A laminated circularly polarized filter antenna
Through the design of a laminated circularly polarized filter antenna, radiation zero points are introduced in the passband and stopband by using cut-angle radiation patches and parasitic patches, which solves the volume increase and insertion loss problems caused by filter cascade in the existing technology, and achieves a wider axial ratio bandwidth and stable filtering performance.
Patent Information
- Application Number
- CN202310343213.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-31
- Publication Date
- 2025-09-05
- Estimated Expiration
- 2043-03-31
AI Technical Summary
In the existing circularly polarized filter antenna design, the filter and antenna need to be cascaded, resulting in an increase in the volume of the RF front-end and insertion loss. In addition, it is difficult to achieve circularly polarized filtering performance with simply designed parasitic elements.
A laminated structure is adopted, including the first and second dielectric substrates, the corner-cut radiation patch, the parasitic patch and the microstrip feed line. The corner-cut design and the arrangement of the parasitic patch introduce radiation zero points in the passband and stopband to achieve a circular polarization filtering effect and avoid additional filtering circuits.
The circular polarization filtering effect with simple structure, flat gain and good stability is achieved, and the axial ratio bandwidth is wider, no additional filtering circuit is required, and the insertion loss is reduced.
Smart Images
Figure CN116345143B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of communications and antennas, in particular to a laminated circularly polarized filtering antenna. Background Art
[0002] In traditional RF front-end designs, there are two key components: filters and antennas. These components are typically designed separately and then cascaded with additional transmission lines to suppress unwanted signals. However, these additional lines can introduce insertion loss, degrading system performance while also occupying circuit area. Therefore, the development of filter antennas is of great significance in modern communications engineering.
[0003] Filter antennas have been extensively researched in recent years. Circularly polarized filter antennas, in particular, have attracted increasing attention due to their improved anti-interference capabilities and wider applicability compared to linearly polarized filter antennas. Currently, most circularly polarized filter antennas still utilize a cascaded approach of circularly polarized antennas and filters to achieve filtering performance. While this approach achieves a good filtering response, it still requires additional filtering structures, which increases the size of the RF front-end. Furthermore, the introduction of the filtering structure / network inevitably results in insertion loss, which in turn reduces the gain and efficiency of the filter antenna.
[0004] Parasitic elements introduce radiation nulls near the passband, suppressing radiation in the near-stopband, thereby achieving a bandpass filtering response. To date, the number of circularly polarized filter antennas designed based on this approach has been limited. This is due to the difficulty of using simple parasitic elements when considering both filtering and circular polarization performance. To date, designing a simple circularly polarized filter antenna that does not require additional filtering circuits or networks remains a considerable challenge. Summary of the Invention
[0005] In order to solve the defects of relatively large size and relatively high internal insertion loss of the filtering antenna, the purpose of the present invention is to provide a laminated circularly polarized filtering antenna with a relatively flat passband, good stability, no additional filtering circuit, and a relatively simple antenna structure.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: a laminated circularly polarized filter antenna, comprising a first dielectric substrate and a second dielectric substrate, wherein a first cut-angle radiating patch, a first parasitic patch, a second parasitic patch, a third parasitic patch, a fourth parasitic patch, and a microstrip feeder are provided on the first dielectric substrate; a second cut-angle radiating patch is provided on the second dielectric substrate, and a cross groove is etched at the center of the second cut-angle radiating patch; the second dielectric substrate is located above the first dielectric substrate, and foam is sandwiched between the two.
[0007] The shape of the first cut-angle radiation patch is a square, and its upper left corner and lower right corner are cut at 45° counterclockwise along the Y-axis, and the Y-axis is the horizontal axis. The first parasitic patch and the second parasitic patch are arranged at equal intervals on the left and right sides of the first cut-angle radiation patch, and the first parasitic patch and the second parasitic patch have the same shape and are both long strips; the first cut-angle radiation patch is connected downward to the microstrip feeder, and the first cut-angle radiation patch and the microstrip feeder are integrated into a design, and the third parasitic patch and the fourth parasitic patch are respectively arranged on the left and right sides of the microstrip feeder, and the third parasitic patch and the fourth parasitic patch have the same shape and are both long strips, and the length of the third parasitic patch and the fourth parasitic patch is less than the length of the first parasitic patch and the second parasitic patch.
[0008] The second cut-angle radiation patch is in the shape of a square, with its upper left corner and lower right corner cut at 45° counterclockwise along the Y axis, where the Y axis is the horizontal axis. The size of the second cut-angle radiation patch is larger than that of the first cut-angle radiation patch.
[0009] The first dielectric substrate and the second dielectric substrate are both made of flame-resistant material with a grade of FR-4 and a dielectric constant of 4.4. A metal floor is provided on the lower surface of the first dielectric substrate, and the metal floor, the first cut-angle radiation patch, the first parasitic patch, the second parasitic patch, the third parasitic patch, the fourth parasitic patch, the microstrip feed line, and the second cut-angle radiation patch are all made of metal copper.
[0010] The dielectric constant of the foam is 1.3. The upper end surface of the foam is adhered to the lower surface of the second dielectric substrate, and the lower end surface of the foam is adhered to the center position of the first cut-angle radiation patch on the first dielectric substrate.
[0011] The centers of the first cut-angle radiation patch, the foam, the second dielectric substrate and the second cut-angle radiation patch coincide with each other.
[0012] It can be seen from the above technical solution that the beneficial effects of the present invention are: first, the antenna structure of the present invention is simple, and there is no additional filtering circuit but it achieves a good filtering effect; second, the gain curve of the antenna in the present invention has good flatness, so it has good stability, and the two radiation zero points are adjustable; third, the antenna axial ratio bandwidth of the present invention is wider than that of the existing circularly polarized filtering antenna structure without additional filtering circuit. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 It is a front view of the present invention;
[0014] Figure 2 is a top view of the present invention;
[0015] Figure 3 It is a structural schematic diagram of the first dielectric substrate and the patch thereon in the present invention;
[0016] Figure 4 It is a structural schematic diagram of the second dielectric substrate and the patch thereon in the present invention;
[0017] Figure 5 is a return loss graph of the present invention;
[0018] Figure 6 is an axial ratio parameter diagram of the present invention;
[0019] Figure 7 is the radiation gain diagram of the present invention;
[0020] Figure 8 This is the xoz plane radiation pattern of the present invention working at a frequency of 2.29 GHZ;
[0021] Figure 9 This is the yoz surface radiation pattern of the present invention working at a frequency of 2.29 GHZ;
[0022] Figure 10 This is the xoz plane radiation pattern of the present invention working at a frequency of 2.45 GHZ;
[0023] Figure 11 This is the yoz surface radiation pattern of the present invention working at a frequency of 2.45 GHZ. DETAILED DESCRIPTION
[0024] like Figure 1 、 2 As shown, a laminated circularly polarized filter antenna includes a first dielectric substrate 1 and a second dielectric substrate 2. A first cut-angle radiating patch 3, a first parasitic patch 4, a second parasitic patch 5, a third parasitic patch 6, a fourth parasitic patch 7, and a microstrip feed line 8 are provided on the first dielectric substrate 1; a second cut-angle radiating patch 9 is provided on the second dielectric substrate 2, and a cross groove 10 is etched at the center of the second cut-angle radiating patch 9; the second dielectric substrate 2 is located above the first dielectric substrate 1, and foam 11 is sandwiched between the two.
[0025] like Figure 3As shown, the shape of the first angled radiation patch 3 is a square, and its upper left corner and lower right corner are angled 45° counterclockwise along the Y axis, and the Y axis is the horizontal axis. The first parasitic patch 4 and the second parasitic patch 5 are arranged at equal intervals on the left and right sides of the first angled radiation patch 3, respectively. The first parasitic patch 4 and the second parasitic patch 5 have the same shape and are both long strips; the first angled radiation patch 3 is connected downwardly to the microstrip feeder 8, and the first angled radiation patch 3 is integrated with the microstrip feeder 8. The third parasitic patch 6 and the fourth parasitic patch 7 are respectively arranged on the left and right sides of the microstrip feeder 8. The third parasitic patch 6 and the fourth parasitic patch 7 have the same shape and are both long strips. The length of the third parasitic patch 6 and the fourth parasitic patch 7 is less than the length of the first parasitic patch 4 and the second parasitic patch 7. Through the first parasitic patch 4 and the second parasitic patch 5, a radiation suppression zero point can be introduced into the antenna on the left side of the passband, thereby realizing the filtering characteristics of the antenna lower stopband; through the third parasitic patch 6 and the fourth parasitic patch 7, a radiation suppression zero point can be introduced into the antenna on the right side of the passband, which is farther away from the passband, thereby further improving the filtering characteristics of the antenna upper stopband.
[0026] like Figure 4 As shown, the second corner-cut radiating patch 9 is square in shape, with its upper left and lower right corners cut 45 degrees counterclockwise along the Y-axis, where the Y-axis is the horizontal axis. The size of the second corner-cut radiating patch 9 is larger than that of the first corner-cut radiating patch 3. A cross-shaped slot 10 is etched at the center of the second corner-cut radiating patch 9. This cross-shaped slot 10 introduces a radiation suppression zero point to the right of the passband and closest to the passband. At the same time, the introduction of the cross-shaped slot 10 can achieve better filtering characteristics in the upper stopband.
[0027] The first dielectric substrate 1 and the second dielectric substrate 2 are both made of flame-resistant material with a grade of FR-4 and a dielectric constant of 4.4. A metal floor 12 is provided on the lower surface of the first dielectric substrate 1, and the metal floor 12, the first cut-angle radiation patch 3, the first parasitic patch 4, the second parasitic patch 5, the third parasitic patch 6, the fourth parasitic patch 7, the microstrip feed line 8, and the second cut-angle radiation patch 9 are all made of metal copper.
[0028] The foam 11 has a dielectric constant of 1.3. The upper surface of the foam 11 is attached to the lower surface of the second dielectric substrate 2, and the lower surface of the foam 11 is attached to the center of the first cut-angle radiating patch 3 on the first dielectric substrate 1. The centers of the first cut-angle radiating patch 3, the foam 11, the second dielectric substrate 2, and the second cut-angle radiating patch 9 coincide with each other.
[0029] In the present invention, a cut-angle design is adopted for the first cut-angle radiation patch 3 and the second cut-angle radiation patch 9. The most basic modes in the rectangular microstrip antenna are TM10 and TM01 modes, which are a pair of orthogonal degenerate modes. The rectangular patch is cut 45° counterclockwise along the Y-axis to introduce a cut-angle perturbation structure, and the resonant frequencies of the two degenerate modes can be separated by adjusting the position of the feeding point, so that the equivalent impedance phase of one mode advances by 45°, while the other impedance phase lags by 45°, and two orthogonal modes are realized in space and time, and a circularly polarized radiation wave is formed in the far field.
[0030] Figure 5 This is the return loss graph of the present invention, with a relative bandwidth of 17.88% (2.19-2.62 GHz);
[0031] Figure 6 This is the axial ratio parameter diagram of the present invention, and the axial ratio bandwidth is 10.17% (2.24-2.48GHz);
[0032] Figure 7 The radiation gain diagram of the present invention has a peak gain of about 6.92 dBi.
[0033] Figure 8 The invention is the normalized radiation pattern of the main polarization and cross polarization of the xoz plane working at a frequency of 2.29 GHZ, and the normalized cross polarization can reach a minimum of -44.93 dB;
[0034] Figure 9 The invention is the normalized radiation pattern of the main polarization and cross polarization of the yoz plane working at a frequency of 2.29 GHZ, and the normalized cross polarization can reach a minimum of -51.93 dB;
[0035] Figure 10 The invention is the normalized radiation pattern of the main polarization and cross polarization of the xoz plane working at a frequency of 2.45 GHz, and the normalized cross polarization can reach a minimum of -31.11 dB;
[0036] Figure 11 The invention is a normalized directivity diagram of the main polarization and cross polarization of the yoz plane working at a frequency of 2.45 GHz, and the normalized cross polarization can reach a minimum of -39.55 dB.
[0037] In summary, the antenna structure of the present invention is simple, without additional filtering circuits, but achieves good filtering effects; the gain curve of the antenna of the present invention has good flatness, and therefore has good stability, and the two radiation zero points are adjustable; the antenna axial ratio bandwidth of the present invention is wider than that of the existing circularly polarized filtering antenna structure without additional filtering circuits.
Claims
1. A laminated circularly polarized filter antenna, characterized in that: The invention comprises a first dielectric substrate (1) and a second dielectric substrate (2), wherein a first cut-angle radiation patch (3), a first parasitic patch (4), a second parasitic patch (5), a third parasitic patch (6), a fourth parasitic patch (7) and a microstrip feed line (8) are arranged on the first dielectric substrate (1); a second cut-angle radiation patch (9) is arranged on the second dielectric substrate (2), and a cross groove (10) is etched at the center of the second cut-angle radiation patch (9); the second dielectric substrate (2) is located above the first dielectric substrate (1), and foam (11) is sandwiched between the two. The shape of the first cut-angle radiation patch (3) is a square, and the upper left corner and the lower right corner thereof are cut at 45° counterclockwise along the Y axis, and the Y axis is the horizontal axis. The first parasitic patch (4) and the second parasitic patch (5) are arranged at equal intervals on the left and right sides of the first cut-angle radiation patch (3), and the first parasitic patch (4) and the second parasitic patch (5) have the same shape and are both long strips; the first cut-angle radiation patch (3) is connected downward to the microstrip feed line (8), and the first cut-angle radiation patch (3) and the microstrip feed line (8) are designed as an integrated whole. The third parasitic patch (6) and the fourth parasitic patch (7) are arranged on the left and right sides of the microstrip feed line (8), respectively. The third parasitic patch (6) and the fourth parasitic patch (7) have the same shape and are both long strips. The length of the third parasitic patch (6) and the fourth parasitic patch (7) is less than the length of the first parasitic patch (4) and the second parasitic patch (5); The second cut-angle radiation patch (9) is in the shape of a square, with its upper left corner and lower right corner cut at 45° counterclockwise along the Y axis, the Y axis being the horizontal axis, and the size of the second cut-angle radiation patch (9) being larger than the size of the first cut-angle radiation patch (3); The centers of the first cut-angle radiation patch (3), the foam (11), the second dielectric substrate (2) and the second cut-angle radiation patch (9) coincide with each other.
2. The laminated circularly polarized filter antenna according to claim 1, wherein: The first dielectric substrate (1) and the second dielectric substrate (2) are both made of flame-resistant material with a grade of FR-4 and a dielectric constant of 4.4; a metal floor (12) is provided on the lower surface of the first dielectric substrate (1); the metal floor (12), the first cut-angle radiation patch (3), the first parasitic patch (4), the second parasitic patch (5), the third parasitic patch (6), the fourth parasitic patch (7), the microstrip feed line (8), and the second cut-angle radiation patch (9) are all made of metal copper.
3. The laminated circularly polarized filter antenna according to claim 1, wherein: The dielectric constant of the foam (11) is 1.3, the upper end surface of the foam (11) is adhered to the lower surface of the second dielectric substrate (2), and the lower end surface of the foam (11) is adhered to the center position of the first cut-angle radiation patch (3) on the first dielectric substrate (1).