WO2019227651A1

WO2019227651A1 - Portable communication terminal and pifa antenna thereof

Info

Publication number: WO2019227651A1
Application number: PCT/CN2018/097580
Authority: WO
Inventors: 高霞; 邱诗彬
Original assignee: 京信通信系统（中国）有限公司; 京信通信系统（广州）有限公司; 京信通信技术(广州)有限公司; 天津京信通信系统有限公司
Priority date: 2018-05-30
Filing date: 2018-07-27
Publication date: 2019-12-05
Also published as: CN108598668A

Abstract

The present invention relates to a portable communication terminal and a PIFA antenna thereof. The PIFA antenna comprises a substrate, a first metal layer, a second metal layer, a radiation sheet, and a parasitic unit, and the radiation sheet is opened thereon with a groove. The radiation sheet has an inherent resonance point, and the groove may redistribute a current on the radiation sheet, thereby changing a current length. Therefore, the radiation sheet may achieve impedance matching at higher frequency points, thereby introducing one new intermediate frequency resonance point. Further, when the radiation sheet is irradiated, electromagnetic waves may also be coupled to the parasitic unit to excite the parasitic unit. The excited parasitic unit may generate a higher frequency resonance, thereby introducing one new high frequency resonance point. Since the groove and the parasitic unit introduce the intermediate frequency resonance point and the high frequency resonance point respectively on the basis of the inherent resonance point of the radiation sheet, the multi-frequency resonance of a PIFA antenna is achieved. Therefore, multi-frequency and wide-band coverage of the foregoing portable communication terminal and PIFA antenna thereof is effectively achieved.

Description

Portable communication terminal and its PIFA antenna

Technical field

The present invention relates to the field of wireless communication technology, and particularly to a portable communication terminal and its PIFA antenna.

Background technique

With the rapid development of wireless communication technology, the demand for portable and home communication products is increasing. Among them, as a core component of signal transmission and reception, the antenna plays an important role. For antennas applied to the aforementioned portable and home products, it is generally required to have the characteristics of small size and wide frequency band coverage.

PIFA (Planar Inverted F) antennas are widely used in the above products due to their low cost, low profile, and wide frequency band coverage. However, portable and home communication products need to consider portability first, so the size is generally designed to be small. Due to the size of the above products, the size of the built-in PIFA antenna is also small.

However, the width of the frequency band covered by existing PIFA antennas is directly related to its size. Therefore, the frequency band covered by the PIFA antenna used in the aforementioned portable and home communication products is narrow.

Summary of the invention

Based on this, it is necessary to provide a portable communication terminal with multiple frequency coverage and its PIFA antenna in response to the problem that the existing PIFA antenna has a narrow frequency band.

A PIFA antenna includes:

The substrate includes a first surface and a second surface opposite to each other, and a mounting area is set at a preset position of the first surface;

A first metal layer and a second metal layer, the first metal layer is overlaid on a region where the first surface is located outside the mounting region, and the positive direction of the second metal layer on the first surface is Projecting an area outside the installation area;

A radiating sheet covering the installation area, the radiating sheet includes a short-circuited end, an open-circuited end, and a feeding end located between the short-circuited end and the open-circuited end, and the short-circuited end is electrically connected to the first metal layer The open end is spaced from the first metal layer, and a slot is formed on the radiation sheet; and

A parasitic unit is disposed on the installation area and is located between the feeding end and the short-circuiting end, and one end of the parasitic unit is electrically connected to the first metal layer.

In one embodiment, the mounting area is located at an edge of the substrate.

In one embodiment, the substrate is provided with a plurality of metallized vias, and the first metal layer and the second metal layer are electrically connected through the plurality of metallized vias.

In one embodiment, a coplanar waveguide structure is disposed on the first metal layer, and the feeding end is electrically connected to the coplanar waveguide structure.

In one embodiment, the groove includes a linear groove and a U-shaped groove. The U-shaped groove includes two opposite and parallel branches. The linear groove is perpendicular to and communicates with one of the branches.

In one embodiment, the U-shaped groove is located at the open end, and the linear groove extends to an edge of the radiation sheet opposite to the open end.

In one embodiment, the width of the parasitic unit gradually decreases in a direction from the end of the parasitic unit far from the first metal layer to the end near the first metal layer.

In one embodiment, the first metal layer, the radiation sheet, and the parasitic unit are an integrally formed structure.

In one embodiment, the PIFA antenna has three resonance frequencies of 0.88 GHz, 1.78 GHz, and 2.48 GHz.

A portable communication terminal includes a housing and the PIFA antenna according to any one of the above-mentioned preferred embodiments. The PIFA antenna is housed in and fixed in the housing.

In the portable communication terminal and its PIFA antenna, the radiation plate has an inherent resonance point, and the slot can redistribute the current on the radiation plate, thereby changing the current length. Therefore, the radiator can achieve impedance matching at higher frequencies, thereby introducing a new intermediate frequency resonance point. Further, when the radiation sheet is radiating, it can also couple electromagnetic waves to the parasitic unit to excite the parasitic unit. The excited parasitic element can generate more high-frequency resonance, thereby introducing a new high-frequency resonance point. Since the slot and the parasitic unit respectively introduce intermediate frequency and high frequency resonance points on the basis of the natural resonance point of the radiation plate, the multi-frequency resonance of the PIFA antenna is realized, thereby enabling the above-mentioned portable communication terminal and its PIFA antenna to achieve multi-frequency and broadband coverage .

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic structural diagram of a part of a portable communication terminal in a preferred embodiment of the present invention;

FIG. 2 is a schematic diagram of a front structure of a PIFA antenna in a preferred embodiment of the present invention; FIG.

3 is a partially enlarged schematic diagram of the PIFA antenna shown in FIG. 2;

4 is a schematic structural diagram of a reverse side of a PIFA antenna in a preferred embodiment of the present invention;

FIG. 5 is a schematic diagram of simulation of reflection coefficients between a PIFA antenna and a conventional PIFA antenna in a preferred embodiment of the present invention; FIG.

6 is a simulated 3D radiation pattern of a PIFA antenna at a preset frequency in a preferred embodiment of the present invention;

FIG. 7 is a schematic diagram of a gain simulation of a PIFA antenna in a preferred embodiment of the present invention.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the accompanying drawings. The drawings show a preferred embodiment of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and comprehensive understanding of the disclosure of the present invention.

It should be noted that when an element is referred to as being “fixed to” another element, it may be directly on the other element or there may be a centered element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the present invention is only for the purpose of describing specific embodiments, and is not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Referring to FIG. 1, the present invention provides a portable communication terminal 10 and a PIFA antenna 100. The portable communication terminal 10 includes a casing 101 and a PIFA antenna 100. The PIFA antenna 100 is housed and fixed in a casing 101. The portable communication terminal 10 may be a network terminal such as a wireless router, a portable WIFI hotspot transmitter, and the casing 101 is generally made of a non-metal material such as PC (polycarbonate) or ABS (acrylonitrile-butadiene-styrene plastic).

Please refer to FIGS. 2 to 4 together. The PIFA antenna 100 in the preferred embodiment of the present invention includes a substrate 110, a first metal layer 120, a second metal layer 130, a radiation sheet 140, and a parasitic unit 150.

The substrate 110 is generally formed of a non-metallic substrate. The shape of the substrate 110 may be an elongated shape, a circular shape, or a rectangular shape, which needs to match the shape of the casing 101. Specifically, in this embodiment, the base material is a FR-4 dielectric (FR-4 is a code of a flame-resistant material grade), the dielectric constant is 4.4, and the thickness is 2 mm. The substrate 110 includes a first surface (not shown) and a second surface (not shown) opposite to each other. As shown in Figure 2, the first surface is the upper surface and the second surface is the lower surface.

In addition, a preset position of the first surface sets a mounting area 111. The mounting area 111 may be one or more, and may be used for fixing the radiation sheet 140 and the parasitic unit 150.

The first metal layer 120 and the second metal layer 130 are respectively disposed on the first surface and the second surface. Specifically, the first metal layer 120 is disposed on a region where the first surface is outside the mounting region 111. Therefore, the first metal layer 120 does not cover the mounting area 111. Moreover, the orthographic projection of the second metal layer 130 on the first surface is located in a region outside the mounting region 111. That is, the second metal layer 130 is disposed on a region of the second surface corresponding to the first metal layer 120. Therefore, a region of the second surface corresponding to the mounting region 111 is also not covered by the second metal layer 130. Specifically, in this embodiment, the orthographic projection of the second metal layer 130 on the first surface overlaps the first metal layer 120.

The first metal layer 120 and the second metal layer 130 may be formed on the surface of the substrate 110 by printing, etching after plating, or the like. The substrate 110 cooperates with the first metal layer 120 and the second metal layer 130 to form a double-layer circuit board structure. Among them, the double-layer circuit board structure is not only beneficial to the impedance matching of the PIFA antenna 100, but also beneficial to the design of the feeding structure. At the same time, radio frequency or digital circuits can be added to the surfaces of the first metal layer 120 and the second metal layer 130, thereby facilitating the miniaturization design of the PIFA antenna 100.

In this embodiment, the substrate 110 is provided with a plurality of metallized vias 113, and the first metal layer 120 and the second metal layer 130 are electrically connected through the plurality of metallized vias 113.

Specifically, the metalized via 113 refers to a solidified metal inside the through hole, so that the through hole is electrically conductive. The metallization vias 113 are used to connect and ground the first metal layer 120 and the second metal layer 130. Wherein, a hole can be drilled on the substrate 110, and then a liquid metal (such as copper) is injected into the hole and solidified to form a metallized via 113.

The radiation sheet 140 is used for receiving and radiating electromagnetic wave signals, and is generally formed of a good conductor such as copper or silver. The radiation sheet 140 has a flat plate shape and is disposed on the mounting area 111. The radiation sheet 140 includes a short-circuit terminal 141, an open-circuit terminal 143, and a feeding terminal 145. The feeding terminal 145 is located between the short-circuit terminal 141 and the open-circuit terminal 143. Among them, the short-circuiting terminal 141, the open-circuiting terminal 143, and the feeding terminal 145 extend in substantially the same direction and are spaced apart from each other. Therefore, the radiation sheet 140 has an inverted F shape.

Further, the short-circuiting end 141 is electrically connected to the first metal layer 120, and the open-circuiting end 143 is spaced from the first metal layer 120. Therefore, the radiation sheet 140, the substrate 110, and the double-layer circuit board structure formed by the substrate 110, the first metal layer 120, and the second metal layer 130 cooperate to form a structure similar to a conventional PIFA antenna.

Traditional PIFA antennas have corresponding resonance points (frequency points at which resonance occurs). Therefore, the PIFA antenna 100 also has a natural resonance point, and the natural resonance point is determined by the size of the PIFA antenna 100 (specifically, the radiation plate 140). Specifically, the sum of the height and length of the radiation plate 140 is about 1 / 4λ, where λ is a wavelength corresponding to the natural resonance point.

Since the portable communication terminal 10 requires portability and small size, it is limited by the size requirement of the portable communication terminal 10, and the size of the radiation sheet 140 is generally designed to be small. Therefore, the natural resonance point is a low-frequency resonance point. That is, without any other improvement, the impedance bandwidth of the PIFA antenna 100 is narrow.

Specifically, in this embodiment, the frequency corresponding to the natural resonance point is 0.88 GHz. The size of the radiation sheet 140 is 52 mm × 17 mm × 2.0 mm.

In addition, a slot 147 is defined in the radiation sheet 140. Specifically, the grooves 147 may be formed on the surface of the conventional radiation sheet 140 by laser etching or the like. The slots 147 can redistribute the current flowing on the radiation sheet 140, thereby increasing the length of the current. After the length of the current is increased, the radiation plate 140 can realize impedance matching at a higher frequency point, thereby introducing a new intermediate frequency resonance point. The frequency of the intermediate frequency resonance point is higher than the frequency of the natural resonance point.

That is, by opening the slot 147, the impedance bandwidth of the PIFA antenna 100 can be further widened on the original basis. The specific frequency value of the intermediate frequency resonance point can be adjusted by adjusting the length, width and position of the slot 147.

In this embodiment, the groove 147 includes a linear groove 1471 and a U-shaped groove 1473. The U-shaped groove 1473 includes two opposite and parallel branches (not shown in the figure), and the linear groove 1471 is perpendicular to and communicates with one of the branches. Among them, the lengths of the two branches may be the same or different, so that the grooves have an inverted Γ shape.

Further, in this embodiment, the U-shaped groove 1473 is located at the open end 143, and the linear groove 1471 extends to an edge of the radiation sheet 140 opposite to the open end 143.

At this time, the current path can be redistributed, thereby increasing the frequency band gap between the intermediate frequency resonance point and the low frequency resonance point, and further introducing the intermediate frequency resonance point. Specifically, in this embodiment, the frequency corresponding to the intermediate frequency resonance point is 1.78 GHz.

The parasitic unit 150 is generally a strip-shaped plate-like structure, and the material thereof may be the same as that of the first metal layer 120 and the radiation sheet 140. The parasitic unit 150 is disposed on the mounting area 111 and is located between the feeding terminal 145 and the short-circuit terminal 141. Moreover, one end of the parasitic unit 150 is electrically connected to the first metal layer 120.

When the radiation sheet 140 performs electromagnetic wave radiation, the radiation sheet 140 can couple the electromagnetic wave to the parasitic unit 150 nearby, thereby exciting the parasitic unit 150. The excited parasitic unit 150 can generate higher frequency resonance, that is, a new high frequency resonance point is introduced, so that impedance matching can be achieved at higher frequency points. The frequency of the high-frequency resonance point is higher than the frequency of the intermediate-frequency resonance point.

That is, by providing the parasitic unit 150, the impedance bandwidth of the PIFA antenna 100 can be further widened on the basis of the original. The specific frequency value of the high-frequency resonance point can be adjusted by adjusting the coupling between the parasitic unit 150 and the feeding end 145 and the size of the parasitic unit 150. Specifically, in this embodiment, the frequency corresponding to the high-frequency resonance point is 2.48 GHz.

In this embodiment, the width of the parasitic unit 150 is gradually reduced in a direction from the end of the parasitic unit 150 away from the first metal layer 120 to the end near the first metal layer 120.

Specifically, the width of the parasitic unit 150 may be continuously reduced gradually, or may be reduced stepwise. The parasitic unit 150 is a gradual parasitic unit, so it can be used to improve the matching of the PIFA antenna 100.

As can be seen from FIG. 5, when there is no parasitic element 150 with gradation, the resonance of 2.48 GHz disappears. Without other improvements to the PIFA antenna, that is, without the parasitic element 150 and the inverted Γ-shaped groove 147, the PIFA antenna 100 only has a resonance point at 0.88 GHz, that is, an inherent resonance point, which covers a frequency band of 0.80. ~ 0.96GHz. When there is a gradually changing parasitic element 150 and an inverted Γ-shaped groove 147, the PIFA antenna 100 has three resonance frequency points: 0.88 GHz, 1.78 GHz, and 2.48 GHz, respectively. At this time, the impedance bandwidth of the PIFA antenna 100 with an antenna reflection coefficient of less than -6dB is two frequency bands of 0.80 to 0.95 GHz and 1.67 to 2.8 GHz. It can be seen that the frequency band covered by the PIFA antenna 100 is relatively wide.

It should be pointed out that the above three resonance points are only a preferred embodiment. In other embodiments, the resonance point of the PIFA antenna 100 can be adjusted by adjusting the size of the radiation sheet 140, the shape and width of the slot 147, and the coupling degree and shape of the parasitic unit 150, as long as the PIFA antenna 100 has a low frequency, an intermediate frequency, The high-frequency resonance point is sufficient.

Due to the functions of the radiating sheet 140, the slot 147, and the parasitic unit 150, the PIPA antenna 100 has three resonance points of low frequency, intermediate frequency and high frequency, so its impedance bandwidth can be significantly expanded. Therefore, the coverage band of the portable communication terminal and its PIFA antenna 100 can also be effectively expanded.

In addition, due to the existence of the slot 147 and the parasitic unit 150, the radiation sheet 140 can achieve multi-frequency or wider frequency band coverage with a smaller size. In addition, the substrate 110, the first metal layer 120, the second metal layer 130, the radiation sheet 140, and the parasitic unit 150 are stacked, so that the PIFA antenna 100 as a whole has a two-dimensional structure. Therefore, the PIFA antenna 100 also has a low profile, which is advantageous for miniaturization of a portable communication terminal.

In addition, under the action of the double-layer circuit board structure (the substrate 110, the first metal layer 120 and the second metal layer 130), the groove 147, and the parasitic unit 150, the energy of the PIFA antenna 100 in the high frequency band is more concentrated, which is more consistent with Demand for portable communication terminals.

As shown in FIG. 6, the gain of the PIFA antenna 100 in the low frequency band is 0.38 to 2.3 dBi, and the gain in the high frequency band is 1.62 to 3.21 dBi. It can be seen that the gain of the high frequency band of the PIFA antenna 100 is higher than the gain of the low frequency band, that is, the energy of the PIFA antenna 100 in the high frequency band is relatively concentrated.

According to the transmission characteristics of electromagnetic waves, the higher the frequency, the shorter the wavelength, and the shorter the wavelength, the shorter the propagation distance. The portable communication terminal is generally used indoors or in a small area, with a small space but a complicated environment. Therefore, the portable communication terminal has a low requirement on the transmission distance, but a high requirement on the penetrability. The above-mentioned PIFA antenna 100 has a high gain in a high frequency band, so it better meets the requirements of a portable communication terminal application scenario.

In this embodiment, the mounting area 111 is located on the edge of the substrate 110. Therefore, the radiation sheet 140 is also located in the edge mounting region 111 of the substrate 110. On the rectangular substrate 110, the mounting region 111 is preferably located at the top corner of the substrate 110.

On the one hand, the radiation sheet 140 is disposed on the edge of the substrate 110 to further facilitate the low directivity of the PIFA antenna 100.

As shown in FIG. 7, the PIFA antenna 100 has good low directivity at four frequency points of 0.88 GHz, 1.88 GHz, 2.14 GHz, and 2.66 GHz. Moreover, the corresponding gains are 2.29dBi, 2.29dBi, 2.07dBi, and 2.43dBi, respectively. It can be seen that the PIFA antenna 100 is suitable for portable products.

On the other hand, since the mounting area 111 and the area corresponding to the mounting area 111 on the second surface cannot cover the metal layer, otherwise the circuit characteristics and radiation characteristics will be changed. Therefore, the areas corresponding to the first metal layer 120 and the second metal layer 130 and the mounting area 111 need to be hollowed out. Setting the mounting area 111 on the edge of the substrate 110 avoids hollowing out the middle portions of the first metal layer 120 and the second metal layer 130, which is beneficial to the first metal layer 120 and the second metal layer 130. Circuit layout of RF circuits.

In this embodiment, the first metal layer 120 is provided with a coplanar waveguide structure 121, and the feeding end 145 is electrically connected to the coplanar waveguide structure 121.

Specifically, the coplanar waveguide structure 121 is used to feed current to the radiation sheet 140. The coplanar waveguide has the characteristics of simple process and wide frequency band, so it is beneficial to expand the frequency band width of the PIFA antenna 100. In addition, the feeding mode of the coplanar waveguide structure 121 can weld the coaxial feed lines in the same plane, which is convenient for processing.

It should be noted that, in other embodiments, other radiation feeding methods may be used to feed the radiation sheet 140.

In this embodiment, the first metal layer 120, the radiation sheet 140, and the parasitic unit 150 are integrated structures.

Specifically, a metal coating layer may be formed on the first surface, and then the first metal layer 120, the radiation sheet 140, and the parasitic unit 150 may be obtained by laser etching, chemical etching, and the like. In this way, the first metal layer 120, the radiation sheet 140, and the parasitic unit 150 are integrated structures, and there are no solder joints between them. Therefore, the consistency between the parts is better, which is beneficial to improving the performance of the PIFA antenna 100.

In the portable communication terminal and its PIFA antenna 100, the radiation plate 140 has an inherent resonance point, and the slot 147 can redistribute the current on the radiation plate 140, thereby changing the current length. Therefore, the radiation plate 140 can achieve impedance matching at a higher frequency, thereby introducing a new intermediate frequency resonance point. Further, when the radiation sheet 140 is radiating, it can also couple electromagnetic waves to the parasitic unit 150 to excite the parasitic unit 150. The excited parasitic unit 150 can generate higher frequency resonance, thereby introducing a new high frequency resonance point. Since the slot 147 and the parasitic unit 150 respectively introduce an intermediate frequency and a high frequency resonance point on the basis of the natural resonance point of the radiation plate 140, a multi-frequency resonance of the PIFA antenna is realized. Therefore, the multi-frequency and broadband coverage of the portable communication terminal and its PIFA antenna are effectively realized.

The technical features of the embodiments described above can be arbitrarily combined. In order to simplify the description, all possible combinations of the technical features in the above embodiments have not been described. However, as long as there is no contradiction in the combination of these technical features, It should be considered as the scope described in this specification.

The above-mentioned embodiments only express several implementation manners of the present invention, and the descriptions thereof are more specific and detailed, but cannot be understood as a limitation on the scope of the invention patent. It should be noted that, for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent shall be subject to the appended claims.

Claims

A PIFA antenna includes:

The substrate includes a first surface and a second surface opposite to each other, and a mounting area is set at a preset position of the first surface;

A first metal layer and a second metal layer, the first metal layer is overlaid on an area where the first surface is outside the mounting area, the second metal layer is overlaid on the second surface, and An orthographic projection of the second metal layer on the first surface is located in an area outside the installation area;

A radiating sheet covering the installation area, the radiating sheet includes a short-circuited end, an open-circuited end, and a feeding end between the short-circuited end and the open-circuited end, and the short-circuited end is electrically connected to the first metal layer The open end is spaced from the first metal layer, and a slot is formed on the radiation sheet; and

A parasitic unit is disposed on the installation area and is located between the feeding end and the short-circuiting end, and one end of the parasitic unit is electrically connected to the first metal layer.
The PIFA antenna according to claim 1, wherein the mounting area is located at an edge of the substrate.
The PIFA antenna according to claim 1, wherein a plurality of metallized vias are provided on the substrate, and the first metal layer and the second metal layer pass through the plurality of metallized vias. Electrical connection.
The PIFA antenna according to claim 1, wherein a coplanar waveguide structure is disposed on the first metal layer, and the feeding end is electrically connected to the coplanar waveguide structure.
The PIFA antenna according to claim 1, wherein the slot includes a linear slot and a U-shaped slot, the U-shaped slot includes two opposite and parallel branches, and the linear slot is perpendicular to one of the branches And connected.
The PIFA antenna according to claim 5, wherein the U-shaped groove is located at the open end, and the linear groove extends to an edge of the radiation sheet opposite to the open end.
The PIFA antenna according to claim 1, wherein a width of the parasitic unit is gradually reduced in a direction along an end of the parasitic unit far from the first metal layer to an end near the first metal layer. small.
The PIFA antenna according to claim 1, wherein the first metal layer, the radiation sheet, and the parasitic unit are an integrally formed structure.
The PIFA antenna according to any one of claims 1 to 8, wherein the PIFA antenna has three resonance frequencies of 0.88 GHz, 1.78 GHz, and 2.48 GHz.
A portable communication terminal, comprising a housing and the PIFA antenna according to any one of claims 1 to 9, wherein the PIFA antenna is housed and fixed in the housing.