A filter slot array antenna based on a half-mode substrate integrated coaxial line

Abstract

The application discloses a filtering slot array antenna based on a half-mode substrate integrated coaxial line, which comprises a half-mode substrate integrated coaxial line slot array antenna, a substrate integrated coaxial line band-pass filter and a half-mode substrate integrated coaxial switching structure, the half-mode substrate integrated coaxial line slot array antenna is an entire structure extending in the vertical direction with the middle adhesive layer being the section of the linear part of the metal inner conductor, the substrate integrated coaxial line band-pass filter is an entire structure extending in the vertical direction with the middle adhesive layer being the section of the curved part of the metal inner conductor, and the metal inner conductor is connected with the middle metal layer through the half-mode substrate integrated coaxial switching structure. The filtering slot array antenna based on the half-mode substrate integrated coaxial line has the characteristics of miniaturization, high integration and high gain.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a filtered slot array antenna. Background Technology

[0002] In recent years, with the rapid development of wireless communication technology, the requirements for antennas in wireless communication systems have become increasingly stringent. Currently, electronic devices in wireless communication systems are moving towards lower power consumption, smaller size, and greater integration. Filtering antennas have become a key research focus for researchers. Filtering antennas can achieve flat in-band gain, increase sufficient stopband depth to meet the requirements of filtering spurious frequencies and higher-order modes, and their good frequency selectivity can extend the bandwidth of existing antennas.

[0003] Traditional filter antenna design methods focus only on the filter and antenna themselves, designing them independently and then cascading them with additional matching circuitry. However, this complicates the structure of the filter antenna, increases its size and losses, and prevents the filter from being directly tested or integrated with other transmission line modules.

[0004] Currently, filters and antennas are commonly integrated into millimeter-wave microsystems as functional components for frequency selection and radiation. Integrating filters and antennas into a single module to form a filter antenna is key to miniaturizing RF front-end equipment. Traditional filter antenna structures are primarily based on microstrip line design, metal rectangular waveguides, or substrate-integrated waveguide technology. Microstrip line-based filter antennas suffer from high insertion loss and low selectivity due to large parasitic radiation loss and low quality factor caused by microstrip line discontinuities. They are highly sensitive to external interference caused by radiation from other passive and active devices on the same substrate and exhibit low gain, resulting in poor operating quality of wireless communication systems. Metal rectangular waveguide-based filter antennas offer advantages such as low loss and high quality factor, as metal rectangular waveguides are commonly used feeding structures in practical applications. However, the transmission stability and accuracy of metal rectangular waveguides directly affect the radiation characteristics and filtering performance of the filter antenna. Furthermore, metal rectangular waveguide structures are large, bulky, complex to manufacture, and difficult to debug, making them difficult to integrate with planar circuits, resulting in high costs and maintenance difficulties in practical applications. Filter antennas based on substrate integrated waveguide technology are not sufficiently integrated with the feeding structure, resulting in easy leakage of electromagnetic energy, insertion loss in the filtering structure, and low antenna gain.

[0005] Therefore, a new technical solution is needed to solve the above problems. Summary of the Invention

[0006] To address the problems arising from existing technologies, this invention provides a filter slot array antenna based on a half-mode substrate integrated coaxial line that features miniaturization, high integration, and high gain.

[0007] To achieve the above objectives, the present invention employs the following technical solution for a filter slot array antenna based on a half-mode substrate integrated coaxial line:

[0008] A filtered slot array antenna based on a half-mode substrate integrated coaxial line includes a top metal conductor, a bottom metal conductor, and a metallized via, characterized in that it further includes an intermediate metal conductor layer and slot radiating elements;

[0009] The intermediate metal conductor layer includes a metal inner conductor with a variable shape, metal stubs disposed on both sides of the curved portion of the metal inner conductor, and short-circuit stubs with one end extending from the curved portion of the metal inner conductor and the other end connected to the metal stubs. The metal stubs and short-circuit stubs play a filtering role.

[0010] The slot radiation unit sequentially includes slots that correspond one-to-one in the vertical direction, a metal disk located on a straight section of the inner metal conductor, a metallized blind via, and an annular groove; the slots are etched on the top metal conductor; the metallized blind via is located at the center of the annular groove, and both the annular groove and the metallized blind via are located on the bottom metal conductor; the metallized blind via contacts the metal disk to connect the intermediate metal conductor layer and the bottom metal conductor.

[0011] Metallized vias run through the entire structure from top to bottom, connecting the top and bottom metal conductors to form a closed structure.

[0012] Furthermore, the aforementioned slit radiation unit comprises five units, each with the same spacing, forming a one-dimensional linear array.

[0013] Furthermore, the metal stubs are arranged at equal intervals on both sides of the inner metal conductor and are connected to the top metal conductor and the bottom metal conductor through metallized through-holes.

[0014] Furthermore, the metal disk, metallized blind via, and annular groove form an impedance matching structure, and the impedance can be adjusted by changing the diameter of the annular groove.

[0015] Furthermore, the annular groove separates the metallized blind via and the bottom metal conductor, forming an open circuit of the impedance matching structure; the end of the inner metal conductor with a metal disk forms a terminal open circuit.

[0016] Furthermore, the filter slot array antenna based on a half-mode substrate integrated coaxial line has, from top to bottom, a top metal conductor, an upper dielectric layer, an intermediate metal conductor layer, an intermediate adhesive layer, a lower dielectric layer, and a bottom metal conductor. The inner metal conductor is located at the center of the upper surface of the intermediate adhesive layer along the length extension direction. The inner metal conductor consists of a straight part and a bent part. The part with the metal disk is parallel to the length extension direction, and the part with the short-circuit stub is bent in an arc shape. The top metal conductor only has half of the straight part of the inner metal conductor that is axially symmetrical. The lengths and widths of the other dielectric layers and metal conductor layers are equal.

[0017] Furthermore, the portion extending vertically into the entire structure with the top metal conductor covering the curved inner metal conductor and the metal stub as the cross-section, and the metallized vias arranged on both sides of the curved portion of the inner metal conductor and coinciding with the metal stub, constitute a bandpass filter based on a substrate-integrated coaxial line.

[0018] Furthermore, taking the top metal conductor as a cross-section along the side symmetrical to the inner metal conductor as the axis, the portion extending vertically into the entire structure, and the metallized through holes regularly arranged along the length and width of the entire structure on one side of the straight portion of the inner metal conductor with the metal disk, are used as a half-mode substrate integrated coaxial slot antenna.

[0019] Furthermore, taking the straight section of the top metal conductor covering the inner metal conductor without the metal disk as the cross section, the portion extending vertically in the entire structure and the metallized through holes regularly arranged on both sides of the straight section of the inner metal conductor without the metal disk along the width and length of the entire structure constitute a half-mold substrate integrated coaxial adapter structure.

[0020] Furthermore, the filter slot array antenna based on the half-mode substrate integrated coaxial line is fabricated using PCB processing technology. Copper is plated on the upper surface of the upper dielectric layer to form the top metal conductor, and slots are etched onto the top metal conductor. Copper is plated on the lower surface of the upper dielectric layer to form the inner metal conductor, metal stubs, and short-circuit stubs. Copper is plated on the upper surface of the lower dielectric layer to form the bottom metal conductor, and annular grooves are etched onto the bottom metal conductor. The upper and lower dielectric layers and the intermediate adhesive layer are laminated and formed. Finally, holes are drilled at the corresponding positions of the metallized through holes and metallized blind holes, and electrical connections are achieved through copper plating between the holes.

[0021] The present invention has the following beneficial effects:

[0022] 1. This invention is based on a half-mode substrate integrated coaxial line design, which reduces the cross-section; no additional structure is added by etching gaps on the half-mode substrate integrated coaxial line; the filter structure is fully integrated with the antenna feed structure - the inner metal conductor - in the middle metal conductor layer; the bandpass filter of the substrate integrated coaxial line is a bent inner metal conductor, and short-circuit stubs are added on the inner metal conductor to reduce the size; all of these effectively achieve miniaturization.

[0023] 2. The integrated design of antenna, filter structure and feeding structure, along with the integration of the filter and antenna feeding structure, facilitates the integration of antenna with microwave and millimeter-wave circuits.

[0024] 3. By introducing gaps into the metal surface to cut the surface current, a displacement current is formed at the gap opening, which excites the gap and causes it to radiate outward. It has excellent characteristics of high radiation efficiency, compact structure and low loss. The filter structure is a closed structure, which significantly suppresses out-of-band electromagnetic energy, improves frequency selectivity, reduces the insertion loss of the filter structure, expands the impedance bandwidth of the slot array antenna and can improve the antenna gain. Attached Figure Description

[0025] Figure 1 This is a structural diagram of the present invention;

[0026] Figure 2 Schematic diagram of the top metal conductor;

[0027] Figure 3 This is a schematic diagram of the structure of the intermediate metal layer and the intermediate adhesive layer.

[0028] Figure 4 Schematic diagram of the underlying metal conductor;

[0029] Figure 5 A schematic diagram of a substrate-integrated coaxial line filter;

[0030] Figure 6 This invention compares the reflection coefficient and peak gain before and after adding a substrate-integrated coaxial filter.

[0031] Figure 7 This is the gain pattern of the main polarization and cross-polarization of the present invention at the center operating frequency of 28 GHz;

[0032] Figure 8 This is a schematic diagram illustrating the 45° linear polarization generated by the gap in this invention.

[0033] In the figure, 1 is the top metal conductor, 2 is the upper dielectric layer, 3 is the inner metal conductor, 4 is the middle adhesive layer, 5 is the lower dielectric layer, 6 is the bottom metal conductor, 7 is the metallized via, 8 is the slot, 9 is the metal disk, 10 is the metallized blind via, 11 is the annular slot, 12 is the metallized via, 13 is the metal stub, 14-18 are short-circuit stubs, Ⅰ is the half-mode substrate integrated coaxial slot array antenna, Ⅱ is the half-mode substrate integrated coaxial adapter structure, and Ⅲ is the substrate integrated coaxial filter. Detailed Implementation

[0034] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0035] Please see Figure 1 As shown, this invention discloses a filter slot array antenna 100 based on a half-mode substrate integrated coaxial line. Vertically, from top to bottom, it includes a top metal conductor 1, an upper dielectric layer 2, an intermediate metal conductor layer, an intermediate adhesive layer 4, a lower dielectric layer 5, and a bottom metal conductor 6. In addition, it is provided with multiple regularly arranged metallized through-holes 7 and slot radiation elements that run from top to bottom through the entire structure 100. The top metal conductor 1 only has half of the straight part along the inner metal conductor 3 that is axially symmetrical. The length and width of the other dielectric layers 2 and metal conductor layers 1 are equal.

[0036] See Figure 3 , 5 As shown, the intermediate metal conductor layer includes an inner metal conductor 3, metal stubs 13, and multiple short-circuit stubs 14-18. The inner metal conductor 3 is located at the center of the length extension direction of the intermediate adhesive layer, and has a straight portion and a curved portion. Metal discs 9 are equally spaced at one straight portion of the inner metal conductor 3. The other straight portion of the inner metal conductor 3 without metal discs 9 connects the curved portion to the straight portion. Metal stubs 13 are located on both sides of the curved portion of the inner metal conductor 3. One end of each short-circuit stub 14-18 extends from the curved portion of the inner metal conductor 3, and the other end is connected to the metal stub 13.

[0037] See Figure 1-4 As shown, the slot radiation unit sequentially includes slots 8 corresponding to each other in the vertical direction, a metal disk 9 located on a straight section of the inner metal conductor 3, a metallized blind via 10, and an annular groove 11; the slots 8 are etched on the top metal conductor 1; the metallized blind via 10 is located at the center of the annular groove 11, and the metallized blind via 10 and the annular groove 11 are located on the bottom metal conductor 6; the metallized blind via 10 contacts the metal disk 9 to connect the intermediate metal conductor layer and the bottom metal conductor 6;

[0038] See Figure 1 As shown, the metallized through-hole 12 runs through the entire structure 100 from top to bottom, and is used to connect the top metal conductor 1 and the bottom metal conductor 6 to form a closed structure. It has good shielding properties, while reducing the mutual coupling between radiation units and promoting the coupling of energy on the inner metal conductor 3 to the top metal conductor 1, so as to achieve effective radiation.

[0039] Semi-SICL (Semi-Substrate Integrated Coaxial Line) is a new type of transmission line improved from SICL (Substrate Integrated Coaxial Line) by reducing the area of ​​the top metal conductor to the area of ​​one side of the bottom metal conductor. When SICL operates only in the main mode, electromagnetic energy is mainly concentrated around the inner conductor, and the maximum tangential electric field on the plane of symmetry along the propagation direction is located on the center line. At this time, the normal magnetic field is zero. Therefore, the plane of symmetry can be used as an equivalent magnetic wall. It is fed by a semi-enclosed semi-substrate integrated coaxial line, which is easy to integrate with other circuits. At the same time, it can effectively reduce the size of the antenna and realize the miniaturization of the antenna.

[0040] See Figures 1 to 8 As shown, the section extending vertically into the entire structure 100, with the top metal conductor 1 as the axis of symmetry along the inner metal conductor 3 as the cross-section, is the half-mode substrate integrated coaxial slot antenna I. The half-mode substrate integrated coaxial slot antenna I mainly includes slot radiating elements and metallized vias. There are five slot radiating elements, each with the same spacing, and adjacent radiating elements are 5.9 mm apart, forming a one-dimensional linear array to improve gain. The slot 8 is 1.9 mm long and 0.3 mm wide. The electric field at slot 8 is perpendicular to the electric field of the top metal conductor 1, and the superposition of the two electric field vectors forms a 45° angle with the slot, enabling the antenna to achieve 45° linear polarization radiation. The inner metal conductor 3 is open-circuited at its end to achieve standing wave excitation of slot 8. The diameter of the metallized blind hole 10 is 0.4 mm, and the inner diameter of the annular groove 11 is 0.8 mm and the outer diameter is 0.95 mm. The metal disk 9, the metallized blind via 10, and the annular groove 11 form an impedance matching structure. The impedance can be adjusted by changing the diameter of the annular groove 11. At the same time, the annular groove 11 separates the metallized blind via 10 from the underlying metal conductor 6, forming an open circuit in the impedance matching structure. The metallized through holes 12 in this part are regularly arranged along the length and width directions on one side of the straight section of the inner metal conductor 3 with the metal disk 9.

[0041] The portion extending vertically into the entire structure 100 with the top metal conductor 1 covering the curved inner metal conductor 3 and the metal stub 13 as the cross-section is the substrate-integrated coaxial line-based bandpass filter III. The substrate-integrated coaxial line-based bandpass filter III includes the inner metal conductor 3, the metal disk 9, the short-circuit stubs 14-18, the metal via 7, and the metal stub 13. The portion of the inner metal conductor 3 with the metal disk 9 is parallel to the length extension direction, and the portion with short-circuit stubs 14-18 is bent in an arc shape. The bending of the inner metal conductor 3 reduces its size. The lengths of short-circuit stubs 14 and 18 are 0.2 mm, those of short-circuit stubs 15 and 17 are 1.05 mm, and that of short-circuit stub 16 is 1.4 mm. Metal stubs 13 are evenly spaced on both sides of the inner metal conductor 3 and are connected to the top metal conductor 1 and the bottom metal conductor 6 through metallized through-holes 7. The metal stubs 13 and short-circuit stubs 14-18 serve to filter the bent portion of the inner metal conductor 3. The metallized through-holes are arranged on both sides of the bent portion of the inner metal conductor 3, coinciding with the metal stubs 13. The spacing between adjacent metallized through-holes 7 in each row is 0.8 mm, and the diameter is 0.5 mm. The appropriate through-hole size and spacing can reduce the processing difficulty and prevent electromagnetic wave leakage.

[0042] Taking the straight section of the inner metal conductor 3 (without the metal disk 9) covered by the top metal conductor 1 as a cross-section, the portion extending vertically into the entire structure 100 is the half-mode substrate integrated coaxial adapter structure II. The half-mode substrate integrated coaxial adapter structure II includes the inner metal conductor 3 (without the disk 9) and metallized vias 12. The metallized vias 12 are regularly arranged along their width and length directions on both sides of the straight section of the inner metal conductor 3 (without the metal disk 9). The half-mode substrate integrated coaxial adapter structure II connects the bandpass filter III based on the substrate integrated coaxial line and the half-mode substrate integrated coaxial line slot antenna I in the middle metal conductor layer through the straight section of the inner metal conductor 3 (without the metal disk 9), providing feed for the slot antenna. The combination of these two components achieves an integrated design for the filter antenna feed, which can significantly suppress out-of-band electromagnetic energy, improve frequency selectivity, and expand the antenna bandwidth.

[0043] The dielectric layer comprises an upper dielectric layer 2, an intermediate adhesive layer 4, and a lower dielectric layer 5. Both the upper dielectric layer 2 and the lower dielectric layer 5 are 0.254 mm thick TaconocTLY-5 printed circuit boards. The intermediate adhesive layer 4 is a 0.1 mm thick FR-27 prepreg. The inner metal conductor 3 has a width of 0.386 mm. The impedance of the substrate-integrated coaxial cable is determined by the substrate thickness and the width of the inner conductor. The port impedance of this invention is 50 ohms, facilitating integration with other integrated circuit structures.

[0044] In this embodiment, all metal materials used are copper. The filter slot array antenna 100 based on a half-mode substrate integrated coaxial line is fabricated using PCB processing technology. Copper is plated on the upper surface of the upper dielectric layer 2 to form the top metal conductor 1. At the same time, the slot 8 is etched onto the top metal conductor 1. Copper is plated on the lower surface of the upper dielectric layer 2 to form the inner metal conductor 3, the metal stub 13, and the short-circuit stubs 14-18. Copper is plated on the upper surface of the lower dielectric layer 5 to form the bottom metal conductor 6. At the same time, the annular groove 11 is etched onto the bottom metal conductor 6. The upper dielectric layer 2, the lower dielectric layer 5, and the intermediate adhesive layer 4 are laminated and formed. Finally, holes are drilled at the corresponding positions of the metallized through holes 12 and the metallized blind holes 10. Electrical connection is achieved by copper plating between the holes.

[0045] In this example, to measure antenna performance, simulation software was used to perform parametric simulation on a filtered slot array antenna 100 based on a half-mode substrate integrated coaxial line. Since the antenna operates in free space, after the antenna model was created, the antenna boundary was set to ideal boundary conditions, and the antenna input port was set to a waveguide port. The performance of the 24GHz-32GHz frequency band was then analyzed and calculated.

[0046] See Figure 6 As shown, a comparison of simulation graphs of the antenna's reflection coefficient and actual gain before and after adding the filter structure is presented: without the filter structure, the antenna's -10dB impedance bandwidth is 27.6-28.3GHz, while with the filter structure, the antenna's -10dB impedance bandwidth is 27.5-28.5GHz, thus expanding the antenna's bandwidth. Simultaneously, the antenna's out-of-band gain is significantly reduced after adding the filter structure.

[0047] See Figure 7 As shown, the antenna's main polarization and cross-polarization gain patterns at the center frequency of 28 GHz are given: the main polarization radiation gain in the maximum radiation direction is 12.02 dBi, and the cross-polarization radiation gain is -7.3 dBi, indicating good cross-polarization performance.

[0048] In summary, the filter slot array antenna based on a half-mode substrate integrated coaxial line of the present invention has the characteristics of miniaturization, high integration and high gain.

Claims

1. A filter slot array antenna based on half-mode substrate integrated coaxial line, comprising a top layer metal conductor, a bottom layer metal conductor, and a metalized via, characterized in that, Also include intermediate metal conductor layer, gap radiation unit; Wherein, the intermediate metal conductor layer includes shape-changing metal inner conductor, metal stubs arranged on both sides of the curved part of the metal inner conductor, short-circuit stubs with one end extending from the curved part of the metal inner conductor and the other end connected with the metal stubs, the metal stubs and the short-circuit stubs play a filtering role. The gap radiation unit sequentially includes one-to-one corresponding slots in the vertical direction, metal discs arranged at a straight line part of the metal inner conductor, metalized blind holes and annular grooves; the slots are etched in the top layer of metal conductor; the metalized blind hole is located at the center of the annular groove, and the annular groove and the metalized blind hole are located on the bottom layer of metal conductor; the metalized blind hole is in contact with the metal disc to connect the intermediate metal conductor layer and the bottom layer of metal conductor; The metalized through hole penetrates through the whole structure from top to bottom and connects the top and bottom layers of metal conductor to form a closed structure.

2. The filter slot array antenna based on the half-mode substrate integrated coaxial line according to claim 1, characterized in that, The gap radiation unit is provided with five radiation units with the same spacing, forming a one-dimensional linear array.

3. The filter slot array antenna based on the half-mode substrate integrated coaxial line according to claim 1, characterized in that, The metal stubs are arranged at equal intervals on both sides of the metal inner conductor and are connected with the top layer of metal conductor and the bottom layer of metal conductor through the metalized through hole.

4. The filter slot array antenna based on the half-mode substrate integrated coaxial line according to claim 1, characterized in that, The metal disc, the metalized blind hole and the annular groove form an impedance matching structure, and the diameter of the annular groove is changed to adjust the impedance.

5. The filter slot array antenna based on half-mode substrate integrated coaxial line according to claim 1, characterized in that, The annular groove separates the metalized blind hole and the bottom layer of metal conductor to form an open circuit of the impedance matching structure; one end of the metal inner conductor provided with the metal disc forms a terminal open circuit.

6. The filter slot array antenna based on half-mode substrate integrated coaxial line according to claim 1, characterized in that, The filter gap array antenna based on the semi-mode substrate integrated coaxial line is provided with a top layer of metal conductor, an upper layer of dielectric layer, an intermediate metal conductor layer, an intermediate adhesive layer, a lower layer of dielectric layer and a bottom layer of metal conductor from top to bottom; the metal inner conductor is located at the center of the upper surface of the intermediate adhesive layer along the length extension direction, the metal inner conductor is composed of a straight line part and a bending part, the part provided with the metal disc is parallel to the length extension direction, the part provided with the short-circuit stub is in an arch-shaped bending, only half of the top layer of metal conductor is left along the axis of the straight line part of the metal inner conductor, and the lengths and widths of the other dielectric layers and metal conductor layers are equal.

7. The filter slot array antenna based on the half-mode substrate integrated coaxial line according to claim 1 or 6, characterized in that, The part extending in the vertical direction of the whole structure with the top layer of metal conductor covering the curved metal inner conductor and the metal stubs and the metalized through hole coinciding with the metal stubs arranged on both sides of the curved part of the metal inner conductor is a band-pass filter based on the substrate integrated coaxial line.

8. The filter slot array antenna based on the half-mode substrate integrated coaxial line according to claim 1 or 6, characterized in that, The part extending in the vertical direction of the whole structure with one side of the top layer of metal conductor along the axis of the metal inner conductor as the cross section and the metalized through hole regularly arranged on one side of the straight line part of the metal inner conductor provided with the metal disc along the length and width extension direction of the whole structure is a semi-mode substrate integrated coaxial line slot antenna.

9. The filter slot array antenna based on half-mode substrate integrated coaxial line according to claim 1 or 6, characterized in that, The part extending in the vertical direction of the whole structure with the straight line part of the metal inner conductor not provided with the metal disc as the cross section of the top layer of metal conductor covering the metal inner conductor and the metalized through hole regularly arranged on both sides of the straight line part of the metal inner conductor not provided with the metal disc along the length and width extension direction of the whole structure is a semi-mode substrate integrated coaxial switching structure.

10. The filter slot array antenna based on half-mode substrate integrated coaxial line according to claim 1, characterized in that, The filter slot array antenna based on the half-mode substrate integrated coaxial line is processed by a PCB processing technology, copper is plated on the upper surface of an upper dielectric layer to form a top metal conductor, and a slot is etched on the top metal conductor; copper is plated on the lower surface of the upper dielectric layer to form a metal inner conductor, a metal stub and a short-circuit branch; copper is plated on the upper surface of a lower dielectric layer to form a bottom metal conductor, and a ring groove is etched on the bottom metal conductor; the upper and lower dielectric layers and an intermediate adhesive layer are laminated and formed; finally, holes are drilled at positions corresponding to the metalized through holes and the metalized blind holes, and electrical connection is realized by copper plating between the holes.

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