-frequency broadband planar mobile phone antenna, including: a metal ground, a dielectric plate arranged above the metal ground, and a metal antenna sheet attached to the surface of the dielectric plate, the metal antenna The sheet includes a first radiating unit, a second radiating unit, a third radiating unit, a fourth radiating unit, a fifth radiating unit and a sixth radiating unit, connecting the first radiating unit, the second radiating unit, the third radiating unit, the fourth radiating unit The first connecting part of the radiating unit, the second connecting part connecting the fifth radiating unit and the metal ground, the third connecting part connecting the sixth radiating unit and the metal ground, and a 50-ohm microstrip feeder connected to the first connecting part.

The first radiating unit is an anti-C-shaped monopole, the second radiating unit is a bent half-containing monopole, the third radiating unit is an F-shaped monopole, the fourth radiating unit is an X-shaped monopole, and the fifth radiating unit The unit is a folded S-shaped branch, and the sixth radiating unit is a reverse C-shaped branch. The first radiating unit, the second radiating unit, the third radiating unit, the fourth radiating unit and the first connecting part are all printed on the upper surface of the dielectric board, the fifth radiating unit, the sixth radiating unit, the second connecting part, the Three connections and a metal ground are printed on the lower surface of the dielectric board.

The left edge of the lower end of the inverted C-shaped monopole is closely connected to the upper end of the right edge of the first connecting part, the folded S-shaped branch includes four short branches, and the left edge of the lower end of the folded S-shaped branch is connected to the upper end of the second connecting part The right edge is tightly connected. The lower part of the reversed C-shaped monopole coincides with the lower part of the folded S-shaped branch, and the upper part of the reversed C-shaped monopole is surrounded by the upper part of the folded S-shaped branch, forming a double strip line structure to improve the C-shaped monopole. The degree of coupling between poles and folded S-shaped branches. The reverse C-shaped monopole and the folded S-shaped branch are coupled with each other to form a dual-strip line structure, which is mainly used for the coverage of the 700-MHz frequency band.

The four short branches have the same length and the same width, and are arranged horizontally and parallel along the lower edge of the middle part of the folded S-shaped branches. The four stubs are mainly used to expand the bandwidth of the 700-MHz band.

The bent half contains the monopole and includes two C-shaped bent branches and two U-shaped bent branches that are half contained each other, and the bent half contains the lower end edge of the monopole, the left side of the two U-shaped bent branches and The uppermost edge of the first connecting portion is tightly connected. The left edge of the lower end of the reverse C-shaped branch is closely connected with the position close to the upper end of the right edge of the third connection part in an inverted L shape. The reverse C-shaped branch is surrounded by a half-folded monopole to form a double strip line structure. The stripline structure is mainly used for the coverage of the 2-GHz frequency band.

The two mutually semi-contained C-shaped bent branches are coupled to each other, and the right edge of the lowermost end of the left C-shaped bent branch is connected with the right C-shaped bent branch through two horizontally arranged U-shaped bent branches. tight connection. The mutually coupled semi-contained C-bend stubs and U-bend stubs are mainly used to expand the bandwidth of the 2-GHz frequency band.

The lower edge of the F-shaped monopole is closely connected to the left end of the rightmost upper edge of the first connecting part, and the F-shaped monopole is mainly used to achieve coverage of the 3.5-GHz frequency band.

The right edge of the lower end of the X-shaped monopole is closely connected to the left edge of the first connecting part, and the X-shaped monopole is mainly used to achieve coverage of the 5-GHz frequency band.

The upper end of the 50-ohm microstrip feeder is tightly connected to the lower end of the first connection part, the lower end of the 50-ohm microstrip feeder is welded to the inner core of the coaxial line, and the length of the 50-ohm microstrip feeder is about 1/2 of the length of the metal ground.

The lower edge of the metal ground coincides with the lower edge of the lower surface of the dielectric board, the upper edge of the metal ground is closely connected with the lower edge of the second connection part, and the lower edge of the third connection part, and the part of the metal ground located directly below the lower end of the 50-ohm microstrip feeder line is connected to the outside of the coaxial line. core soldering.

Compared with the prior art, the utility model has the following advantages and effects:

The multi-frequency broadband planar mobile phone antenna of the utility model adopts bending radiation branches, multi-branch technology and double-strip line coupling structure, and rationally arranges six radiation units in a limited space to achieve miniaturization, multi-frequency and broadband In order to achieve the coverage of all communication frequency bands of LTE/WWAN/WLAN/WiMAX.

Description of drawings

Fig. 1 is a schematic structural view of the multi-frequency broadband planar mobile phone antenna of the present invention.

Fig. 2(a) is a structural schematic diagram of the metal antenna piece attached to the upper surface of the dielectric plate of the present invention.

Fig. 2(b) is a structural schematic diagram of the multi-frequency broadband planar mobile phone antenna of the present invention attached to the metal antenna piece on the upper surface of the dielectric board and half containing a monopole.

Fig. 2(c) is a structural schematic diagram of the X-shaped monopole in the metal antenna sheet attached to the upper surface of the dielectric plate of the multi-frequency broadband planar mobile phone antenna of the present invention.

Fig. 2(d) is a structural schematic diagram of the first connection part of the metal antenna sheet attached to the upper surface of the dielectric plate of the multi-frequency broadband planar mobile phone antenna of the present invention.

Fig. 3 is a schematic diagram of the structure of the multi-frequency broadband planar mobile phone antenna of the present invention attached to the metal antenna sheet and the metal ground on the lower surface of the dielectric board.

Fig. 4 is a return loss diagram of the multi-frequency broadband planar mobile phone antenna of the present invention.

Fig. 5 (a1) is the radiation pattern of the YOZ plane when the multi-frequency broadband planar mobile phone antenna of the present invention is at 80OMHZ.

Fig. 5 (a2) is the radiation pattern of the XOZ plane when the multi-frequency broadband planar mobile phone antenna of the present invention is at 80OMHZ.

Fig. 5 (a3) is the radiation pattern of the XOY plane when the multi-frequency broadband planar mobile phone antenna of the present invention is at 80OMHZ.

Fig. 5 (b1) is the radiation pattern of the YOZ plane when the multi-frequency broadband planar mobile phone antenna of the present invention is at 200OMHZ.

Fig. 5 (b2) is the radiation pattern of the XOZ plane of the multi-frequency broadband planar mobile phone antenna of the present invention at 200OMHZ.

Fig. 5 (b3) is the radiation pattern of the XOY plane of the multi-frequency broadband planar mobile phone antenna of the present invention at 200OMHZ.

Fig. 5 (c1) is the radiation pattern of the YOZ plane when the multi-frequency broadband planar mobile phone antenna of the present invention is at 350OMHZ.

Fig. 5 (c2) is the radiation pattern of the XOZ plane when the multi-frequency broadband planar mobile phone antenna of the present invention is at 350OMHZ.

Fig. 5 (c3) is the radiation pattern of the XOY plane when the multi-frequency broadband planar mobile phone antenna of the present invention is at 350OMHZ.

Fig. 5 (d1) is the radiation pattern of the YOZ plane when the multi-frequency broadband planar mobile phone antenna of the present invention is at 550OMHZ.

Fig. 5 (d2) is the radiation pattern of the XOZ plane when the multi-frequency broadband planar mobile phone antenna of the present invention is at 550OMHZ.

Fig. 5 (d3) is the radiation pattern of the XOY plane when the multi-frequency broadband planar mobile phone antenna of the present invention is at 550OMHZ.

Detailed ways

The utility model will be further described in detail below in conjunction with the embodiments and accompanying drawings, but the implementation of the utility model is not limited thereto.

Example

As shown in Figure 1, it is a structural schematic diagram of a multi-frequency broadband planar mobile phone antenna of the present invention. The TLY-5 dielectric board 3, and the metal antenna sheet 1 and the metal antenna sheet 2 attached to the upper surface and the lower surface of the TLY-5 dielectric board 3 respectively. Among them, the metal ground 4 is used to simulate the circuit board of the mobile phone.

The TLY-5 dielectric plate 3 has a length of 125mm, a width of 65mm, a thickness of 0.508mm, and a relative permittivity of 2.2.

As shown in Figure 2 (a), it is a structural schematic diagram of a multi-frequency broadband planar mobile phone antenna of the present invention attached to the metal antenna sheet on the surface of the dielectric plate, and Figure 3 is a multi-frequency broadband planar mobile phone antenna of the present invention Schematic diagram of the structure of the metal antenna sheet and the metal ground attached to the lower surface of the dielectric board. As shown in Figure 2(a) and Figure 3, the metal antenna sheet 1 includes a first radiating unit 1A, a second radiating unit 1B, a third radiating unit 1C, a fourth radiating unit 1D, a first connecting part 1E and a 50-ohm micro With feeder 1F, six parts are located on the same plane and arranged on the upper surface of TLY-5 dielectric board 3; metal antenna sheet 2 includes fifth radiating unit 2A, sixth radiating unit 2B, second connecting part 2C and third connecting part 2D , the four parts are located on the same plane and arranged on the lower surface of the TLY-5 dielectric board 3 . The horizontal length of the metal antenna sheet 1 is 65 mm, which is equal to the width of the TLY-5 dielectric board 3 .

As shown in Fig. 2(d), it is a structural schematic diagram of the first connection part in the metal antenna sheet attached to the upper surface of the dielectric plate by a multi-frequency broadband planar mobile phone antenna of the present invention. As shown in FIG. 2( d ), the first connection part 1E includes a connection part 1E1 , a connection part 1E2 , a connection part 1E3 , a connection part 1E4 , a connection part 1E5 and a connection part 1E6 . The connecting part 1E1 has a horizontal length of 7.2 mm and a vertical length of 0.9 mm; the connecting part 1E2 starts from the upper end of the right edge of the connecting part 1E1 and extends horizontally to the right by 10.3 mm, and the line width of the connecting part 1E2 is 0.4 mm; the connecting part 1E3 consists of From the right end of the upper edge of the connecting part 1E2, extend vertically upwards by 1.7mm, and the line width of the connecting part 1E3 is 1.9mm; from the left end of the upper edge of the connecting part 1E1, the connecting part 1E6 extends vertically upwards by 2.3mm, and the line width of the connecting part 1E6 The lower edge of the connecting part 1E4 coincides with the upper edge of the connecting part 1E6, the horizontal length of the connecting part 1E4 is 6 mm, the vertical length is 0.7 mm, and the horizontal distance between the left edge of the connecting part 1E4 and the left edge of the connecting part 1E6 is 2 mm ; Connecting part 1E5 starts from the right end of the upper edge of connecting part 1E4 and extends vertically upwards by 1.7 mm. The line width of connecting part 1E5 is 0.7 mm. As shown in Figure 3, the second connecting part 2C is arranged vertically upwards by 2.4mm from the upper edge of the metal ground 4 to the horizontal distance of 24mm from the left end point, and the line width is 1.2mm; the third connecting part 2D is from the upper edge of the metal ground 4 to the left end Points at a horizontal distance of 13mm extend vertically upwards by 4.8mm, and continuously extend horizontally to the left by 4.5mm, with a line width of 1.2mm.

As shown in Figure 2(a), the first radiating unit 1A is an inverted C-shaped monopole, the second radiating unit 1B is a half-folded monopole, the third radiating unit 1C is an F-shaped monopole, and the fourth The radiation unit 1D is an X-shaped monopole, the fifth radiation unit 2A is a folded S-shaped branch, and the sixth radiation unit 2B is an inverted C-shaped branch.

The extended length of the inverted C-shaped monopole 1A is 81mm, and the line width is 0.7mm; the inverted C-shaped monopole 1A starts from the upper end point of the right edge of the connecting part 1E3, extends horizontally to the right by 39.5mm, and extends vertically upward for 10.3mm. mm arrangement, continuous horizontal extension 31.2mm arrangement to the left. The right edge of the reverse C-shaped monopole 1A coincides with the right edge of the upper surface of the TLY-5 dielectric plate 3 . The folded S-shaped branch 2A includes four short branches. The unfolded length of the folded S-shaped branch 2A is 129mm, and the line width is 1.2mm; mm arrangement, continuous vertical extension of 3.525mm arrangement, continuous horizontal extension of 5mm to the left, continuous vertical extension of 3.375mm arrangement, continuous horizontal extension of 33.3mm to the left, continuous vertical extension of 5.7mm arrangement, continuous horizontal extension of 38.3 to the right mm arrangement; the uppermost edge and the right edge of the folded S-shaped branch 2A coincide with the upper edge and the right edge of the lower surface of the TLY-5 medium plate 3 respectively. The lower end of the inverted C-shaped monopole 1A overlaps with the lower end of the folded S-shaped branch 2A, and the upper end of the inverted C-shaped monopole 1A is surrounded by the upper end of the folded S-shaped branch 2A, forming a double-strip line structure. Improve the coupling degree between the C-shaped monopole 1A and the folded S-shaped branch 2A. The inverted C-shaped monopole 1A is coupled with the folded S-shaped branch 2A to form a dual stripline structure, which is mainly used for the coverage of the 700-MHz frequency band.

The folded S-shaped branch 2A includes four short branches with a length of 3.2 mm and a width of 1.2 mm, which are arranged horizontally and parallel along the lower edge of the middle part of the folded S-shaped branch 2A. The four short branches are from left to right, and the left edge The horizontal distances from the upper left edge of the folded S-shaped branch 2A are 7.5mm, 11.5mm, 23.5mm, and 27.5mm in sequence. The four stubs are mainly used to expand the bandwidth of the 700-MHz band.

As shown in Fig. 2(b), it is a structural schematic diagram of a multi-frequency broadband planar mobile phone antenna of the present invention attached to the metal antenna piece on the upper surface of the dielectric plate and half containing a monopole. As shown in Figure 2(b), the bent half-contained monopole 1B includes two mutually semi-contained C-shaped bent branches 1B1, C-shaped bent branches 1B2 and a U-shaped bent branch composed of two U-shaped bent branches Section group 1B3. The reverse C-shaped branch 2B has a developed length of 44.9mm and a line width of 1.2mm; the reverse C-shaped branch 2B starts at a vertical distance of 0.6mm from the right edge of the third connection part 2D to the upper end point, extends horizontally to the right for 6.8mm, and is arranged continuously and vertically Extend upwards by 10.8mm, continuously extend horizontally to the left by 19.8mm, and continuously extend vertically downward by 7.5mm; the leftmost edge of the reverse C-shaped branch 2B coincides with the left edge of the upper surface of the TLY-5 dielectric board 3 . The inverted C-shaped branch 2B surrounds and bends half to contain the monopole 1B to form a double-stripline structure, and the double-stripline structure is mainly used for coverage of the 2-GHz frequency band.

The C-shaped bent branch 1B1 has a developed length of 23mm and a line width of 0.8mm; the C-shaped bent branch 1B1 extends horizontally to the left by 5mm from the right end of the upper edge of the connecting part 1E5, and is arranged continuously vertically upward by 4.3mm. The right extension is 10.7mm arranged, and the continuous vertical extension is arranged by 3mm. The C-shaped bent branch 1B2 has a developed length of 26.3mm and a line width of 0.8mm; the C-shaped bent branch 1B2 starts from the upper end of the rightmost edge of the U-shaped bent branch group 1B3, extends horizontally to the right for 6.5mm, and is arranged continuously and vertically Extend upwards by 6.9mm and extend horizontally by 12.9mm to the left. In the U-shaped bent branch group 1B3, the openings of the two U-shaped bent branches are arranged side by side in a horizontal direction, and the unfolded length of the two U-shaped bent branches is 6.6mm, the line width is 0.2mm, and the inner groove width is 0.2mm; The leftmost side of the U-shaped bent branch group 1B3 is closely connected with the lower right edge of the C-shaped bent branch 1B1 through a square with a side length of 0.2 mm; a square with a side length of 0.2 mm passes between two U-shaped bent branches tight connection. The mutually coupled semi-comprising C-shaped bent stub 1B1, C-shaped bent stub 1B2 and U-shaped bent stub group 1B3 work together to expand the bandwidth of the 2-GHz frequency band.

The line width of the F-shaped monopole 1C is 0.7mm, and the F-shaped monopole 1C includes a vertical branch and two upper and lower horizontal branches. The vertical branches start from the left end of the upper edge of the connecting part 1E3, and extend vertically upwards by 5.3mm; the upper horizontal branches start from the upper end of the right edge of the vertical branches, and extend horizontally to the right by 7.5mm; the lower horizontal branches start from the right edge of the vertical branches. It starts at 2.2mm from the end point and extends horizontally to the right by 6mm. The F-shaped monopole 1C is mainly used to achieve the coverage of the 3.5-GHz frequency band.

As shown in Fig. 2 (c), it is a structural diagram of a multi-frequency broadband planar mobile phone antenna of the present invention attached to the X-shaped monopole in the metal antenna sheet on the upper surface of the dielectric plate. As shown in Figure 2(c), the X-shaped monopole 1D is composed of several parts closely connected by dotted lines, mainly including eight right triangles 1D1a, 1D1b, 1D1c, 1D1d, 1D3a, 1D3b, 1D3c, 1D3d and three Quadrilaterals 1D2a, 1D2b, 1D4. Right triangles 1D1a, 1D1b, 1D1c, and 1D1d are congruent right triangles, the length of each horizontal side is 2.5mm, and the length of each vertical side is 2mm; right triangles 1D3a, 1D3b, 1D3c, 1D3d are congruent right triangles, The length of the right-angled side is 2mm, and the length of the vertical right-angled side is 2.5mm; the quadrilateral 1D2a and 1D2b are congruent quadrilaterals, the horizontal side length is 6mm, and the vertical side length is 0.5mm; the horizontal side length of the quadrilateral 1D4 is 2mm, The vertical side length is 5mm. The X-shaped monopole 1D is mainly used to achieve the coverage of the 5-GHz frequency band.

The line width of 50 ohm microstrip feeder 1F is 1.5mm, starting from the right end point of the lower edge of connection part 1E1, extending vertically downward for 54.1mm, and the lower end of 50 ohm microstrip feeder 1F is welded to the inner core of the coaxial line.

The length of the metal ground 4 is 110mm, which is less than the length of the TLY-5 medium plate 3, and the width is 65mm, which is equal to the width of the TLY-5 medium plate 3; The lower edge, left edge, and right edge of the lower surface of the board 3 overlap, the upper edge of the metal ground 4 is closely connected with the lower edge of the second connection part 2C, and the lower edge of the third connection part 2D, and the metal ground 4 is located in the 50 ohm microstrip The part directly below the lower end of the feeder 1F is welded to the outer core of the coaxial line.

As shown in Figure 4, it is the return loss figure of a kind of multi-frequency broadband planar mobile phone antenna of the present invention, it can be seen from the simulation results that the covered frequency bands are respectively: 695MHz-980MHz, 1700MHz-2698MHz, 3100MHz-3830MHz, 4520MHZ-, S11 is greater than 6dB, in line with the common standards of mobile phones.

As shown in Figure 5 (a1), 5 (a2) and 5 (a3), it is the radiation pattern of a kind of multi-frequency broadband planar mobile phone antenna of the present invention at 80OMHZ, as shown in Figure 5 (b1), 5 (b2) Shown in and 5 (b3), it is the radiation pattern of a kind of multi-frequency broadband planar mobile phone antenna of the present invention at 2000MHZ, as shown in Fig. 5 (c1), Fig. 5 (c2) and Fig. 5 (c3), it is The radiation pattern of a multi-frequency broadband planar mobile phone antenna of the utility model at 3500 MHz, as shown in Figure 5 (d1), Figure 5 (d2) and Figure 5 (d3), is a multi-frequency broadband planar antenna of the utility model The radiation pattern of the mobile phone antenna at 5500MHz can be seen from the figure that a multi-band broadband planar mobile phone antenna of the present invention has better omnidirectionality in these frequency bands and is suitable for mobile phone applications.

The above-mentioned embodiment is a preferred implementation mode of the present utility model, but the implementation mode of the present utility model is not limited by the above-mentioned embodiment, and any other changes, modifications and substitutions made without departing from the spirit and principle of the present utility model , combination, and simplification, all should be equivalent replacement methods, and are all included in the protection scope of the present utility model.

Claims (10)

1. A multi-frequency broadband planar mobile phone antenna, is characterized in that, comprises: metal ground, dielectric plate and metal antenna sheet, described dielectric plate is arranged on the top of metal ground, and described metal antenna sheet is attached to the medium plate surface; The metal antenna sheet includes: a first radiating unit, a second radiating unit, a third radiating unit, a fourth radiating unit, a fifth radiating unit, a sixth radiating unit, a first connection part, a second connection part, a third connection part and microstrip feeder; the first connecting part is used to connect the first radiating unit, the second radiating unit, the third radiating unit and the fourth radiating unit, and the second connecting part is used to connect the fifth radiating unit and the metal ground, the third connection part is used to connect the sixth radiating unit and the metal ground, and the microstrip feeder is connected to the first connection part. 2. multi-frequency broadband planar mobile phone antenna according to claim 1, is characterized in that, the first radiating element is a reverse C-shaped monopole, the second radiating element is a half-folded monopole, and the third radiating element is F-shaped monopole, the fourth radiating unit is an X-shaped monopole, the fifth radiating unit is a folded S-shaped branch, and the sixth radiating unit is an inverted C-shaped branch; the first radiating unit, the second radiating unit, the third The radiation unit, the fourth radiation unit and the first connection part are all printed on the upper surface of the dielectric board, the fifth radiation unit, the sixth radiation unit, the second connection part, the third connection part and the metal ground are connected, and the fifth radiation unit The unit, the sixth radiating unit, the second connection part, the third connection part and the metal ground are all printed on the lower surface of the dielectric board, and the microstrip feeder is a 50 ohm microstrip feeder. 3. multi-frequency broadband planar mobile phone antenna according to claim 2, is characterized in that, the lower end left edge of described anti-C shape monopole and the right edge upper end of first connecting part are closely connected, and described folded S-shaped branch There are four short branches, the left edge of the lower end of the folded S-shaped branch is closely connected with the upper right edge of the second connecting part; the lower end of the reverse C-shaped monopole coincides with the lower end of the folded S-shaped branch, and the The upper end of the inverted C-shaped monopole is completely surrounded by the upper end of the folded S-shaped branch, forming a double strip line structure to improve the coupling between the C-shaped monopole and the folded S-shaped branch; the inverted C-shaped monopole The subs and the folded S-shaped branches are coupled to each other to form a double-strip line structure. 4. multi-frequency broadband planar mobile phone antenna according to claim 3, is characterized in that, the length and the width of each short branch in the described four short branches are all the same, and horizontally along the lower edge of the middle part of the folded S-shaped branch. parallel arrangement. 5. The multi-frequency broadband planar mobile phone antenna according to claim 2, wherein the bent half includes a monopole including two C-shaped bent stubs and two U-shaped bent stubs that are included in half, and the bent The half includes the lower end edge of the monopole, the left side of the two U-shaped bent branches and the uppermost edge of the first connecting part; the lower left edge of the reverse C-shaped branch is connected to the right The position close to the upper end of the edge is closely connected, the third connection part is in an inverted L shape, and the inverted C-shaped branch is bent around and half contains a monopole to form a double stripline structure. 6. The multi-frequency broadband planar mobile phone antenna according to claim 5, characterized in that, two C-shaped bent branches that are half-contained are coupled to each other, wherein the lower end of a C-shaped bent branch is connected to the C-shaped bent branch. The edge of the opposite side is closely connected with another C-shaped bent branch through a U-shaped bent branch, there are two U-shaped bent branches, and the two U-shaped bent branches are arranged side by side; The C-bend stub and the U-bend stub are included to expand the bandwidth of the 2-GHz frequency band. 7. The multi-frequency broadband planar mobile phone antenna according to claim 2, characterized in that, the lower edge of the F-shaped monopole is closely connected to the left end of the rightmost upper edge of the first connecting portion. 8. The multi-frequency broadband planar mobile phone antenna according to claim 2, characterized in that, the right edge of the lower end of the X-shaped monopole is closely connected to the left edge of the first connecting portion. 9. The multi-frequency broadband planar mobile phone antenna according to claim 2, characterized in that, the upper end of the 50 ohm microstrip feeder is closely connected with the lower end of the first connection part, and the lower end of the 50 ohm microstrip feeder is connected with the same The inner core of the axis is welded, and the length of the 50 ohm microstrip feeder is about 1/2 of the length of the metal ground. 10. The multi-frequency broadband planar mobile phone antenna according to claim 1, wherein the lower edge of the metal ground coincides with the lower edge of the lower surface of the dielectric plate, and the lower edge of the second connecting portion and the lower edge of the third connecting portion Both are closely connected with the upper edge of the metal ground.