CN105789901A - Multi-band antenna free of lumped parameter element for high-screen ratio mobile terminal - Google Patents

Abstract

A multi-band antenna for mobile terminals with high screen-to-body ratio without lumped parameter elements belongs to the technical field of broadband antennas for mobile terminals, and is characterized in that it adopts a single-stage sub-antenna with driving branches combined with double-branches coupled to ground branches. Antenna main body, dielectric plate, microstrip feeder and metal floor, among which: antenna main body is composed of T-shaped driving branch and double-branch coupling parasitic ground branch, which generate two 1/4 wavelength resonance modes in the low frequency band, and at the same time Combined with the 3/4 wavelength mode of the driving branch, the 3/4 wavelength mode of the long-coupling parasitic ground branch, and then introduce the 1/4 wavelength resonance mode of the short-coupling parasitic ground branch and the tuning branch to realize low-band LTE700, GSM850, GSM900 and The full coverage of high-frequency DCS, PCS, UMTS, LTE2300 and LTE2500 also eliminates the loss caused by lumped parameter components.

Description

Multiband Antennas for High Screen-to-Body Mobile Terminals without Lumped Parameter Components

technical field

The invention belongs to the technical field of wide-band antennas for mobile terminals, and relates to a multi-band WWAN/LTE antenna that does not use lumped parameter elements and is suitable for mobile terminal equipment with a high screen-to-body ratio

Background technique

With the rapid development of wireless communication technology, the technologies of the second generation mobile communication system (the second generation, 2G), the third generation mobile communication system (the third generation, 3G) and the fourth generation mobile communication system (the fourth generation, 4G) have matured and are widely used in the world. be applied within the scope. Due to the communication needs of modern intelligent mobile terminals, broadband mobile terminal antennas, such as mobile phones, tablet computers, notebooks and other equipment, need to cover the global mobile communication system GSM850 (824-894MHz) and GSM900 (880-960MHz) of the 2G mobile communication system at the same time , digital cellular system DCS (1710-1880MHz) and personal communication system, PCS (1850-1990MHz), 3G mobile communication system universal mobile communication system UMTS (1920-2170MHz), 4G mobile communication system LTE system LTE700 (698-787MHz ), LTE2300 (2300-2400MHz) and LTE2500 (2500-2690MHz), the coexistence of 2G/3G/4G mobile communication systems will be maintained for a long time in the future. In addition, with the development of mobile terminal devices towards high screen-to-body ratio, slimming, narrow bezels, and metallization, the design space for mobile terminal mobile phone antennas is becoming more and more narrow. How to design 2G antennas in a small space size /3G/4G communication requirements antennas have become a challenge in the field of mobile terminal antenna design.

In order to realize broadband mobile terminal antennas in a small space size, the mainstream antenna form usually selected is a monopole antenna. In the mobile communication frequency band, it usually has two resonance modes (1/4 wavelength resonance mode and 3/4 wavelength resonance mode). In addition to the two basic resonant modes, the monopole antenna can also combine multiple matching techniques to achieve broadband characteristics in a small space, such as: coupled feeding matching technology, lumped parameter element matching technology, distributed parameter element matching technology and reconfigurable technologies. No matter which technology is used, due to the limitation of the 1/4 wavelength resonance mode of the basic resonance mode of the monopole antenna, it is difficult to match LTE700, GSM850, and GSM900 in the low frequency band, because the 1/4 wavelength in the low frequency band is often already compatible with mobile The size of terminal equipment is comparable, but mobile terminal equipment can only provide a small part of space for antenna design. In order to realize a broadband mobile terminal antenna with a small size, lumped parameter component matching technology is widely used in mobile terminal antenna design, only to adjust the low frequency bandwidth or generate a new resonance point at low frequency to widen the low frequency band. However, the introduction of lumped parameter elements often causes losses. Therefore, the present invention adopts the form of a monopole antenna in which the driving branch is combined with the double-branch coupling ground branch. In the low-frequency band LTE700, GSM850, and GSM900, two 1/4 wavelength resonance modes are generated to realize low-frequency band coverage. The 3/4 wavelength mode of the branch, the 3/4 wavelength mode of the long-coupling parasitic ground branch and the introduction of the 1/4 wavelength resonance mode and the tuning branch of the short-coupling parasitic ground branch realize the high-band DCS, PCS, UMTS, LTE2300 and LTE2500 cover. The present invention proposes a mobile terminal WWAN/LTE antenna, which realizes LTE700, GSM850, GSM900, DCS, PCS, UMTS, LTE2300 and LTE2500 frequency bands without using any lumped parameter elements and on the premise of a non-floor height of only 8mm The coverage meets the small-size antenna design requirements in the 2G/3G/4G communication frequency band.

Contents of the invention

The present invention proposes a mobile terminal WWAN/LTE antenna capable of covering multiple frequency bands without using lumped parameter elements and under the condition of small non-floor height.

The present invention is characterized in that it contains: an antenna main body (1), a dielectric board (2), a microstrip feeder (3) and a metal floor (4), wherein:

Dielectric plate (2), the length, width and height are represented by X, Y, Z, which are 128mm×70mm×0.8mm respectively, and the coordinate origin is in the upper left corner,

The metal floor (4), with a length and width of 120mm×70mm, is printed on the medium plate (2), and the bottom of the metal floor (4) is also aligned with the medium plate along the width direction,

The microstrip feeder (3), with a length and width of 40mm×1.5mm, is located on the back of the dielectric board (2), the left side is 10mm away from the left edge of the dielectric board (2), and the antenna feed point (5) passes through After passing through the metal floor (4), it is connected to the lower end point of the microstrip feeder (3), and the feed current flows into the antenna main body (1) along the negative X-axis direction,

The antenna main body (1) is composed of "T"-shaped driving branches (1a) and double-branch coupling parasitic ground branches (1a, 1b, 1d, 1e), wherein,

"T"-shaped drive branch (1a), printed on the top of the back of the dielectric board (2) along the negative Y-axis direction, wherein: the length and width of the vertical part of the branch is 5.5mm x 1.5mm, and the lower side is connected with the microstrip The feeding current outflow end of the feeder line (3) is connected, and the upper side is connected with a horizontal branch branch with a length and width of 70mm×2mm,

The double-branch coupled parasitic ground branch is composed of a long coupled parasitic ground branch (1b), a short coupled parasitic ground branch (1c), a tuning branch (1d) and a short-circuit branch (1e), wherein,

The long coupled parasitic branch (1b) is composed of the first long coupled parasitic branch (1b1), the second long coupled parasitic branch (1b2) and the third long coupled parasitic branch (1b3), wherein:

The first long coupled parasitic ground branch (1b1) is horizontally printed on the top of the front of the medium board, the length and width are 67mm×2mm, the distance from the right end to the right edge of the medium board (2) is 3mm, and the width in the X-axis direction is 2mm ,

The second long coupled parasitic ground branch (1b2) is the part extending outward along the negative x-axis at the upper left corner of the dielectric plate (2), and the length from the coordinate origin along the negative Y-axis direction is 8mm, along the negative X-axis direction The width is 5mm, and the lower side of its long side is connected to the left end of the upper side of the first coupling parasitic ground branch (1b1),

The third long coupled parasitic ground branch (1b3), the bottom edge is connected to the top edge of the second long coupled ground branch (1b2) along the negative Y axis, the length is 28mm, and the wide side along the negative X axis is 3mm,

The second long coupled parasitic ground branch (1b2) is turned inward by 90° relative to the front side of the medium plate (2) along the folded edge with the first long coupled ground branch (1b1),

Short-coupling parasitic ground branches (1c), printed on the front of the dielectric board (2) along the negative Y-axis direction, with a length of 31mm, the left end is 36mm away from the left edge of the dielectric board, and the lower side is away from the metal floor (4) 0.3mm of the top side,

Tuning branch (1d), used to adjust or widen the frequency band of the antenna, composed of the first tuning branch (1d1), the second tuning branch (1d2), the third tuning branch (1d3) and the fourth tuning branch (1d4) ,in:

The first tuning branch (1d1), the length along the negative Y-axis direction and the width along the X-axis direction are 2mm×1mm, and its long side is 14mm away from the right end side of the first long coupled parasitic ground branch (1b1). The bottom edge is connected to the right side,

The second tuning branch (1d2) is the part extending upward from the upper right corner of the medium plate (2) to the negative X-axis direction, and the length from the right edge of the medium plate (2) along the y-axis direction is 40mm, along the negative The height in the X-axis direction is 10 mm, the bottom edge is connected to the top edge of the first long coupled parasitic ground branch (1b1), and the second tuning branch (1d2) is along the first long coupled ground branch (1b1) ), the folded edge of the medium plate (2) is turned inward by 90° relative to the front side of the medium plate (2), and the second tuning branch (1d2) moves toward the medium plate (2) along the fold line in the horizontal direction at 1/2 of its height. ) varus 90°,

The third tuning stub (1d3) has a length of 3mm along the negative Y-axis direction and a height of 4mm along the X-axis direction, starting at a distance of 13mm from the left edge of the dielectric board (2), and parasitic with the first long coupling The ground branch (1b1) is connected to the left side of the base,

The fourth regulating branch (1d4) is in the shape of "┌" and is flat, starting from the negative X-axis, along the bottom edge of the negative Y-axis direction directly connected to the top edge of the third coupled parasitic ground branch (1b3) The length is 10mm, and the length of the top side is 15mm. The height difference between the bottom side and the bottom surface of the horizontal branch protruding to the right of the "┌" type fourth tuning branch (1d4) is 2mm. "┌" type fourth tuning branch (1d4) together with the third long coupled parasitic branch (1b3) along the third long coupled parasitic branch (1b3) and the second long coupled parasitic branch ( 1b2) The folding line at the junction is turned inside out at an angle of 90° relative to the front side of the medium board (2),

The short-circuit branch (1e) is connected to the short-circuit point (6) at the front top of the metal floor (4) in the center of the bottom. ) starting from the right edge, the length along the Y-axis direction is 3 mm, and the left side edge of the short-circuit branch (1e) is respectively connected to the first long-coupled parasitic ground branch (1b1) and the short-coupled parasitic ground branch ( 1c) to the right side.

Compared with the existing invention technology, the present invention has the following obvious advantages:

1. Under the condition of not using lumped parameter components, using the driving branch combination to couple the parasitic ground branch, realize covering eight frequency bands of WWAN/LTE in a small non-floor size.

2. Due to the small non-floor size and wide frequency band coverage, it is suitable for the communication and design requirements of today's high-screen-to-body mobile terminal equipment.

3. The antenna has a simple structure and is easy to manufacture, and can be mass-produced at a low cost.

Description of drawings

FIG. 1 is a front view of the mobile terminal WWAN/LTE antenna proposed by the present invention, and the dimension unit is millimeter (mm).

FIG. 2 is a back view and specific dimensions of an example antenna proposed by the present invention, and the dimension unit is millimeter (mm).

Fig. 3 is the front plane development diagram and specific dimensions of the example antenna proposed by the present invention, and the dimension unit is millimeter (mm).

Fig. 4 is the measured antenna reflection coefficient of the example antenna proposed by the present invention.

FIG. 5 is an actual measured antenna radiation pattern of the example antenna proposed by the present invention.

FIG. 6 is the measured antenna gain of the example antenna proposed by the present invention.

Fig. 7 is the measured antenna efficiency of the example antenna proposed by the present invention.

detailed description

The present invention proposes a mobile terminal WWAN/LTE antenna capable of covering multiple frequency bands without using lumped parameter elements and under the condition of small non-floor height. Its front view is shown in Figure 1. It can be seen from the figure that the antenna proposed by the present invention is mainly composed of four parts: the antenna main body, the dielectric board, the microstrip feeder, and the metal floor. The main part of the antenna is printed on the dielectric board, and part of it is folded to form a three-dimensional folded structure in space.

The material used for the dielectric plate is FR4, and the loss tangent is 0.02. The metal floor printed on the front of the dielectric board is connected to the main body of the antenna, which approximately replaces the screen and circuit components of the mobile terminal device, and also plays a role in radiating and guiding electromagnetic waves.

The main body of the antenna is composed of "T"-shaped driving branches and double-branch coupling parasitic ground branches. Among them, the "T" driving branch is directly fed by the feed microstrip line and participates in the antenna radiation, and the double-branch coupling parasitic ground branch is composed of a long coupling parasitic ground branch, a short coupling parasitic ground branch, a short-circuit branch and a tuning branch. The current flows from the metal floor through the short-circuit branch into the double-branch coupled parasitic ground branch in a coupling manner, so as to realize the radiation of electromagnetic waves. The tuning stub serves to fine-tune the frequency band of the antenna.

The working principle of the designed antenna of the present invention is as follows: "T" drives the branch to generate two monopole resonance modes of quarter wavelength and three quarter wavelength. Long-coupled parasitic ground branches generate quarter-wavelength and three-quarter-wavelength resonant modes of two monopoles. Short coupled parasitic ground branches produce a monopole quarter-wavelength resonant mode. Among them, the resonant frequency of the quarter-wavelength mode generated by the "T" driving branch and the quarter-wavelength resonance mode generated by the long-coupled parasitic ground branch is in the low frequency band, covering LTE700, GSM850 and GSM900 frequency bands. The resonant frequencies of the three-quarter wavelength mode generated by the "T"-shaped driving branch, the three-quarter wavelength resonance mode generated by the long-coupled parasitic ground branch, and the quarter-resonant mode of the short-coupled parasitic ground branch are in the high frequency band, The three resonance modes work together to form a wide frequency band in the high frequency band, covering DCS, PCS, UMTS, LTE2300 and LTE2500 frequency bands. In addition, tuning stubs are used for fine-tuning of the antenna frequency band.

In order to verify that the antenna of the present invention can achieve multi-band coverage without using lumped parameter elements and under the condition of a small non-floor height, an example antenna was made according to the original dimensions marked in Fig. 1, Fig. 2 and Fig. 3, and The reflection coefficient, antenna pattern, gain and antenna radiation efficiency of the antenna are obtained through the test.

The test results of the antenna reflection coefficient of the example antenna are shown in Figure 4. The -6dB impedance bandwidth of the example antenna is 285MHz (695MHz-980MHz) and 1.05GHz (1690MHz-2740MHz), covering LTE700, GSM850, GSM900, DCS, PCS, , UMTS, LTE2300 and LTE2500 to meet the current 2G/3G/4G communication needs.

The test results of the radiation pattern of the example antenna are shown in Figure 5. Figure 5 shows the radiation patterns of the example antenna at frequencies of 725MHz, 825MHz, 925MHz, 1750MHz, 2350MHz, and 2600MHz. From Figure 5, it can be seen that the radiation pattern of the antenna at the three frequency points (725MHz, 825MHz, 925MHz) in the low frequency band is close to the shape of the dipole radiation pattern. At the three frequency points in the high frequency band (1750MHz, 2350MHz, 2600MHz), since the resonance mode mixes the 1/4 wavelength and 3/4 wavelength resonance modes, the radiation pattern becomes irregular and has a certain inclination towards the floor. directionality.

The test result of example antenna gain is as shown in Figure 6, in low frequency band (LTE700, GSM850, GSM900), the measured gain of example antenna is-0.2dBi-3.73dBi; ), the measured gain of the example antenna is 1.98dBi-3.91dBi, which is sufficient to meet the gain requirements of the wireless communication of the mobile terminal.

The test results of the radiation efficiency of the example antenna are shown in Figure 7. In the low frequency band (LTE700, GSM850, GSM900), the measured radiation efficiency of the example antenna is 54.5%-92.3%; in the high frequency band (DCS, PCS, UMTS, LTE2300 and LTE2500), the measured radiation efficiency of the example antenna is 64.7%-90.5%. In the frequency band required by 2G/3G/4G communication, the energy can be radiated well.

In summary, the present invention proposes a small-sized multi-band mobile terminal antenna structure of 8mm×70mm×5.8mm without using lumped parameter elements, which can cover modern 2G/3G/4G communication requirements LTE700, GSM850, GSM900, DCS, PCS, UMTS, LTE2300 and LTE2500 frequency bands, and has high antenna gain and efficiency in the covered frequency bands, fully meeting the small size and multi-band requirements of modern wireless communications.

Claims (1)

1. The multi-band antenna for high screen-to-body ratio mobile terminals without lumped parameter components is characterized in that it contains: antenna body (1), dielectric plate (2), microstrip feeder (3) and metal floor (4 ),in: Dielectric plate (2), the length, width and height are represented by X, Y, Z, which are 128mm×70mm×0.8mm respectively, and the coordinate origin is in the upper left corner, The metal floor (4), with a length and width of 120mm×70mm, is printed on the medium plate (2), and the bottom of the metal floor (4) is also aligned with the medium plate along the width direction, The microstrip feeder (3), with a length and width of 40mm×1.5mm, is located on the back of the dielectric board (2), the left side is 10mm away from the left edge of the dielectric board (2), and the antenna feed point (5) passes through After passing through the metal floor (4), it is connected to the lower end point of the microstrip feeder (3), and the feed current flows into the antenna main body (1) along the negative X-axis direction, The antenna main body (1) is composed of "T"-shaped driving branches (1a) and double-branch coupling parasitic ground branches (1a, 1b, 1d, 1e), wherein, "T"-shaped drive branch (1a), printed on the top of the back of the dielectric board (2) along the negative Y-axis direction, wherein: the length and width of the vertical part of the branch is 5.5mm x 1.5mm, and the lower side is connected with the microstrip The feeding current outflow end of the feeder line (3) is connected, and the upper side is connected with a horizontal branch branch with a length and width of 70mm×2mm, The double-branch coupled parasitic ground branch is composed of a long coupled parasitic ground branch (1b), a short coupled parasitic ground branch (1c), a tuning branch (1d) and a short-circuit branch (1e), wherein, The long coupled parasitic branch (1b) is composed of the first long coupled parasitic branch (1b1), the second long coupled parasitic branch (1b2) and the third long coupled parasitic branch (1b3), wherein: The first long coupled parasitic ground branch (1b1) is horizontally printed on the top of the front of the medium board, the length and width are 67mm×2mm, the distance from the right end to the right edge of the medium board (2) is 3mm, and the width in the X-axis direction is 2mm , The second long coupled parasitic ground branch (1b2) is the part extending outward along the negative x-axis at the upper left corner of the dielectric plate (2), and the length from the coordinate origin along the negative Y-axis direction is 8mm, along the negative X-axis direction The width is 5mm, and the lower side of its long side is connected to the left end of the upper side of the first coupling parasitic ground branch (1b1), The third long coupled parasitic ground branch (1b3), the bottom edge is connected to the top edge of the second long coupled ground branch (1b2) along the negative Y axis, the length is 28mm, and the wide side along the negative X axis is 3mm, The second long coupled parasitic ground branch (1b2) is turned inward by 90° relative to the front side of the medium plate (2) along the folded edge with the first long coupled ground branch (1b1), Short-coupling parasitic ground branches (1c), printed on the front of the dielectric board (2) along the negative Y-axis direction, with a length of 31mm, the left end is 36mm away from the left edge of the dielectric board, and the lower side is away from the metal floor (4) 0.3mm of the top side, Tuning branch (1d), used to adjust or widen the frequency band of the antenna, composed of the first tuning branch (1d1), the second tuning branch (1d2), the third tuning branch (1d3) and the fourth tuning branch (1d4) ,in: The first tuning branch (1d1), the length along the negative Y-axis direction and the width along the X-axis direction are 2mm×1mm, and its long side is 14mm away from the right end side of the first long coupled parasitic ground branch (1b1). The bottom edge is connected to the right side, The second tuning branch (1d2) is the part extending upward from the upper right corner of the medium plate (2) to the negative X-axis direction, and the length from the right edge of the medium plate (2) along the y-axis direction is 40mm, along the negative The height in the X-axis direction is 10 mm, the bottom edge is connected to the top edge of the first long coupled parasitic ground branch (1b1), and the second tuning branch (1d2) is along the first long coupled ground branch (1b1) ), the folded edge of the medium plate (2) is turned inward by 90° relative to the front side of the medium plate (2), and the second tuning branch (1d2) moves toward the medium plate (2) along the fold line in the horizontal direction at 1/2 of its height. ) varus 90°, The third tuning stub (1d3) has a length of 3mm along the negative Y-axis direction and a height of 4mm along the X-axis direction, starting at a distance of 13mm from the left edge of the dielectric board (2), and parasitic with the first long coupling The ground branch (1b1) is connected to the left side of the base, The fourth regulating branch (1d4) is in the shape of "┌" and is flat, starting from the negative X-axis, along the bottom edge of the negative Y-axis direction directly connected to the top edge of the third coupled parasitic ground branch (1b3) The length is 10mm, and the length of the top side is 15mm. The height difference between the bottom side and the bottom surface of the horizontal branch protruding to the right of the "┌" type fourth tuning branch (1d4) is 2mm. "┌" type fourth tuning branch (1d4) together with the third long coupled parasitic branch (1b3) along the third long coupled parasitic branch (1b3) and the second long coupled parasitic branch ( 1b2) The folding line at the junction is turned inside out at an angle of 90° relative to the front side of the medium board (2), The short-circuit branch (1e) is connected to the short-circuit point (6) at the front top of the metal floor (4) in the center of the bottom. ) starting from the right edge, the length along the Y-axis direction is 3 mm, and the left side edge of the short-circuit branch (1e) is respectively connected to the first long-coupled parasitic ground branch (1b1) and the short-coupled parasitic ground branch ( 1c) to the right side.