Circularly polarized antenna broadband feed network
By designing Wilkinson's power splitter and microstrip line structure in circular polarized antennas, combined with step opening branches, the problem of insufficient bandwidth of circular polarized antennas in the existing technology is solved, and broadband performance expansion in the ISM frequency band is achieved and phase accuracy, suitable for high reliability wireless communication scenarios.
Patent Information
- Application Number
- CN202411200519.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-08-23
- Filing Date
- 2024-08-29
- Publication Date
- 2024-12-10
AI Technical Summary
Existing circularly polarized antennas have high bandwidth requirements in the ISM band, but existing feeding networks cannot effectively expand bandwidth, and it is difficult to maintain phase accuracy and low loss.
A metal patch layer structure including the first, second and third Wilkinson power dividers, coupling lines and microstrip lines is designed. Through the bending and resistance setting of the microstrip lines, four signals are realized. The amplitude and phase difference are 90° in sequence, and the transmission zero frequency difference is enhanced by step open branches, reducing phase deviation, and combining printed circuit board technology to achieve miniaturization and efficient production.
It realizes broadband performance expansion in the ISM frequency band, maintains phase accuracy and low insertion loss, is suitable for high-reliability wireless communication scenarios, and reduces production costs.
Smart Images
Figure CN119108809A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of wireless communication and antennas, and in particular relates to a circularly polarized antenna broadband feeding network. Background Art
[0002] The Industrial, Scientific and Medical (ISM) band is a radio spectrum area designated worldwide for non-communication applications, which is allowed to be used without a license. The most commonly used frequency bands in the ISM band include 902-928MHz (USA), 863-870MHz (Europe), 2.4-2.4835GHz and 5.725-5.850GHz, of which the 2.4GHz and 5.8GHz bands are widely used in civilian devices such as wireless LAN (Wi-Fi), Bluetooth, wireless mouse and keyboard, cordless phones and wireless power transmission.
[0003] The electric field vector of the electromagnetic wave radiated by the circularly polarized antenna rotates along a fixed point. Compared with the linearly polarized antenna, it has better robustness in reception and can resist signal loss caused by polarization mismatch. Therefore, circularly polarized antennas are increasingly used in the ISM band, including wireless sensor networks, remote monitoring systems, drone communications, wireless charging systems, Internet of Things (IoT) devices, etc., especially in situations that require high reliability and robustness. The above application scenarios also put forward higher requirements on the bandwidth of circularly polarized antennas. Among them, a broadband feeding network is one of the important prerequisites for expanding the bandwidth of circularly polarized antennas. Summary of the invention
[0004] The present invention provides a circularly polarized antenna broadband feeding network, which has the advantages of broadband, high isolation, low loss, precise phase control, small size, easy production and manufacturing, and strong flexibility.
[0005] The technical solution adopted by the present invention is as follows:
[0006] A circular polarization antenna broadband feeding network comprises a dielectric substrate, a metal floor arranged on the back of the dielectric substrate, and a metal patch layer arranged on the front of the dielectric substrate.
[0007] The metal patch layer is used to divide the input signal into four equal-amplitude signals with phases differing by 90°; the metal patch layer includes a first Wilkinson power divider, a second Wilkinson power divider, a third Wilkinson power divider, a first coupling line, a second coupling line, and a plurality of microstrip lines.
[0008] Among them, the input end of the first Wilkinson power divider is the signal input port of the feeding network, and the two output ends are respectively connected to the input ends of the second Wilkinson power divider and the third Wilkinson power divider through two sections of bent microstrip lines with an electrical length difference of 180 degrees, providing two Wilkinson power dividers with two signals of equal amplitude and a phase difference of 180 degrees.
[0009] One of the output ends of the second Wilkinson power divider extends to the feeding point B through a section of bent microstrip line; the other output end is connected to the first coupling line through a section of microstrip line.
[0010] The first coupling line is composed of two rectangular microstrip lines of the same size and arranged in parallel; one end of the two rectangular microstrip lines is connected, and the other end is connected to the second Wilkinson power divider and the feeding point A through a section of microstrip line.
[0011] One of the output ends of the third Wilkinson power divider extends to the feeding point D through a section of bent microstrip line; the other output end is connected to the second coupling line through a section of microstrip line.
[0012] The second coupling line is composed of two rectangular microstrip lines of the same size and arranged in parallel; one end of the two rectangular microstrip lines is connected, and the other end is connected to the third Wilkinson power divider and the feeding point C through a section of microstrip line.
[0013] The four signals outputted from the feed point A, feed point B, feed point C and feed point D have equal amplitudes and phases that differ by 90° respectively, and the lines connecting the four feed points form a square.
[0014] Preferably, one end of the first coupling line communicating with the second coupling line is further connected with a stepped open branch.
[0015] Preferably, the stepped open branch is formed by sequentially connecting at least two sections of rectangular microstrip lines with different widths.
[0016] Preferably, in the first coupling line and the second coupling line, the width of the gap between the two rectangular microstrip lines is 0.3 mm.
[0017] Preferably, the stepped open-circuit branches are bent to reduce the area of the broadband feeding network, which is beneficial to the miniaturized design of the antenna.
[0018] Preferably, the bends of each microstrip line are chamfered to reduce signal reflection and loss, thereby further improving the broadband performance and efficiency of the overall network.
[0019] Preferably, the resistor arranged between the two branch lines of each Wilkinson power divider is 100 ohms.
[0020] The principles and beneficial effects of the present invention are:
[0021] 1. The present invention connects microstrip lines of different lengths at the two output ends of the first Wilkinson power divider to achieve an input signal difference of 180 degrees between the second Wilkinson power divider and the third Wilkinson power divider, thereby ensuring accurate adjustment of the signal phase at different frequencies and achieving continuity and stability of circular polarization. At the same time, since the main path of the phase shifter has a bandpass characteristic, when a 90-degree phase shift is achieved by combining a coupling line and a step-open branch, the impedance ratio of the microstrip lines at both ends of the step-open branch is increased, thereby increasing the frequency difference of its transmission zero point. However, this method will cause the phase deviation within the bandwidth to become larger. Therefore, in order to reduce the phase shift caused by the increase in bandwidth, the gap width between the coupling lines is reduced, and the coupling degree is increased. In this way, good phase accuracy can be maintained while increasing the bandwidth, and the broadband of the feeding network can be expanded to cover the ISM frequency band range, while maintaining phase accuracy, low insertion loss and good matching.
[0022] 2. Each Wilkinson power divider of the present invention not only evenly divides the input signal into two paths, but also significantly improves the isolation between the output ports by introducing a 100 ohm isolation resistor on the branch line, thereby ensuring network stability and efficiency.
[0023] 3. The microstrip line part and the stepped open-circuit branch part of the present invention can be bent, which provides greater design freedom for the adaptability of antenna size and shape, and enhances the compatibility of the product in different application scenarios. In addition, by adopting a cut-angle design at the 90-degree corner of the microstrip line, the reflection and loss of the signal are reduced, further improving the broadband performance and efficiency of the overall network.
[0024] 4. The entire feeding network of the present invention can be easily realized through the printed circuit board (PCB) process, which reduces the production cost and makes large-scale production and application possible. It can be widely used in wireless sensor networks, remote monitoring systems, drone communications, wireless charging systems and various scenarios requiring high reliability and robust wireless communication. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 FIG. 1 is a schematic top view of a feeding network in an embodiment.
[0026] Figure 2 This is a partial dimensioning diagram of the feed network in the embodiment.
[0027] Figure 3 It is a dimensioning diagram of the stepped open-circuit branches and coupled line parts of the feed network in the embodiment.
[0028] Figure 4 : is the return loss of the feeding network and the insertion loss of each port in the embodiment.
[0029] Figure 5is the phase difference between each output port and the second port of the feeding network in the embodiment.
[0030] Figure 6 is the isolation between the output ports of the feeding network in the embodiment.
[0031] Explanation of the accompanying drawings: 00. dielectric substrate, 11. first Wilkinson power divider, 21. second Wilkinson power divider, 22. third Wilkinson power divider, 31. third long microstrip line, 32. fourth wavelength microstrip line, 41. first coupled line, 42. second coupled line, 51. first step open-circuit branch, 52. second step open-circuit branch, 61. first microstrip line, 62. second microstrip line, 71. 100 ohm resistor, 72. 100 ohm resistor, 73. 100 ohm resistor. DETAILED DESCRIPTION
[0032] In order to further illustrate the technical solutions and beneficial effects of the present invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.
[0033] The broadband circular polarization antenna feeding network of this embodiment is intended to realize a broadband circular polarization microstrip antenna with four-point feeding. Figure 1 As shown, it includes: a dielectric substrate, a metal floor arranged on the back of the dielectric substrate, and a metal patch layer arranged on the front of the dielectric substrate.
[0034] The metal patch layer is used to divide the input signal into four equal-amplitude signals with phases differing by 90°; the metal patch layer includes a first Wilkinson power divider, a second Wilkinson power divider, a third Wilkinson power divider, a first coupling line, a second coupling line, and a plurality of microstrip lines.
[0035] Among them, the input end of the first Wilkinson power divider is the signal input port of the feeding network, one of the output ends is connected to the input end of the second Wilkinson power divider through a bent first microstrip line, and the other output end is connected to the input end of the third Wilkinson power divider through a bent second microstrip line; the electrical length difference between the first microstrip line and the second microstrip line is half a wavelength to achieve a 180-degree phase shift, providing two Wilkinson power dividers with two signals of equal amplitude and a phase difference of 180 degrees.
[0036] A 100-ohm resistor is provided between the two branch lines of each Wilkinson power divider to enhance the isolation between the output ports.
[0037] The first output end of the second Wilkinson power divider extends to the feeding point B through a third microstrip line of three-quarter wavelength; the second output end is connected to the first coupling line through a section of microstrip line.
[0038] The first coupling line is a quarter-wavelength coupling line, which is composed of two rectangular microstrip lines of the same size and arranged in parallel; the gap between the two rectangular microstrip lines is 0.3 mm wide, the upper ends are connected through a rectangular patch with a longitudinal length of 1 mm, and the lower ends are connected to the second Wilkinson power divider and the feeding point A through a section of microstrip line. The total length of the microstrip line and the coupling line between the second output end of the second Wilkinson power divider and the feeding point A is half a wavelength, so as to achieve a phase lead of 90 degrees over the feeding point B.
[0039] The first output end of the third Wilkinson power divider extends to the feeding point D through a fourth microstrip line of three-quarter wavelength; the second output end is connected to the second coupling line through a section of microstrip line.
[0040] The second coupling line has the same structural dimensions as the first coupling line, and the other ends of its two rectangular microstrip lines are respectively connected to the third Wilkinson power divider and the feeding point C through a section of microstrip line. The total length of the microstrip line and the coupling line between the second output end of the third Wilkinson power divider and the feeding point C is half a wavelength, so as to achieve a phase lead of 90 degrees over the feeding point D.
[0041] Feeding points A, B, C, and D are arranged counterclockwise. The four output signals are of equal amplitude and their phases differ by 90°. At the same time, the lines connecting the four feeding points form a square, ensuring the symmetry and circular polarization characteristics of the antenna radiation pattern.
[0042] One end of the first coupling line communicating with the second coupling line is also connected to a two-step ladder open-circuit branch; one step of the ladder is bent to reduce the size.
[0043] The second-order stepped open-circuit branches, the Weil metal power divider, and the 90-degree corners of each bent microstrip line are designed with a cut-off angle to reduce signal reflection and loss at the corners.
[0044] like Figure 2 and Figure 3As shown, in this embodiment, the specific dimensions are: S0=1mm, W0=1.5mm, W1=0.8mm, L0=5mm, L1=5.7mm, L2=8.5mm, L3=3mm, S1=0.3mm, W0=1.5mm, W2=2.5mm, W3=0.8mm, W4=4.8mm, L9=8mm, L4=46.1mm, L5=56.7mm, L6=4 7mm, L7=3.5mm, L8=20mm, L10=8mm, L11=22.9mm, L12=8.3mm, L13=6mm, L14=8mm, L15=15.8 mm, L16=7.5mm, L17=1mm, L19=7mm, L19=8mm, L20=15.8mm, D0=2.4mm, D1=1.3mm, D2=1.3mm.
[0045] Combined with Figure 3 It can be seen that its S11 is less than 15dB in the range of 2-3GHz, and the curves of S21, S31, S41, and S51 are basically overlapped, indicating that equal power signal output is achieved. Figure 4 It can be seen that the phase difference between each port and port A is 90 degrees, achieving better phase control. Figure 5 It can be seen that the isolation between adjacent ports in the range of 2-2.8GHz is less than -20dB, achieving good isolation.
[0046] The present invention can be realized through printed circuit board technology, has low cost, is easy to mass-produce, and is suitable for civilian wireless receiving and transmitting systems, such as wireless sensor networks, remote monitoring systems, drone communications, wireless charging systems, and Internet of Things (IoT) devices.
[0047] Through the above specific implementation methods, the broadband circularly polarized antenna feeding network of the present invention achieves excellent broadband performance and low insertion loss in the IS M frequency band, and is suitable for various occasions requiring high robustness and reliability of communication.
[0048] Although we have described the core execution mode of this innovation in detail, it does not mean that its application is limited to the scenarios or examples described in the document. In fact, its applicability spans across multiple fields that are consistent with the spirit of this innovation. It is entirely feasible for industry professionals to explore and implement further variations. Therefore, as long as it does not deviate from the basic concept established by the patent claim and its equivalent principle, this innovation should not be narrowly interpreted as being limited to the details or exemplary cases specifically mentioned in the text.
Claims
1. A circular polarization antenna broadband feeding network, comprising a dielectric substrate, a metal floor arranged on the back of the dielectric substrate, and a metal patch layer arranged on the front of the dielectric substrate; It is characterized in that The metal patch layer is used to divide the input signal into four equal-amplitude signals whose phases differ by 90° in sequence; the metal patch layer includes a first Wilkinson power divider, a second Wilkinson power divider, a third Wilkinson power divider, a first coupling line, a second coupling line, and a plurality of microstrip lines; The input end of the first Wilkinson power divider is the signal input port of the feeding network, and the two output ends are respectively connected to the input ends of the second Wilkinson power divider and the third Wilkinson power divider through two sections of bent microstrip lines with an electrical length difference of 180 degrees, providing two Wilkinson power dividers with two signals of equal amplitude and a phase difference of 180 degrees; One of the output ends of the second Wilkinson power divider is extended to the feeding point B through a section of bent microstrip line; the other output end is connected to the first coupling line through a section of microstrip line; The first coupling line is composed of two rectangular microstrip lines of the same size and arranged in parallel; one end of the two rectangular microstrip lines is connected, and the other end is connected to the second Wilkinson power divider and the feeding point A through a section of microstrip line; One of the output ends of the third Wilkinson power divider extends to the feeding point D through a section of bent microstrip line; the other output end is connected to the second coupling line through a section of microstrip line; The second coupling line is composed of two rectangular microstrip lines of the same size and arranged in parallel; one end of the two rectangular microstrip lines is connected, and the other end is connected to the third Wilkinson power divider and the feeding point C through a section of microstrip line; The four signals outputted from the feed point A, feed point B, feed point C and feed point D have equal amplitudes and phases that differ by 90° respectively, and the lines connecting the four feed points form a square.
2. A circularly polarized antenna broadband feeding network as claimed in claim 1, It is characterized in that One end of the first coupling line communicating with the second coupling line is also connected with a stepped open-circuit branch.
3. A circularly polarized antenna broadband feeding network as claimed in claim 2, It is characterized in that The step-open branch is formed by sequentially connecting at least two sections of rectangular microstrip lines with different widths.
4. A circularly polarized antenna broadband feeding network as claimed in claim 3, It is characterized in that In the first coupling line and the second coupling line, the width of the gap between the two rectangular microstrip lines is 0.3 mm.
5. A circularly polarized antenna broadband feeding network as claimed in claim 4, It is characterized in that The step-opening branches are arranged in a bent manner.
6. A circularly polarized antenna broadband feeding network as claimed in claim 5, It is characterized in that The bending part of the bent microstrip line is cut corners.
7. A circularly polarized antenna broadband feeding network as claimed in claim 6, It is characterized in that The resistor set between the two branch lines of each Wilkinson power divider is 100 ohms.