Electrically small antenna broadband matching circuit, printed circuit board, active antenna, and device

Abstract

The application provides an electrically small antenna broadband matching circuit, a printed circuit board, an active antenna and a device. The electrically small antenna broadband matching circuit comprises a field effect transistor, a direct current power supply module, a first biasing module, a second biasing module and a third biasing module. The drain of the field effect transistor is used as an output end of the electrically small antenna broadband matching circuit and is connected with a transmission line. The gate of the field effect transistor is used as an input end of the electrically small antenna broadband matching circuit and is connected with an output end of the electrically small antenna. The first biasing module is connected with the direct current power supply module. The first biasing module, the second biasing module and the third biasing module are used for direct current biasing of the field effect transistor in an ohmic region with a preset output impedance. The field effect transistor is used for amplifying a signal input by the electrically small antenna and performing impedance matching with the transmission line. The scheme provided by the application reduces the power consumption of the electrically small antenna matching circuit.

Description

Technical Field

[0001] This application relates to communication technology, and more particularly to a broadband matching circuit for an electrically small antenna, a printed circuit board, an active antenna, and related equipment. Background Technology

[0002] With the development of mobile communication technology, the space available for antennas within communication devices is becoming increasingly smaller. Electrically small antennas (EMTs) have a physical size much smaller than the free-space wavelength of electromagnetic waves at their operating frequency, allowing for electromagnetic wave transmission and reception within a smaller physical footprint. However, limited by the Jules Rimet limit and Bode-Fano matching constraints, EMTs have lower radiation gain and narrower radiation bandwidth than conventional antennas, making them difficult to apply in modern broadband communication systems.

[0003] Currently, impedance matching between electrically small antennas and transmission lines can be achieved through matching circuits, reducing echo reflections and improving the radiation gain and bandwidth of the electrically small antennas. Non-Foster circuits are now commonly used for impedance matching to enable the use of electrically small antennas in broadband communications. However, non-Foster circuits require multiple transistors, resulting in complex circuit structures and high power consumption. Summary of the Invention

[0004] This application provides a broadband matching circuit, printed circuit board, active antenna, and device for electrically small antennas, in order to solve the problem of high power consumption in the matching circuit of electrically small antennas in the prior art.

[0005] According to a first aspect of this application, a broadband matching circuit for an electrically small antenna is provided, comprising: a field-effect transistor (FET), a DC power supply module, a first bias module, a second bias module, and a third bias module; the drain of the FET is connected to a first terminal of the first bias module and serves as the output terminal of the broadband matching circuit for the electrically small antenna; the source of the FET is connected to a first terminal of the second bias module; the gate of the FET serves as the input terminal of the broadband matching circuit for the electrically small antenna and is connected to the output terminal of the electrically small antenna and the first terminal of the third bias module; a second terminal of the first bias module is connected to the DC power supply module; the second terminals of the second and third bias modules are both grounded; the first, second, and third bias modules are used to DC bias the FET in the ohmic region where the output impedance is a preset value; the FET is used to amplify the signal input to the electrically small antenna and perform impedance matching with a target port, the target port being connected to the output terminal of the broadband matching circuit for the electrically small antenna.

[0006] According to a second aspect of this application, a printed circuit board is provided, including a broadband matching circuit for an electrically small antenna as described in the first aspect.

[0007] According to a third aspect of this application, an active antenna is provided, including an electrically small antenna and a broadband matching circuit for the electrically small antenna as described in the first aspect.

[0008] According to a fourth aspect of this application, an electronic device is provided, including an active antenna as described in the third aspect.

[0009] The electrically small antenna broadband matching circuit, printed circuit board, active antenna, and device provided in this application include: a field-effect transistor (FET), a DC power supply module, a first bias module, a second bias module, and a third bias module; the drain of the FET is connected to the first terminal of the first bias module and serves as the output terminal of the electrically small antenna broadband matching circuit; the source of the FET is connected to the first terminal of the second bias module; the gate of the FET serves as the input terminal of the electrically small antenna broadband matching circuit and is connected to the output terminal of the electrically small antenna and the first terminal of the third bias module; the second terminal of the first bias module is connected to the DC power supply module. The circuit is simple: the second and third bias modules are connected in a block; both the second terminals of the second and third bias modules are grounded; the first, second, and third bias modules are used to DC bias the field-effect transistor (FET) in the ohmic region where the output impedance is a preset value; the FET is used to amplify the signal input to the electrically small antenna and perform impedance matching with the target port, which is connected to the output terminal of the electrically small antenna broadband matching circuit; since the first, second, and third bias modules are used to bias the FET in the ohmic region where the output impedance is a preset value, the DC power supply module is connected to the first bias module, resulting in a simple circuit structure. The FET, biased in the ohmic region, amplifies the signal input to the electrically small antenna. The FET's output impedance is a preset value and it has broadband stability, enabling it to match the impedance of the target port, thereby improving the radiation gain and radiation bandwidth of the electrically small antenna and broadening its radiation bandwidth to a wide frequency band. Besides the DC power supply module, the circuit only has the FET as an active device; the FET, biased in the ohmic region, has low DC power consumption. In summary, the solution proposed in this application features a simple structure for the electrically small antenna broadband matching circuit, which also reduces the power consumption of the electrically small antenna matching circuit. Attached Figure Description

[0010] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0011] Figure 1 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to the first embodiment of this application;

[0012] Figure 2 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna provided according to the second embodiment of this application;

[0013] Figure 3 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to an embodiment of this application;

[0014] Figure 4 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to an embodiment of this application;

[0015] Figure 5 This is a schematic diagram of a broadband matching circuit structure for an electrically small antenna according to an embodiment of this application;

[0016] Figure 6 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna provided in the third embodiment of this application;

[0017] Figure 7 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna provided in the fourth embodiment of this application;

[0018] Figure 8 This is a schematic diagram of a small antenna broadband matching circuit structure provided according to the fifth embodiment of this application;

[0019] Figure 9 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to an embodiment of this application;

[0020] Figure 10a These are the simulation results of the reflection coefficient of the electrically small antenna provided in Example 1 of this application in the frequency range of 20MHz to 2GHz, respectively without and after passing through a matching network;

[0021] Figure 10b The results show the gain simulation of the electrically small antenna provided in Example 1 of this application in the frequency range of 20MHz to 2GHz, with and without a matching network, as well as the gain improvement value of the matching network on the electrically small antenna.

[0022] Figure 11a These are the simulation results of the reflection coefficient of the electrically small antenna provided in Example 2 of this application in the frequency range of 20MHz to 2GHz, respectively without and after passing through a matching network;

[0023] Figure 11b The results show the gain simulation of the electrically small antenna provided in Example 2 of this application in the frequency range of 20MHz to 2GHz, with and without a matching network, as well as the gain improvement value of the matching network on the electrically small antenna.

[0024] Figure 12a These are the simulation results of the reflection coefficient of the electrically small antenna provided in Example 3 of this application in the frequency range of 20MHz to 2GHz, respectively without and after passing through a matching network;

[0025] Figure 12bThese are the gain simulation results of the electrically small antenna provided in Example 3 of this application in the frequency range of 20MHz to 2GHz, with and without a matching network, and the gain improvement value of the matching network on the electrically small antenna.

[0026] Figure label:

[0027] 1-Electrically small antenna, 2-Electrically small antenna broadband matching circuit, 20-Field effect transistor, 21-First bias module, 210-First resistor, 211-First inductor, 212-First capacitor, 22-Second bias module, 220-Second resistor, 221-Second capacitor, 23-Third bias module, 230-Third resistor, 24-DC power supply module, 25-DC blocking module, 250-Third capacitor, 3-Target port.

[0028] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0029] The prior art involved in this application will be described in detail and analyzed below.

[0030] Electrically small antennas (EMS) are antennas with a maximum geometric dimension less than 0.1λ, where λ is the wavelength of the electromagnetic wave at the operating frequency of the EMS. The small radiation resistance and large reactance of EMS reduce their radiation gain and bandwidth performance. Impedance matching can improve the performance of EMS. Non-Foster circuits can counteract the large reactance of EMS, breaking the limits of gain-bandwidth theory, improving the impedance characteristics of EMS, broadening the antenna's bandwidth, and increasing its gain. This enables the use of EMS in broadband communication systems, reducing the antenna size in communication equipment. However, non-Foster circuits have a complex circuit structure, including multiple transistors, which leads to higher power consumption.

[0031] Therefore, in the face of the problem of high power consumption in the matching circuit of electrically small antennas in the existing technology, the inventors, through creative research, found that in order to reduce the power consumption of the matching circuit of electrically small antennas and improve the impedance characteristics of electrically small antennas, it is necessary to reduce the number of active devices and enable the electrically small antenna to be impedance matched with the transmission line through the matching circuit. Therefore, the inventors propose the following broadband matching circuit for an electrically small antenna, comprising: a field-effect transistor (FET), a DC power supply module, a first bias module, a second bias module, and a third bias module; the drain of the FET is connected to the first terminal of the first bias module and serves as the output terminal of the broadband matching circuit for the electrically small antenna; the source of the FET is connected to the first terminal of the second bias module; the gate of the FET serves as the input terminal of the broadband matching circuit for the electrically small antenna and is connected to the output terminal of the electrically small antenna and the first terminal of the third bias module; the second terminal of the first bias module is connected to the DC power supply module; the second terminals of the second and third bias modules are both grounded; the first, second, and third bias modules are used to DC bias the FET in the ohmic region where the output impedance is a preset value; the FET is used to amplify the signal input to the electrically small antenna and perform impedance matching with the target port, the target port being connected to the output terminal of the broadband matching circuit for the electrically small antenna. Since the first, second, and third bias modules are used to bias the field-effect transistor (FET) in the ohmic region where the output impedance is a preset value, and the DC power supply module is connected to the first bias module, the circuit structure is simple. The FET, biased in the ohmic region, amplifies the signal input to the electrically small antenna. The FET's output impedance is a preset value and it has wideband stability, enabling it to match the impedance of the target port, thereby improving the radiation gain and bandwidth of the electrically small antenna and broadening its radiation bandwidth to a wide frequency band. Besides the DC power supply module, the circuit only has the FET as an active device; the FET, biased in the ohmic region, has low DC power consumption. In summary, the solution in this application features a simple structure for the electrically small antenna broadband matching circuit and reduces the power consumption of the matching circuit.

[0032] The electrically small antenna broadband matching circuit, printed circuit board, active antenna, and device provided in this application aim to solve the above-mentioned technical problems of the prior art. The technical solutions of this application and how they solve the aforementioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0033] Example 1

[0034] Figure 1 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to the first embodiment of this application, as shown below. Figure 1As shown, the broadband matching circuit 2 for the electrically small antenna provided in this embodiment includes: a field-effect transistor 20, a DC power supply module 24, a first bias module 21, a second bias module 22, and a third bias module 23.

[0035] The drain of the field-effect transistor 20 is connected to the first terminal of the first bias module 21 and serves as the output terminal of the electrically small antenna broadband matching circuit 2.

[0036] The source of the field-effect transistor 20 is connected to the first end of the second bias module 22.

[0037] The gate of the field-effect transistor 20 serves as the input terminal of the electrically small antenna broadband matching circuit 2, and is connected to the output terminal of the electrically small antenna 1 and the first terminal of the third bias module 23.

[0038] The second end of the first bias module 21 is connected to the DC power supply module 24.

[0039] The second terminals of both the second bias module 22 and the third bias module are grounded.

[0040] The first bias module 21, the second bias module 22, and the third bias module 23 are used to DC bias the field-effect transistor 20 in the ohmic region where the output impedance is a preset value.

[0041] The field-effect transistor 20 is used to amplify the signal input to the electrically small antenna 1 and to perform impedance matching with the target port 3, which is connected to the output of the electrically small antenna broadband matching circuit 2.

[0042] In this embodiment, the electrically small antenna is used to receive electromagnetic wave signals and can be of various antenna types such as patch antenna, dipole antenna, and monopole antenna.

[0043] The field-effect transistor 20 can be NMOS, HEMT, etc. NMOS is short for N-Metal-Oxide-Semiconductor, and HEMT is short for High Electron Mobility Transistor.

[0044] The DC power module 24 is used to provide power to the field-effect transistor 20.

[0045] The first bias module 21 and the second bias module 22 are used to control the drain voltage, source voltage, and drain current of the field-effect transistor 20, and the third bias module 23 is used to control the gate voltage of the field-effect transistor to DC bias the field-effect transistor 20 in the ohmic region where the output impedance is a preset value, ensuring that the output terminal of the field-effect transistor is impedance matched with the target port. The ohmic region is also called the variable resistance region or the non-saturation region.

[0046] The preset value is the impedance value of the target port; for example, the preset value can be 50 ohms or 75 ohms. By matching the output impedance of the field-effect transistor 20 with the impedance value of the target port, impedance matching is achieved between the electrically small antenna and its broadband matching circuit and the target port, thereby reducing the echo reflection of the output signal. For example, when the output terminal of the electrically small antenna broadband matching circuit is connected to the transmission line, the impedance value of the target port is the impedance value of the transmission line, and the output impedance of the field-effect transistor is matched with the impedance of the transmission line, thereby reducing the echo reflection of the output signal transmitted to the transmission line.

[0047] The first bias module, second bias module, and third bias module are all composed of passive components. The first bias module may include at least one resistor, the second bias module may include at least one resistor, and the third bias module is a purely resistive module that may include at least one resistor. For example, each of the first, second, and third bias modules may consist of one resistor, two resistors in parallel, or two resistors in series. The first bias module 21, second bias module 22, and third bias module 23 are respectively connected to the drain, source, and gate of the field-effect transistor 20. The first bias module is connected to the DC power supply module. The resistance values ​​or equivalent resistance values ​​of the first bias module 21, second bias module 22, and third bias module 23 can be adjusted according to the model of the field-effect transistor 20 and the DC voltage value provided by the DC power supply module 24 to DC bias the field-effect transistor 20 in the ohmic region where the output impedance is a preset value.

[0048] In this embodiment, the gate of the field-effect transistor (FET) serves as the RF input terminal of the broadband matching circuit for the electrically small antenna, and the drain of the FET serves as the RF output terminal of the same circuit. The electrically small antenna 1 receives electromagnetic wave signals and converts these signals into voltage signals, which are then input to the broadband matching circuit 2. Specifically, the electrically small antenna 1 inputs the converted voltage signal to the gate of the FET 20. Here, because the equivalent capacitance of the FET and the equivalent capacitance of the electrically small antenna itself divide the voltage signal converted by the antenna, the voltage signal output by the antenna is not completely input to the FET. However, the FET is DC biased in the ohmic region by the first, second, and third bias modules. Therefore, the FET can amplify the voltage signal and output it from the drain, offsetting the voltage division loss of the antenna itself and thus improving the radiation gain. Simultaneously, the output impedance of the FET has a broadband and stable characteristic, enabling it to match the impedance value of the target port over a wide frequency band, reducing the return reflection of the output signal, and thus broadening the radiation bandwidth of the electrically small antenna. The broadband matching circuit for electrically small antennas provided in this embodiment matches the output impedance of the field-effect transistor with the target port, making it suitable for antennas of various sizes and types, and reducing the limitations and complexity of electrically small antenna design.

[0049] The electrically small antenna broadband matching circuit provided in this embodiment includes a field-effect transistor (FET), a DC power supply module, a first bias module, a second bias module, and a third bias module. The drain of the FET is connected to the first terminal of the first bias module and serves as the output terminal of the electrically small antenna broadband matching circuit. The source of the FET is connected to the first terminal of the second bias module. The gate of the FET serves as the input terminal of the electrically small antenna broadband matching circuit and is connected to the output terminal of the electrically small antenna and the first terminal of the third bias module. The second terminal of the first bias module is connected to the DC power supply module. The second terminals of both the second and third bias modules are grounded. The first, second, and third bias modules are used to DC bias the FET within an ohmic region where the output impedance is a preset value. The FET amplifies the signal input to the electrically small antenna and performs impedance matching with the target port, which is connected to the output terminal of the electrically small antenna broadband matching circuit. Because the first, second, and third bias modules are used to bias the FET within an ohmic region where the output impedance is a preset value, and the DC power supply module is connected to the first bias module, the circuit structure is simple. The field-effect transistor (FET) is biased in the ohmic region, amplifying the signal input to the electrically small antenna. The FET's output impedance is a preset value and exhibits broadband stability, enabling it to match the impedance of the target port. This, in turn, improves the radiation gain and bandwidth of the electrically small antenna, broadening its radiation bandwidth to a wide frequency band. Besides the DC power supply module, the circuit contains only the FET as the active device. The FET, biased in the ohmic region, has low DC power consumption. In summary, this embodiment provides a simple structure for the electrically small antenna broadband matching circuit and reduces its power consumption.

[0050] Example 2

[0051] Figure 2 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to the second embodiment of this application, as shown below. Figure 2 As shown, the broadband matching circuit for the electrically small antenna provided in this embodiment, based on the first embodiment, includes a first bias module 21 with a first resistor 210. The first end of the first resistor 210 is connected to the drain of the field-effect transistor 20, and the second end of the first resistor is connected to the DC power supply module.

[0052] In this embodiment, the first bias module 21 may include a first resistor 210. The first and second terminals of the first resistor 210 are connected to the drain of the field-effect transistor and the DC power supply module, respectively. The first bias module and the second bias module together divide the voltage provided by the DC voltage module. Then, in cooperation with the third bias module, the field-effect transistor is DC biased in the ohmic region. The resistance value of the first resistor 210 can be adjusted according to the electrical parameters of the field-effect transistor, such as the operating voltage range and operating current in the ohmic region, the output voltage of the DC power supply module, the resistance value of the second bias module, and the resistance value of the third bias module, thereby biasing the field-effect transistor in the ohmic region and ensuring that the output impedance of the field-effect transistor is a preset value.

[0053] The broadband matching circuit for the electrically small antenna provided in this embodiment includes a first resistor 210 in the first bias module 21. The first end of the first resistor 210 is connected to the drain of the field-effect transistor 20, and the second end of the first resistor is connected to the DC power supply module. Since the first resistor can cooperate with the second bias module and the third bias module to divide the voltage provided by the DC power supply module, and the resistance value of the first resistor can be adjusted, the first bias module can DC bias the field-effect transistor in the ohmic region where the output impedance is a preset value.

[0054] As an optional implementation method, Figure 3 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to an embodiment of this application, such as... Figure 3 As shown, based on Embodiment 2, the first bias module 21 further includes a first inductor 211. The first end of the first inductor 211 is connected to the drain of the field-effect transistor 20; the second end of the first inductor 211 is connected to the first end of the first resistor 210, so that the first end of the first resistor 210 is connected to the drain of the field-effect transistor 20 through the first inductor 211.

[0055] In this embodiment, the first inductor 211 can be connected in series with the first resistor 210 to form the first bias module 21. Since the current in the inductor cannot change abruptly, the first inductor 211 can stabilize the current of the input field-effect transistor, thereby filtering out the AC signal that may exist in the DC power supply module and avoiding the AC signal in the DC power supply module from interfering with the output signal of the broadband matching circuit of the small electric antenna. At the same time, it can prevent the AC signal from changing the bias of the field-effect transistor, so as to ensure that the first bias circuit, the second bias circuit and the third bias circuit can provide a stable bias voltage for the field-effect transistor, thereby ensuring that the output impedance of the field-effect transistor is stable at a preset value.

[0056] As an alternative implementation, the first inductor 211 can also be located between the first resistor 210 and the DC power module 24. The first end of the first inductor 211 can be connected to the second end of the first resistor 210, and the second end of the first inductor 211 can be connected to the DC power module.

[0057] The electrically small antenna broadband matching circuit provided in this embodiment further includes, through the first bias module, a first inductor, the first end of which is connected to the drain of the field-effect transistor; the second end of the first inductor is connected to the first end of the first resistor, so that the first end of the first resistor is connected to the drain of the field-effect transistor 20 through the first inductor; since the first inductor can filter out AC signals, it can avoid interference of AC signals to the output signal of the electrically small antenna broadband matching circuit, and ensure that the output impedance of the field-effect transistor is stable at a preset value.

[0058] As an optional implementation method, Figure 4 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to an embodiment of this application, such as... Figure 4 As shown, based on Embodiment 2, the first bias module 21 further includes a first capacitor 212. The first terminal of the first capacitor 212 is connected to the second terminal of the first resistor 210 and the DC power supply module, and the second terminal of the first capacitor 212 is grounded.

[0059] In this embodiment, the two ends of the first capacitor 212 are connected to the DC power supply module and ground respectively. Since the impedance of the capacitor to high-frequency signals is smaller than that of the resistor to high-frequency signals, the first capacitor 212 can provide an AC shunt for the AC signals that may exist in the DC power supply module, thereby filtering out the AC signals and preventing the AC signals from interfering with the output signal of the broadband matching circuit of the small antenna. At the same time, it can prevent the AC signals from changing the bias of the field-effect transistor, so as to ensure that the output impedance of the field-effect transistor is stable at a preset value.

[0060] The electrically small antenna broadband matching circuit provided in this embodiment further includes a first capacitor through the first bias module. The first end of the first capacitor is connected to the second end of the first resistor and the DC power supply module, and the second end of the first capacitor is grounded. Since the first capacitor can filter out the AC signal in the DC power supply module, it can avoid the interference of AC signal on the output signal of the electrically small antenna broadband matching circuit and ensure that the output impedance of the field-effect transistor is stable at a preset value.

[0061] As an optional implementation method, Figure 5 This is a schematic diagram of a broadband matching circuit structure for an electrically small antenna according to an embodiment of this application, such as... Figure 5As shown, as an optional implementation, based on any of the above embodiments, the first bias module 21 may include: a first resistor 210, a first inductor 211, and a first capacitor 212. The first end of the first inductor 211 is connected to the drain of the field-effect transistor 20; the second end of the first inductor 211 is connected to the first end of the first resistor 210, so that the first end of the first resistor 210 is connected to the drain of the field-effect transistor 20 through the first inductor 211; the first end of the first capacitor 212 is connected to the second end of the first resistor 210 and the DC power supply module 24; and the second end of the first capacitor is grounded.

[0062] In this embodiment, since capacitors have the characteristic of blocking DC and passing AC, and the higher the AC frequency, the easier it is for AC to pass through; and inductors have the characteristic of blocking AC and passing DC, and the higher the AC frequency, the less likely it is for AC to pass through, the first inductor and the first resistor are connected in series and located between the DC power supply module and the field-effect transistor. This can isolate the AC signal from the DC power supply module. At the same time, the two ends of the first capacitor are connected to the DC power supply module and ground, which can further filter out the AC signal from the DC power supply module. The combined effect of the first inductor and the first capacitor can further ensure the stability of the output impedance value of the field-effect transistor and avoid the interference of AC signals on the output signal of the electrically small antenna broadband matching circuit, so as to ensure that the electrically small antenna broadband matching circuit can stably amplify and extend the output signal of the electrically small antenna to a wide bandwidth.

[0063] Example 3

[0064] Figure 6 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to the third embodiment of this application, as shown below. Figure 6 As shown, the broadband matching circuit for the electrically small antenna provided in this embodiment, based on any of the above embodiments, includes a second bias module 22 comprising: a second resistor 220 and a second capacitor 221. The first end of the second resistor 220 is connected to the source of the field-effect transistor 20, and the second end of the second resistor 220 is grounded; the first end of the second capacitor 221 is connected to both the first end of the second resistor 220 and the source of the field-effect transistor 20, and the second end of the second capacitor 221 is connected to the second end of the second resistor 220 and grounded.

[0065] In this embodiment, the second resistor 220, the first bias module 21 and the third bias module 23 together bias the field-effect transistor 20 in the ohmic region where the output impedance is a preset value.

[0066] The second terminal 23 of the third bias module is grounded, the second terminal of the second resistor 220 is grounded, and the first terminal of the second resistor 220 is connected to the source of the field-effect transistor 20. This allows the field-effect transistor 20 to be stably biased in the ohmic region, providing a stable static operating point for the field-effect transistor 20. Consequently, the signal input to the broadband matching circuit of the electrically small antenna 1 can be stably amplified by the field-effect transistor 20.

[0067] The second capacitor 221 is connected in parallel with the second resistor 220, and does not affect the DC bias state of the field-effect transistor. At the same time, the second capacitor 221 can provide an AC path for the AC signal input to the broadband matching circuit of the electrically small antenna, avoiding the negative feedback effect of the second resistor 220 on the AC signal input to the broadband matching circuit of the electrically small antenna, so as to ensure that the signal does not attenuate, and thus ensure the AC gain of the field-effect transistor.

[0068] The electrically small antenna broadband matching circuit provided in this embodiment includes a second resistor 220 and a second capacitor 221 via a second bias module 22. The first end of the second resistor 220 is connected to the source of the field-effect transistor 20, and the second end of the second resistor 220 is grounded. The first end of the second capacitor 221 is connected to both the first end of the second resistor 220 and the source of the field-effect transistor 20, and the second end of the second capacitor 221 is connected to the second end of the second resistor 220 and grounded. Since the second capacitor does not affect the DC bias of the field-effect transistor and can provide an AC path for the AC signal input to the electrically small antenna broadband matching circuit, it ensures the AC gain of the field-effect transistor on the AC signal input to the electrically small antenna broadband matching circuit. Consequently, it ensures that the electrically small antenna broadband matching circuit can improve the radiation gain of the electrically small antenna.

[0069] Example 4

[0070] Figure 7 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to the fourth embodiment of this application, as shown below. Figure 7 As shown, the broadband matching circuit for the electrically small antenna provided in this embodiment, based on any of the above embodiments, includes a third bias module 23 comprising a third resistor 230. The first terminal of the third resistor 230 is connected to the gate of the field-effect transistor 20, and the second terminal of the third resistor 230 is grounded.

[0071] In this embodiment, the third bias module 23 may include a third resistor 230.

[0072] The first terminal of the third resistor 230 is connected to the gate of the field-effect transistor (FET), and the second terminal of the third resistor 230 is grounded to control the gate voltage of the FET and provide a stable static operating point for the FET. The resistance value of the third resistor 230 can be adjusted according to the resistance values ​​of the first bias module 21, the second bias module 22, and the voltage value of the DC power supply module 24. When the third bias module 23 only includes the third resistor 230, the circuit structure is simple and easy to integrate and miniaturize.

[0073] The electrically small antenna broadband matching circuit provided in this embodiment includes a third resistor 230 through the third bias module 23; the first end of the third resistor 230 is connected to the gate of the field-effect transistor 20, and the second end of the third resistor 230 is grounded; since the third bias resistor can control the gate voltage of the field-effect transistor, and there is only one resistor, the electrically small antenna broadband matching circuit of this application is easy to integrate and miniaturize.

[0074] Example 5

[0075] Figure 8 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to the fifth embodiment of this application, as shown below. Figure 8 As shown, the electrically small antenna broadband matching circuit provided in this embodiment, based on any of the above embodiments, further includes a DC blocking module 25. The first end of the DC blocking module 25 is connected to the drain of the field-effect transistor 20, and the second end of the DC blocking module 25 serves as the output end of the electrically small antenna broadband matching circuit 2.

[0076] In this embodiment, the DC blocking module can be composed of a third capacitor 250. The third capacitor 250 is used to isolate the DC power supply module from the interference of the broadband matching circuit output signal of the electrically small antenna. At the same time, the third capacitor 250 and the input impedance of the target port together form a filter circuit. The capacitance value of the third capacitor 250 can be adjusted according to the signal frequency of the electrically small antenna input to the broadband matching circuit of the electrically small antenna and the input impedance value of the target port to ensure that the energy of the radio frequency signal output from the drain of the field effect transistor is transmitted to the maximum extent.

[0077] The electrically small antenna broadband matching circuit provided in this embodiment also includes a DC blocking module. The first end of the DC blocking module is connected to the drain of the field-effect transistor, and the second end of the DC blocking module serves as the output end of the electrically small antenna broadband matching circuit. Since the DC blocking module can match the input impedance of the target port, the energy of the radio frequency signal output from the drain of the field-effect transistor is transmitted to the maximum extent, and interference signals of other frequencies are filtered out. Therefore, the radiation gain of the electrically small antenna can be further guaranteed.

[0078] As an optional implementation method, Figure 9 This is a schematic diagram of the broadband matching circuit structure of the electrically small antenna according to an embodiment of this application, such as... Figure 9 As shown, based on Embodiment 5, the broadband matching circuit for the electrically small antenna includes a field-effect transistor 20, a first bias module 21, a second bias module 22, a third bias module 23, a DC power supply module 24, and a DC blocking module 25. The gate of the field-effect transistor 20 is connected to the electrically small antenna 1.

[0079] The first bias module 21 consists of a first resistor 210, a first inductor 211, and a first capacitor 212. The first end of the first inductor 211 is connected to the drain of the field-effect transistor. The second end of the first inductor 211 is connected to the first end of the first resistor 210. The second end of the first resistor 210 is connected to the first end of the first capacitor 212 and the DC power supply module 24. The second end of the first capacitor 212 is grounded.

[0080] The second bias module 22 consists of a second resistor 220 and a second capacitor 221. The first end of the second resistor 220 is connected to the source of the field-effect transistor and the first end of the second capacitor 221. The second end of the second resistor 220 is connected to the second end of the second capacitor 221 and grounded.

[0081] The third bias module 23 consists of a third resistor 230, and the first end of the third capacitor is connected to the gate of the field-effect transistor.

[0082] The DC blocking module 25 consists of a third capacitor 250. The first end of the third capacitor 250 is connected to the drain of the field-effect transistor, and the second end of the third capacitor 250 is connected to the target port 3.

[0083] The electrically small antenna broadband matching circuit provided in this embodiment has a simple structure, including a DC power supply module, a first bias module, a second bias module, a third bias module, and a DC blocking module. It is easy to integrate and miniaturize, allowing a broadband electrically small antenna to be implemented using only a single circuit board. Furthermore, it can simultaneously cover a wide frequency band.

[0084] The following examples illustrate the gain of the electrically small antenna after connecting it to the broadband matching circuit of this application, and the gain improvement of the electrically small antenna output signal by the broadband matching circuit of this application. In the following examples, the drain of the field-effect transistor in the broadband matching circuit of the electrically small antenna is connected to a 50-ohm transmission line through a DC blocking module. That is, the input impedance of the target port is the transmission line impedance, which is 50 ohms.

[0085] Example 1

[0086] This example uses a microstrip antenna with a radiating patch size of 2mm × 1.6mm. The dielectric parameters of the microstrip antenna are: dielectric constant ε r =4.4, loss tangent Δ = 0.02. Adjust the bias circuit to make the drain-source voltage V of the field-effect transistor... DS=0.34V, drain current is I D =13.3mA, output impedance is approximately 50 ohms.

[0087] For ease of description, the broadband matching circuit for the electrically small antenna provided in this application will be referred to as the matching network in the following text.

[0088] Figure 10a The simulation results of the reflection coefficient of the electrically small antenna provided in Example 1 of this application are shown in the frequency range of 20MHz to 2GHz, with and without a matching network.

[0089] Figure 10b The simulation results of the gain of the electrically small antenna provided in Example 1 of this application in the frequency range of 20MHz to 2GHz are shown, with and without a matching network, as well as the gain improvement value of the matching network on the electrically small antenna.

[0090] The reflection coefficient, also known as the reflection parameter, is obtained by modeling and simulating the gain of the electrically small antenna in the simulation software HFSS. The reflection coefficient and gain of the electrically small antenna after passing through the matching network are obtained by simulating the gain of the electrically small antenna after passing through the matching network in the simulation software Microwave Office. The gain improvement value is obtained by subtracting the gain of the electrically small antenna itself from the gain of the electrically small antenna after passing through the matching network.

[0091] Figure 10a In the frequency range of 20MHz to 2GHz, the reflection parameter of the pre-matched small antenna is about 0dB, and the reflection parameter after matching is less than -10dB.

[0092] Figure 10b In the frequency range of 20MHz to 2GHz, the gain of the electrically small antenna itself is -120dB to -35dB; the gain of the electrically small antenna after passing through the matching network is -50dB to -10dB, and the gain improvement is 70dB to 25dB.

[0093] from Figure 10a and Figure 10b As can be seen from the example, the electrical small antenna in Example 1 has reduced reflection parameters and significantly improved gain after passing through the matching network, indicating that the broadband matching circuit for the electrical small antenna provided in this application has good working performance.

[0094] Example 2

[0095] This example uses a dipole antenna with a total length of 30mm. The bias circuit is adjusted to make the drain-source voltage V of the field-effect transistor... DS =0.5V, drain current is I D =11.4mA, output impedance is approximately 50 ohms.

[0096] Figure 11aThe simulation results of the reflection coefficient of the electrically small antenna provided in Example 2 of this application are shown in the frequency range of 20MHz to 2GHz, with and without a matching network.

[0097] Figure 11b The simulation results of the gain of the electrically small antenna provided in Example 2 of this application in the frequency range of 20MHz to 2GHz are shown, with and without a matching network, and the gain improvement value of the matching network on the electrically small antenna is also shown.

[0098] Figure 11a In the frequency range of 20MHz to 2GHz, the reflection parameter of the pre-matched small antenna is about 0dB, and the reflection parameter after matching is less than -10dB.

[0099] Figure 11b In the frequency range of 20MHz to 2GHz, the gain of the electrically small antenna itself is -100dB to -20dB; the gain of the electrically small antenna after passing through the matching network is from 0dB to 0dB, and the gain improvement value is from 100dB to 20dB.

[0100] from Figure 11a and Figure 11b As can be seen from the example, the electrical small antenna in Example 2 has reduced reflection parameters and significantly improved gain after passing through the matching network, indicating that the broadband matching circuit for the electrical small antenna provided in this application has good working performance.

[0101] Example 3

[0102] This example uses a dipole antenna with a total length of 3mm. The bias circuit is adjusted to make the drain-source voltage V of the field-effect transistor... DS =0.77V, drain current is I D =9.37mA, output impedance is approximately 50 ohms.

[0103] Figure 12a The simulation results of the reflection coefficient of the electrically small antenna provided in Example 3 of this application are shown in the frequency range of 20MHz to 2GHz, with and without a matching network.

[0104] Figure 12b The simulation results of the gain of the electrically small antenna provided in Example 3 of this application in the frequency range of 20MHz to 2GHz are shown, respectively without and with a matching network, as well as the gain improvement value of the electrically small antenna by the matching network.

[0105] Figure 12a In the frequency range of 20MHz to 2GHz, the reflection parameter of the pre-matched small antenna is about 0dB, and the reflection parameter after matching is less than -10dB.

[0106] Figure 12bIn the frequency range of 20MHz to 2GHz, the gain of the electrically small antenna itself is -100dB to -20dB; the gain of the electrically small antenna after passing through the matching network is -10dB to -10dB, and the gain improvement value is 90dB to 10dB.

[0107] from Figure 12a and Figure 12b As can be seen from the example, the reflection parameters of the electrically small antenna in Example 3 are reduced and the gain is significantly improved after passing through the matching network, indicating that the broadband matching circuit for the electrically small antenna provided in this application has good working performance.

[0108] Embodiments of this application also provide a printed circuit board, which includes a broadband matching circuit for an electrically small antenna as provided in any one of embodiments one through five.

[0109] Embodiments of this application also provide an active antenna, which includes an electrically small antenna and an electrically small antenna broadband matching circuit as provided in any of embodiments one to five. The active antenna is connected to the gate of the field-effect transistor in the electrically small antenna broadband matching circuit.

[0110] Embodiments of this application also provide an electronic device including the aforementioned active antenna, which is used to receive electromagnetic wave signals. The active antenna reduces the space occupied by the antenna within the electronic device. With reduced antenna space, the electronic device has more usable space to accommodate more components and achieve more functions. Alternatively, reduced antenna space allows for a smaller size of the electronic device, making it more portable.

[0111] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0112] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A broadband matching circuit for a small electrically conductive antenna, characterized in that, include: Field-effect transistor, DC power supply module, first bias module, second bias module, third bias module; The drain of the field-effect transistor is connected to the first terminal of the first bias module and serves as the output terminal of the broadband matching circuit of the electrically small antenna. The source of the field-effect transistor is connected to the first terminal of the second bias module; The gate of the field-effect transistor serves as the input terminal of the broadband matching circuit of the electrically small antenna, and is connected to the output terminal of the electrically small antenna and the first terminal of the third bias module. The second terminal of the first bias module is connected to the DC power supply module; The second terminals of both the second bias module and the third bias module are grounded; The first bias module, the second bias module, and the third bias module are used to DC bias the field-effect transistor in the ohmic region where the output impedance is a preset value. A field-effect transistor is used to amplify the signal input to the electrically small antenna and perform impedance matching with the target port, which is connected to the output of the electrically small antenna broadband matching circuit.

2. The broadband matching circuit for a small electrically conductive antenna according to claim 1, characterized in that, The first bias module includes: a first resistor; The first end of the first resistor is connected to the drain of the field-effect transistor, and the second end of the first resistor is connected to the DC power supply module.

3. The broadband matching circuit for a small electrically conductive antenna according to claim 2, characterized in that, The first bias module further includes: a first inductor; The first terminal of the first inductor is connected to the drain of the field-effect transistor; The second end of the first inductor is connected to the first end of the first resistor, so that the first end of the first resistor is connected to the drain of the field-effect transistor through the first inductor.

4. The broadband matching circuit for a small electrically conductive antenna according to claim 2, characterized in that, The first bias module further includes: a first capacitor; The first terminal of the first capacitor is connected to the second terminal of the first resistor and the DC power supply module, and the second terminal of the first capacitor is grounded.

5. The broadband matching circuit for a small electrically conductive antenna according to claim 1, characterized in that, The second bias module includes: a second resistor and a second capacitor; The first terminal of the second resistor is connected to the source of the field-effect transistor, and the second terminal of the second resistor is grounded. The first terminal of the second capacitor is connected to the first terminal of the second resistor and the source of the field-effect transistor, and the second terminal of the second capacitor is connected to the second terminal of the second resistor and grounded.

6. The broadband matching circuit for a small electrically conductive antenna according to claim 1, characterized in that, The third bias module includes a third resistor, the first end of which is connected to the gate of the field-effect transistor, and the second end of which is grounded.

7. The broadband matching circuit for a small electrically conductive antenna according to claim 1, characterized in that, Also includes: The DC blocking module has its first end connected to the drain of the field-effect transistor, and its second end serves as the output of the broadband matching circuit for the electrically small antenna.

8. A printed circuit board, characterized in that, Includes the broadband matching circuit for the electrically small antenna as described in any one of claims 1-7.

9. An active antenna, characterized in that, Includes electrically small antennas and the electrically small antenna broadband matching circuit as described in any one of claims 1-7.

10. An electronic device, characterized in that, Including the active antenna as described in claim 9.

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