A ring-shaped windmill-type structure microstrip array antenna

Abstract

The present invention proposes a microstrip array antenna with an annular windmill-type structure, which relates to the technical field of communication antennas, including a substrate, an inner ring arm, an inner ring wing, an outer ring arm and an outer ring wing. A feeding point is arranged on the substrate, and an inner ring circle and an outer ring circle are arranged with the feeding point as the center of the circle, and the inner ring circle is located inside the outer ring circle; the two ends of the inner ring arm are respectively connected to the feeding point and the circumference of the inner ring circle; the inner ring wing is arranged on the circumference of the inner ring circle, and one end is connected to the inner ring arm; the outer ring arm connects the circumference of the inner ring circle and the outer ring circle, and one end is connected to the inner ring wing; the outer ring wing is arranged on the circumference of the outer ring circle, and one end is connected to the outer ring arm. The present invention, through the innovative inner and outer ring structures and windmill-shaped design, can provide efficient dual-frequency radiation characteristics while being miniaturized, meeting the requirements of the 5G communication system for multi-band, miniaturization, and efficient transmission.

Description

Technical Field

[0001] The invention relates to the technical field of communication antennas, and in particular to a microstrip array antenna with an annular windmill-type structure. Background Art

[0002] In the 5G era, mobile phones, as a mobile terminal with a very wide range of applications, need to cover ultra-wide frequency bands to meet the requirements of multiple communication protocols. With the rapid development of mobile communication systems, the required terminal antennas must be better and better, such as multi-band, easy to match, and miniaturized. For the research and development of 5G networks, at the current stage of development, my country mainly chooses the FR1 frequency band in order to popularize 5G technology into people's lives as soon as possible. Therefore, the research on multi-band antennas suitable for the FR1 frequency band is highly sought after by domestic researchers.

[0003] At present, there have been many studies and technical solutions for the design of antennas in FR1 band (below 5GHz) communication systems. For example, microstrip antennas, as a common type of antenna, have received widespread attention in FR1 band applications. The advantages of microstrip antennas include simple structure, easy integration, low cost, and are very suitable for small devices such as mobile terminals. However, existing microstrip antenna designs usually face the problem of insufficient radiation characteristics in the FR1 band. Traditional microstrip antennas are usually directional radiation antennas with a relatively single radiation pattern and lack of omnidirectional radiation capabilities. In practical applications, especially in mobile communication environments, antennas need to have omnidirectional radiation characteristics to ensure uniform reception and transmission of signals in all directions. Therefore, how to design an antenna that can achieve omnidirectional radiation has become an urgent problem to be solved. Summary of the invention

[0004] In view of this, the present invention proposes a microstrip array antenna with a ring-shaped windmill-type structure. Through the innovative inner and outer ring structures and windmill-shaped design, it can provide efficient dual-frequency radiation characteristics while being miniaturized, thus meeting the requirements of the 5G communication system for multi-band, miniaturization, and efficient transmission.

[0005] The technical solution of the present invention is achieved in this way:

[0006] The present invention provides a microstrip array antenna with a ring-shaped windmill-type structure, comprising a substrate, an inner ring arm, an inner ring wing, an outer ring arm and an outer ring wing, wherein:

[0007] A feeding point is arranged on the substrate, and an inner ring circle and an outer ring circle are arranged with the feeding point as the center, and the inner ring circle is located inside the outer ring circle;

[0008] The two ends of the inner ring arm are respectively connected to the feeding point and the circumference of the inner ring circle;

[0009] The inner ring wing is arranged on the circumference of the inner ring circle, and one end is connected to the inner ring arm;

[0010] The outer ring arm connects the circumference of the inner ring circle and the outer ring circle, and one end is connected to the inner ring wing;

[0011] The outer ring wing is arranged on the circumference of the outer ring circle, and one end is connected to the outer ring arm;

[0012] The inner ring arm, inner ring wing, outer ring arm and outer ring wing are all microstrip line structures and are combined to form a conductive unit. The four conductive units are rotationally symmetrical with the feeding point as the symmetry center to form a windmill-shaped single-sided feeding microstrip on one side of the substrate.

[0013] On the basis of the above technical solution, preferably, the four inner ring arms are connected at a feeding point to form a cross structure, and a forty-five degree angle is formed between the outer ring arm and any adjacent inner ring arm.

[0014] On the basis of the above technical solution, preferably, it also includes a feeding post, the number of the single-sided feeding microstrips is two, and they are respectively arranged on both sides of the substrate, the feeding post passes through the substrate through the feeding point and connects the two single-sided feeding microstrips, the projections of the eight inner ring wings on the same side of the substrate form an inner closed circular loop, the projections of the eight outer ring wings on the same side of the substrate form an outer closed circular loop, the projections of the inner ring arms on both sides of the substrate on the same side overlap, and the projections of the outer ring arms on both sides on the same side overlap.

[0015] Further preferably, the length of the inner ring wing is one eighth of the circumference of the inner ring, and the length of the outer ring wing is one eighth of the circumference of the outer ring.

[0016] Further preferably, the width of the inner closed circular loop is greater than the width of the outer closed circular loop.

[0017] On the basis of the above technical solution, preferably, the inner ring arm and the outer ring arm are both straight strip structures, and the width of the inner ring arm is smaller than the width of the outer ring arm.

[0018] More preferably, the width of the inner ring arm is 1.5-2.5 mm, and the width of the outer ring arm is 1.7-4.3 mm.

[0019] Further preferably, the inner diameter of the inner closed circular loop is 3.03-5.03 mm, and the inner diameter of the outer closed circular loop is 7.35-12.35 mm.

[0020] More preferably, the width of the inner closed circular loop is 1.5-4.5 mm, and the width of the outer closed circular loop is 0.5-4 mm.

[0021] The annular windmill-type structure microstrip array antenna of the present invention has the following beneficial effects compared with the prior art:

[0022] (1) By setting up an inner and outer ring structure, the antenna achieves good omnidirectional radiation performance in two frequency bands, ensuring that the antenna can radiate electromagnetic waves evenly in all directions. The antenna, through its innovative inner and outer ring structure and windmill-shaped design, can provide efficient dual-frequency radiation characteristics while being miniaturized, meeting the requirements of the 5G communication system for multi-band, miniaturization, and efficient transmission.

[0023] (2) The impedance matching characteristics of the antenna are optimized by designing the size and structure of the inner and outer rings. In the two operating frequency bands, the reflection coefficient of the antenna is low, ensuring low reflection loss and efficient signal transmission. This optimization improves the working stability and reliability of the antenna and can better support high-frequency applications such as 5G communications;

[0024] (3) By optimizing the size of the inner and outer rings and the spacing between the loops, the coupling effect between the rings is reduced, thereby effectively avoiding the problems of uneven current distribution and deterioration of the radiation pattern. This design ensures that the antenna can achieve a stable radiation pattern in both frequency bands, greatly improving the actual application performance of the antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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.

[0026] Figure 1 It is a schematic structural diagram of the microstrip array antenna of the annular windmill type structure of the present invention;

[0027] Figure 2 A schematic diagram of the dimensions of the microstrip array antenna of the annular windmill type structure of the present invention;

[0028] Figure 3 This is a current distribution simulation diagram of the microstrip array antenna with an annular windmill-type structure according to the present invention;

[0029] Figure 4 A reflection coefficient / frequency diagram of a preferred embodiment of the microstrip array antenna with an annular windmill-type structure according to the present invention;

[0030] Figure 5-7 A schematic diagram of reflection coefficient / frequency of the inner diameter variation of the closed circular loop in the annular windmill-type structure microstrip array antenna of the present invention;

[0031] Figure 8-10 It is a schematic diagram of the reflection coefficient / frequency of the inner diameter variation of the outer closed circular loop of the annular windmill-type structure microstrip array antenna of the present invention;

[0032] Figure 11-13 It is a schematic diagram of reflection coefficient / frequency of the width variation of the inner ring arm of the ring-shaped windmill-type structure microstrip array antenna of the present invention;

[0033] Figure 14-16 A schematic diagram of reflection coefficient / frequency of the width variation of the outer ring arm of the ring-shaped windmill-type structure microstrip array antenna of the present invention;

[0034] Figure 17-19 A schematic diagram of reflection coefficient / frequency of a closed circular loop with a width variation in a microstrip array antenna with an annular windmill-type structure according to the present invention;

[0035] Figure 20-22 A schematic diagram of reflection coefficient / frequency of the width variation of the outer closed circular loop of the annular windmill-type structure microstrip array antenna of the present invention;

[0036] Fig.23 The 3D radiation pattern of the microstrip array antenna with an annular windmill-type structure of the present invention;

[0037] Fig.24 The simulated two-dimensional radiation pattern of the microstrip array antenna with a ring-shaped windmill-type structure of the present invention having a resonant frequency of 3.24 GHz;

[0038] Fig.25 This is a simulated two-dimensional radiation pattern of the microstrip array antenna with a ring-shaped windmill-type structure of the present invention with a resonant frequency of 4.91 GHz. DETAILED DESCRIPTION

[0039] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The loop antenna is one of the common forms of terminal antennas. It refers to a radiation structure in which a metal conductor is wound into a certain shape and the two ends of the conductor are used as the feed end. Because the loop antenna has the characteristics of multi-mode resonance, it is easy to achieve multi- / wideband coverage, and its design principle is simple, so it has a wide range of applications, especially the square loop antenna and circular loop antenna. In principle, the loop antenna is equivalent to an infinitesimal magnetic dipole; therefore, the mathematical expression of its radiation field distribution is the same as that of an infinitesimal magnetic dipole.

[0041] The loop antenna is a commonly used form in antenna design, which uses its two ends as the feeding end. From the structure of the loop antenna, its surface current path is a closed one, and it can be seen that the coupling effect between it and the ground plane is small. This structural feature makes the loop antenna have a relatively stable performance and can be used in complex working environments with dissipation and interference. For an independent loop antenna, it is difficult to excite the λ / 4 working mode, and it generally works mainly in the λ / 2 and λ modes. In addition, the loop antenna can also resonate in the frequency doubling mode. With the appropriate tuning method, the loop antenna can be excited to work in an additional mode at 2λ, and a multi-resonance mode can be obtained, and the multi-resonance mode can meet the multi-band requirements of mobile communications. These advantages of the loop antenna have made it widely studied and designed in the fields of mobile phone built-in antennas.

[0042] Traditional single-frequency antennas can usually only work within one frequency band and cannot meet the multi-frequency band requirements of modern communication systems such as 5G. In addition, the radiation pattern is usually directional radiation, which cannot radiate signals evenly in all directions, easily causing communication blind spots.

[0043] This embodiment mainly proposes a dual-frequency antenna based on an Alford ring structure for use in the FR1 frequency band. Compared with a single-frequency antenna, the design of a dual-frequency antenna adds a loop, and the corresponding current distribution becomes more complicated, and the problems encountered in the design are also more complicated, such as the need to consider the coupling effect between the rings. However, this does not mean that the design experience of a single-frequency antenna is completely useless; the design of a dual-frequency antenna still requires continuous improvement based on the principle and structure of a single-frequency antenna to meet the needs of practical applications.

[0044] like Figure 1 As shown, the annular windmill-type structure microstrip array antenna of the present invention includes a substrate 1, an inner ring arm 2, an inner ring wing 3, an outer ring arm 4 and an outer ring wing 5. Through the innovative inner and outer ring structures and windmill-shaped design, it can provide efficient dual-frequency radiation characteristics while being miniaturized, meeting the requirements of the 5G communication system for multi-band, miniaturization and efficient transmission. The windmill-shaped structure mainly includes four blades, each of which is composed of an inner ring arm 2, an inner ring wing 3, an outer ring arm 4 and an outer ring wing 5.

[0045] A feeding point is provided on the substrate 1, and an inner circle and an outer circle are provided with the feeding point as the center. The inner circle is located inside the outer circle. The substrate 1 is a square plate with a size of 40mm x 40mm and a thickness of 0.7-1mm. The substrate 1 is made of FR-4 material with a relative dielectric constant of ε r =4.4, suitable for high-frequency millimeter wave applications.

[0046] The inner circle and the outer circle are not actual structures set on the substrate 1, but are designed for parameters corresponding to the dual-frequency setting of the antenna to set the inner and outer ring structures. The inner circle and the outer circle are both set around the feeding point, and the radii are set to be small and large, so that the inner circle is located inside the outer circle, and the diameter of the outer circle is not larger than the size of the substrate 1.

[0047] The two ends of the inner ring arm 2 are respectively connected to the feeding point and the circumference of the inner ring circle; the inner ring wing 3 is arranged on the circumference of the inner ring circle, and one end is connected to the inner ring arm 2; the outer ring arm 4 connects the circumference of the inner ring circle and the outer ring circle, and one end is connected to the inner ring wing 3; the outer ring wing 5 is arranged on the circumference of the outer ring circle, and one end is connected to the outer ring arm 4.

[0048] The inner ring wing 3 and the outer ring wing 5 are both arc-shaped structures. The inner ring wing 3 is arranged on the circumference of the inner ring circle and corresponds to a partial arc of the inner ring circle. Correspondingly, the outer ring wing 5 is arranged on the circumference of the outer ring circle and corresponds to a partial arc of the outer ring circle.

[0049] The inner ring arm 2 , inner ring wing 3 , outer ring arm 4 and outer ring wing 5 are all microstrip line structures and are combined to form a conductive unit, and the four conductive units are rotationally symmetrical with the feeding point as the symmetry center to form a windmill-shaped single-sided feeding microstrip on one side of the substrate 1 .

[0050] The conductive unit formed by the inner ring arm 2, the inner ring wing 3, the outer ring arm 4 and the outer ring wing 5 is the blade structure in the windmill-shaped design.

[0051] In this embodiment, the four inner ring arms 2 are connected at the feeding point to form a cross structure, and the outer ring arm 4 forms an angle of forty-five degrees with any adjacent inner ring arm 2 .

[0052] like Figure 1 As shown, the cross formed by the four inner ring arms 2 is regarded as the XY axis, and the four outer ring arms 4 are set at inclination angles of 45°, 135°, -45° and -135° respectively. The two diagonal outer ring arms 4 are connected and combined with the four inner ring arms 2, the outer ring circle can be divided into eight areas, each of the eight areas has an inner ring wing 3 or an outer ring wing 5, and the inner ring wing 3 and the outer ring wing 5 are alternately arranged in the eight areas, with the clockwise direction as the head and the counterclockwise direction as the tail. The inner ring arm 2 is connected to the tail end of the inner ring wing 3, and the outer ring arm 4 is connected to the head section of the inner ring wing 3 and the tail end of the outer ring wing 5.

[0053] In this embodiment, a feeding column 5 is also provided, and the number of the single-sided feeding microstrips is two, which are respectively provided on both sides of the substrate 1. The feeding column 5 passes through the substrate 1 through the feeding point and connects the two single-sided feeding microstrips. The projections of the eight inner ring wings 3 on the same side of the substrate 1 form an inner closed circular loop, and the projections of the eight outer ring wings 5 ​​on the same side of the substrate 1 form an outer closed circular loop. The projections of the inner ring arms 2 on both sides of the substrate 1 on the same side coincide, and the projections of the outer ring arms 4 on both sides coincide.

[0054] by Figure 1 The front side is shown, wherein the solid line portion is the single-sided feeding microstrip on the front side, and the dotted line portion is the single-sided feeding microstrip on the back side. It can be seen that when the substrate 1 is rotated one hundred and eighty degrees so that the back side faces forward, the single-sided feeding microstrip on the back side will overlap with the single-sided feeding microstrip on the front side. This arrangement will cause the eight outer ring wings 5 ​​to form a discontinuous outer closed circular loop, while the eight inner ring wings 3 will form a discontinuous inner closed circular loop. The inner and outer loops correspond to two frequency signals respectively, and the loop width of the inner closed circular loop is greater than the loop width of the outer closed circular loop, so that the inner closed circular loop corresponds to a frequency band with a higher resonant frequency, while the outer closed circular loop corresponds to a frequency band with a lower resonant frequency.

[0055] As a preferred embodiment, in order to ensure the consistency of the radiation effect of the antenna in different directions, the length of the inner ring wing 3 is one-eighth of the circumference of the inner ring, and the length of the outer ring wing 5 is one-eighth of the circumference of the outer ring, so that the lengths of the inner ring wings 3 are consistent, and the outer ring wings 5 ​​are also arranged to be the same size.

[0056] In this embodiment, the inner ring arm 2 and the outer ring arm 4 are both in a straight strip structure, and the width of the inner ring arm 2 is smaller than the width of the outer ring arm 4 .

[0057] like Figure 2 As shown, the length and width of the substrate 1 are both L0 and the thickness is H, the width of the inner ring arm 2 is t1, the width of the outer ring arm 4 is t2, the inner diameter of the inner closed circular loop is R1, the inner diameter of the outer closed circular loop is R2, the width of the inner closed circular loop is W1, and the width of the outer closed circular loop is W2. In this embodiment, taking the dual frequencies of 3.24 GHz and 4.91 GHz as an example, since L0 and H are already determined when designing the antenna, no change adjustment is required, that is, L0 = 40 mm, H = 0.7 mm. According to simulation experiments, as shown in FIG. Figure 3As shown, when the resonant frequency is 3.24 GHz, the current is mainly distributed on the four sides of the outer ring. It can be seen that near the 3.24 GHz frequency, the outer ring side plays the main radiation role. Since the thickness of the dielectric substrate 1 is very thin, its influence can be ignored. The outer ring current is evenly distributed, and an omnidirectional pattern can be formed in this frequency band. When the resonant frequency is 4.91 GHz, the current is mainly distributed on the four sides of the inner ring. It can be seen that near the 4.91 GHz frequency, the inner ring side plays the main radiation role. Ignoring the influence of the dielectric substrate, the inner ring current is evenly distributed, and an omnidirectional pattern can be formed near this frequency band. This is consistent with the principle that the effective length of the antenna is inversely proportional to its own resonant frequency.

[0058] Ideally, when the current of the antenna is distributed on the outer ring, there is no current on the inner ring, so it has no effect on the radiation of the outer ring; but in reality, due to the unreasonable design of the transition zone of the outer ring, a certain amount of current will appear on the inner ring, thus affecting the radiation of the outer ring and making the radiation pattern worse. Similarly, when the antenna current is mainly distributed on the inner ring, this situation will also occur, and the arm of the outer ring can act as the transition zone of the inner ring, thereby optimizing its radiation pattern. Therefore, in order to obtain a good omnidirectional radiation pattern, the transition zone must be reasonably designed.

[0059] Changes in the physical size of the antenna will have a great impact on the antenna's resonant frequency. The physical size of the antenna is negatively correlated with the corresponding resonant frequency. Therefore, when the physical size of the antenna is determined, the corresponding resonant frequency is also determined. The relationship between the physical size of the antenna and the resonant frequency can be explained as follows: under the condition of a certain speed of light, the physical size of the antenna is proportional to the wavelength, and the wavelength is inversely proportional to the frequency, so the physical size is inversely proportional to the resonant frequency. Because the present annular windmill-type structure microstrip array antenna is a dual-ring structure, a resonant frequency is not only related to the physical size of the corresponding ring, but also to the physical size of the other ring; so for the design of a resonant frequency, it is necessary to consider the physical sizes of the two rings comprehensively.

[0060] The structural parameters of the antenna will have a great impact on its impedance matching, such as the side length, arm width and wing width of the antenna. In this way, the arm and wing width of the inner and outer rings can be reasonably designed to meet the required impedance matching. In the actual simulation process, it can be found that near certain specific values, the reflection coefficient peak is the lowest and the bandwidth is the largest. However, the design experience for single frequency can only be used as a reference, and the changes in the arm width and wing width are not simply proportional or inversely proportional to the impedance characteristics of the antenna; therefore, for the impedance matching problems encountered in dual frequency, more adjustments and research are needed to optimize the antenna impedance matching characteristics as much as possible.

[0061] Each parameter of the antenna is not isolated. To optimize the antenna performance, it needs to be coordinated with other parameters. The designed antenna must be simulated and calculated, and continuously adjusted and optimized. The final selected parameter range is as follows:

[0062] The width of the inner ring arm 2 is 1.5-2.1 mm;

[0063] The width of the outer ring arm 4 is 1.7-4.3 mm;

[0064] The inner diameter of the inner closed circular loop is 3.03-5.03 mm;

[0065] The inner diameter of the outer closed circular loop is 7.35-12.35 mm;

[0066] The width of the inner closed circular loop is 1.5-4.5 mm;

[0067] The width of the outer closed circular loop is 0.5-2.5 mm.

[0068] The width of the inner ring arm 2 is t1, the width of the outer ring arm 4 is t2, the inner diameter of the inner closed circular loop is R1, the inner diameter of the outer closed circular loop is R2, the width of the inner closed circular loop is W1, and the width of the outer closed circular loop is W2.

[0069] like Figure 5-7 As shown, they are reflection coefficient / frequency diagrams of R1=3.03mm, R1=3.78mm, and R1=5.03mm respectively.

[0070] like Figure 8-10 As shown, they are reflection coefficient / frequency diagrams for R2=7.35mm, R2=11.35mm, and R2=12.35mm respectively.

[0071] like Figure 11-13 As shown, they are reflection coefficient / frequency schematic diagrams for t1=1.5mm, t1=2mm, and t1=2.1mm respectively.

[0072] like Figure 14-16 As shown, they are reflection coefficient / frequency diagrams for t2=1.7mm, t2=3.4mm, and t2=4.3mm respectively.

[0073] like Figure 17-19 As shown, they are reflection coefficient / frequency diagrams for W1=1.5mm, W1=4mm, and W1=4.5mm respectively.

[0074] like Figure 20-22 As shown, they are reflection coefficient / frequency diagrams for W2=0.5mm, W2=2mm, and W2=2.5mm respectively.

[0075] It can be seen that changes in W1, W2, R1, and R2 will cause the reflection coefficient / frequency curve to shift and not meet the requirements. And t1 and t2 are related to the magnitude of the current and will also affect the reflection coefficient / frequency curve.

[0076] Therefore, according to the simulation experiment, a better parameter in this embodiment is obtained, such as Figure 2 As shown, the width of the inner ring arm 2 is t1=1.6mm, the width of the outer ring arm 4 is t2=2.8mm, the inner diameter of the inner closed circular loop is R1=3.53mm, the inner diameter of the outer closed circular loop is R2=10.35mm, the width of the inner closed circular loop is W1=2.5mm, and the width of the outer closed circular loop is W2=1.5mm. It should be noted that the changes in the reflection coefficient / frequency curve caused by the above-mentioned different size modifications are all single variable adjustments made on the basis of the optimal parameters.

[0077] According to the optimal parameters, the designed antenna is simulated using AltairFEKO software. The simulated 3D radiation pattern, H-plane radiation pattern and E-plane radiation pattern are shown as follows: Figure 23-25 As shown in the figure, it can be seen from the radiation pattern that the antenna has good horizontal omnidirectionality. Figure 4 As shown in the figure, it is the reflection coefficient curve of the antenna simulation. It can be seen from the figure that its resonant frequencies are 3.24GHz and 4.91GHz; the reflection coefficient at the resonance point of 3.24GHz is about -23.1dB, and the reflection coefficient at the resonance point of 4.91GHz is about -17.1dB. At the two resonance points, the impedance matching of the system is relatively good.

[0078] The annular windmill-type structure microstrip array antenna in this embodiment can work stably in the two frequency bands of 3.3-3.6GHz and 4.8-5.0GHz, meeting the dual-frequency requirements of 5G communication in the FR1 frequency band, and the inner and outer ring structures achieve good omnidirectional radiation performance in the two frequency bands, ensuring that the antenna can radiate electromagnetic waves evenly in all directions. Subsequent simulation results also verified that the designed omnidirectional radiation performance is good. At the same time, the impedance matching characteristics of the antenna are optimized by designing the size and structure of the inner and outer rings. In the two operating frequencies of 3.24GHz and 4.91GHz, the reflection coefficients of the antenna are approximately "-23.1dB and -17.1dB", respectively, ensuring low reflection loss and efficient signal transmission. This optimization improves the working stability and reliability of the antenna, and can better support high-frequency applications such as 5G communications.

[0079] In addition, in the traditional dual-band antenna design, the coupling effect between multiple loops may cause problems such as uneven current distribution and unstable radiation, affecting the performance of the antenna. The design of this embodiment reduces the coupling effect between the loops by optimizing the size of the inner and outer loops and the spacing between the loops, thereby effectively avoiding the problems of uneven current distribution and deterioration of the radiation pattern. This design ensures that the antenna can achieve a stable radiation pattern in both frequency bands, greatly improving the actual application performance of the antenna.

[0080] The use of the annular windmill-type microstrip array antenna in this embodiment can be divided into the following steps: 1. Current drive: The signal current starts to flow from the central connection point and is evenly distributed to the four "windmill blades". Each blade transmits the signal through the microstrip line, so that the current is distributed along the blade, thereby achieving radiation. 2. Omnidirectional radiation: The symmetrical distribution of the current enables the antenna to radiate electromagnetic waves evenly in all directions, thus forming an omnidirectional radiation pattern. Due to the design of the antenna, electromagnetic waves can be radiated evenly from each "windmill blade" to the outside world. 3. Signal input: The high-frequency signal is input through the feed port, and the signal is transmitted to the central connection point of the antenna after impedance matching. 4. By adjusting the length, width and bending angle of the antenna blades, the resonant frequency and bandwidth of the antenna can be fine-tuned to ensure that the antenna has a lower reflection coefficient and a larger working bandwidth in the target frequency band. 5. The design of the windmill-shaped antenna ensures that the radiated signal is horizontally polarized, which is very important for applications in mobile communications, wireless local area networks (WLANs) and other high-speed wireless communication systems.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A microstrip array antenna with a ring-shaped windmill structure, characterized in that: It comprises a base plate (1), an inner ring arm (2), an inner ring wing (3), an outer ring arm (4) and an outer ring wing (5), wherein: A feeding point is arranged on the substrate (1), and an inner circle and an outer circle are arranged with the feeding point as the center, wherein the inner circle is located inside the outer circle; Two ends of the inner ring arm (2) are respectively connected to the feeding point and the circumference of the inner ring circle; The inner ring wing (3) is arranged on the circumference of the inner ring circle, and one end of the inner ring wing is connected to the inner ring arm (2); The outer ring arm (4) connects the circumference of the inner ring circle and the outer ring circle, and one end is connected to the inner ring wing (3); The outer ring wing (5) is arranged on the circumference of the outer ring circle, and one end of the outer ring wing is connected to the outer ring arm (4); The inner ring arm (2), the inner ring wing (3), the outer ring arm (4) and the outer ring wing (5) are all microstrip line structures and are combined to form a conductive unit, and the four conductive units are rotationally symmetrical with the feeding point as the symmetry center to form a windmill-shaped single-sided feeding microstrip on one side of the substrate (1).

2. The microstrip array antenna with a ring-shaped windmill structure as claimed in claim 1, characterized in that: The four inner ring arms (2) are connected at a feeding point to form a cross-shaped structure, and an angle of forty-five degrees is formed between the outer ring arm (4) and any adjacent inner ring arm (2).

3. The microstrip array antenna with an annular windmill structure as claimed in claim 1, characterized in that: It also includes a feeding column (5), wherein the number of the single-sided feeding microstrips is two and they are respectively arranged on both sides of the substrate (1), the feeding column (5) passes through the substrate (1) through a feeding point and connects the two single-sided feeding microstrips, the projections of the eight inner ring wings (3) on the same side of the substrate (1) form an inner closed circular loop, the projections of the eight outer ring wings (5) on the same side of the substrate (1) form an outer closed circular loop, the projections of the inner ring arms (2) on the same side of the substrate (1) overlap, and the projections of the outer ring arms (4) on the same side overlap.

4. The microstrip array antenna with an annular windmill structure as claimed in claim 3, characterized in that: The length of the inner ring wing (3) is one eighth of the circumference of the inner ring, and the length of the outer ring wing (5) is one eighth of the circumference of the outer ring.

5. The microstrip array antenna with an annular windmill structure as claimed in claim 3, characterized in that: The loop width of the inner closed circular loop is greater than the loop width of the outer closed circular loop.

6. The microstrip array antenna with a ring-shaped windmill structure as claimed in claim 1, characterized in that: The inner ring arm (2) and the outer ring arm (4) are both in the form of a straight strip structure, and the width of the inner ring arm (2) is smaller than the width of the outer ring arm (4).

7. The microstrip array antenna with a ring-shaped windmill structure as claimed in claim 6, characterized in that: The width of the inner ring arm (2) is 1.5-2.5 mm, and the width of the outer ring arm (4) is 1.7-4.3 mm.

8. The ring-shaped windmill-type microstrip array antenna according to claim 3, characterized in that: The inner diameter of the inner closed circular loop is 3.03-5.03 mm, and the inner diameter of the outer closed circular loop is 7.35-12.35 mm.

9. The microstrip array antenna with a ring-shaped windmill structure as claimed in claim 8, characterized in that: The width of the inner closed circular loop is 1.5-4.5 mm, and the width of the outer closed circular loop is 0.5-4 mm.

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