CN215646757U - Design circuit convenient to antenna matching - Google Patents
Design circuit convenient to antenna matching Download PDFInfo
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- CN215646757U CN215646757U CN202121695636.4U CN202121695636U CN215646757U CN 215646757 U CN215646757 U CN 215646757U CN 202121695636 U CN202121695636 U CN 202121695636U CN 215646757 U CN215646757 U CN 215646757U
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Abstract
The utility model discloses a design circuit convenient for antenna matching, which is characterized by comprising a filter circuit A1, wherein the filter circuit A1 is connected with a matching circuit A2, and the capacitance of the matching circuit A2 is adjustable; the matching circuit A2 is respectively connected with an antenna circuit A3, a first voltage division circuit A4 and a second voltage division circuit A5; the matching circuit is provided with a capacitor for coarse tuning and a capacitor for fine tuning. According to the utility model, the antenna parameters are measured through the antenna test points, the main circuit capacitance in the matching circuit is roughly adjusted, and then the parallel capacitance is finely adjusted again through the matched test points, so that an excellent antenna matching scheme is obtained, and the antenna emission performance is improved.
Description
Technical Field
The utility model relates to the field of antennas, in particular to a design circuit convenient for antenna matching.
Background
With the development and progress of science and technology, communication technology has been rapidly developed and advanced, the popularization of intelligent electronic products has been improved to an unprecedented level, more and more intelligent terminals or electronic devices become an indispensable part of people's lives, such as smart phones, smart televisions, computers and the like, and the interconnection of everything based on the intelligent electronic devices also becomes a new trend. The universal interconnection is understood to mean that direct communication connection can be realized between objects, and in current products, communication connection between two objects is realized through antennas respectively configured on the two objects. Impedance matching is a common operating condition in radio communication technology that reflects the power transfer relationship between the input circuit and the output circuit. When the circuit achieves impedance matching, maximum power transfer will be achieved. Conversely, when the circuit impedance is mismatched, not only is maximum power transfer not achieved, but damage may also occur to the circuit.
The single-ended NFC antenna matching circuit disclosed in chinese patent document has publication No. CN212725599U and publication date 2021-03-16, and includes a PCB board, a chip mounted on the PCB board, and an NFC antenna; a receiving circuit connected to the chip; the low-pass filter circuit and the matching circuit are connected with the chip; two ends of the matching circuit are respectively connected with the low-pass filter circuit and the NFC antenna; the circuit consists of a first capacitor, a second capacitor and a resistor; the first capacitor and the resistor are connected in series in the circuit, and the second capacitor is connected in parallel in the circuit; the first capacitor, the second capacitor and the resistor are matched and connected with each other to form a single-end matching circuit. When the matching value is debugged, only 2 capacitance values and resistance values are needed to be debugged, so that the circuit and parts in the circuit are simplified, and the cost and the debugging difficulty are reduced. However, the circuit cannot rapidly obtain the optimal parameters of antenna matching on the basis of improving the debugging rate, and cannot enable the antenna matching to reach or approach the optimal scheme.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the problems that an antenna matching circuit cannot quickly obtain an antenna matching scheme and matching parameters cannot approach to optimal parameters in the prior art, and provides a design circuit convenient for antenna matching.
In order to achieve the purpose, the utility model adopts the following technical scheme:
a design circuit for facilitating antenna matching comprises a filter circuit A1, wherein the filter circuit A1 is connected with a matching circuit A2, and the capacitance of the matching circuit A2 is adjustable; the matching circuit a2 is connected to the antenna circuit A3, the first voltage-dividing circuit a4, and the second voltage-dividing circuit a5, respectively.
In the utility model, to match the antenna, firstly, various parameters and resonant frequency of the antenna to be matched are measured; then calculating parameters of each matching capacitor in the matching circuit according to the measured antenna parameters; firstly, a coarse tuning capacitor in a matching circuit is connected, the antenna matching is coarsely tuned, then the fine tuning capacitor is adjusted and combined according to a Smith adjusting circle, and the whole matching circuit is adjusted according to the actual function requirement; and finally, obtaining an innate matching scheme close to the optimal parameters.
Preferably, the filter circuit a1 includes an interface P1, a first test terminal of the interface P1 is connected to one end of an inductor L1 and connected to a first rf output terminal, and the other end of the inductor L1 is connected to one end of a capacitor C5; the second test end of the interface P1 is connected with one end of an inductor L2 and is connected with a second radio frequency output end, and the other end of the inductor L2 is connected with one end of a capacitor C8; the other end of the capacitor C5 and the other end of the capacitor C8 are connected to ground.
The filter circuit can screen wave bands and signals with different frequencies, achieves the purpose of filtering noise signals in the circuit by setting parameters of capacitance and inductance in the filter circuit, and can filter out second harmonic waves to enable antenna matching parameters in the circuit to be more accurate. The interface P1 included in the filter circuit is used to test the actual impedance of the entire circuit after matching is complete.
Preferably, the matching circuit a2 includes a capacitor C4, one end of the capacitor C4 is connected to one end of the capacitor C2 and to one end of the capacitor C5, and the other end of the capacitor C4, the other end of the capacitor C2, one end of the capacitor C6 and one end of the capacitor C7 are connected; the other end of the capacitor C6, the other end of the capacitor C7, the other end of the capacitor C9 and the other end of the capacitor C10 are connected with one another and grounded; one end of the capacitor C9, one end of the capacitor C10, the other end of the capacitor C11 and the other end of the capacitor C12 are connected; one end of the capacitor C11 is connected with one end of the capacitor C12 and is connected with one end of the capacitor C8.
The matching circuit is the key point of the whole design circuit, and four parts are used for matching the antenna impedance. The first part is a capacitor C2 and a capacitor C4 which are connected in parallel; the second part is a capacitor C6 and a capacitor C7 which are connected in parallel; the third part is a capacitor C9 and a capacitor C10 which are connected in parallel; the fourth part is a capacitor C11 and a capacitor C12 connected in parallel. Each section has a coarse tuning capacitor and a fine tuning capacitor for obtaining a more accurate and closer match scheme to the optimal parameters.
Preferably, the antenna circuit a3 includes an interface P2, the first test end of the interface P2 is connected to one end of a resistor R1 and the second antenna interface, and the other end of the resistor R1 is connected to one end of a capacitor C7; the second test end of the interface P2 is connected with one end of a resistor R2 and the first antenna interface, and the other end of the resistor R2 is connected with one end of a capacitor C10.
The interface P2 is an antenna test point for connecting the antenna to be matched to test various parameters, and the resistor R1 and the resistor R2 are connected with the antenna in series and used for setting the quality factor of the antenna in the antenna circuit.
Preferably, the first voltage divider circuit a4 includes a capacitor C3, one end of the capacitor C3 is connected to one end of a capacitor C6, the other end of the capacitor C3 is connected to one end of a capacitor C1, the other end of the capacitor C1 is grounded, and one end of the capacitor C1 is connected to the first rf input terminal.
Preferably, the second voltage divider circuit a5 includes a capacitor C13, one end of the capacitor C13 is connected to one end of a capacitor C9, the other end of the capacitor C13 is connected to one end of a capacitor C14, the other end of the capacitor C14 is grounded, and one end of the capacitor C14 is connected to the second rf input terminal.
The utility model is designed with the first voltage division circuit and the second voltage division circuit, which can reduce the receiving energy on the receiving end of the circuit, divide the energy pressure and protect the circuit in the normal working range.
Preferably, in the matching circuit a2, the capacitor C2, the capacitor C4, the capacitor C6, the capacitor C7, the capacitor C9, the capacitor C10, the capacitor C11, and the capacitor C12 are impedance matching capacitors, and the capacitors are detachable and replaceable.
In the utility model, the capacitor C2, the capacitor C12, the capacitor C7 and the capacitor C10 are fine tuning capacitors, the capacitor C4, the capacitor C6, the capacitor C11 and the capacitor C9 are coarse tuning capacitors, and the circuits are not fixedly connected in the circuit and can be freely detached and replaced by capacitors with different capacitance values, thereby achieving the purpose of coarse tuning and fine tuning the matching circuit.
The utility model has the following beneficial effects: antenna parameters are measured through the antenna test points, the main circuit capacitance in the matching circuit is roughly adjusted, and then the parallel capacitance is finely adjusted again through the matched test points, so that an excellent antenna matching scheme is obtained, and the antenna emission performance is improved; a coarse tuning capacitor and a fine tuning capacitor are arranged, and the parameter precision of antenna matching is improved through secondary adjustment, so that the matching result is closer to the optimal parameter; the matching circuit is adjustable, and is connected with the circuit through the detachable capacitors with different capacitance values, so that the efficiency of the antenna in the impedance matching process is improved.
Drawings
FIG. 1 is a circuit schematic of a design circuit of the present invention;
FIG. 2 is a test chart after coarse tuning according to an embodiment of the present invention;
FIG. 3 is a test chart after trimming according to an embodiment of the present invention.
Detailed Description
The utility model is further described with reference to the following detailed description and accompanying drawings.
As shown in fig. 1, a design circuit for facilitating antenna matching includes a filter circuit a1, the filter circuit a1 is connected to a matching circuit a2, and the capacitance of the matching circuit a2 is adjustable; the matching circuit a2 is connected to the antenna circuit A3, the first voltage-dividing circuit a4, and the second voltage-dividing circuit a5, respectively.
The filter circuit A1 comprises an interface P1, a first test end of the interface P1 is connected with one end of an inductor L1 and is connected with a first radio frequency output end RFO1, and the other end of the inductor L1 is connected with one end of a capacitor C5; the second test end of the interface P1 is connected to one end of the inductor L2 and connected to the second rf output terminal RFO2, and the other end of the inductor L2 is connected to one end of the capacitor C8; the other end of the capacitor C5 and the other end of the capacitor C8 are connected to ground.
The matching circuit A2 comprises a capacitor C4, one end of a capacitor C4 is connected with one end of the capacitor C2 and is connected with one end of a capacitor C5, and the other end of a capacitor C4, the other end of a capacitor C2, one end of a capacitor C6 and one end of the capacitor C7 are connected; the other end of the capacitor C6, the other end of the capacitor C7, the other end of the capacitor C9 and the other end of the capacitor C10 are connected with the ground; one end of the capacitor C9, one end of the capacitor C10, the other end of the capacitor C11 and the other end of the capacitor C12 are connected; one end of the capacitor C11 is connected to one end of the capacitor C12 and to one end of the capacitor C8.
The antenna circuit A3 comprises an interface P2, wherein a first test end of the interface P2 is connected with one end of a resistor R1 and one end of a second antenna interface ATX2, and the other end of the resistor R1 is connected with one end of a capacitor C7; the second test end of the interface P2 is connected with one end of the resistor R2 and the first antenna interface ATX1, and the other end of the resistor R2 is connected with one end of the capacitor C10.
The first voltage division circuit a4 includes a capacitor C3, one end of the capacitor C3 is connected to one end of the capacitor C6, the other end of the capacitor C3 is connected to one end of the capacitor C1, the other end of the capacitor C1 is grounded, and one end of the capacitor C1 is connected to the first rf input RFI 1.
The second voltage division circuit a5 includes a capacitor C13, one end of the capacitor C13 is connected to one end of the capacitor C9, the other end of the capacitor C13 is connected to one end of the capacitor C14, the other end of the capacitor C14 is grounded, and one end of the capacitor C14 is connected to the second rf input RFI 2.
In the matching circuit a2, the capacitor C2, the capacitor C4, the capacitor C6, the capacitor C7, the capacitor C9, the capacitor C10, the capacitor C11, and the capacitor C12 are capacitors for impedance matching, and all the capacitors can be removed and replaced in capacitance.
In the utility model, to match the antenna, firstly, various parameters and resonant frequency of the antenna to be matched are measured; then calculating parameters of each matching capacitor in the matching circuit according to the measured antenna parameters; firstly, a coarse tuning capacitor in a matching circuit is connected, the antenna matching is coarsely tuned, then the fine tuning capacitor is adjusted and combined according to a Smith adjusting circle, and the whole matching circuit is adjusted according to the actual function requirement; and finally, obtaining an innate matching scheme close to the optimal parameters.
The filter circuit can screen wave bands and signals with different frequencies, achieves the purpose of filtering noise signals in the circuit by setting parameters of capacitance and inductance in the filter circuit, and can filter out second harmonic waves to enable antenna matching parameters in the circuit to be more accurate. The interface P1 included in the filter circuit is used to test the actual impedance of the entire circuit after matching is complete.
The matching circuit is the key point of the whole design circuit, and four parts are used for matching the antenna impedance. The first part is a capacitor C2 and a capacitor C4 which are connected in parallel; the second part is a capacitor C6 and a capacitor C7 which are connected in parallel; the third part is a capacitor C9 and a capacitor C10 which are connected in parallel; the fourth part is a capacitor C11 and a capacitor C12 connected in parallel. Each part is provided with a coarse tuning capacitor and a fine tuning capacitor for obtaining a matching scheme which is more accurate and closer to the optimal parameter, the perfect matching capacitor with the optimal parameter value is 146 picofarads as an example, the actual capacitor element does not have a capacitor with 146 picofarads, therefore, a capacitor with 140 picofarads is selected as the coarse tuning capacitor, and the fine tuning replacement is carried out by selecting a capacitor with 20 picofarads in parallel.
The interface P2 is an antenna test point for connecting the antenna to be matched to test various parameters, and the resistor R1 and the resistor R2 are connected with the antenna in series and used for setting the quality factor of the antenna in the antenna circuit.
The utility model is designed with the first voltage division circuit and the second voltage division circuit, which can reduce the receiving energy on the receiving end of the circuit, divide the energy pressure and protect the circuit in the normal working range.
In the utility model, the capacitor C2, the capacitor C12, the capacitor C7 and the capacitor C10 are fine tuning capacitors, the capacitor C4, the capacitor C6, the capacitor C11 and the capacitor C9 are coarse tuning capacitors, and the circuits are not fixedly connected in the circuit and can be freely detached and replaced by capacitors with different capacitance values, thereby achieving the purpose of coarse tuning and fine tuning the matching circuit.
The specific debugging process of the antenna matching in the embodiment of the utility model is as follows, firstly, the NFC antenna to be matched is connected through the interface P2, and the parameters of the antenna are measured. Connecting an antenna by using a network analyzer, and setting the measurement frequency between 1MHz and 200 MHz; testing to obtain the series equivalent resistance and the series equivalent inductance of the antenna under the frequency of 1MHz, wherein the series equivalent resistance is 994 megaohms, and the series equivalent inductance is 1418 nanohenries; the antenna was then tested for resonant frequency and parallel equivalent resistance at resonant frequency, where resonant frequency was 38.81MHz and parallel equivalent resistance was 7541 ohms.
On the basis of obtaining required antenna parameters, calculating a calculated value of a required matched capacitor, selecting a parallel calculated capacitance value of a coarse tuning capacitor C4 and a fine tuning capacitor C2 as 114 picofarads, a parallel calculated capacitance value of a coarse tuning capacitor C11 and a fine tuning capacitor C12 as 114 picofarads, a parallel calculated capacitance value of a coarse tuning capacitor C6 and a fine tuning capacitor C7 as 74 picofarads, a parallel calculated capacitance value of a coarse tuning capacitor C9 and a fine tuning capacitor C10 as 74 picofarads, selecting a proper coarse tuning capacitor according to the calculated capacitance value to connect into a matching circuit to carry out coarse tuning of antenna matching, wherein the coarse tuning result is shown in fig. 2, a dotted line in fig. 2 shows standing wave ratios under different frequency conditions after coarse tuning, and a solid line shows a motion track in a scanning frequency range after coarse tuning. The circled points in circle 1 represent the matching points in the current situation after coarse adjustment, and the circled points in circle 2 represent the best matching points in the ideal situation.
On the basis of the test result obtained by coarse adjustment, the matching result is finely adjusted according to the adjustment rule of the Smith adjustment circle, fine adjustment capacitors C2, C12, C7 and C12 are selected by fine adjustment, and the fine adjustment capacitors are connected in parallel on the basis of the capacitance value of the coarse adjustment capacitor, so that the test result is shown in figure 3, and the dotted line in figure 3 represents standing-wave ratios at different frequencies after fine adjustment, thereby realizing the representation of the motion trajectory in the scanning frequency range after fine adjustment. After the matching is completed, the parameters of the whole design circuit are tested using the interface P1, and the parameters measured by the P1 are the actual impedance of the whole transmission circuit.
The above embodiments are described in detail for the purpose of illustration and understanding, and no unnecessary limitations are to be understood therefrom, and any modifications, equivalents, and improvements made within the spirit and principle of the present invention should be included therein.
Claims (7)
1. A design circuit for facilitating antenna matching, comprising a filter circuit A1, wherein the filter circuit A1 is connected with a matching circuit A2, and the capacitance of the matching circuit A2 is adjustable; the matching circuit a2 is connected to the antenna circuit A3, the first voltage-dividing circuit a4, and the second voltage-dividing circuit a5, respectively.
2. The design circuit for facilitating antenna matching according to claim 1, wherein the filter circuit a1 includes an interface P1, a first test terminal of the interface P1 is connected to one terminal of an inductor L1 and connected to a first rf output terminal, and another terminal of the inductor L1 is connected to one terminal of a capacitor C5; the second test end of the interface P1 is connected with one end of an inductor L2 and is connected with a second radio frequency output end, and the other end of the inductor L2 is connected with one end of a capacitor C8; the other end of the capacitor C5 and the other end of the capacitor C8 are connected to ground.
3. The design circuit for facilitating antenna matching according to claim 1, wherein the matching circuit a2 comprises a capacitor C4, one end of the capacitor C4 is connected to one end of the capacitor C2 and to one end of the capacitor C5, the other end of the capacitor C4, the other end of the capacitor C2, one end of the capacitor C6 and one end of the capacitor C7 are connected; the other end of the capacitor C6, the other end of the capacitor C7, the other end of the capacitor C9 and the other end of the capacitor C10 are connected with one another and grounded; one end of the capacitor C9, one end of the capacitor C10, the other end of the capacitor C11 and the other end of the capacitor C12 are connected; one end of the capacitor C11 is connected with one end of the capacitor C12 and is connected with one end of the capacitor C8.
4. The design circuit for facilitating antenna matching according to claim 1, wherein the antenna circuit a3 includes an interface P2, a first test end of the interface P2 is connected to one end of a resistor R1 and a second antenna interface, and the other end of the resistor R1 is connected to one end of a capacitor C7; the second test end of the interface P2 is connected with one end of a resistor R2 and the first antenna interface, and the other end of the resistor R2 is connected with one end of a capacitor C10.
5. The design circuit for facilitating antenna matching according to claim 1, wherein the first voltage divider circuit a4 comprises a capacitor C3, one end of the capacitor C3 is connected to one end of a capacitor C6, the other end of the capacitor C3 is connected to one end of a capacitor C1, the other end of the capacitor C1 is grounded, and one end of the capacitor C1 is connected to the first rf input terminal.
6. The design circuit for facilitating antenna matching according to claim 1, wherein the second voltage divider circuit a5 comprises a capacitor C13, one end of the capacitor C13 is connected to one end of a capacitor C9, the other end of the capacitor C13 is connected to one end of a capacitor C14, the other end of the capacitor C14 is grounded, and one end of the capacitor C14 is connected to the second rf input terminal.
7. The design circuit for facilitating antenna matching according to claim 3, wherein in the matching circuit A2, the capacitors C2, C4, C6, C7, C9, C10, C11 and C12 are impedance matching capacitors, and the capacitors can be removed and replaced.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121695636.4U CN215646757U (en) | 2021-07-23 | 2021-07-23 | Design circuit convenient to antenna matching |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121695636.4U CN215646757U (en) | 2021-07-23 | 2021-07-23 | Design circuit convenient to antenna matching |
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| CN215646757U true CN215646757U (en) | 2022-01-25 |
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| CN202121695636.4U Active CN215646757U (en) | 2021-07-23 | 2021-07-23 | Design circuit convenient to antenna matching |
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