CN106450741B - Multi-frequency LTE antenna adopting novel impedance matching structure - Google Patents

Abstract

The invention discloses a multi-frequency LTE antenna adopting a novel impedance matching structure, which comprises a substrate, a first radiation metal strap, a first metal patch, a microstrip line, a floor, a second radiation metal strap and a second metal patch. The second metal patch is divided into an annular patch and a central patch by a closed annular gap, the first metal patch is connected with the central patch through a metal probe, and the second metal patch is connected with the floor through a metal short-circuit line at a short-circuit point and connected with the first radiation metal strap through the short-circuit probe. The metal probe and the metal short circuit line form two distributed inductors, the overlapped part of the first metal patch, the central patch and the annular patch and the closed annular gap form two distributed capacitors, and the inductance and the capacitance of the impedance matching circuit can be controlled by adjusting the sizes of the distributed capacitors and the inductors. The antenna can effectively improve impedance matching without increasing the size and the structural complexity of the antenna, and has the advantages of no need of introducing lumped elements and low cost.

Description

A Multi-band LTE Antenna Using a New Impedance Matching Structure

technical field

The invention relates to the field of radio frequency technology, in particular to a multi-frequency LTE antenna adopting a novel impedance matching structure.

Background technique

In a mobile phone, the performance of the antenna affects the communication capability of the mobile phone, directly determines the transmission and reception performance of the mobile phone, and even the quality of the antenna design determines the survival space of the mobile phone in the market. Judging from the current technological development, LTE (LongTerm Evolution, the long-term evolution of 3G) technology is the core technology of the fourth-generation mobile communication (4G) and its continued development. Compared with 3G, LTE has a qualitative leap in technology and application: it has a higher communication rate (up to 100Mbit/s), greatly improves spectrum utilization, and effectively alleviates the current increasingly serious spectrum resource conflict. 698- 960MHz is the key frequency band for the development of LTE and LTE_A (LTE_Advanced, the evolution of LTE technology), while the frequency bands currently allocated to LTE in China are mainly between 1.7-2.6GHz, lacking low frequency bands. In realizing the large-scale and sustainable LTE technology During the development process, the design of small multi-band LTE antennas with working bandwidth covering 698-960MHz frequency band and 1.7-2.6GHz frequency band has become a research hotspot. This antenna is suitable for both LTE and LTE_A systems, which can avoid compatibility problems caused by antennas However, the 698-960MHz frequency band is relatively low, and it is difficult to achieve an antenna design that completely covers this frequency band while maintaining a small antenna size.

The current solution to this design problem is to use a combined antenna composed of multiple radiating elements, introduce an impedance matching network composed of lumped capacitance and inductance, and add lumped capacitance/distributed capacitance/collection capacitance to the appropriate position of the radiation element of the antenna. Total inductance/distributed inductance. These existing design methods will increase the design difficulty and processing cost of the antenna, and the structure is complex, and the flexibility of the impedance matching network is poor.

It can be seen that how to overcome the problems of complex structure and poor flexibility in the prior art is an urgent problem to be solved by those skilled in the art.

Contents of the invention

The purpose of the present invention is to provide a multi-frequency LTE antenna adopting a novel impedance matching structure, which is used to overcome the problems of complex structure and poor flexibility in the prior art.

In order to solve the above technical problems, the present invention provides a multi-band LTE antenna adopting a novel impedance matching structure, including a substrate 1, a first radiation metal strip 8 and a first metal patch 11 respectively printed on the front surface 2 of the substrate 1 , a microstrip line 16, a floor 4 printed on the back 3 of the substrate 1, a second radiating metal strip 7, and a second metal patch 20;

The floor 4, the second radiating metal strip 7, and the second metal patch 20 are on the same plane, and the first radiating metal strip 8 and the second radiating metal strip 7 have a first overlapping portion 9 And all are C-shaped, the openings all face the floor 4, the second metal patch 20 is divided into an annular patch 12 and a central patch 13 by a closed annular gap 15, the first metal patch 11 and the The second metal patch 20 has a second overlapping portion 14 and a non-overlapping portion, the second overlapping portion 14 includes the central patch 13, and the first metal patch 11 and the central patch 13 pass through a metal probe. One end of the annular patch 12 is connected to the second radiating metal strip 7, and the other end of the annular patch 12 is connected to the floor 4 at the short-circuit point 19 through a metal short-circuit line 18 and passed through The short-circuit probe 6 is connected to the first radiating metal strip 8 .

Preferably, the microstrip line 16 is a 50Ω microstrip line.

Preferably, the width of the end 10 of the second radiating metal strip 7 is greater than the width of the rest of the second radiating metal strip 7 .

Preferably, the width of the end 10 of the second radiating metal strip 7 is 4.5 mm, and the width of the rest of the second radiating metal strip 7 is 2 mm.

Preferably, the central patch 13 is rectangular.

Preferably, the first metal patch 11 is rectangular.

Preferably, the second metal patch 20 is rectangular, the width of the second metal patch 20 is the same as the width of the first metal patch, and the length of the second metal patch 20 is longer than that of the first metal patch. The length of the first metal patch.

Preferably, the first metal patch 11 is symmetrical with respect to the floor 4 .

Preferably, the base plate 1 is rectangular, and the floor 4 is rectangular.

In the multi-frequency LTE antenna provided by the present invention, the metal probe and the metal short circuit form two distributed inductors respectively, and the overlapping part and the closed annular gap of the first metal patch and the central patch and the annular patch respectively form two distributed inductors. These distributed inductors and distributed capacitors form a new impedance matching structure, so the antenna can effectively improve the impedance matching of the antenna without increasing the antenna size and structural complexity, and the antenna structure is simple, compared with the existing The cost is lower for the required lumped components of the technology.

Description of drawings

In order to illustrate the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. As far as people are concerned, other drawings can also be obtained based on these drawings on the premise of not paying creative work.

FIG. 1 is a front view of a multi-frequency LTE antenna provided by an embodiment of the present invention;

FIG. 2 is a side view of a multi-frequency LTE antenna provided by an embodiment of the present invention;

Fig. 3 is a front view of the multi-frequency LTE antenna after removing the metal probe 5 and the closed annular gap 15 in Fig. 1 provided by an embodiment of the present invention;

Fig. 4 is a front view of a multi-frequency LTE antenna after removing the metal probe 5 in Fig. 1 provided by an embodiment of the present invention;

FIG. 5 is a frequency response curve diagram of the bandwidth |S ₁₁ | of the antenna corresponding to FIG. 1 provided by an embodiment of the present invention;

In the figure, 1 is the substrate, 2 is the front of the substrate 1, 3 is the back of the substrate 1, 4 is the floor, 7 is the second radiating metal strip, 8 is the first radiating metal strip, 9 is the first radiating metal strip 8 and The first overlapping part of the second radiating metal strip 7, 10 is the end of the second radiating metal strip 7, 11 is the first metal patch, 12 is the ring patch of the second metal patch 20, 13 is the second metal patch The central patch of the sheet 20, 14 is the second overlapping part of the first metal patch 11 and the second metal patch 20, 15 is the closed annular gap of the second metal patch 20, 16 is the microstrip line, and 17 is the feeder Point 18 is a metal short circuit, 19 is a short circuit point, and 20 is a second metal patch.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The core of the present invention is to provide a multi-frequency LTE antenna adopting a novel impedance matching structure, which is used to overcome the problems of complex structure and poor impedance matching flexibility in the prior art.

In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is a front view of a multi-band LTE antenna provided by an embodiment of the present invention. Fig. 2 is a side view of a multi-band LTE antenna provided by an embodiment of the present invention. As shown in the figure, the multi-band LTE antenna includes a substrate 1, a first radiating metal strip 8 printed on the front 2 of the substrate 1, a first metal patch 11, a microstrip line 16, and a floor printed on the back 3 of the substrate 1. 4. The second radiating metal strip 7 and the second metal patch 20 .

The floor 4, the second radiating metal strip 7, and the second metal patch 20 are on the same plane, the first radiating metal strip 8 and the second radiating metal strip 7 have a first overlapping portion 9 and are both C-shaped, and the openings are all facing the floor 4. The second metal patch 20 is divided into an annular patch 12 and a central patch 13 by the closed annular gap 15, the first metal patch 11 and the second metal patch 20 have a second overlapping portion 14 and a non-overlapping portion, the second The two overlapping parts 14 include a central patch 13, the first metal patch 11 and the central patch 13 are connected by a metal probe 5, one end of the annular patch 12 is connected with the second radiating metal strip 7, and the other end of the annular patch 12 The metal short-circuit line 18 is connected to the floor 4 at the short-circuit point 19 and connected to the first radiation metal strip 8 through the short-circuit probe 6 .

In a specific implementation, the substrate 1 can be rectangular, and the floor 4 can also be rectangular. As shown in FIG. 7. The second metal patch 20 . The medium of the substrate 1 can be FR4 medium with a dielectric constant of 4.4 and a thickness of 1.6 mm. It can be understood that each parameter of the substrate 1 can be selected according to actual needs, and the above-mentioned specific parameters are only one application scenario, which does not mean that there is only one selection method.

In FIG. 1 , dotted lines indicate structures on the back side of the substrate 1 , thin solid lines indicate structures on the front side 2 of the substrate 1 , and thick solid lines indicate overlapping portions. The first metal patch 11 and the second metal patch 20 have a second overlapping portion 14, and the second overlapping portion 14 can be regarded as a capacitor C1 for capacitively coupling and feeding the antenna.

The closed annular gap 15 divides the second metal patch 20 into two parts, one part is the annular patch 12 outside the closed annular gap 15, and the other part is the central patch 13 inside the closed annular gap 15. The closed annular gap 15 can be regarded as is the distributed capacitance C2.

As shown in Figure 1, the left end of the annular patch 12 is directly connected to the second radiating metal strip 7, and the right end is connected to the floor 4 through the metal short-circuit line 18 at the short-circuit point 19 and connected to the first radiating metal strip 8 through the short-circuit probe 6. connect. The metal short circuit 18 can be regarded as a distributed inductor L2. In a specific implementation, the shape of the metal short circuit 18 is not required, and the total length can be set according to the actual situation. For example, in a specific implementation, it can be 20 mm and the width is 0.4 mm.

The first metal patch 11 and the central patch 13 are connected through a metal probe 5, which can be regarded as a distributed inductor L1.

It can be seen from the above description that because of the existence of the closed annular slot 15, the annular patch 12 and the central patch 13 are separated, so the antenna proposed by the present invention still belongs to coupling feeding.

Wherein, in a specific implementation manner, both the first metal patch 11 and the central patch 13 are rectangular. The second metal patch 20 is rectangular, the width of the second metal patch 20 is the same as that of the first metal patch 11 , and the length of the second metal patch 20 is longer than that of the first metal patch 11 .

In the multi-frequency LTE antenna provided in this embodiment, the feeding probe and the metal short-circuit line respectively constitute two distributed inductors, and the overlapping part and the closed annular gap of the first metal patch and the central patch and the annular patch respectively form two distributed inductors. Distributed capacitors, these distributed inductors and distributed capacitors constitute the new impedance matching structure proposed by the present invention, the size of the inductance and capacitance of the impedance matching circuit can be controlled by adjusting the size of these distributed capacitors and inductors, so as to obtain an ideal impedance matching effect . Therefore, the antenna can effectively improve the impedance matching of the antenna without increasing the size and structure complexity of the antenna, and the antenna has a simple structure and a lower cost than the required lumped elements in the prior art.

It should be noted that, in FIG. 2 , the metal probe 5 and the short-circuit probe 6 are stacked together. Therefore, the upper part of the thicker part in FIG. 2 is the feeding probe 5 , and the lower part is the short-circuit probe 6 .

On the basis of the above embodiments, the microstrip line 16 is a 50Ω microstrip line 16 .

As shown in FIG. 1 , one end of the microstrip line 16 is connected to the first metal sheet, and the other end is a feed point 17 , which is connected to the feed source through the feed to realize the feed.

On the basis of the above embodiments, the width of the end of the second radiating metal strip 7 is greater than the width of the rest of the second radiating metal strip 7 .

As shown in FIG. 1 , the end of the second radiating metal strip 7 is widened, and the widened part is marked as 10 in the figure. By widening the end of the second radiating metal strip 7 , the radiation efficiency can be improved and the impedance bandwidth can be improved. In one embodiment, the width of the end of the second radiating metal strip 7 is 4.5mm, and the width of the rest of the second radiating metal strip 7 is 2mm.

On the basis of the above embodiments, the first metal patch 11 is symmetrical with respect to the floor 4 .

It can be understood that if the first metal patch 11 is not symmetrical with respect to the floor 4, the current on the floor 4 will be uneven; if it is symmetrical with respect to the floor 4, the current on the floor 4 can be made uniform to achieve better Effect.

In order to make the multi-band LTE antenna provided by the present invention more clear to those skilled in the art, a specific simulation diagram is used below for illustration.

In the above, C1, C2 and L1, L2 constitute an effective impedance matching structure or a coupled feeding structure. Reasonably setting the sizes of C1, C2 and L1 and L2 can effectively improve the impedance matching, and effectively feed the first radiating metal strip 8 and the second radiating metal strip 7, so as to obtain an ideal and certain frequency selection Sexual impedance bandwidth.

If the closed annular gap 15 and the metal probe 5 are removed, at low frequencies, since the capacitive reactance of the second overlapping portion 14 is relatively large, it is easy to cause impedance mismatch and cannot completely cover the LTE700 frequency band. Therefore, metal probes 5 are introduced to suppress excessive capacitive input impedance of the antenna at low frequencies and improve impedance matching. After the feeding probe 5 is introduced, if there is no closed annular gap 15, the effect of the second overlapping portion 14 will become very weak, and the antenna becomes a direct feed rather than a capacitive coupling feed. At this time, the antenna input The inductance of the impedance will be greatly increased, resulting in a serious mismatch of the input impedance of the antenna. To solve this problem, a closed annular gap 15 is further introduced. In this way, on the one hand, the capacitive coupling feeding of the antenna can be maintained, and on the other hand, the closed annular gap 15 can act as a capacitor. Near 700MHz, the capacitive reactance of the second overlapping portion 14 is relatively small. Due to the introduction of the metal probe 5, the inductive reactance of the circuit is relatively large, but the existence of the closed annular gap 15 also introduces a part of the capacitance, so the metal probe 5 Although the needle 5 effectively increases the inductive reactance of the antenna input impedance, the existence of the closed annular gap 15 increases the capacitive reactance of the circuit, so that the input impedance of the antenna changes from capacitive to weak inductive, so the impedance matching near 700MHZ It has been effectively improved, and a new resonance point has been created, and the low-frequency bandwidth of the antenna effectively covers the 698-1088MHz frequency band.

If the closed annular gap 15 and the metal probe 5 are removed, as the frequency increases, the capacitive reactance of the second overlapping portion 14 becomes smaller, and the inductive reactance of the metal short circuit 18 connected to the floor 4 will increase, causing the input Impedance is inductive. After adding the feeding probe 5, as the frequency increases, for the antenna without the closed annular gap 15, since the capacitive reactance of the second overlapping portion 14 becomes relatively smaller, the inductive reactance of the feeding probe 5 becomes larger, At this time, it can be considered that the current is mainly coupled to the antenna radiating element through the second overlapping portion 14, so the circuit presents relatively large capacitance, so the impedance matching cannot be improved, but becomes worse. Therefore, after introducing the metal probe 5, and then introducing the closed annular gap 15, the metal probe 5 and the closed annular gap 15 are in a series state, and the introduction of the closed annular gap 15 makes the sense of the branch where the feeding probe 5 is located The reactance value becomes smaller, and the inductive reactance of the branch is no longer in an infinite state, but the branch is still inductive, which can be equivalent to an inductance, and the inductance and the capacitance C1 formed by the second overlapping part 14 are connected in parallel. , their parallel connection effectively reduces the capacitive reactance of the capacitance presented to the outside by these two branches, and then in series with the metal short circuit 18, the capacitance presented to the outside is greatly reduced, so at high frequencies (1.69-2.50 GHz) with good impedance matching.

FIG. 3 is a front view of a multi-band LTE antenna provided by an embodiment of the present invention after removing the metal probe 5 and the closed annular gap 15 in FIG. 1 . FIG. 4 is a front view of a multi-band LTE antenna without the metal probe 5 in FIG. 1 provided by an embodiment of the present invention. FIG. 5 is a frequency response curve diagram of the bandwidth |S ₁₁ | of the antenna corresponding to FIG. 1 provided by an embodiment of the present invention.

In order to verify the multi-frequency LTE mobile phone antenna that the present invention proposes, carried out the bandwidth | S of the antenna corresponding to Fig. 1 | S ₁₁ | frequency response curve figure (Fig. 5), the bandwidth | ₁₁ | frequency response curves and the corresponding impedance frequency response curves in Figure 1, Figure 3 and Figure 4.

The simulation results show that the high and low frequency bandwidths that can be obtained by the antenna shown in Figure 1 are -10dB bandwidth, so compared with the existing multi-frequency LTE mobile phone antenna, the antenna design proposed by the application has lower reflection energy and higher radiation efficiency. In addition, the edges of the low-frequency and high-frequency bandwidth curves of the antenna design in the present invention are relatively steep, and have relatively good frequency selectivity, which can reduce the performance requirements for the filters cascaded at the rear end of the antenna, and the planar structure adopted in this design , the structure is simple, the production cost can be reduced, and it is suitable for various multifunctional small hand-held devices. To sum up, the antenna shown in FIG. 1 can effectively cover the 698-1088MHz frequency band and the 1.69-2.50GHz frequency band under the -10dB impedance bandwidth and has good frequency selectivity.

The multi-band LTE antenna can be used on a terminal device, such as a mobile phone or a tablet computer.

The multi-band LTE antenna provided by the present invention using a novel impedance matching structure has been introduced in detail above. Each embodiment in the description is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for relevant details, please refer to the description of the method part. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (9)

1. The multi-frequency LTE antenna adopting the novel impedance matching structure is characterized by comprising a substrate (1), a first radiation metal strap (8), a first metal patch (11), a microstrip line (16) and a floor (4), a second radiation metal strap (7) and a second metal patch (20) which are respectively printed on the front surface (2) of the substrate (1), wherein the floor (4), the second radiation metal strap (7) and the second metal patch (20) are printed on the back surface (3) of the substrate (1);

the floor (4), second radiating metal strap (7) second metal patch (20) are on the coplanar, first radiating metal strap (8) with second radiating metal strap (7) have first overlapping portion (9) and all are the C form, and the opening all is oriented floor (4), second metal patch (20) are cut apart into annular patch (12) and central patch (13) by closed annular gap (15), first metal patch (11) with second metal patch (20) have second overlapping portion (14) and non-overlapping portion, second overlapping portion (14) include central patch (13), first metal patch (11) with central patch (13) are connected through metal probe (5), the one end of annular patch (12) with second radiating metal strap (7) is connected, the other end of annular patch (12) is through metal short circuit line (18) with floor (4) meet in short circuit point (19) and through metal probe (6) with first radiating metal patch (13).

2. The multi-frequency LTE antenna according to claim 1, characterized in that the microstrip line (16) is a 50Ω microstrip line.

3. The multi-frequency LTE antenna according to claim 1, characterized in that the end (10) width of the second radiating metallic strip (7) is larger than the width of the rest of the second radiating metallic strip (7).

4. A multi-frequency LTE antenna according to claim 3, characterized in that the end (10) of the second radiating metallic strip (7) is 4.5mm wide, the remaining part of the second radiating metallic strip (7) being 2mm wide.

5. The multi-frequency LTE antenna according to claim 1, characterized in that the central patch (13) is rectangular.

6. The multi-frequency LTE antenna according to claim 1, characterized in that the first metal patch (11) is rectangular.

7. The multi-frequency LTE antenna of claim 6 wherein the second metal patch (20) is rectangular, the width of the second metal patch (20) being the same as the width of the first metal patch, the length of the second metal patch (20) being greater than the length of the first metal patch.

8. The multi-frequency LTE antenna according to any one of claims 1 to 7, characterized in that the first metal patch (11) is symmetrical with respect to the floor (4).

9. The multi-frequency LTE antenna according to claim 1, characterized in that the substrate (1) is rectangular and the floor (4) is rectangular.

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