WO2017177495A1

WO2017177495A1 - Circularly polarized antenna and wireless communication device thereof

Info

Publication number: WO2017177495A1
Application number: PCT/CN2016/081642
Authority: WO
Inventors: 胡沥; 徐利军
Original assignee: 上海安费诺永亿通讯电子有限公司
Priority date: 2016-04-15
Filing date: 2016-05-11
Publication date: 2017-10-19
Also published as: CN105914465A

Abstract

Provided is a circularly polarized antenna, wherein same utilizes balanced differential signal driving. A first transmission line and a second transmission line are driven by a positive signal; and a third transmission line and a fourth transmission line are driven by a negative signal. A phase difference is configured rationally, so that there is a positive-90-degree or negative-90-degree phase difference between the first transmission line and the second transmission line; and there is a positive-90-degree or negative-90-degree phase difference between the third transmission line and the fourth transmission line. When the antenna transmits a signal, the first transmission line and the third transmission line can form a vertically polarized wave by means of radiation at a radiating body under the drive of a balanced differential signal; and the second transmission line and the fourth transmission line can form a horizontally polarized wave by means of radiation at the radiating body under the drive of the balanced differential signal. Owing to the phase differences of the transmission lines, the vertically polarized wave and the horizontally polarized wave are orthogonal to each other, thereby synthesizing a circularly polarized wave, and thus realizing circularly polarized radiation of the antenna. The circularly polarized antenna is suitable for various wireless communication devices capable of performing receiving or transmitting, especially for a wearable electronic device, and improves the user experience.

Description

Circularly polarized antenna and its wireless communication device

Technical field

The present invention relates to the field of antenna technologies, and in particular, to a circularly polarized antenna and a wireless communication device thereof.

Background technique

Smart devices are developing at a faster speed, products are changing with each passing day, and smartphones are basically popular. Nowadays, wearable smart devices have become the new favorite of manufacturers and become a new hot spot in the consumption of electronic products. From Apple Watch to Xiaomi Bracelet, wearable smart devices have gradually become accepted and loved by the public. However, due to its limited size, the smart device's related functions or performance can not meet the customer's needs. For example, most smart watches on the market do not have GPS (Global Positioning System) positioning function, and some have positioning functions, but they The positioning performance is relatively poor. It is difficult to design a circularly polarized GPS antenna on the above because of the limited size of the watch. At present, the smart watch antenna with GPS function adopts linear polarization, which leads to poor reception efficiency and affects the customer experience. The same is true for other smart devices. Due to the size limitation, it is difficult to install antennas with better radiation performance, which may cause the related functions or related performance of the products to fail to meet customer needs.

Summary of the invention

The technical problem to be solved by the present invention is to provide a circularly polarized antenna, which adopts a balanced differential feeding mode, respectively excites two orthogonal modes, and implements a circularly polarized antenna technology through appropriate phase distribution.

It can be applied to small smart wearable devices to enhance antenna radiation performance and enhance user experience.

In order to solve the above problems, the present invention provides a circularly polarized antenna, including:

a balanced differential feed unit for receiving or transmitting a balanced differential signal;

a transmission line, configured to transmit the balanced differential signal, including a first transmission line, a second transmission line, a third transmission line, and a fourth transmission line, and each of the first transmission line, the second transmission line, the third transmission line, and the fourth transmission line a balanced differential feed unit, the first transmission line and the second transmission line transmitting a positive signal of the balanced differential signal and configured to have a phase difference of plus or minus 90 degrees, the third transmission line and the first The four transmission lines transmit the negative signals of the balanced differential signals and are configured to have a phase difference of plus or minus 90 degrees;

a radiator connecting the ends of the first transmission line, the second transmission line, the third transmission line, and the fourth transmission line for radiation;

Wherein, when the balanced differential feed unit receives or transmits the balanced differential signal, the first transmission line and the third transmission line form a first pair of balanced differential transmission lines, and the transmission signal radiation forms a first direction polarization signal, where the The second transmission line and the fourth transmission line form a second pair of balanced differential transmission lines, and the transmission signal radiation forms a second direction polarization signal, and the phases of the first direction polarization signal and the second direction polarization signal are different by 90 degrees or minus 90 degrees. , thereby synthesizing a circularly polarized wave.

According to an embodiment of the present invention, the first transmission line and the beginning end of the second transmission line are connected and connected to the positive port of the balanced differential feeding unit; the third transmission line and the beginning end of the fourth transmission line are connected and connected to the balance The negative port of the differential feed unit.

According to an embodiment of the invention, the balanced differential feed unit and the transmission line are connected by a power divider to achieve signal isolation between the first pair of balanced differential transmission lines and the second pair of balanced differential transmission lines, the power divider includes a three-port power splitter and a second three-port power splitter; a start end of the first transmission line and the second transmission line are respectively connected to two ports of the first three-port power splitter, the balanced differential feed unit a positive port is connected to the other port of the first three-port power splitter; a start end of the third transmission line and the fourth transmission line are respectively connected to two ports of the second three-port power splitter, the balance The negative port of the differential feed unit is connected to the other port of the second three port power splitter.

According to an embodiment of the present invention, the first transmission line is provided with a first 90-degree phase shifting network, such that the transmission signals of the first transmission line and the second transmission line are different in phase by 90 degrees or minus 90 degrees; a third 90-degree phase shifting network is provided on the third transmission line, such that the third transmission line and the The transmission signal of the fourth transmission line has a phase difference of plus or minus 90 degrees.

According to an embodiment of the present invention, the first 90-degree phase shifting network and/or the second 90-degree phase shifting network is constituted by a transmission line whose transmission coefficient S21 has a phase of positive 90 degrees or minus 90 degrees; Alternatively, the first 90 degree phase shifting network and/or the second 90 degree phase shifting network is composed of a lumped device whose phase of the transmission coefficient S21 is plus or minus 90 degrees.

According to an embodiment of the invention, the balanced differential feed unit and the transmission line are connected by a 3dB bridge, the 3dB bridge comprising a first 3dB bridge and a second 3dB bridge; the first transmission line and the The beginning ends of the two transmission lines are respectively connected to the two ports of the first 3dB bridge, and the two ports of the first 3dB bridge have the same amplitude, the phase difference is 90 degrees or minus 90 degrees, and the balanced differential feed unit a positive port is connected to the other port of the first 3dB bridge, such that the transmission signals of the first transmission line and the second transmission line are out of phase by 90 degrees or minus 90 degrees; the third transmission line and the fourth The beginning ends of the transmission lines are respectively connected to the two ports of the second 3dB bridge, and the two ports of the second 3dB bridge have the same amplitude, the phase difference is 90 degrees or minus 90 degrees, and the balanced differential feeding unit The negative port is connected to the other port of the second 3dB bridge such that the transmission signals of the third transmission line and the fourth transmission line are out of phase by 90 degrees or minus 90 degrees.

According to an embodiment of the invention, the balanced differential feed unit comprises a single-ended to differential balun circuit having a positive port, a negative port and a single-ended RF port for converting between a single-ended RF signal and a differential signal .

According to an embodiment of the invention, the balanced differential feed unit comprises an IC chip with a balanced differential circuit and a balanced differential port.

According to an embodiment of the present invention, the transmission coefficients S21 of the first transmission line and the third transmission line are equal or nearly equal; the transmission coefficients S21 of the second transmission line and the fourth transmission line are equal or nearly equal; the first transmission line and The transmission coefficient S21 of the third transmission line and the transmission coefficient S21 of the second transmission line and the fourth transmission line are equal in amplitude, and the phase difference is plus or minus 90 degrees.

According to an embodiment of the present invention, each end of the first transmission line, the second transmission line, the third transmission line, and the fourth transmission line is connected to the radiator through a matching network, or directly connected to the radiator.

According to an embodiment of the invention, there is further included a printed wiring board on which the balanced differential feed unit, the transmission line, and the radiator are disposed.

According to an embodiment of the present invention, the radiator is four discrete components respectively connected to respective ends of the first transmission line, the second transmission line, the third transmission line, and the fourth transmission line, and disposed on the printed circuit board The position and spacing on the top depends on the antenna operating frequency.

According to an embodiment of the invention, the radiator is four discrete components respectively connected to respective ends of the first transmission line, the second transmission line, the third transmission line and the fourth transmission line, and the four discrete components are balanced and balanced. The electrical unit is symmetrically disposed centrally and disposed on an edge of the printed wiring board.

According to an embodiment of the invention, the radiator is integrated or connected to a metal structural component of an electronic device employing the circularly polarized antenna, the metallic structural component being a discrete component or an integrated component.

According to an embodiment of the invention, the metal structural component is a metal casing composed of at least two non-conducting metal conductors or a monolithic metal conductor.

The present invention also provides a wireless communication device comprising a communication circuit and an antenna device connected to the communication circuit, the antenna device employing the circularly polarized antenna of any of the preceding embodiments.

According to an embodiment of the invention, the wireless communication device is a wearable smart device.

After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art: driving with balanced differential signals (including positive signals and negative signals), the first transmission line and the second transmission line are driven by a positive signal, the third transmission line and the fourth The transmission line is driven by a negative signal, and the phase difference is reasonably configured such that the first transmission line and the second transmission line have a positive 90 degree or negative 90 degree phase difference, and the third transmission line and the fourth transmission line have a positive 90 degree or a negative 90 degree phase. Poor, when the antenna transmits a signal, the first transmission line and the third transmission line can form a vertically polarized wave in the radiation body driven by the balanced differential signal, and the second transmission line and the fourth transmission line can be radiated under the driving of the balanced differential signal. The radiation forms a horizontally polarized wave. Due to the phase difference of the transmission line, the vertically polarized wave and the horizontally polarized wave are orthogonal to each other, and thus can be synthesized into a circularly polarized wave to realize circularly polarized radiation of the antenna.

DRAWINGS

1 is a schematic structural view of an intelligent wearable device according to an embodiment of the present invention;

2 is a cross-sectional structural view of the smart wearable device of FIG. 1 taken along line A-A;

3 is a schematic structural view of a circularly polarized antenna according to an embodiment of the present invention;

4 is a schematic structural diagram of a circularly polarized antenna according to another embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a circularly polarized antenna according to still another embodiment of the present invention; FIG.

6 is a schematic structural view of a circularly polarized antenna according to still another embodiment of the present invention;

7 is a schematic structural view of a circularly polarized antenna according to still another embodiment of the present invention;

FIG. 8 is a schematic diagram of a horizontal current when a circularly polarized antenna is excited according to an embodiment of the present invention; FIG.

9 is a schematic diagram of vertical current during excitation of a circularly polarized antenna according to an embodiment of the present invention;

FIG. 10 is a schematic diagram of return loss of a circularly polarized antenna according to an embodiment of the present invention; FIG.

11 is a schematic diagram showing a two-dimensional direction of a circularly polarized antenna according to an embodiment of the present invention;

Figure 12 is a schematic view showing the axial ratio of a circularly polarized antenna according to an embodiment of the present invention;

Figure 13 is a graph showing the efficiency of a circularly polarized antenna according to an embodiment of the present invention.

detailed description

The above described objects, features and advantages of the present invention will become more apparent from the aspects of the appended claims.

Numerous specific details are set forth in the description below in order to provide a thorough understanding of the invention. However, the present invention can be implemented in many other ways than those described herein, and a person skilled in the art can make a similar promotion without departing from the spirit of the invention, and thus the invention is not limited by the specific embodiments disclosed below.

The circularly polarized antenna of the present invention can be used in any wireless communication device that realizes transmitting or receiving circularly polarized waves, and can be made smaller in size, especially suitable for use in wearable smart devices, circular polarization Better antenna performance can enhance the customer experience.

In one embodiment, the circularly polarized antenna of the present invention is used in a smart watch, but is not limited thereto, wherein the smart watch may have a variation or an increase or decrease component, and the circularly polarized antenna may also be used outside the smart watch. Other wireless communication devices, such as mobile terminals and the like.

Referring to FIG. 1, the smart watch may include a watch metal frame 1 and a watch screen 2, and the watch screen is mounted on one side of the watch metal frame 2. The material of the watch metal frame 1 may be, for example, stainless steel, and of course other. The metal material, the watch screen 2 can be, for example, a watch touch screen. Referring to FIG. 2, the smart watch may further include a battery panel 3, a multilayer printed wiring board 4 and a watch rear case 5 as viewed from a cross section. The watch rear case 5 is mounted on the other side of the watch metal frame 1, and the watch rear case 5 is non- Metal, can be made of plastic. Generally speaking, the multilayer printed wiring board 4 and the watch metal frame 1 cannot be directly connected, and may be connected by an inductor or a capacitor to reduce the negative influence of the metal frame of the watch, and a certain gap 6 is provided between them, which may be 1 mm. .

Referring to FIG. 3, the circularly polarized antenna of the present embodiment includes: a balanced differential feed unit 8, a transmission line, and a radiator. Referring to FIGS. 1-3, when the circularly polarized antenna of the present embodiment is applied to a smart watch, a printed circuit board may be further included, and the latter two layers of the multilayer printed wiring board 4 of the smart watch may be used as a circularly polarized antenna. The feeder network layer, the radiator can also be used with the watch metal frame 1 of the smart watch or integrated on the watch metal frame 1 or connected to the watch metal frame 1.

The balanced differential feed unit 8 receives or transmits a balanced differential signal, and the balanced differential signal includes a positive signal and a negative signal. When the antenna transmits a signal, the balanced differential feed unit 8 outputs a balanced differential signal to drive the transmission line to form a circularly polarized wave, and the antenna receives the signal. At this time, the balanced differential power feeding unit 8 receives the balanced differential signal formed by the transmission line decomposing the circularly polarized wave.

The transmission line is used to transmit a balanced differential signal, and the transmission line includes a first transmission line 701, a second transmission line 702, a third transmission line 703, and a fourth transmission line 704. The respective ends of the first transmission line 701, the second transmission line 702, the third transmission line 703, and the fourth transmission line 704 are connected to the balanced differential feeding unit 8. The first transmission line 701 and the second transmission line 702 transmit a positive signal of the balanced differential signal, and the signals transmitted by the first transmission line 701 and the second transmission line 702 are out of phase by 90 degrees or minus 90 degrees. Third transmission line 703 And the fourth transmission line 704 transmits a negative signal of the balanced differential signal, and the phases of the third transmission line 703 and the fourth transmission line 704 are different by 90 degrees or minus 90 degrees. The phase difference of the first transmission line 701 and the second transmission line 702, and the phase difference of the third transmission line 703 and the fourth transmission line 704 are both positive 90 degrees or the same negative 90 degrees to achieve left-hand circular polarization or right-hand circular polarization.

The radiator includes four feed ends respectively connected to respective ends of the first transmission line 701, the second transmission line 702, the third transmission line 703, and the fourth transmission line 704, and the radiator is used to implement signal radiation of the circularly polarized antenna.

When the balanced differential power feeding unit 8 receives or transmits the balanced differential signal, the first transmission line 701 and the third transmission line 703 form a first pair of balanced differential transmission lines, and the transmission signals of the first pair of balanced differential transmission lines form a first direction polarization signal. The second transmission line 702 and the fourth transmission line 704 form a second pair of balanced differential transmission lines, and the transmission signals of the second pair of balanced differential transmission lines form a second direction polarization signal, and the phases of the first direction polarization signal and the second direction polarization signal are different. Positive 90 degrees or minus 90 degrees to achieve circularly polarized radiation of the antenna.

Taking the antenna transmit signal as an example, the balanced differential feed unit 8 outputs a balanced differential signal, and the first transmission line 701 and the third transmission line 703 are respectively formed by the radiation of the radiator under the differential drive of the positive signal and the negative signal, respectively. The directionally polarized signal forms an antenna radiation pattern such as a vertically polarized antenna, and the second transmission line 702 and the fourth transmission line 704 respectively form a second direction pole by radiation of the radiator under differential driving of the positive signal and the negative signal, respectively. The signal is formed to form a horizontally polarized antenna radiation pattern. The vertically polarized antenna radiation pattern and the horizontally polarized antenna radiation pattern are just orthogonal, and since the phases between the two radiation modes are 90 degrees out of phase, they can be synthesized into circularly polarized waves.

In one embodiment, the first transmission line 701 and the beginning of the second transmission line 702 are connected and connected to the positive port of the balanced differential feed unit 8, such that the beginnings of the first transmission line 701 and the second transmission line 702 simultaneously receive the balanced differential feed unit 8. The positive signal; the third transmission line 703 is connected to the beginning of the fourth transmission line 704 and connected to the negative port of the balanced differential feed unit 8, so that the beginnings of the third transmission line 703 and the fourth transmission line 704 simultaneously receive the negative of the balanced differential feed unit 8. signal.

Optionally, the balanced differential feed unit 8 and the transmission line are connected by a power splitter to achieve the first Signal isolation between the balanced differential transmission line and each of the second pair of balanced differential transmission lines. The power splitter includes a first three-port power splitter 901 and a second three-port power splitter 902. The beginnings of the first transmission line 701 and the second transmission line 702 are respectively connected to two ports of the first three-port power divider 901 (the output signals of the two ports are preferably not different), and the positive port connection of the balanced differential feeding unit 8 is balanced. To the other port of the first three-port power splitter 901, the other port is used to input and output a positive signal of the balanced differential feed unit 8. The beginnings of the third transmission line 703 and the fourth transmission line 704 are respectively connected to two ports of the second three-port power divider 902 (the output signals of the two ports are preferably not different), and the negative port connection of the balanced differential feeding unit 8 is balanced. To the other port of the second three-port power splitter 902, the other port is used to input and output a negative signal of the balanced differential feed unit 8.

Referring to Figures 3, 4 and 7, each power divider is formed by extension of the transmission line. The first transmission line 701 and the second transmission line 702 are connected by respective extension lines and connected to the positive port of the balanced differential feed unit 8, and the third transmission line 703 and the fourth transmission line 704 are connected by respective extension lines and connected to the balanced differential feed. The negative port of unit 8.

Referring to FIG. 5, each of the three-port power splitters may be selected as

Wilkinson power splitters

911 and 912, and an isolation resistor R1, a third transmission line 703 and a fourth transmission line are added between the first transmission line 701 and the second transmission line 702. An isolation resistor R2 is added between 704 to isolate signal interference. The power splitter of the foregoing embodiment is not limited, and other power splitters may be employed in the present invention.

In order to properly configure the phase difference between the transmission lines as needed. Optionally, the first transmission line 701 is provided with a first 90-degree phase shifting network 10, and the first transmission line 701 and the second transmission line 702 transmit signals to the radiator under the driving of the positive signal, and the phase difference is positive or negative 90 degrees. The third transmission line 703 is provided with a second 90-degree phase shifting network 11, and the third transmission line 703 and the fourth transmission line 704 are driven by a negative signal to transmit signals to the radiator with a phase difference of 90 degrees or minus 90 degrees. Thereby, the radiator radiates the first direction polarization signal and the second direction polarization signal, and the two are exactly orthogonal to form a circularly polarized wave.

The first 90 degree phase shifting network 10 and/or the second 90 degree phase shifting network 10 may be constituted by a length of transmission line whose transmission coefficient S21 is positively 90 degrees or minus 90 degrees. Alternatively, the first 90 degree phase shifting network 10 and/or the second 90 degree phase shifting network 10 may be composed of lumped devices, the lumped The phase of the transmission coefficient S21 of the device is plus or minus 90 degrees.

Specifically, each phase shifting network can be implemented by a microstrip delay line or an analog/digital phase shifter, but the specific form is not limited and can be implemented in various circuit forms.

In one embodiment, referring to Figure 6, the balanced differential feed unit 8 and the transmission line pass through a 3dB bridge (the 3db bridge is also called a co-frequency combiner, which is capable of continuously transmitting power in a certain direction along the transmission line). The sampling can be performed by dividing an input signal into two signals that are equal amplitude and having a phase difference of 90°. The 3dB bridge includes a first 3dB bridge 921 and a second 3dB bridge 922. The first ends of the first transmission line 701 and the second transmission line 702 are respectively connected to two ports of the first 3dB bridge 921. The two ports of the first 3dB bridge 921 have the same amplitude, the phase difference is 90 degrees or minus 90 degrees, and the balance difference is The positive port of the feeding unit 8 is connected to the other port of the first 3dB bridge 921, so that the transmission signals of the first transmission line 701 and the second transmission line 702 are out of phase by 90 degrees or minus 90 degrees; the third transmission line 703 and the fourth The beginning of the transmission line 704 is respectively connected to two ports of the second 3dB bridge 922, and the two ports of the second 3dB bridge 922 have the same amplitude, the phase difference is 90 degrees or minus 90 degrees, and the negative port of the balanced differential feeding unit 8 is balanced. The other port of the second 3dB bridge 922 is connected such that the transmission signals of the third transmission line 703 and the fourth transmission line 704 are out of phase by 90 degrees or minus 90 degrees. An isolation resistor R3 is disposed on the first 3dB bridge, and an isolation resistor R4 is disposed on the second 3dB bridge 922 to isolate the interference signal.

The first 3dB bridge 921 is used in place of the first three-port power splitter 901 and the first 90-degree phase shifting network 10 to provide high isolation, equal amplitude, and 90 degree phase difference between the first transmission line 701 and the second transmission line 702. The signal, likewise, replaces the second three-port power divider 902 and the second nine-degree phase shift network 11 with a second 3dB bridge 922, providing high isolation, equal amplitude, and having third transmission line 703 and fourth transmission line 704 A 90 degree phase difference signal.

In one embodiment, the balanced differential feed unit 8 includes a single-ended to differential balun circuit. The balanced differential feed units shown in FIGS. 3-7 are balun circuits, but are not limited, and other outputs can be balanced. The circuit of the differential signal can be used in the present embodiment. The form of the circuit can be a discrete component or an integrated chip or other form of component, and is not limited. Single-ended to differential balun circuit with positive terminal Port, negative port and single-ended RF ports for conversion between single-ended RF signals and differential signals. The single-ended RF port is the total port, and the positive port and the negative port are the same-amplified inverting port. The positive port and the negative port are respectively connected with the connection point of the first transmission line 701 and the second transmission line 702, and the connection point of the third transmission line 703 and the fourth transmission line 704 to provide a transmission line balanced differential signal; or, the positive port and the negative port respectively The other port of the first 3dB bridge 921, the other port of the second 3dB bridge 922, provides a transmission line balanced differential signal.

In one embodiment, balanced differential feed unit 8 may include an IC chip with a balanced differential circuit and a balanced differential port. The balanced differential ports of the IC chip are respectively connected to the connection points of the first transmission line 701 and the second transmission line 702, the connection points of the third transmission line 703 and the fourth transmission line 704, or the balanced differential port of the IC chip and the first 3dB bridge 921. The other port of the other port, the second port of the second 3dB bridge 922, provides a transmission line balanced differential signal.

Preferably, the transmission coefficients S21 (input return loss) of the first transmission line 701 and the third transmission line 703 are equal or nearly equal; the transmission coefficients S21 of the second transmission line 702 and the fourth transmission line 704 are equal or nearly equal; the first transmission line 701 The transmission coefficient S21 of the third transmission line 703 and the transmission coefficient S21 of the second transmission line 702 and the fourth transmission line 704 are equal in amplitude, and the phase difference is plus or minus 90 degrees.

The respective ends of the first transmission line 701, the second transmission line 702, the third transmission line 703, and the fourth transmission line 704 may be connected to the radiator through a matching network. The matching network can for example be composed of LC circuits, but other forms of form are also possible. The respective ends of the first transmission line 701, the second transmission line 702, the third transmission line 703, and the fourth transmission line 704 may also be directly connected to the radiator.

In one embodiment, the circularly polarized antenna further comprises a printed wiring board, which may be a layer on the multilayer printed wiring board 4 of the smart watch shown in FIGS. 1 and 2 or with reference to FIGS. 3-7 or Several floors. The printed circuit board is used to set the balanced differential feed unit, the transmission line and the radiator. Of course, other circularly polarized antennas can be provided as needed, such as matching networks, isolation resistors, and the like.

The radiator can be an integral component or a separate component for connecting the transmission line and radiating the signal. The shape of the radiator is not limited, and may be, for example, a circle as shown in FIG. 3, or may be FIG. The rectangular shape shown may also be formed by discrete components as shown in Fig. 7, but the form in each figure is merely illustrative and not limiting, and the form of the radiator may be designed according to actual needs.

In Fig. 4, the printed wiring board 4' has a rectangular shape, and the watch metal frame 1' has an integrated rectangular frame. The radiator is connected to the watch metal frame 1', and the printed wiring board 4' and the watch metal frame 1' have slits 6'. In Fig. 7, the printed wiring board 4" is rectangular, and the radiator 1" is four discrete components, which may not be integrated or connected to the metal frame of the watch.

Optionally, the radiator may be four discrete components respectively connected to the ends of the first transmission line 701, the second transmission line 702, the third transmission line 703, and the fourth transmission line 704, and the position of the radiator on the printed circuit board is The spacing depends on the antenna operating frequency and the radiator can be placed at the edge of the printed wiring board. The circularly polarized antennas shown in Figures 3-7 all have the radiator disposed at the edge of the printed wiring board, but it is understood that the radiator may not be disposed on the edge of the printed wiring board, and does not affect the operation of the circularly polarized antenna. Just fine.

Specifically, referring to FIG. 7, the radiator 1" is four discrete components respectively connected to the respective ends of the first transmission line 701, the second transmission line 702, the third transmission line 703, and the fourth transmission line 704, and the four discrete components are balanced. The feeding unit 8 is symmetrically arranged centrally and disposed on the edge of the printed wiring board. The printed wiring board is arranged reasonably, and the radiator is disposed at the edge of the printed wiring board, which can reduce the overall volume, but is not limited.

Optionally, the radiator is integrated or connected to a metal structural component of an electronic device employing a circularly polarized antenna, and the metal structural component is a discrete component or an integrated component. That is to say, the metal structural component of the electronic device using the circularly polarized antenna of the embodiment of the invention may be integrated with the radiator or connected to the radiator or directly as a radiator.

The metal structural component can be, for example, a metal casing composed of at least two non-conducting metal conductors or a monolithic metal conductor, the specific form being determined according to the metal structural components of the actual electronic device. There are no restrictions here.

A wireless communication device according to an embodiment of the present invention includes a communication circuit and an antenna device connected to the communication circuit, and the antenna device adopts the circularly polarized antenna of any of the foregoing embodiments.

Optionally, the wireless communication device is a wearable smart device.

Preferably, the wireless communication device is, for example, the smart watch shown in FIG. 1 and FIG. 2, and the circularly polarized antenna of the embodiment of the present invention realizes circular polarized wave radiation by a balanced differential feed mode, and can be set to a small volume of a smart watch or the like. In electronic devices, better transmission performance than existing antennas is used to enhance the user experience. The circularly polarized antenna can be placed on the rear two layers of the multi-layer printed circuit board of the smart watch, and the radiator of the circularly polarized antenna can be connected or integrated on the metal frame of the watch of the smart watch.

In the present embodiment, a circularly polarized antenna is applied to the smart watch of Fig. 1, see Fig. 8 and Fig. 9, respectively, for the current distribution on the metal frame 1 of the watch when the circularly polarized antenna is horizontally and vertically excited.

The circularly polarized antenna of the smart watch GPS is designed according to an embodiment of the present invention, and the analysis result of the antenna is given by FIG. 10-13. The antenna performance is better than that of the existing antenna while the volume can be adapted to the smart watch. Figure 10 shows the return loss, with a return loss of -5dB as the reference point and a frequency coverage of 1560MHz-1600MHz. Figure 11 is an antenna pattern including right-hand circular polarization and left-hand circular polarization patterns. Figure 12 is an axial ratio diagram with axial ratios less than 5 dB in the 1570 MHz-1590 MHz band. Figure 13 shows the efficiency curve with efficiency close to 60% for each frequency point.

The present invention is disclosed in the above preferred embodiments, but it is not intended to limit the scope of the invention, and the present invention may be made without departing from the spirit and scope of the invention. The scope of protection should be determined by the scope defined by the claims of the present invention.

Claims

A circularly polarized antenna, comprising:

a balanced differential feed unit for receiving or transmitting a balanced differential signal;

a transmission line, configured to transmit the balanced differential signal, including a first transmission line, a second transmission line, a third transmission line, and a fourth transmission line, and each of the first transmission line, the second transmission line, the third transmission line, and the fourth transmission line a balanced differential feed unit, the first transmission line and the second transmission line transmitting a positive signal of the balanced differential signal and configured to have a phase difference of plus or minus 90 degrees, the third transmission line and the first The four transmission lines transmit the negative signals of the balanced differential signals and are configured to have a phase difference of plus or minus 90 degrees;

a radiator connecting the ends of the first transmission line, the second transmission line, the third transmission line, and the fourth transmission line for radiation;

Wherein, when the balanced differential feed unit receives or transmits the balanced differential signal, the first transmission line and the third transmission line form a first pair of balanced differential transmission lines, and the transmission signal radiation forms a first direction polarization signal, where the The second transmission line and the fourth transmission line form a second pair of balanced differential transmission lines, and the transmission signal radiation forms a second direction polarization signal, and the phases of the first direction polarization signal and the second direction polarization signal are different by 90 degrees or minus 90 degrees. , thereby synthesizing a circularly polarized wave.
The circularly polarized antenna according to claim 1, wherein a first port of said first transmission line and said second transmission line are connected and connected to a positive port of said balanced differential feeding unit; said third transmission line and said fourth transmission line The beginning of the connection is connected and connected to the negative port of the balanced differential feed unit.
The circularly polarized antenna according to claim 2, wherein the balanced differential feed unit and the transmission line are connected by a power divider to realize signal isolation between the first pair of balanced differential transmission lines and the second pair of balanced differential transmission lines. The power splitter includes a first three-port power splitter and a second three-port power splitter; a start end of the first transmission line and the second transmission line are respectively connected to two ports of the first three-port power splitter a positive port of the balanced differential feed unit is connected to another port of the first three-port power splitter; a start end of the third transmission line and the fourth transmission line are respectively connected to the second three-port power splitter Two ports, the negative port of the balanced differential feed unit is connected to the second three-port power splitter Another port.
The circularly polarized antenna according to claim 2, wherein the first transmission line is provided with a first 90-degree phase shifting network, so that the phase of the transmission signals of the first transmission line and the second transmission line are different 90 degrees or minus 90 degrees; the third transmission line is provided with a second 90 degree phase shifting network, so that the transmission signals of the third transmission line and the fourth transmission line are different in phase by 90 degrees or minus 90 degrees.
The circularly polarized antenna according to claim 4, wherein said first 90-degree phase shifting network and/or second 90-degree phase shifting network is constituted by a length of transmission line, and a phase of said transmission line S21 is Positive 90 degrees or minus 90 degrees; or, the first 90 degree phase shifting network and / or the second 90 degree phase shifting network is composed of a lumped device, the phase of the transmission coefficient S21 of the lumped device is positive 90 degrees or Negative 90 degrees.
The circularly polarized antenna according to claim 1, wherein said balanced differential feed unit and said transmission line are connected by a 3dB bridge, said 3dB bridge comprising a first 3dB bridge and a second 3dB bridge The first ends of the first transmission line and the second transmission line are respectively connected to two ports of the first 3dB bridge, and the two ports of the first 3dB bridge have the same amplitude and a phase difference of 90 degrees or minus 90 degrees. The positive port of the balanced differential feed unit is connected to another port of the first 3dB bridge, such that the transmission signals of the first transmission line and the second transmission line are different in phase by 90 degrees or minus 90 degrees; The beginning ends of the third transmission line and the fourth transmission line are respectively connected to two ports of the second 3dB bridge, and the two ports of the second 3dB bridge have the same amplitude and a phase difference of 90 degrees or minus 90 degrees. The negative port of the balanced differential feed unit is connected to the other port of the second 3dB bridge such that the transmission signals of the third transmission line and the fourth transmission line are out of phase by 90 degrees or minus 90 degrees.
The circularly polarized antenna according to any one of claims 2 to 6, wherein the balanced differential feed unit comprises a single-ended to differential balun circuit having a positive port, a negative port, and a single-ended RF port. Used to achieve conversion between single-ended RF signals and differential signals.
The circularly polarized antenna according to any one of claims 2 to 6, wherein the balanced differential feed unit comprises an IC chip having a balanced differential circuit and a balanced differential port.
The circularly polarized antenna according to claim 1, wherein transmission coefficients S21 of said first transmission line and said third transmission line are equal or nearly equal; transmission coefficient S21 of said second transmission line and said fourth transmission line are equal or close Equivalent; the transmission coefficient S21 of the first transmission line and the third transmission line is equal to the transmission coefficient S21 of the second transmission line and the fourth transmission line, and the phase difference is 90 degrees or minus 90 degrees.
The circularly polarized antenna according to claim 1, wherein each end of the first transmission line, the second transmission line, the third transmission line, and the fourth transmission line is connected to the radiator through a matching network, or directly connected to the Radiation body.
A circularly polarized antenna according to claim 1, further comprising a printed wiring board on which said balanced differential feed unit, transmission line and radiator are disposed.
The circularly polarized antenna according to claim 11, wherein the radiator is four discrete components connected to respective ends of the first transmission line, the second transmission line, the third transmission line, and the fourth transmission line, And the position and spacing provided on the printed circuit board depend on the antenna operating frequency.
The circularly polarized antenna according to claim 11, wherein the radiator is four discrete components connected to respective ends of the first transmission line, the second transmission line, the third transmission line, and the fourth transmission line, The four discrete components are symmetrically disposed centered on the balanced differential feed unit and disposed on the edge of the printed wiring board.
The circularly polarized antenna according to claim 11, wherein said radiator is integrated or connected to a metal structural member of an electronic device using said circularly polarized antenna, said metal structural member being a discrete component or an integrated component .
The circularly polarized antenna according to claim 14, wherein said metal structural member is a metal casing, said metal casing being composed of at least two non-conducting metal conductors or a single piece of metal Conductor composition.
A wireless communication device comprising a communication circuit and an antenna device connected to the communication circuit, wherein the antenna device employs the circularly polarized antenna according to any one of claims 1-6, 9-15.
The wireless communication device of claim 16 wherein said wireless communication device is a wearable smart device.