Balanced differential signal antenna

Abstract

The invention discloses a balanced differential signal antenna. The balanced differential signal antenna comprises at least two antenna main bodies, the at least two antenna extension parts are respectively connected with the antenna main body and are formed by electronic wires; the LC matching circuit is connected with the antenna main body and is used for adjusting the inductance L and the capacitance C; and the LC balun circuit is connected with the matching circuit and is used for generating differential signals with the phase difference of 180 degrees and equal amplitude. The overall antenna bandwidth can be improved, the two antennas are adopted, differential signals with the phase difference of 180 degrees are achieved, the two antennas are made to generate forward current, the antenna gain is improved, and therefore the receiving sensitivity of the whole machine is improved, the problem that in the prior art, a built-in function integrated chip is poor in receiving sensitivity can be solved, and the antenna can be widely applied to FM radios, FM radios and the like. The antenna can be applied to products such as DAB digital broadcasting, VHF / UHF, 2.4 G emission receivers and the like.

Description

Technical Field

[0001] The present invention relates to the field of antennas, and in particular to a balanced differential signal antenna. Background Art

[0002] With the development of technology, the integration of chips is getting higher and higher. Many individual functions are integrated into the main control chip, such as radio function, 433MHz remote control, UHF band transmission and reception, 2.4G band, etc. This has led to a decrease in the overall receiving sensitivity compared to before. In addition, the space left for antennas in current consumer electronic products is getting smaller and smaller, and the requirements for antennas are getting higher and higher. In a limited space, common antennas such as dipole antennas and monopole antennas have large spatial signal fluctuations and narrow bandwidth in a poor signal environment. Due to their small size, the antenna radiation efficiency will be greatly reduced in a lower frequency band.

[0003] Traditional antenna types generally include monopole or dipole antennas. Monopole antennas have high requirements for the size and environment of the internal space, are easily interfered, operate in a lower frequency band and have a longer wavelength, so they have certain requirements for the size of the PCB board and require a sufficiently large ground area to realize the mirror current. When there is not enough ground surface, the antenna radiation efficiency will decrease. Therefore, this type of antenna has certain limitations. The dipole antenna is connected to the PCB through a 50Ω coaxial cable feeding point. Since the dipole antenna itself is a balanced antenna, but the coaxial cable itself is unbalanced, using this type of feeding point will cause current imbalance and performance degradation. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a balanced differential signal antenna, which uses a dual antenna method and generates a differential signal with a phase difference of 180° and equal amplitude between the two antennas through matching and differential circuit adjustment. In this way, the two antennas can generate forward currents, thereby improving the radiation gain and efficiency of the antenna.

[0005] The present invention is implemented by the following technical solution: A balanced differential signal antenna, comprising:

[0006] at least two antenna bodies;

[0007] at least two antenna extensions, respectively connected to the antenna body and formed of electronic wires;

[0008] An LC matching circuit, connected to the antenna body, for adjusting the size of the inductance L and the capacitance C;

[0009] An LC balun circuit, connected to the matching circuit, for generating differential signals with a phase difference of 180° and equal amplitude;

[0010] A PCB board, carrying the matching circuit and the balun circuit;

[0011] A coaxial cable is connected to the balun circuit and is used for feeding.

[0012] As a preferred technical solution, the antenna body and the antenna extension part are connected via a solder pad, and the resonant frequency and impedance of the antenna are adjusted by changing the number of turns of the antenna body and the length of the antenna extension part.

[0013] As a preferred technical solution, the PCB board is made of FR4 material with a relative dielectric constant εr=4.4, and the board thickness is 1 mm.

[0014] As a preferred technical solution, the antenna body is composed of a winding coil of dielectric material, and the resonant frequency and impedance of the antenna are adjusted by changing the number of turns of the winding coil and the length of the extended part of the antenna.

[0015] As a preferred technical solution, the antenna frequency band is used in 50 to 3000 MHz.

[0016] As a preferred technical solution, the balun circuit is further connected to the two antennas via an isolation resistor to increase the isolation between the two antennas.

[0017] A balanced differential signal antenna of the present invention comprises:

[0018] at least two antenna bodies;

[0019] an antenna extension connected to each antenna body;

[0020] An LC balun circuit, connected to the PCB board, is used to convert an unbalanced signal into a balanced differential signal;

[0021] A PCB board, used for carrying the antenna body and the LC balun circuit;

[0022] The coaxial cable is connected to the LC balun circuit and is used for signal feeding and output.

[0023] As a preferred technical solution, the antenna extension part is composed of an electronic wire with a diameter of 2.1 mm.

[0024] As a preferred technical solution, the extended portion of the antenna is connected to the PCB board via a solder pad, and the resonant frequency of the antenna can be adjusted by changing the length of the electronic wire.

[0025] As a preferred technical solution, the PCB board is made of FR4 material with a relative dielectric constant εr=4.4 and a board thickness of 1 mm, and the antenna frequency band is applied in 700-900 MHz.

[0026] The beneficial effects of the present invention are as follows: the present invention can improve the overall antenna bandwidth, adopt two antennas, realize a differential signal with a phase difference of 180°, make the two antennas generate a forward current, improve the antenna gain, and thus improve the receiving sensitivity of the whole machine, thus making up for the poor receiving sensitivity of the built-in functional integrated chip in the prior art, and can be widely used in products such as FM radios, DAB digital broadcasting, VHF / UHF, 2.4G transmitters and receivers, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a structural schematic diagram of embodiment 1 of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0030] Figure 3 This is an equivalent schematic diagram of the antenna (88-108MHz) of the present invention;

[0031] Figure 4 This is the equivalent schematic diagram of the antenna (700-900MHz);

[0032] Figure 5 This is the simulation result diagram of the balun circuit in the antenna (88-108MHz) frequency band;

[0033] Figure 6 This is the simulation result diagram of the balun circuit in the antenna (700-900MHz) frequency band;

[0034] Figure 7 This is the return loss diagram for the (88-108MHz) frequency band;

[0035] Figure 8 This is the voltage standing wave ratio diagram for the frequency band (88-108MHz);

[0036] Fig. 9 This is the return loss diagram for the (700-900MHz) frequency band;

[0037] Fig.10 This is the voltage standing wave ratio diagram for the frequency band (700-900MHz);

[0038] Fig.11 is the (700-900MHz) antenna radiation pattern;

[0039] Description of reference numerals:

[0040] 1. Antenna body; 2. PCB board; 3. Antenna extension part; 4. LC matching circuit; 5. Isolation resistor; 6. LC balun circuit; 7. Soldering point; 8. Coaxial cable. DETAILED DESCRIPTION

[0041] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0042] Any feature disclosed in this specification (including any additional claims, abstract and drawings), unless otherwise stated, may be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0043] Example 1

[0044] A balanced differential antenna of the present invention can be used in the antenna frequency band of 50 to 3000 MHz. The antenna of the present patent is composed of an antenna body 1, an antenna extension part 3, a matching circuit, a balun circuit, a PCB board 2, and a coaxial cable 8. The antenna body 1 can be in the form of a winding coil, a ceramic antenna, an FPC antenna, etc., and the antenna extension part 3 can be in the form of an electronic wire, a spring, a coil, an FPC, etc. The protection scope of the antenna of the present invention is not limited to this. Any changes or replacements that are not conceived through creative labor should be covered within the protection scope of this patent. For ordinary technicians in the technical field to which this patent belongs, without departing from the concept of the present invention, they can also make several simple deductions or replacements, which should be deemed to belong to the protection scope of this patent.

[0045] Specifically, Figure 1 As shown, the dielectric material winding coil is connected to the electronic wire through a pad. The resonant frequency and impedance of the antenna can be adjusted by changing the number of turns of the winding coil and the length of the electronic wire. The left and right sides are symmetrical structures. The winding coil is connected to the LC matching circuit. By adjusting the size of the inductor L and the capacitor C, good antenna impedance characteristics can be achieved. After being connected through a balun circuit, a differential signal with a phase difference of 180° and equal amplitude is generated between the two antennas. The isolation resistor is passed in the middle to increase the isolation between the two antennas, and finally fed through a coaxial cable.

[0046] Taking the 88-108MHz antenna as an example, first preliminarily calculate the number of turns of the winding coil, and then preliminarily calculate the number of coil turns through the formula λ=c / f (where C is the speed of light 3*10^8m / s, and f is the operating frequency 98MHz). The winding coil is equivalent to an inductor, and the open-circuit electronic wire connected to the tail end is equivalent to a capacitor. By adjusting the number of coil turns and the length of the electronic wire, and then adjusting the matching circuit, the antenna self-resonance frequency can have good impedance characteristics at 88-108MHz.

[0047] The antenna ultimately needs to be fed by a coaxial cable. Since the coaxial cable feeding is unbalanced, a balun circuit is added between the two matched antennas to generate a differential signal with a phase difference of 180° and equal amplitude between the two antennas. In this way, both antennas can generate forward current, thereby improving the radiation gain and efficiency of the antenna. The isolation resistor 5 in the middle can improve the isolation between the two antennas.

[0048] like Figure 3 As shown, L1, L2, C1, C2, C3, and C4 constitute an antenna matching circuit, R1 is an isolation resistor 5, and L3, L4, C5, and C6 constitute a balun circuit. The balun circuit has three ports, one single port and two differential ports. The amplitudes of the two differential ports are equal and the phase difference is 180°.

[0049] Example 2

[0050] like Figure 2 As shown, a balanced differential signal antenna of the present invention comprises two antenna bodies 1; an antenna extension part 3 connected to each antenna body 1;

[0051] The LC balun circuit 6 is connected to the PCB board 2 and is used to convert an unbalanced signal into a balanced differential signal; the PCB board 2 is used to carry the antenna body 1 and the LC balun circuit 6;

[0052] It also includes a coaxial cable 8 connected to the LC balun circuit 6 for feeding in and outputting signals.

[0053] Among them, the antenna extension part 3 is composed of an electronic wire with a diameter of 2.1mm. The antenna extension part 3 is connected to the PCB board 2 through a solder pad. The resonant frequency of the antenna can be adjusted by changing the length of the electronic wire. The PCB board 2 is made of FR4 material with a relative dielectric constant εr=4.4 and a board thickness of 1mm. The antenna frequency band is used in 700-900MHz.

[0054] Figure 4 This is an equivalent schematic diagram of the antenna (700-900MHz) of the present invention, wherein L1, L2, C1, and C2 constitute an antenna balun circuit. The balun circuit has three ports, a single port and two differential ports. The amplitudes of the two differential ports are equal and the phase difference is 180°.

[0055] like Figure 5 As shown, Figure 5 The simulation results of the balun circuit in the frequency band of the patented antenna (88-108MHz) are as follows: At the center frequency of 98MHz, the balun circuit composed of L3=110nH, L4=110nH, C5=24pF, and C6=24pF can achieve equal amplitudes at the two antenna ports, a phase difference of 180° at the ports, and realize two differential signals, which meets our design requirements.

[0056] like Figure 6 As shown, Figure 6 The simulation results of the balun circuit in the frequency band of the patented antenna (700-900MHz) are as follows: At the center frequency of 800MHz, the balun circuit composed of L1=15nH, L2=15nH, C1=2.7pF, and C2=2.7pF can achieve equal amplitudes at the two antenna ports, a phase difference of 180° between the ports, and realize two differential signals, which meets our design requirements.

[0057] Freq(MHz) Efficiency(%) Gain(dBi) 700MHz 58.29 1.09 710MHz 59.9 1.14 720MHz 61.61 1.45 730MHz 63.52 1.52 740MHz 65.11 1.86 750MHz 68.01 2.09 760MHz 70.24 2.85 770MHz 72.12 3.09 780MHz 75.74 3.67 790MHz 74.39 3.69

[0058] Table 1

[0059] Freq(MHz) Efficiency(%) Gain(dBi) 800MHz 76.7 4.5 810MHz 75.8 4.33 820MHz 75.13 4.31 830MHz 76.15 4.4 840MHz 68.46 3.34 850MHz 65.84 3.01 860MHz 63.29 3.11 870MHz 62.44 3.14 880MHz 61.52 3.16 890MHz 60.71 3.22 900MHz 57.73 2.8

[0060] Table 2

[0061] Table 1 and Table 2 show the antenna gain and efficiency in the (700-900MHz) frequency band. From the simulation results and the antenna schematic diagram, the patented antenna uses two antennas, matching circuits and balun circuits to achieve equal amplitudes at the two antenna ports, and a 180° phase difference at the ports, so that the two antennas can achieve forward current, thereby improving the antenna gain and efficiency. Figure 7 , Figure 8 According to the actual test results, the antenna can cover the 88-108MHz frequency band, and the return loss and voltage standing wave ratio data are good. Fig. 9 , Fig.10 , Fig.11 According to the actual test results, the antenna can cover the 700-900MHz frequency band, the return loss and voltage standing wave ratio data are good, and the overall gain and efficiency of the antenna are relatively high;

[0062] The antenna of the present invention solves the problem that the monopole antenna is easily interfered and the dipole antenna is unbalanced in a small space. Since the bandwidth, radiation gain and efficiency of the antenna of the present invention are improved, it not only makes up for the poor sensitivity of the built-in integrated radio chip in the prior art, but also solves the problem of narrow antenna bandwidth and low radiation efficiency in the small size of the UHF frequency band on the market. The functional scope of the antenna of the present invention is not limited to this, and it can also be widely used in consumer electronic products, Bluetooth speakers, radios, car radios, 433 intercoms, VHF / UHF conference systems, 2.4G broadcasting and other products.

[0063] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that are not conceived through creative work should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined in the claims.

Claims

1. A balanced differential signal antenna, characterized in that: include: At least two antenna bodies (1); At least two antenna extension parts (3), respectively connected to the antenna body (1) and composed of electronic wires; An LC matching circuit (4), connected to the antenna body (1), and used to adjust the size of the inductance L and the capacitance C; An LC balun circuit (6), connected to the matching circuit, for generating differential signals with a phase difference of 180° and equal amplitude; A PCB board (2), carrying the matching circuit and the balun circuit; A coaxial cable (8) is connected to the balun circuit and is used for power feeding.

2. The balanced differential signal antenna according to claim 1, characterized in that: The antenna main body (1) and the antenna extension part (3) are connected via a solder pad, and the resonant frequency and impedance of the antenna are adjusted by changing the number of turns of the antenna main body (1) and the length of the antenna extension part (3).

3. The balanced differential signal antenna according to claim 1, characterized in that: The PCB board (2) is made of FR4 material with a relative dielectric constant εr=4.4, and has a board thickness of 1 mm.

4. The balanced differential signal antenna according to claim 1, characterized in that: The antenna body (1) is composed of a winding coil made of dielectric material, and the resonant frequency and impedance of the antenna can be adjusted by changing the number of turns of the winding coil and the length of the antenna extension part (3).

5. The balanced differential signal antenna according to claim 1, characterized in that: The antenna frequency band is used in 50~3000MHz.

6. The balanced differential signal antenna according to claim 1, characterized in that: The balun circuit is further connected to the two antennas via an isolation resistor (5) to increase the isolation between the two antennas.

7. A balanced differential signal antenna, characterized in that: include: At least two antenna bodies (1); an antenna extension (3) connected to each antenna body (1); An LC balun circuit (6), connected to the PCB board (2), for converting an unbalanced signal into a balanced differential signal; A PCB board (2), used for carrying the antenna body (1) and the LC balun circuit (6); The coaxial cable (8) is connected to the LC balun circuit (6) and is used for signal input and output.

8. The balanced differential signal antenna according to claim 1, characterized in that: The antenna extension part (3) is made of an electronic wire with a diameter of 2.1 mm.

9. The balanced differential signal antenna according to claim 1, characterized in that: The antenna extension part (3) is connected to the PCB board (2) via a soldering pad, and the resonant frequency of the antenna can be adjusted by changing the length of the electronic wire.

10. The balanced differential signal antenna according to claim 1, characterized in that: The PCB board (2) is made of FR4 material with a relative dielectric constant εr=4.4 and a board thickness of 1 mm. The antenna frequency band is applied in the range of 700-900 MHz.

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