CN111129744A

CN111129744A - High-gain antenna circuit

Info

Publication number: CN111129744A
Application number: CN202010045708.4A
Authority: CN
Inventors: 王巍桦
Original assignee: Ningbo Yaolong Software Technology Co ltd
Current assignee: Ningbo Yaolong Software Technology Co ltd
Priority date: 2020-01-16
Filing date: 2020-01-16
Publication date: 2020-05-08

Abstract

The present invention relates to a high gain antenna circuit, comprising: a circuit board configured to carry a radiating element; and a plurality of radiating elements configured to receive and/or transmit wireless signals and comprising a first radiating element and a second radiating element, wherein the first radiating element has a first central operating frequency and a first operating frequency band, and the second radiating element has a second central operating frequency and a second operating frequency band, wherein the plurality of radiating elements are configured such that the first central operating frequency is different from the second central operating frequency and the first and second operating frequency bands at least partially overlap each other. The invention can improve the gain of the antenna under various application environments while improving the frequency bandwidth of the antenna and not increasing the circuit area.

Description

High-gain antenna circuit

Technical Field

The invention generally relates to the technical field of antennas, and particularly relates to a high-gain antenna circuit.

Background

In recent years, with the progress of wireless communication technology, a plurality of high-tech industries based on the technology are developed vigorously, and for example, a great amount of technical innovation based on wireless communication and business model innovation based on the technical innovation emerge in the industries such as logistics, smart home, intelligent entrance guard, security and the like.

An important component of wireless communication is an antenna. The function of the antenna is to selectively receive and transmit wireless signals. The performance of the antenna will greatly affect the efficiency and quality of wireless communications. For example, in some situations in the field of internet of things, the signal strength is weak, and the common omnidirectional antenna design often cannot provide a good signal due to its low gain characteristic, and thus cannot meet the requirements of some applications, such as inside a safe, a steel cabinet and a door lock that is far away from a wireless router, where the signal shielding is severe. Generally, an external antenna usually has good signal quality, but a special antenna housing and an opening are usually required to be designed for the antenna, and a radio frequency connector is used to connect the antenna and an internal circuit, which may result in higher product cost, for example, the product process is more complicated, the product volume is also larger, and the external antenna is not suitable for the miniaturization requirement of the internet of things market.

The parameters of the antenna are influenced by many factors, such as whether the environment around the antenna is close to a ferromagnetic substance, whether the environment is close to a large object which has an absorption or reflection effect on electromagnetic waves, and the like, which directly influence the performance of the antenna. That is, the performance of the antenna may change due to the change of the operating environment, even decreasing below the communication requirement. However, currently, with the popularization of internet of things devices, the mobility of products is higher and higher, and one product is often required to be used in a plurality of occasions, which results in more and more use occasions and more complexity of the antenna, so that it is necessary to reduce the restriction on the use occasions of the antenna, and the product has greater adaptability, thereby having a larger market.

On the other hand, the design cost and the modification cost of the antenna are high. This is because, to reduce costs, antennas are often constructed on printed circuit boards, PCBs, which are time consuming and complicated in design and commissioning processes and involve a variety of considerations, such as material dielectric constant, material thickness, material impedance, and the like. Once the design is complete, the cost of its design changes will be high. Moreover, a well-designed antenna often needs to be retested and adjusted again with respect to rf parameters when a PCB supplier is replaced, and may also need to be modified in its geometric design if the influence is large. In order to ensure the quality of wireless communication signals of products, raw material manufacturers and production processes of PCBs are often required to be specified. Due to the limitation on manufacturers, the manufacturers cannot be replaced randomly according to the technical development of the PCB. Thus, there is also a need for an antenna circuit that can be adapted to a wider variety of applications without the need for circuit modifications.

Disclosure of Invention

The present invention is directed to a high-gain antenna circuit, which can increase the gain of an antenna in various application environments while increasing the frequency bandwidth of the antenna and not increasing the circuit area.

This object is achieved by the invention by a high-gain antenna circuit comprising:

a circuit board configured to carry a radiating element; and

a plurality of radiating elements configured to receive and/or transmit wireless signals and comprising a first radiating element and a second radiating element, wherein the first radiating element has a first central operating frequency and a first operating frequency band and the second radiating element has a second central operating frequency and a second operating frequency band, wherein the plurality of radiating elements are configured such that the first central operating frequency is different from the second central operating frequency and the first operating frequency band and the second operating frequency band at least partially overlap each other.

In the present invention, the term "radiating element" refers to a structure in an antenna for receiving and/or transmitting signals, such as an antenna transceiving element, an antenna branching element, and the like. The term "operating band (or operating band) of a radiating element" refers to a frequency range in which the radiating element can receive and transmit signals, or a frequency band defined by a technical specification, such as a frequency bandwidth when an antenna gain is reduced by three decibels, or an operating frequency bandwidth of an antenna at a specified standing wave ratio. The term "central operating frequency of the radiating element" refers to the frequency at which the radiating element reaches maximum transmit and receive power in the operating frequency band. In the present invention, in order to realize different central operating frequencies and overlapping operating frequency bands of the respective radiating elements, various parameters of the respective radiating elements may be different from each other, and these parameters include, but are not limited to, size (such as length, width, thickness, etc.), shape (such as zigzag, arc, straight, etc.), material type (such as different radiation branch materials are selected), material parameters (dielectric constant of radiation branch materials, degree of matching of resistances between materials, etc.), and so on.

In a preferred embodiment of the invention, it is provided that the printed circuit board has a first side and a second side facing away from the first side, and that each radiation element comprises:

a first radiating branch and a second radiating branch, wherein the first radiating branch is on a first face and the second radiating branch is on a second face, wherein radiating branches on the same face of adjacent radiating elements are connected in parallel with each other and to a feed line; and

a plurality of feed lines, wherein each of the plurality of feed lines is assigned to one or more of the plurality of radiating elements, and the plurality of feed lines are connected to each other and to a power source or a signal source.

In a further preferred embodiment of the invention, it is provided that the difference between the first central operating frequency and the second central operating frequency is greater than 2%, for example 10%, 90%, of the smaller of the first central operating frequency and the second central operating frequency. By this preferred solution, the operating band of the entire antenna circuit can be optimally extended. For example, in the case of using a broadband radiating element, the upper limit of the difference between the first size and the second size may be greater than 90%, for example, 200%.

In a further preferred embodiment of the invention, it is provided that the radiating branch of the first radiating element has a first dimension and the radiating branch of the second radiating element has a second dimension, wherein the first dimension is different from the second dimension and the difference between the first dimension and the second dimension is greater than 2% of the smaller of the first dimension and the second dimension, such that the first central operating frequency is different from the second central operating frequency and the first operating frequency band and the second operating frequency band at least partially overlap one another. The above dimension is preferably the length of the radiating branch. However, other parameters are also conceivable, such as the width and thickness of the radiating branches, in the light of the teaching of the present invention.

In a further preferred embodiment of the invention, it is provided that the radiating branch of the first radiating element has a first shape and the radiating branch of the second radiating element has a second shape, wherein the first shape differs from the second shape such that the first central operating frequency differs from the second central operating frequency and the first operating frequency band and the second operating frequency band at least partially overlap one another. The shape of the radiating branches is, for example, meander, arc, straight, wave, sine, dog-leg, triangle, butterfly, etc. By providing different shapes, excessive size differences between the radiating branches can be avoided, thereby simplifying the design and possibly saving circuit area. For example, in the case of different shapes, the lengths of the radiating branches may be substantially the same.

In one embodiment of the invention, it is provided that the first and second radiating branches of the plurality of radiating elements have the same or different shapes and/or lengths. By enabling the two radiation supports of the same radiation unit to have different shapes and lengths, the central working frequency and the working frequency range of each radiation unit can be adjusted more flexibly, and therefore the gain and the total bandwidth of the antenna can be optimized.

In a preferred embodiment of the invention, it is provided that the plurality of radiation elements comprises 4 radiation elements, wherein the first and second radiation elements are arranged adjacent to one another and the third and fourth radiation elements are adjacent to one another. With 4 radiating elements, a good compromise between the total bandwidth of the antenna and the circuit complexity and length can be achieved. Other numbers of radiating elements are also contemplated under the teachings of the present invention.

In a further preferred embodiment of the invention, it is provided that the radiating branch of the first radiating element and the radiating branch of the third radiating element have a first size and the radiating branches of the second radiating element and the fourth radiating element have a second size, wherein the first size is different from the second size and the difference between the first size and the second size is greater than 2% of the smaller of the first size and the second size, such that the first central operating frequency is different from the second central operating frequency and the first operating frequency band and the second operating frequency band at least partially overlap one another. In this preferred embodiment, the antenna circuit design can be simplified by having the first and third radiating elements and the second and fourth radiating elements have radiating branches of the same size.

In one embodiment of the invention, it is provided that the plurality of feed lines comprises a first feed line and a second feed line, the first feed line being assigned to the first and second radiating elements and the second feed line being assigned to the third and fourth radiating elements, and wherein the shape and/or size of the first feed line differs from the shape and/or size of the second feed line. By means of this embodiment, the feed of the individual radiating elements can be optimized.

In a further embodiment of the invention, it is provided that the shape of the first or second feed line comprises: straight, bent, and curved. Other shapes are also contemplated under the teachings of the present invention.

In a further embodiment of the invention, it is provided that the first radiating element has a first number of radiating branches and the second radiating element has a second number of radiating branches, the first number differing from the second number, so that the first central operating frequency differs from the second central operating frequency and the first operating frequency band and the second operating frequency band overlap one another at least in part. By providing the radiating elements with different numbers of radiating branches, the central operating frequency and the operating frequency band of each radiating element can be adjusted accordingly, and the sizes of the radiating elements are substantially the same, thereby simplifying the design.

In a further embodiment of the invention, it is provided that the high-gain antenna circuit is configured for 2.4GHz wireless communication.

The invention has at least the following beneficial effects: the present invention is based on the research and unique findings that the receiving capability of the antenna may be greatly changed when the antenna is arranged under materials with different thicknesses and types, such as plastic, wood, etc., and even the signal is poor and cannot be received, mainly because the existing antenna is composed of a plurality of radiation units with the same frequency characteristics (i.e. a plurality of radiation units have the same central operating frequency), which may cause: once the signals of the radiating elements are shielded by a covering made of a certain material, the signal gain of the whole antenna is greatly reduced; if a plurality of radiating elements with mutually different central operating frequencies (with a difference of more than 2%) but with operating frequency bands partially overlapping each other are provided in the antenna, this situation can be avoided better, which is based on the following insight of the inventors: a specific material generally has a large attenuation to a signal of a frequency band of a certain frequency point or a certain narrow frequency range, and since the antenna of the present invention has a plurality of radiation elements whose central operating frequencies are different from each other, even if the material has a significant shielding and attenuation to a signal of one radiation element in the antenna, other radiation elements in the antenna can still normally transmit and receive signals because of having different central operating frequencies; thereby, the gain of the antenna in various application occasions can be improved, and the frequency bandwidth of the antenna can be expanded.

Drawings

The invention is further elucidated with reference to the drawings in conjunction with the detailed description.

Fig. 1 to 3 show a first embodiment of an antenna circuit according to the invention; and

fig. 4 to 15 show further embodiments of the antenna according to the invention.

Detailed Description

It should be noted that the components in the figures may be exaggerated and not necessarily to scale for illustrative purposes. In the figures, identical or functionally identical components are provided with the same reference symbols.

In the present invention, "disposed on …", "disposed over …" and "disposed over …" do not exclude the presence of an intermediate therebetween, unless otherwise specified. Further, "disposed on or above …" merely indicates the relative positional relationship between two components, and may also be converted to "disposed below or below …" and vice versa in certain cases, such as after reversing the product direction.

In the present invention, the embodiments are only intended to illustrate the aspects of the present invention, and should not be construed as limiting.

In the present invention, the terms "a" and "an" do not exclude the presence of a plurality of elements, unless otherwise specified.

It is further noted herein that in embodiments of the present invention, only a portion of the components or assemblies may be shown for clarity and simplicity, but those of ordinary skill in the art will appreciate that, given the teachings of the present invention, required components or assemblies may be added as needed in a particular scenario.

It is also noted herein that, within the scope of the present invention, the terms "same", "equal", and the like do not mean that the two values are absolutely equal, but allow some reasonable error, that is, the terms also encompass "substantially the same", "substantially equal". By analogy, in the present invention, the terms "perpendicular", "parallel" and the like in the directions of the tables also cover the meanings of "substantially perpendicular", "substantially parallel".

Fig. 1 to 3 show a first embodiment of an antenna circuit according to the invention. In the present embodiment, the antenna circuit 100 is shown as being arranged on a first side a and a second side B of a printed circuit board PCB and having four radiating elements. In other embodiments, other forms of circuit boards and other numbers of radiating elements may be employed.

As shown in fig. 1, which is a view of the antenna from a side a, the antenna circuit 100 includes four radiation units 101 and 104, which include:

a first radiating element 101 having first and second radiating branches 101A, 101B, the first radiating branch 101A being arranged on a first side a of the PCB and the second radiating branch 101B being arranged on a second side B of the PCB circuit board, the first and second radiating branches 101A, 101B being connected to feed

lines

105A and 105B, respectively.

A second radiating element 102 having first and

second radiating branches

102A, 102B, the first radiating branch 102A being arranged on a first side a of the PCB and the second radiating branch 102B being arranged on a second side B of the PCB circuit board, the first and

second radiating branches

102A, 102B being connected to feed

lines

105A and 105B, respectively.

A third radiating element 103 having first and

second radiating branches

103A, 103B, the first radiating branch 103A being arranged at a first side a of the PCB and the second radiating branch 103B being arranged at a second side B of the PCB circuit board, the first and

second radiating branches

103A, 103B being connected to feed

lines

105A and 105B, respectively.

A fourth radiation unit 104 having first and

second radiation branches

104A, 104B, the first radiation branch 104A being arranged at a first side a of the PCB and the second radiation branch 104B being arranged at a second side B of the PCB circuit board, the first and

second radiation branches

104A, 104B being connected to feed

lines

105A and 105B, respectively.

A feed line 105 comprising first and

third feed lines

105A and 106A arranged on the first face a, and second and

fourth feed lines

105B and 106B arranged on the second face B, the first feed line 105A and the third feed line 106A being continuous wires, the second feed line 105B and the fourth feed line 106B being continuous wires. The first feeder line 105A is used to connect the first radiation branch 101A and the second radiation branch 102A of the first and

second radiation elements

101 and 102 disposed on the first plane a, the second feeder line 105B is used to connect the second radiation branch 101B and the second radiation branch 102B of the first and

second radiation elements

101 and 102 disposed on the second plane B, the third feeder line 106A is used to connect the first radiation branch 103A and the first radiation branch 104A of the third and fourth radiation elements 103 and 104 disposed on the first plane a, and the fourth feeder line 106B is used to connect the second radiation branch 103B and the second radiation branch 104B of the third and fourth radiation elements 103 and 104 disposed on the second plane B. The third feed line and the fourth feed line are connected to the input output port 107.

In the present invention, in order to realize different central operating frequencies and overlapping operating frequency bands of the respective radiating elements, various parameters of the respective radiating elements 101 and 104 of the antenna 100 may be different from each other, and these parameters include, but are not limited to, dimensions (such as length, width, thickness, etc.), shapes (such as meander, arc, straight, etc.), material types (such as different radiating branch materials are selected), material parameters (dielectric constants of the radiating branch materials, degrees of matching resistances between materials, etc.), and so on. In the present invention, the central operating frequency and the operating frequency band of each of the radiating elements 101-104 may be set to be suitable for 2.4G or 5G wireless communication, for example.

Fig. 2 and 3 show the graphic design of an antenna embodiment of the present invention on the first side a and the second side B of the PCB, respectively.

In one embodiment of the present invention, the PCB is made of FR4 material, 1.6 mm thick, double-sided board. The copper foil had a thickness of 0.5 ounces. The

layout design

101A, 102A, 101B, 102B, 103A, 104A, 103B, 104B radiation branches have transverse branch length of 22.3mm, width of 1.0mm, vertical branch length of 4.5mm and width of 1.0mm, and

feeder lines

105A and 105B on the first surface A and the B surface are 47mm and 1.5mm respectively. The length of the feed line 106A on the A surface and the length of the feed line 106B on the B surface are both 22mm, and the width is 2.8 mm. The signal connection of the signal input/output port 107 is the coplanar waveguide shown in fig. 6. Simulation results showed a maximum gain of 4.10 dBi. For example, for WI-FI frequency band, the allowable value of dielectric constant is 5.1-5.2, and the frequency bandwidth with standing wave ratio less than 2 is about 95 MHz. Such PCB dielectric constants typically need to be customized to be obtained, which inevitably results in increased product cost and inconvenience in product production. By adopting the technology of the invention, the length of the radiation branch of the 103B and 104B is increased by 4.5mm, namely the length is increased by 7 percent, while other radiation units are unchanged, the simulation result is that the maximum gain is 3.98dBi, and the frequency bandwidth of the WI-FI central frequency point with the standing-wave ratio less than 2 is increased to 500 MHz. In other words, the antenna circuit of the present invention has a significantly increased bandwidth compared to prior art antennas with the same material, thereby improving antenna performance in multiple scenarios. In addition, for example, for the WI-FI frequency band range, simulation shows that the dielectric constant allowable range of the PCB is expanded to 3.8-4.9, and the standing wave ratio in the WIFI frequency band range of 2.4G can still be ensured to be less than 2. Wherein a slight reduction of the maximum gain has no substantial effect on the antenna performance, while PCBs of such a range of dielectric constants need only be available using inexpensive PCB materials and common PCB production processes, and need not be customized. Therefore, the invention can also be beneficial to improving the yield of products and reducing the cost of the PCB.

In some embodiments, other branches or structures may be added to the structure of the antenna to adjust the performance of the antenna, such as fine tuning the resonant frequency or increasing the resonant frequency band to improve the bandwidth. In the embodiment shown in fig. 4,

short branches

41, 42, 43, 44 are used to further improve the return loss characteristics.

In some embodiments, the radiating branches may have different widths, or different lengths. E.g., 101A, 101B may be of different lengths than 102A, 102B, which may be used as antennas for both frequencies. The width of its PCB trace may also be a different width.

As shown in fig. 4, which is one embodiment of a B-side view, the

feed lines

105A and 105B are configured as curved fold lines, and the

feed lines

106A and 106B are substantially linear. In other embodiments, the

feed lines

105A and 105B may also be configured as arcs. By means of the differently shaped feed line configurations, an adjustment of the central operating frequency and the operating frequency band of the associated radiating element can be achieved, whereby a difference in the central operating frequency of the radiating elements is achieved and the operating frequency bands at least partly overlap each other. The adjustment of the directional pattern radiated by the antenna can be achieved by adjusting the signal phase difference between the radiating

elements

101, 102 and 103, 104 through the setting of the length of the feed line 105.

As shown in fig. 5, in one embodiment, the radiating branches may be configured in a bent shape or an arc shape. This reduces the total occupied PCB board area of the antenna.

An embodiment using coplanar waveguides for feeding the antenna is shown in fig. 6. Where 600 is a via connecting a-plane and B-plane ground lines, 4 vias are shown. And 602 is an antenna signal input-output line. Reference numeral 601 denotes a ground line in which the signal line 602 is wrapped on the first surface a, and 603 denotes a ground line on the B surface. 601 and 603 are electrically connected by vias. The feed line 106A of the first side a is directly connected to the signal line 602, and at least one safety distance defined by the process of the PCB manufacturer is maintained between the signal line 602 and the ground line 601. The spacing is typically above 6 mils. The feeder line of the second surface B is directly connected with the ground wire.

As shown in fig. 7, in one embodiment, the input signal may also be a coaxial cable instead of a PCB trace. And 73 is an input cable. 71 is the copper layer of the input port on the first side a, connected to the outer copper cladding of the coaxial cable, and connected by vias to the first feed line on the second side B, the input signal of the cable being connected by the inner conductor of the cable to the position shown of the input cable 72 and directly connected to the feed line on the first side a.

Although the figures of the present invention show the opposite radiating branches distributed on both sides AB of the PCB, e.g. 101A, 101B are placed on both sides of the PCB. They may be partially or fully placed on the same surface of the PCB. This tends to introduce problems with crossing of the tracks. The trace crossing problem may be solved by appropriate PCB traces, by using vias, or by using conventional technical methods such as coaxial cables.

An embodiment lacking radiating branches is shown in fig. 8, 9. Here, the first radiation element 101 lacks the first radiation branch, and the fourth radiation element 104 lacks the first radiation branch. Depending on the design conditions of the actual product, in order to avoid conflicts between internal components, such as size, appearance, etc., embodiments may be designed to lack one or two radiating branches, which may degrade slightly in performance, but still operate properly and have high gain characteristics.

In the embodiments of fig. 10, 11 and 12, the feed line and the radiating branch are connected to another plane by vias. Where 110 is a via to make the connection.

In the embodiment of fig. 12, the feed line and most of the radiating elements lie in the a and B planes, with one radiating branch 101A lying in a different 3 rd plane than the other radiating elements.

In the embodiment of fig. 13, 14, the radiating branches take the form of specially shaped embodiments. Only a portion of the branches are shown, and the other branches may be the same or different.

In the embodiment of fig. 15, the radiation branches corresponding to the radiation elements shown are triangular, so that the radiation elements become broadband bowtie antenna radiation elements.

The radiation elements of the antenna in the embodiment of the present invention are all dipole antenna elements, but the radiation elements may be other types of antennas. For example, the radiating element may be, but is not limited to, the following types of antennas: such as monopole antennas, clover antennas, tapered slot antennas, inverted-F antennas, planar inverted-F antennas, patch antennas, folded dipole antennas, loop antennas, bowtie antennas, helical antennas, log periodic dipole antennas, slot antennas, waveguide antennas, parabolic reflector antennas, and the like.

Although some embodiments of the present invention have been described herein, those skilled in the art will appreciate that they have been presented by way of example only. Numerous variations, substitutions and modifications will occur to those skilled in the art in light of the teachings of the present invention without departing from the scope thereof. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

1. A high gain antenna circuit, comprising:

a circuit board configured to carry a radiating element; and

2. The high gain antenna circuit of claim 1, wherein the circuit board has a first face and a second face facing away from the first face, and each radiating element comprises:

3. The high gain antenna circuit of claim 2, wherein the difference between the first center operating frequency and the second center operating frequency is greater than 2% of the lesser of the first center operating frequency and the second center operating frequency.

4. The high gain antenna circuit of claim 2, wherein the radiating branch of the first radiating element has a first size and the radiating branch of the second radiating element has a second size, wherein the first size is different from the second size, and the difference between the first size and the second size is greater than 2% of the smaller of the first size and the second size, such that the first center operating frequency is different from the second center operating frequency and the first operating frequency band and the second operating frequency band at least partially overlap each other.

5. The high gain antenna circuit of claim 2, wherein the radiating branch of the first radiating element has a first shape and the radiating branch of the second radiating element has a second shape, wherein the first shape is different from the second shape such that the first central operating frequency is different from the second central operating frequency and the first and second operating frequency bands at least partially overlap one another.

6. The high gain antenna circuit according to claim 2, wherein the first and second radiating branches of the plurality of radiating elements have the same or different shapes and/or lengths.

7. The high gain antenna circuit of claim 2, wherein the plurality of radiating elements comprises 4 radiating elements, wherein the first and second radiating elements are disposed adjacent to each other and the third and fourth radiating elements are adjacent to each other.

8. The high gain antenna circuit of claim 7, wherein the radiating branch of the first radiating element and the radiating branch of the third radiating element have a first size, and the radiating branches of the second radiating element and the fourth radiating element have a second size, wherein the first size is different from the second size, and the difference between the first size and the second size is greater than 2% of the smaller of the first size and the second size, such that the first center operating frequency is different from the second center operating frequency and the first operating frequency band and the second operating frequency band at least partially overlap each other.

9. The high gain antenna circuit according to claim 7, wherein the plurality of feed lines comprises a first feed line and a second feed line, the first feed line being assigned to the first and second radiating elements and the second feed line being assigned to the third and fourth radiating elements, and wherein a shape and/or size of the first feed line is different from a shape and/or size of the second feed line.

10. The high gain antenna circuit of claim 9, wherein the shape of the first feed line or the second feed line comprises: straight, bent, and curved.

11. The high gain antenna circuit according to claim 1, wherein the first radiating element has a first number of radiating branches and the second radiating element has a second number of radiating branches, wherein the first number is different from the second number such that the first central operating frequency is different from the second central operating frequency and the first operating frequency band and the second operating frequency band at least partially overlap each other.

12. The high-gain antenna circuit of claim 1, wherein the high-gain antenna circuit is configured for 2.4GHz wireless communication.