A broadband filtered dual circularly polarized array antenna

Abstract

The invention discloses a broadband filtering dual circular polarization array antenna, which belongs to the field of antenna technology. The antenna includes a feeding structure, a dielectric substrate and a floor from top to bottom; the feeding structure includes a circular serial feeding strip, a swastika-shaped branch and four umbrella-shaped excitation strips; the floor includes four circular holes, and the end of each umbrella-shaped excitation strip is 4mm-6mm away from the edge of the circular hole. The feeding structure cooperates with the circular hole to generate stronger circular polarization excitation, synthesizes a circular polarization wave with higher circular polarization purity as a whole, and realizes circular polarization radiation with higher gain and more stability; at the same time, the swastika-shaped branch and the slender slit constitute a low-frequency filtering structure, which cooperates with the umbrella-shaped excitation strip to generate radiation zero points at low frequencies and high frequencies, thereby improving the out-of-band suppression level of the antenna.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a broadband filtering dual circular polarization array antenna. Background Art

[0002] Broadband circularly polarized antennas are widely used in various scenarios due to their advantages such as resistance to multipath fading and interference, high bandwidth, and flexible orientation between transmitters and receivers. In satellite communication systems, in order to increase channel capacity and reduce the impact of multipath interference, broadband dual circularly polarized microstrip antennas with high isolation characteristics are used. In radio frequency communication systems, the use of circularly polarized microstrip filter antennas with high gain characteristics can not only provide a longer communication distance, but also solve problems such as multipath loss, insensitivity to device orientation, and interference. Broadband filtered circularly polarized antennas integrate circularly polarized antennas and filtering functions into one, and on the basis of realizing broadband circularly polarized radiation, they can also improve the antenna's anti-interference ability and reduce the size of the RF front end. The filtering function of the circularly polarized antenna is generally filtered by cascading filters, but this is not conducive to antenna integration design, and the cascading of filters leads to increased insertion loss, which is not conducive to effective antenna radiation.

[0003] Currently, there are few studies on broadband filtered dual circularly polarized antennas with stable gain. Generally, the out-of-band radiation suppression characteristics of the antenna are achieved by loading special structures on the radiation structure, adding parasitic structures, and cascading filters on the feed. However, this often leads to low out-of-band suppression levels and low gain, which makes it difficult to meet the current needs of high-speed, high-bandwidth and dual circularly polarized communications. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of the prior art and provide a broadband filtering dual circular polarization array antenna.

[0005] The object of the present invention is achieved through the following technical solutions: a broadband filtering dual circular polarization array antenna, the antenna comprising a feeding structure, a dielectric substrate and a floor from top to bottom, the feeding structure being connected to the floor via a coaxial line;

[0006] The feeding structure comprises a circular series feed strip, a swastika-shaped branch and four umbrella-shaped excitation strips, wherein the circular series feed strip comprises a plurality of arc strips which are connected in series and not closed at the head and tail to form an opening, and a straight line extending from the center of the circular series feed strip is connected to an arc strip at the opening; the swastika-shaped branch comprises four vertical branch groups, and the vertical branch groups comprise a first branch arranged on the circular series feed strip and a second branch vertically connected to the first branch; the straight line segment in the umbrella-shaped excitation strip is connected to the intersection of the first branch and the second branch, and the arc segment in the umbrella-shaped excitation strip is bent toward the second branch, and the four umbrella-shaped excitation strips are centrally symmetrically distributed;

[0007] The floor also includes four circular holes, the edges of which are provided with an inwardly concave rectangular disturbance structure and an outwardly convex elliptical disturbance structure, the angle between the rectangular disturbance structure and the elliptical disturbance structure is in the range of 40°-50°, and the ends of each umbrella-shaped excitation strip are 4mm-6mm away from the edges of the circular holes.

[0008] In one example, the circular series feed strip includes four arc strips, and in counterclockwise order from the opening, the outer radii of the four arc strips are 12mm-13mm, 12.5mm-13.5mm, 10mm-11mm, and 9.5mm-10mm respectively.

[0009] In one example, the length of the second branch in the swastika-shaped branches is greater than a quarter wavelength of the frequency at the radiation zero point.

[0010] In one example, the feeding structure further includes four impedance matching adjustment branches, which are vertically arranged on the first branch and extend in the opposite direction to the second branch.

[0011] In one example, the floor comprises four elongated slots distributed symmetrically around the center.

[0012] In one example, the length of the elongated slit groove is 18 mm-21 mm, the width is 1.5 mm-1.8 mm, and the edge of the elongated slit groove is 30 mm-33 mm away from the center of the floor.

[0013] In one example, the radius of the circular hole groove is 42mm-48mm, and the center of the circular hole groove is 76mm-78mm away from the center of the floor; two concave rectangular disturbance structures and two convex elliptical disturbance structures are provided on the edge of the circular hole groove, the width of the rectangular disturbance structure is 6mm-7mm, and the long axis length of the elliptical disturbance structure is 12mm-13mm.

[0014] In one example, the floor further includes four elongated grooves, each of which is disposed between two circular hole grooves.

[0015] In one example, the length of the long strip groove is 55mm-63mm, the width is 3mm-4mm, and the edge of the long strip groove is 40mm-45mm away from the top of the floor.

[0016] In one example, the four circular holes and the four long strip grooves are all distributed in a centrally symmetrical manner.

[0017] It should be further explained that the technical features corresponding to the above examples can be combined or replaced with each other to form a new technical solution.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. In one example, an umbrella-shaped excitation strip is used to asymmetrically excite the circular aperture slot to generate stronger circular polarization excitation, and the umbrella-shaped excitation strip extends at the end of the swastika-shaped branch node, and can be integrated with the swastika-shaped branch node as a whole, so that the structure is simpler. At the center of the feeding structure, there are sequentially connected annular branches (circular serial feed strips). The circular serial feed strips are combined with other structures (such as impedance matching adjustment branches, swastika-shaped branches, etc.) to generate good power distribution and sequential phase shift of 90°, so that the antenna is excited at a single circular aperture slot, and circular polarization is achieved. On the basis of circular polarization, a circular polarization wave with higher circular polarization purity can be synthesized as a whole, so as to achieve higher gain and more stable circular polarization radiation;

[0020] At the same time, the swastika-shaped branches and the elongated slits form a low-frequency filtering structure, which is beneficial to the integrated design of the antenna, and the swastika-shaped branches can make the current at the low frequency concentrated at its end, while the current distribution at the umbrella-shaped excitation strip is very weak, and it cannot effectively excite the circular hole slot of the antenna to radiate, thereby generating a radiation zero point at the low frequency; the elongated slit slot at the floor is designed at the end of the swastika-shaped branch, and at high frequencies it can excite the elongated slit slot through the swastika-shaped branch and generate strong resonance. At high frequencies, the electric field energy on the floor is strongest at the elongated slit slot. The strong resonance of the elongated slit slot destroys the original circular polarization radiation mode, making it impossible for the antenna to radiate well at the corresponding high frequency, so a radiation zero point is generated at the high frequency. By controlling the position of the radiation zero point, the radiation characteristics of the antenna can be optimized, ensuring good radiation performance in the required working frequency band, and improving the out-of-band suppression level of the antenna, thereby improving the overall communication quality.

[0021] 2. In one example, an impedance matching adjustment branch is also designed on the feeding structure to additionally adjust the antenna impedance matching, so that the antenna impedance matching is easier to adjust without significantly changing the parameter structure.

[0022] 3. In one example, a circular hole slot is designed on the floor, which has a double elliptical convex and double rectangular concave perturbation structure, which can generate circularly polarized radiation under the effective excitation of the umbrella-shaped excitation strip, and the circular hole slot with the double elliptical and double rectangular perturbation structure is rotated 90° in the center in sequence and then symmetrically distributed on the floor in a four-leaf clover shape. In addition, four long strip slots are also symmetrically distributed on the floor, which are used to change the current distribution on the antenna floor and effectively improve the impedance matching of the antenna at high frequencies. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings. The accompanying drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The same reference numerals are used in these drawings to represent the same or similar parts. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0024] Figure 1 A schematic diagram of an antenna structure provided for an example of the present invention;

[0025] Figure 2 The feeding structure intention provided for an example of the present invention;

[0026] Figure 3 A schematic diagram of various structural dimensions of a feeding structure provided in an example of the present invention;

[0027] Figure 4 A schematic diagram of a floor structure provided for an example of the present invention;

[0028] Figure 5 A schematic diagram of the structural dimensions of a portion of the floor provided as an example of the present invention;

[0029] Figure 6 A schematic diagram of the structural dimensions of another part of the floor provided as an example of the present invention;

[0030] Figure 7 A current distribution diagram of a feeding structure at a low-frequency radiation zero point provided for an example of the present invention;

[0031] Figure 8 An electric field distribution diagram at the high-frequency radiation zero point provided for an example of the present invention;

[0032] Fig. 9 Input return loss |S provided for an example of the present invention 11 | Curve graph;

[0033] Fig.10 An antenna axial ratio curve diagram provided for an example of the present invention;

[0034] Fig.11 A left-hand circular polarization gain curve of an antenna provided for an example of the present invention;

[0035] Fig.12 A right-hand circular polarization gain curve diagram provided for an example of the present invention.

[0036] In the figure: 1-feeding structure; 2-feeding probe; 3-dielectric substrate; 4-floor; 5-swastika-shaped branch; 6-impedance matching adjustment branch; 7-umbrella-shaped excitation strip; 8-circular series feeding strip; 9-circular hole slot; 10-long strip slot; 11-slender slit slot; 12-feeding hole slot. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. 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.

[0038] In the description of the present invention, it should be noted that the directions or positional relationships indicated by "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are directions or positional relationships based on the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the use of ordinal numbers (e.g., "first and second", "first to fourth", etc.) is to distinguish objects, and is not limited to this order, and cannot be understood as indicating or implying relative importance.

[0039] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0041] In one example, a broadband filtered dual circular polarization array antenna, such as Figure 1 As shown, the antenna includes a feeding structure 1, a dielectric substrate 3 and a floor 4 from top to bottom. The input end of the feeding structure 1 is connected to the feeding probe 2 (coaxial inner conductor), and the coaxial outer conductor is connected to the metal layer at the center of the floor 4.

[0042] like Figure 2As shown, the feeding structure includes a circular series feed strip 8, a swastika branch 5 and four umbrella-handle-shaped excitation strips 7. The circular series feed strip includes multiple segments of serial arc strips, which are not closed at the ends to form an opening, and the opening serves as the input end of the feeding structure; a straight strip extends from the center of the circular series feed strip, and the straight strip is connected to an end of the arc strip at the opening. The swastika-shaped branch includes four vertical branch groups distributed symmetrically to the center, and the vertical branch group includes a first branch and a second branch. The first branch is arranged on the circular series feed strip, and the angle between adjacent first branches is 90°. The second branch is vertically connected to the end of the first branch. The umbrella-handle-shaped excitation strip includes a first straight segment, an arc segment and a second straight segment connected in sequence. The first straight segment is connected to the intersection of the first branch and the second branch, and the arc segment bends toward the second branch. The four umbrella-handle-shaped excitation strips are distributed symmetrically to the center.

[0043] Furthermore, the dielectric substrate is made of FR4, has a relative dielectric constant of 4.4, a dielectric loss of 0.02, and a size of 250 mm*250 mm*1.6 mm.

[0044] Furthermore, if Figure 1 As shown, four circular holes 9 are also provided on the floor, preferably the four circular holes 9 are centrally symmetrically distributed, and the end of each umbrella-shaped excitation strip 7 is 4mm-6mm away from the edge of the circular hole 9. The edge of the circular hole is provided with two concave rectangular perturbation structures and two convex elliptical perturbation structures, and the angle between the rectangular perturbation structure and the elliptical perturbation structure is 40°-50°, and can be 46°. The scanning parameter design can be performed according to the simulation results of the realized axial ratio. The rectangular holes and the long strips are preferably centrally symmetrically distributed.

[0045] In one example, the circular series feed strip includes four arc strips of approximately 90 degrees, namely the first arc strip, the second arc strip, the third arc strip, and the fourth arc strip. The first arc strip, the second arc strip, the third arc strip, and the fourth arc strip are connected in series and are not closed at the beginning and the end, thereby forming an opening. From the opening in a counterclockwise order, the outer radii of the four arc strips are 12mm-13mm, 12.5mm-13.5mm, 10mm-11mm, and 9.5mm-10mm, respectively. For the convenience of design, the inner radii of the four arc strips are all designed to be 9.4mm-9.6mm. Preferably, if Figure 3 As shown, in this example, the radii R0, the first arc strip R1, the second arc strip R2, the third arc strip R3, and the fourth arc strip R4 of the circular series feed strip are 9.4 mm, 12.5 mm, 12.7 mm, 10.3 mm, and 9.6 mm, respectively.

[0046] Furthermore, the umbrella-shaped excitation strip is used to bias the circular slots in the floor gaps, and the range covered by the excitation strip can reflect the degree of excitation to a certain extent. Figure 3 As shown, the radius of the arc end of the umbrella-shaped excitation strip is about 11mm-12mm, and the length of the second straight line segment is 12mm-13mm.

[0047] In one example, the length of the first branch in the swastika-shaped branch is 14 mm-15 mm, and the length of the second branch is determined according to the frequency at the radiation zero point required by the design, which is slightly higher than λg / 4 of the frequency at the radiation zero point, where λg is the waveguide wavelength.

[0048] In one example, if Figure 2 As shown, the feeding structure also includes four impedance matching adjustment branches 6, which are vertically arranged on the first branch and extend in the opposite direction to the second branch. The size of the impedance matching adjustment branch is determined according to the impedance adjustment degree at the high frequency during design. Generally, in order to reduce its transmission impact on the entire feeding network, it is not easy to be too large or too long. The length of the impedance matching adjustment branch is 2mm-4mm and the width is 0.5mm-1mm.

[0049] like Figure 4 As shown, a feeding hole slot 12 is provided in the center of the floor to facilitate coaxial feeding. Furthermore, four elongated slit slots 11 are provided on the floor in a symmetrically distributed manner.

[0050] In one example, if Figure 4 As shown, the floor further includes four long strip grooves 10 . Preferably, the four long strip grooves 10 are all centrally symmetrically distributed, and each long strip groove 10 is arranged between two circular hole grooves 9 .

[0051] In one example, if Figure 5-Figure 6 As shown, the radius of the circular hole groove is 42mm-48mm, and the distance between the center of the circular hole groove and the center of the floor is 76mm-78mm; the width of the rectangular disturbance structure is 6mm-7mm, and the length of the major axis of the elliptical disturbance structure is 12mm-13mm. Preferably, the length of the long strip groove is 55mm-63mm, the width is 3mm-4mm, and the distance between the edge of the long strip groove and the vertex of the floor is 40mm-45mm. Preferably, the length of the elongated slit groove is 18mm-21mm, the width is 1.5mm-1.8mm, and the distance between the edge of the elongated slit groove and the center of the floor is 30mm-33mm.

[0052] The above examples are combined to obtain a preferred example of the present invention, in which the swastika-shaped branches, matching adjustment branches, umbrella-shaped excitation strips and circular series feeding strips together constitute a feeding structure, which serves as the upper metal layer of the dielectric substrate; a floor with circular holes, long strips and feeding holes etched with a double elliptical double rectangular perturbation structure serves as the lower metal layer of the dielectric substrate, and the floor 4 is both the ground layer of the antenna and the radiation surface of the antenna.

[0053] The present invention only etches a special slot structure (circular hole slot, long strip slot, and slender slit slot) on the floor below the dielectric substrate, and symmetrically arranges them on the floor by rotating the center by 90 degrees. A simplified sequential feeding structure is provided above the dielectric substrate, and a low-frequency filtering structure composed of a swastika-shaped branch and the slender slit slot on the floor is loaded. The overall feeding presents a "swastika"-shaped structure, and an η-shaped feeding strip (umbrella-shaped excitation strip) for exciting the floor is connected to each end of the swastika-shaped structure. The current distribution at the umbrella-shaped excitation strip is very weak, and the circular hole slot of the antenna cannot be effectively excited to radiate, thereby generating a radiation zero point at a low frequency; four slender slit slots that are sequentially rotated and symmetrically distributed are provided below the swastika-shaped feeding structure, which are used to generate a high-frequency radiation zero point. Since the lower floor of the substrate serves as both the antenna stratum structure and the antenna radiation structure, and there is no other structure blocking it above and below, it can achieve good dual circular polarization characteristics, that is, the upper part of the floor is right-hand circular polarization, and the lower part is left-hand circular polarization, and the entire design can be regarded as an antenna array formed by rotating the unit sequence of the umbrella-shaped excitation strip excitation circular slot, so the antenna has good gain. The finally designed antenna has good broadband dual circular polarization radiation performance and filtering characteristics, which can increase the anti-interference ability of the circularly polarized antenna and improve the long-distance communication performance of the antenna, and is better suitable for today's complex application environment with increasing radiation interference.

[0054] As for the filtering structure realized by the antenna, the present invention is that the design of the swastika-shaped branch and the slender slit groove at the floor makes the antenna have good filtering characteristics. The swastika-shaped branch can make the current at the low frequency concentrated at its end, while the current distribution at the umbrella-shaped excitation strip is very weak, which cannot effectively excite the circular hole groove of the antenna to radiate, thereby generating a radiation zero point at low frequency, which helps to improve the frequency selectivity of the antenna. The current distribution of the feeding structure at the low-frequency radiation zero point is as follows: Figure 7 The slender slot on the floor is designed at the end of the swastika-shaped branch. At high frequencies, it can excite the slender slot through the swastika-shaped branch and produce strong resonance. At high frequencies, the electric field energy on the floor is strongest at the slender slot. The strong resonance of the slender slot destroys the original circular polarization radiation mode, making the antenna unable to radiate well at the corresponding high frequency. Therefore, a radiation zero point is generated at high frequencies, effectively reducing interference in the high frequency band. The electric field distribution at the high-frequency radiation zero point is shown in the figure. Figure 8 shown.

[0055] Furthermore, the antenna of the present invention is simulated to obtain the input return loss of the antenna |S 11 |As Fig. 9 As shown, |S 11 |The frequency band below -10dB is 1.88GHz-4.54GHz, and the antenna axis is Fig.10As shown, in the frequency band of 1.88GHz-3.19GHz, the antenna left-hand circular polarization gain and right-hand circular polarization gain are as follows: Figure 11-Figure 12 As shown, the radiation suppression level at the zero point of the left-hand circularly polarized low-frequency radiation reaches more than 25dB, the radiation level suppression at the zero point of the high-frequency radiation reaches more than 20dB, the radiation suppression level at the zero point of the right-hand circularly polarized low-frequency radiation reaches more than 35dB, the radiation level suppression at the zero point of the high-frequency radiation reaches more than 20dB, and within the frequency band where the axial ratio is less than 3dB, the left-hand circular polarization gain and the right-hand circular polarization gain of the antenna are greater than 6dBic, and the maximum gain is 8.8dBic. It can be seen that the antenna designed in the present invention can take into account the dual circular polarization radiation, broadband design, and radiation filtering design of the antenna at the same time, has good dual circular polarization radiation performance, and has good out-of-band radiation suppression performance.

[0056] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A broadband filtering dual circular polarization array antenna, characterized in that: The antenna comprises a feeding structure, a dielectric substrate and a floor from top to bottom, and the feeding structure is connected to the floor via a coaxial line; The feeding structure comprises a circular series feed strip, a swastika-shaped branch and four umbrella-shaped excitation strips, wherein the circular series feed strip comprises a plurality of arc strips which are connected in series and not closed at the head and tail to form an opening, and a straight line extending from the center of the circular series feed strip is connected to an arc strip at the opening; the swastika-shaped branch comprises four vertical branch groups, and the vertical branch groups comprise a first branch arranged on the circular series feed strip and a second branch vertically connected to the first branch; the straight line segment in the umbrella-shaped excitation strip is connected to the intersection of the first branch and the second branch, and the arc segment in the umbrella-shaped excitation strip is bent toward the second branch, and the four umbrella-shaped excitation strips are centrally symmetrically distributed; The floor also includes four circular holes, the edges of which are provided with a concave rectangular disturbance structure and a convex elliptical disturbance structure, the angle between the rectangular disturbance structure and the elliptical disturbance structure is 40°-50°, and the ends of each umbrella-shaped excitation strip are 4mm-6mm away from the edges of the circular holes; The floor further comprises four elongated slots which are centrally symmetrically distributed.

2. The broadband filtering dual circular polarization array antenna according to claim 1, characterized in that: The circular series feed strip includes four arc strips. From the opening in a counterclockwise order, the outer radii of the four arc strips are 12mm-13mm, 12.5mm-13.5mm, 10mm-11mm, and 9.5mm-10mm respectively.

3. The broadband filtering dual circular polarization array antenna according to claim 1, characterized in that: The length of the second branch in the swastika-shaped branches is greater than a quarter wavelength of the frequency at the radiation zero point.

4. The broadband filtering dual circular polarization array antenna according to claim 1, characterized in that: The feeding structure also includes four impedance matching adjustment branches, which are vertically arranged on the first branch and extend in the opposite direction to the second branch.

5. The broadband filtering dual circular polarization array antenna according to claim 1, characterized in that: The length of the elongated slit groove is 18mm-21mm, the width is 1.5mm-1.8mm, and the edge of the elongated slit groove is 30mm-33mm away from the center of the floor.

6. The broadband filtering dual circular polarization array antenna according to claim 1, characterized in that: The radius of the circular hole groove is 42mm-48mm, and the center of the circular hole groove is 76mm-78mm away from the center of the floor; the edge of the circular hole groove is provided with two concave rectangular disturbance structures and two convex elliptical disturbance structures, the width of the rectangular disturbance structure is 6mm-7mm, and the long axis length of the elliptical disturbance structure is 12mm-13mm.

7. The broadband filtering dual circular polarization array antenna according to claim 1, characterized in that: The floor also includes four long strip grooves, each of which is arranged between two circular hole grooves.

8. The broadband filtering dual circular polarization array antenna according to claim 7, characterized in that: The length of the long strip groove is 55mm-63mm, the width is 3mm-4mm, and the edge of the long strip groove is 40mm-45mm away from the top of the floor.

9. The broadband filtering dual circular polarization array antenna according to claim 7, characterized in that: The four circular hole grooves and the four long strip grooves are all distributed in a centrally symmetrical manner.

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