Double-leaf radiation patch and fractal feed double-leaf antenna

Abstract

The invention relates to the technical field of antennas, and discloses a double-blade radiation patch which is in a flat shape with a narrow middle part and two wide ends. The invention further discloses a fractal feed double-leaf antenna, a reflecting plate, a first micro-strip plate, a fractal feed structure, a second micro-strip plate, a coupling structure with a coupling gap, a third micro-strip plate and the double-leaf radiation patch are sequentially arranged from one end of the antenna to the other end of the antenna, and in the direction perpendicular to the reflecting plate, the fractal feed structure is arranged on the first micro-strip plate, and the fractal feed structure is arranged on the second micro-strip plate. The fractal feed structure and the coupling slot are arranged in a coupling manner, and the double-leaf radiation patch is correspondingly arranged right above the coupling slot. The antenna adopts a fractal structure for feeding, a single feed point introduces a double-branch structure and is respectively coupled to two slots, and meanwhile, a secondary matching branch is introduced, so that the current distribution is effectively improved, and the impedance matching is further improved. The unit spacing in the form can be one time of wavelength of high frequency, and a large-spacing antenna under the condition of a single feed point is successfully realized.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a double-leaf radiating patch and a fractal-fed double-leaf antenna. Background Art

[0002] In recent years, with the increasing demand for applications such as high-resolution detection, long-distance communication, and weak signal detection, array antennas have developed in the direction of large-scale.

[0003] The main reasons restricting the application of large phased arrays are as follows:

[0004] (1) High hardware cost. As the aperture increases, the cost of active components increases proportionally.

[0005] (2) Smaller array element spacing makes it difficult to layout active components, especially in the millimeter wave frequency band;

[0006] (3) Large phased arrays are heavy and difficult to dissipate heat.

[0007] Using large-pitch arrays is an effective way to reduce the number of array elements and reduce costs. Large-pitch periodic arrays designed according to conventional methods are bound to have grating lobes. In order to solve this problem, many experts, scholars and engineering technicians have conducted extensive research on grating lobe suppression technology and have achieved outstanding results in large-pitch array grating lobe suppression technology. At present, there are many optimization algorithms, such as genetic algorithms, simulated annealing algorithms, particle swarm algorithms, differential evolution methods, FFT (Fast Fourier Transform), etc., which have been widely studied and applied in grating lobe suppression and have achieved good results.

[0008] However, in practical applications, the design of large-spacing antennas is a major difficulty. As the spacing between units increases, the antenna beam width becomes narrower, the mutual coupling between units is very different from the conventional unit spacing, and the input impedance of the radiating unit changes dramatically with frequency, resulting in antenna mismatch and large power reflection. Therefore, the research on large-spacing antennas has become a difficult problem that needs to be solved urgently. Summary of the invention

[0009] The present invention provides a double-leaf radiation patch and a fractal feeding double-leaf antenna to solve the above problems.

[0010] The present invention is achieved through the following technical solutions:

[0011] A double-leaf radiating patch is flat with a narrow middle portion and wide ends.

[0012] As an optimization, rounded corners are provided between the first side edges at both ends of the radiation patch and the second side edges connecting the middle portion to the end portion of the radiation patch.

[0013] The present invention also discloses a fractal-fed double-leaf antenna, which is provided with a reflector, a first microstrip plate, a fractal feeding structure, a second microstrip plate, a coupling structure with a coupling slot, a third microstrip plate and the aforementioned double-leaf radiation patch in sequence from one end to the other end of the antenna, wherein the fractal feeding structure is coupled with the coupling slot in a direction perpendicular to the reflector, and the double-leaf radiation patch is correspondingly arranged directly above the coupling slot.

[0014] As an optimization, the fractal feeding structure includes a main feeder line and two primary matching branches whose length directions are respectively arranged perpendicular to the length direction of the main feeder line, and a secondary matching branch whose length direction is parallel to the length direction of the main feeder line is arranged at one end of the two primary matching branches away from the main feeder line.

[0015] As an optimization, each end of the secondary matching branch is respectively provided with a tertiary matching branch whose length direction is perpendicular to the length direction of the secondary matching branch.

[0016] As an optimization, two coupling slots are provided, and the two coupling slots are coupled to two primary matching branches respectively.

[0017] As an optimization, two of the double-leaf radiation patches are respectively arranged directly above each of the coupling gaps, and the projection of the central axis through the end of the double-leaf radiation patch on the coupling structure coincides with the central axis passing perpendicularly through the length direction of the secondary matching branch.

[0018] As an optimization, the length and width of the reflector are represented as D x and D y , D x and D y The absolute value of the difference between the wavelength of the highest operating frequency of the antenna and the wavelength of the antenna is within a preset range.

[0019] As an optimization, the coupling gap is in an "H" shape that matches the primary matching branch and the secondary matching branch.

[0020] As an optimization, the two primary matching branches are asymmetrically distributed along the center of the antenna azimuth plane.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] The antenna of the present invention adopts fractal structure feeding, and introduces a double branch structure into a single feed point, which is coupled to two slots respectively, and introduces a secondary matching branch at the same time, which effectively improves the current distribution and thus improves the impedance matching. This form of unit spacing can achieve 1 times the wavelength of the highest operating frequency of the antenna, successfully realizing a large spacing antenna with a single feed point.

[0023] The present invention adopts a double-leaf patch as a radiation patch. The narrower part in the middle of the gradient structure improves high-frequency radiation, and the wider part at the edge improves low-frequency radiation, thereby effectively widening the bandwidth. At the same time, the smooth arc structure reduces discontinuity and is conducive to improving impedance matching. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0025] Figure 1 is a schematic diagram of the structure of the antenna unit without showing the microstrip board;

[0026] Figure 2 It is a structural schematic diagram of the fractal feeding structure;

[0027] Figure 3 It is a schematic diagram of the structure of the improved fractal feeding structure;

[0028] Figure 4 Schematic diagram of a coupling structure with a coupling gap;

[0029] Figure 5 is a schematic diagram of the structure of the radiation patch;

[0030] Figure 6 This is a schematic diagram of the structure of a Ku-band large-spacing antenna structure in an embodiment;

[0031] Figure 7 for Figure 6 Schematic diagram of the feeding structure of the Ku-band large-spacing antenna structure;

[0032] Figure 8 for Figure 6 Schematic diagram of the coupling structure with coupling gaps of the Ku-band large-spacing antenna structure;

[0033] Fig. 9 for Figure 6 A schematic diagram of the structure of the radiation patch of the Ku-band large-spacing antenna structure;

[0034] Fig.10 It is a schematic diagram of the standing wave of the antenna unit;

[0035] Fig.11 is the antenna unit radiation pattern, where (a) is the E-plane lobe, the solid line is the main polarization, and the dotted line is the cross-polarization; (b) is the H-plane lobe, the solid line is the main polarization, and the dotted line is the cross-polarization. DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0037] This embodiment 1 provides a double-leaf radiation patch, such as Figure 5 As shown, the radiation patch is flat with a narrow middle portion and wide ends.

[0038] On the one hand, the use of a double-leaf radiating patch improves the current distribution on the radiating patch. Compared with a rectangular patch, the narrower middle part of the gradient patch improves high-frequency radiation, and the wider edge part improves low-frequency radiation, thereby effectively widening the bandwidth.

[0039] In some embodiments, a rounded corner is provided between a first side edge at both ends of the radiation patch and a second side edge connecting the middle portion to the end portion of the radiation patch.

[0040] In this way, the smooth arc-shaped structure reduces discontinuity and is conducive to improving impedance matching.

[0041] Next, a fractal-fed dual-leaf antenna according to Embodiment 2 is introduced.

[0042] This large spacing antenna adopts fractal structure feeding, and adopts double-leaf radiating patch as radiating patch, which effectively improves current distribution and impedance matching, and widens the antenna unit bandwidth. In the case of single feeding point, the unit spacing of the antenna form shown in the present invention can be 1 times the wavelength of high frequency, which effectively reduces the cost and weight of active components, and has a low profile height and is easy to process. Next, the fractal feeding double-leaf antenna of Example 2 is specifically introduced.

[0043] A reflector, a first microstrip plate, a fractal feeding structure, a second microstrip plate, a coupling structure with a coupling gap, a third microstrip plate, and the double-leaf radiation patch described in Example 1 are sequentially arranged from one end of the antenna to the other end. Figure 1 shown.

[0044] Specifically, the reflector is located at the bottom.

[0045] Wherein, in a direction perpendicular to the reflector, the fractal feeding structure is coupled with the coupling slot, and the double-leaf radiating patch is correspondingly arranged directly above the coupling slot. Specifically, there is no limit on the distance between two radiating patches directly above the same coupling slot.

[0046] The antenna unit size is D x ×D y , D x and D yThe absolute value of the difference between the wavelength of 1 times the highest operating frequency of the antenna is within the preset range. The specific preset range is formulated according to the actual working conditions and product design tolerance. This is a conventional design method for those skilled in the art and will not be described in detail here. Here, if the antenna operating frequency range is f1~f2, f1 is low frequency and f1 is high frequency. High frequency refers to the highest operating frequency of the antenna.

[0047] The reflector serves as the mounting surface of the antenna unit, and the radiation is controlled above the reflector.

[0048] In some embodiments, the fractal feeding structure includes a main feeder line and two first-level matching branches whose length directions are respectively arranged perpendicular to the length direction of the main feeder line, and a second-level matching branch whose length direction is parallel to the length direction of the main feeder line is arranged at one end of the two first-level matching branches away from the main feeder line.

[0049] It should be noted that the length direction mentioned in the present invention refers to the direction of the longest side of a shape, and is not limited to the x-axis or y-axis direction.

[0050] like Figure 2 As shown, the feeding port is located on the left side, and the fractal feeding structure includes a main feeding line, a primary matching branch and a secondary matching branch. The current enters the main feeding line from the feeding port, and then enters the primary matching branch 1-1 and the primary matching branch 1-2. The ends of the primary matching branch 1-1 and the primary matching branch 1-2 (the end away from the main feeding line) are respectively added with secondary matching branches 2-1, 2-2, 2-3 and 2-4. The secondary matching branches are used to improve the current distribution, thereby improving the impedance matching. The two primary matching branches are asymmetrically distributed along the center of the antenna azimuth plane. In this embodiment, the antenna azimuth plane refers to the left and right direction, that is, the direction parallel to the ground.

[0051] In some embodiments, each end of the secondary matching branch is respectively provided with a tertiary matching branch whose length direction is perpendicular to the length direction of the secondary matching branch.

[0052] That is to say, this fractal feeding structure can also be improved, that is, using three-level matching branches to further improve the current distribution, such as Figure 3 The improved fractal feeding structure is shown.

[0053] In some embodiments, the coupling gap is provided with two, such as Figure 4 The two coupling slots shown in the slot 1 and slot 2 are respectively coupled with two primary matching branches. The coupling slot is in an "H" shape that matches the primary matching branch and the secondary matching branch.

[0054] The first-level matching branch 1-1 and the first-level matching branch 1-2 are coupled to the gap 1 and the gap 2 respectively. Figure 4 The coupling gap uses two identical H-shaped gaps. The current distribution of the H-shaped gap is more uniform, which increases the coupling and widens the bandwidth.

[0055] In some embodiments, two of the double-leaf radiating patches are respectively arranged directly above each of the coupling gaps, and the projection of the central axis through the ends of the double-leaf radiating patches on the coupling structure coincides with the central axis perpendicular to the length direction of the secondary matching branch.

[0056] That is, the radiation patch uses 4 identical double-leaf patches, such as Figure 5 As shown. The use of a double-leaf radiating patch improves the current distribution on the radiating patch. Compared with a rectangular patch, the narrower part in the middle of the gradient patch improves high-frequency radiation, and the wider part at the edge improves low-frequency radiation, thereby effectively widening the bandwidth. At the same time, the smooth arc structure reduces discontinuity and is conducive to improving impedance matching.

[0057] The dimensions of each structure in the double-leaf antenna of the present invention can be obtained by a genetic algorithm (or other optimization algorithms), and the specific process is as follows:

[0058] S1. Determine the influencing factor that affects the bandwidth change. Specifically, the influencing factor that affects the bandwidth change is the width W of the middle part of the double-leaf radiation patch. patch 2. Width W of the end patch 1. Total length L patch 1; The length of the coupling gap L slot1 and width W slot1 ; and the length of the feed structure L m , the position L of the first-level matching branch k1 , L k2 , width W m1 , length L m1 , the width of the secondary matching branch W m2 , length L m2 .

[0059] S2. Establish an optimization model, encode the influencing factors, and solve the optimization model based on a genetic algorithm to obtain a feasible solution set, wherein the feasible solution set includes at least one element, one element is a feasible individual, and each feasible individual in the feasible solution set includes all the influencing factors that have been matched;

[0060] The specific process is:

[0061] S2.1, set the number of iterations of the genetic algorithm and the number of individuals to be solved in each generation of the population;

[0062] S2.2. Establish an optimization model, wherein the optimization model includes an objective function and a total constraint condition, wherein the objective function is to minimize the VSWR within the working bandwidth.

[0063] minVSWR;

[0064] Wherein, VSWR is the voltage standing wave ratio of the antenna;

[0065] S2.3, width W patch 2. Width W patch 1. Total length L patch 1. Length L slot1 , Width W slot1 Length L m 、Location L k1 、Location L k2 , Width W m1 Length L m1 , Width W m2 Length L m2 Encode to obtain the encoding value of the individual to be solved, and randomly generate an initial population consisting of several individuals to be solved based on the total constraint condition, let the initial population be the parent population, let the individual to be solved in the parent population be the parent individual, and the encoding value of each parent individual includes the width W patch 2. Width W patch 1. Total length L patch 1. Length L slot1 , Width W slot1 Length L m 、Location L k1 、Location L k2 , Width W m1 Length L m1 , Width W m2 Length L m2 ;

[0066] S2.4, manufacturing a double-leaf antenna according to the coding values ​​of each parent individual of the parent population, and obtaining the VSWR of the antenna manufactured according to the influencing factor;

[0067] S2.5, calculating a fitness function according to the bandwidth, and calculating the fitness value of each parent individual in the parent population according to the fitness function and sorting them;

[0068] S2.6, save the first M parent individuals with the largest fitness values ​​in the parent population, then select parent individuals from all parent individuals except the first M parent individuals with the largest fitness values ​​through roulette wheel to perform crossover mutation operations to obtain child individuals, then calculate the fitness values ​​of the child individuals after crossover mutation and sort them, reinsert the child individuals into the parent population according to the fitness values, select a set number of individuals to be solved to form a new parent population, and then return to S2.4;

[0069] S2.7. Repeat S2.4-S2.6 until the number of iterations is reached or the objective function value is within the specified threshold range. The parent population finally obtained is the feasible solution set, and the parent individuals in the parent population are feasible individuals.

[0070] Specifically, the fitness function may be consistent with the objective function.

[0071] S3. Taking each element in the feasible solution set as the optimal individual.

[0072] At that time, the size of the fractal-fed bilobate antenna can be designed according to the optimal individual results.

[0073] Next, the fractal feeding double-leaf antenna in the present invention is described by using a specific example.

[0074] This embodiment provides a Ku-band large-spacing antenna.

[0075] The Ku-band large-spacing antenna adopts microstrip form, and the microstrip board adopts Rogers RT / duroid 6002, whose dielectric constant is 2.94 and loss tangent is 0.0012.

[0076] The antenna consists of a microstrip plate, a reflector, a feeding structure, a coupling slot and a radiation patch, such as Figure 1 and Figure 6 As shown. The antenna azimuth plane unit spacing is D x =18.75mm, pitch unit spacing is D y =18.75mm.

[0077] The antenna units are, from bottom to top, a reflector, microstrip plate 1 (the first microstrip plate), a feeding structure, microstrip plate 2 (the second microstrip plate), a coupling slot, microstrip plate 3 (the third microstrip plate), and a radiation patch.

[0078] The thickness of the three-layer microstrip board is h s1 、h s2 、h s3 The thickness of the reflector, feed structure, coupling gap and radiation patch are h respectively. c1 、h c2 、h c3 、hc4 , the overall height of the antenna unit is h, h = hs1 + hs2 + hs3 + hc1 + h c2 +hc3+h c4 .

[0079] The reflector is located below the antenna unit and has a size of D x ×D y , the reflector serves as the mounting surface of the antenna unit, and the radiation is controlled above the reflector.

[0080] Feed structure such as Figure 7 The feed adopts a fractal structure, which consists of a main feed line, a primary matching branch, and a secondary matching branch.

[0081] The feed port is located on the left side of the antenna unit, and the width of the main feed line is W. m , length L m The main feeder connects two first-level matching branches 1-1 and 1-2. The width of the first-level matching branch is W. m1 , the length is L m1 .

[0082] Each first-level matching branch is connected to two second-level matching branches (2-1, 2-2, 2-3 and 2-4) above and below, and the width of the second-level matching branch is W. m2 , length L m2 The secondary matching branches are used to improve the current distribution, thereby improving the impedance matching and widening the antenna bandwidth.

[0083] The distance from the first-level matching branch 1-1 to the center of the antenna azimuth plane is L k1 , the distance from the matching branch 1-2 to the center of the antenna azimuth plane is L k2 The first-level matching branches 1-1 and 1-2 are coupled to slots 1 and 2 respectively. The first-level matching branches 1-1 and 1-2 are asymmetrically distributed along the center of the antenna azimuth plane. k1 =4.1mm, L k2 =5.3mm. By optimizing the positions of the primary matching branches 1-1 and 1-2, the impedance matching can be improved and the directional pattern can be optimized.

[0084] The gap structure consists of two identical H-shaped gaps, such as Figure 8 As shown, the two slots are symmetrically distributed along the center of the antenna unit azimuth plane, and the center distance between the two slots is L slot , the long seam length of the H-shaped gap is L slot1 , width W slot1 , the short slit length is L slot2 , width W slot2 .W slot1 =0.75mm, W slot2=0.65mm. The H-type gap current distribution is more uniform, which increases coupling and widens the bandwidth. slot2 , L slot2 To optimize the coupling amount and improve impedance matching.

[0085] The radiation patch is composed of 4 identical double-leaf patches, such as Fig. 9 As shown, the distance between the centers of the two-leaf patches in the azimuth plane is L patchx , the spacing in the pitch plane is L patchy The length of the double leaf patch is L patch1 , the widths at the edge and center are W patch1 and W patch2 .L patch1 =6.4mm, W patch1 =4.1mm, W patch2 =1.75mm. By optimizing W patch1 , W patch2 It can improve the impedance matching of low frequency and high frequency.

[0086] The use of a double-leaf radiating patch improves the current distribution on the radiating patch. Compared with a rectangular patch, the narrower part in the middle of the gradient patch improves high-frequency radiation, and the wider part at the edge improves low-frequency radiation, thereby effectively widening the bandwidth. At the same time, the smooth arc structure reduces discontinuity and is conducive to improving impedance matching.

[0087] Antenna unit standing wave Fig.10 As shown in the figure, it can be seen that in the frequency range of 14 to 16 GHz, the standing wave of the antenna unit is <2, that is, the antenna bandwidth below the standing wave 2 reaches 13.3%.

[0088] Antenna unit lobes Fig.11 As shown in the figure, we can see that the gain of a single antenna unit is as high as 10.8dB and the cross-polarization level is lower than -40dB.

[0089] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A double-leaf radiation patch, characterized in that: The radiation patch is flat and narrow in the middle and wide at both ends.

2. A double-leaf radiation patch according to claim 1, characterized in that: A rounded corner is provided between the first side edges at both ends of the radiation patch and the second side edges connecting the middle portion to the end portion of the radiation patch.

3. A fractal-fed dual-leaf antenna, characterized in that: A reflector, a first microstrip plate, a fractal feeding structure, a second microstrip plate, a coupling structure with a coupling slot, a third microstrip plate and the double-leaf radiation patch described in claims 1 and 2 are arranged in sequence from one end to the other end of the antenna, wherein the fractal feeding structure is coupled with the coupling slot in a direction perpendicular to the reflector, and the double-leaf radiation patch is correspondingly arranged directly above the coupling slot.

4. A fractal-fed dual-leaf antenna according to claim 3, characterized in that: The fractal feeding structure includes a main feeder line and two primary matching branches whose length directions are respectively arranged perpendicular to the length direction of the main feeder line, and a secondary matching branch whose length direction is parallel to the length direction of the main feeder line is arranged at one end of the two primary matching branches away from the main feeder line.

5. A fractal-fed dual-leaf antenna according to claim 4, characterized in that: The end of each of the secondary matching branches is respectively provided with a tertiary matching branch whose length direction is perpendicular to the length direction of the secondary matching branch.

6. A fractal-fed dual-leaf antenna according to claim 4 or 5, characterized in that: There are two coupling slots, and the two coupling slots are coupled to two primary matching branches respectively.

7. A fractal-fed dual-leaf antenna according to claim 6, characterized in that: Two of the double-leaf radiating patches are respectively arranged directly above each of the coupling gaps, and the projection of the central axis through the ends of the double-leaf radiating patches on the coupling structure coincides with the central axis perpendicular to the length direction of the secondary matching branch.

8. A fractal-fed dual-leaf antenna according to claim 3, characterized in that: The length and width of the reflector are represented by D x and D y , D x and D y The absolute value of the difference between the wavelength of the highest operating frequency of the antenna and the wavelength of the antenna is within a preset range.

9. A fractal-fed dual-leaf antenna according to claim 4, characterized in that: The coupling gap is in an "H" shape that matches the primary matching branch and the secondary matching branch.

10. A fractal-fed dual-leaf antenna according to claim 3, characterized in that: The two primary matching branches are asymmetrically distributed along the center of the antenna azimuth plane.

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