Single-layer differential feed three-frequency filtering antenna

Abstract

The application relates to a differential feeding three-frequency filtering antenna with consistent polarization and similar radiation patterns, belonging to the field of radio frequency devices of 5G communication equipment, and comprising a dielectric substrate, a main radiation patch, four parasitic radiation patches, a feeding cable and a grounding plate. The main radiation patch is composed of two mirror-symmetrical driving patches, open-circuit branches are arranged on the adjacent ends of the two driving patches in a staggered mode, so as to form an interdigital coupling structure; an open ring slot, a row of short-circuit through holes and a pair of parasitic open-circuit branches are arranged on each driving patch. The four parasitic radiation patches are L-shaped and are distributed at the four corners of the main radiation patch, and through holes are arranged on the parasitic radiation patches. The feeding cable comprises two ports powered by coaxial cables, which are excited in an equal-amplitude but opposite-phase mode to realize differential feeding. The feeding cable is connected with the main radiation patch after penetrating through the grounding plate, the dielectric substrate and the through holes.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency devices for 5G communication equipment, and relates to a single-layer differential-fed tri-band filter antenna. Background Technology

[0002] With the development of internet multimedia, the number of terminal devices is increasing, placing higher demands on communication quality. To accommodate the growing number of access points, antennas are constantly adding new frequency bands. According to wireless communication standards, mobile communication system frequency bands include 2G / 3G / 4G / 5G, Bluetooth, WLAN, etc. The emergence of different communication frequency bands inevitably raises the issue of utilization of multiple bands. Wireless communication devices typically integrate multiple systems, so antennas also need to cover multiple frequency bands to work together. However, multiple antenna systems not only increase space requirements but also cause coupling and interference between antennas.

[0003] Multi-band antennas integrate multiple operating frequency bands into a single module, thereby reducing the size of the RF front-end. Multi-band antennas with consistent polarization and similar radiation characteristics in each band generally avoid increasing system complexity during the planning phase of base station or wireless access point systems. On one hand, differential-fed antennas are easier to integrate with widely used differential circuits and systems compared to single-ended-fed antennas, offering high common-mode noise suppression, better polarization resolution, and symmetrical radiation patterns. However, few studies have employed differentially fed multi-band antennas. On the other hand, integrating filtering capabilities into the antenna further simplifies circuit design and reduces system losses. Therefore, it is highly desirable for multi-band antennas to possess both differential and filtering characteristics; such systems would significantly reduce the number of processing components and the performance pressure on any RF front-end or back-end. However, differentially fed multi-band filtered antennas are rarely reported, let alone those with consistent polarization and similar radiation patterns in each operating frequency band. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a single-layer differentially fed tri-band filter antenna, which has consistent polarization and similar wide-side radiation characteristics in each frequency band. It consists of a main radiating patch and four parasitic radiating patches.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A single-layer differential-fed tri-band filter antenna includes a dielectric substrate, on which a main radiating patch, four parasitic radiating patches and a feed cable are provided, and a ground plane is provided below the dielectric substrate. The main radiating patch consists of two mirror-symmetrical driving patches. On the adjacent ends of the two driving patches, there are staggered open-circuit stubs, thus forming an interdigital coupling structure. Each driving patch has an open annular groove, a row of short-circuit vias, and a pair of symbiotic open-circuit stubs. The four parasitic radiation patches are L-shaped and distributed at the four corners of the main radiation patch. The parasitic radiation patches are provided with vias. The feed cable includes two ports powered by a coaxial cable, which are excited in a manner with equal amplitude but opposite phase to achieve differential feeding; the feed cable passes through a ground plane, a dielectric substrate and a via and is connected to the main radiating patch.

[0006] Furthermore, the thickness of the main radiating patch, the parasitic radiating patch, and the grounding plate are all made of copper with a thickness of 0.010mm to 0.025mm.

[0007] Furthermore, the insertion length L2 of the staggered arrangement of the metal main radiating patches, i.e., the interdigitated structure, is 1.7mm~2.7mm, the width W2 of the insertion portion is 0.1mm~1.4mm, the spacing G2 between the insertion portion and the driving patch is 0.15mm~0.45mm, and the spacing G3 between the insertion portions is 0.17mm~0.97mm; the distance L1 from the feed point to the edge of the driving patch is 9.5mm~10.5mm, the distance G1 from the edge of the feed point of the driving patch is 0.4mm~1.4mm, and the center distance D1 between the two feed points is 1.3mm~2.3mm; the outward extension of the quarter-wavelength co-occurring open-circuit stubs at both ends of the driving patch has a length L3 of 3.9mm~4.9mm and a width W3 of 0.7mm~1.7mm, and the stub length L4 is 4.0mm~5.0mm and the width W4 is 0.1mm. ~1.1mm; the length S1 of the etched annular groove of the driver patch is 13.9mm~14.9mm, the shorter side length S3 of the annular groove is 1.7mm~2.7mm, the width W6 is 0.1mm~0.3mm, and the distance Sx between the annular groove and the interdigitated structure of the driver patch is 7.5mm~8.5mm; the spacing D2 between the shorting posts on the driver patch is 2.18mm~3.18mm, and the distance D3 between the shorting posts of the driver patch and the feed hole is 2.7mm~3.7mm.

[0008] Furthermore, the length L5 of the L-shaped metal parasitic radiation patch is 13.8 mm, the length L6 is 7.5 mm, and the width W5 is 3.6 mm; the distance G4 from the parasitic radiation patch to the driving patch is 0.5 mm; the spacing D5 between the metallized vias on the parasitic radiation patch is 0.6 mm to 1.6 mm, and the diameter D6 of the vias is 0.3 mm to 1.3 mm.

[0009] Furthermore, the thickness H of the dielectric substrate is 3mm~4mm; its relative permittivity... ɛr Between 3 and 4, the loss tangent is 0.0035.

[0010] The beneficial effects of the present invention are as follows: (1) By introducing an interdigital structure on the driving patch, not only is the structural performance and performance of the antenna not seriously sacrificed, but the TM of the antenna can also be reduced. 1,0 TM 1,2 TM 1,4 and inverted TM 2,0 The operating frequencies of the four resonant modes enable the miniaturization of the antenna. (2) Introducing a pair of open-circuit quarter-wavelength co-occurring stubs on each driving patch can further reduce the antenna TM. 1,2 TM 1,4 The operating frequency of the mode can further realize the miniaturization of the antenna; at the same time, a radiation null point can be introduced to improve the filtering performance. (3) By introducing a row of short-circuit vias on the driving patch and introducing an open ring slot, the impedance bandwidth of the antenna can be expanded and the filtering performance can be improved. In addition, due to the adoption of differential feeding, it also exhibits high cross-polarization discrimination and high common-mode rejection level. The antenna is simple in form, compact in structure, and easy to integrate, which can make it applicable to mobile / portable routing equipment, such as converting the 5G signal of the mobile operator into the WIFI signal usually required by the user equipment. It also has the advantages of low price and easy mass production.

[0011] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0012] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is an overall schematic diagram of the single-layer differential-fed tri-frequency filter antenna described in this invention; Figure 2 This is a structural diagram of the metal main radiating patch of the single-layer differential-fed tri-frequency filter antenna described in this invention; Figure 3 This is a structural diagram of the metal parasitic radiating patch of the single-layer differential-fed tri-frequency filter antenna described in this invention; Figure 4 This is a side view of the single-layer differential-fed tri-band filter antenna described in this invention; Figure 5 The single-layer differential-fed tri-band filter antenna of this invention exhibits frequency and reflection coefficient |S| under differential signal excitation. dd11| Relationship diagram between realized gain; Figure 6 The single-layer differential-fed tri-band filter antenna of this invention exhibits frequency and reflection coefficient |S| under common-mode signal excitation. cc11 | Relationship diagram between realized gain; Figure 7 This invention describes a single-layer differentially fed three-frequency filter antenna with an achievable two-dimensional gain radiation pattern at the center frequency of the low-frequency passband. Figure 8 The single-layer differential-fed three-frequency filter antenna described in this invention has an achievable two-dimensional gain radiation pattern at the center frequency of the intermediate frequency passband. Figure 9 This invention describes a single-layer differentially fed three-frequency filter antenna with an achievable two-dimensional gain radiation pattern at the center frequency of the high-frequency passband. Among them: 1-metal main radiating patch, 2-metal parasitic radiating patch, 3-ground plane, 4-via, 5-interdigital coupling structure, 6-dielectric substrate, 7-open annular groove, 8-open stub, 9-coaxial cable, 10-shielding layer. Detailed Implementation

[0013] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0014] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0015] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they 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, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0016] Please see Figures 1-4 A single-layer differential-fed tri-band filter antenna includes a metal main radiating patch 1, a metal parasitic radiating patch 2, a dielectric substrate 6, a ground plane 3, and a feed cable. The metal main radiating patch 1 is composed of two approximately mirror-symmetrical metal driving patches, with open-circuit stubs extending from these two driving patches forming an interdigital coupling structure 5. Each driving patch includes an open annular slot 7, a row of short-circuit vias 4, and a pair of coexisting open-circuit stubs. The metal parasitic radiating patch 2 is L-shaped and has vias 4. The dielectric substrate 6 is a single-layer structure, with the ground plane 3 located directly below it. The feed cable includes two ports powered by a 50Ω coaxial cable 9, which are excited with equal amplitude but opposite phase to achieve the required differential feeding. Through the feed cable connection port, the exposed inner core wire at the upper end of the feed cable passes through the ground plane 3, the dielectric substrate 6, and the vias 4 before connecting to the metal main radiating patch 1. The feed cable includes an inner core wire and a shielding layer 10.

[0017] In this embodiment, the thickness of the main metal radiating patch 1, the parasitic metal radiating patch 2, and the grounding plate 3 is all 0.018 mm.

[0018] The adjacent portions of the main metal radiating patch 1 form an interdigital coupling structure 5. The insertion length L2 of the interdigital coupling structure 5 in the staggered arrangement of the main metal radiating patch 1 is 2.2 mm, the width W2 of the insertion portion is 0.6 mm, the spacing G2 between the insertion portion and the driving patch is 0.25 mm, and the spacing G3 between the insertion portions is 0.57 mm. Furthermore, the distance L1 from the feed point to the edge of the driving patch is 10.0 mm, the edge distance G1 of the feed point of the driving patch is 0.9 mm, and the center distance D1 between the two feed points is 1.8 mm. The driving patch has quarter-wavelength co-occurring open-circuit stubs at both ends. The outward extension length L3 is 4.4mm and the width W3 is 1.2mm, the branch length L4 is 4.5mm and the width W4 is 0.6mm; the length S1 of the etched opening annular groove of the driver patch is 14.4mm, the shorter side length S3 of the opening annular groove is 2.2mm, the width W6 is 0.2mm, and the distance Sx between the opening annular groove and the interdigital coupling structure 5 of the driver patch is 8.0mm; the spacing D2 between the shorting posts on the driver patch is 2.68mm, and the distance D3 between the shorting post of the driver patch and the feed hole is 3.2mm.

[0019] In this embodiment, the length L5 of the metal parasitic radiation patch 2 is 13.8 mm, the length L6 is 7.5 mm, and the width W5 is 3.6 mm; the distance G4 from the metal parasitic radiation patch 2 to the driving patch is 0.5 mm, and the distance D4 between the metal parasitic radiation patch 2 and the open-circuit symbiotic branch is 3.08 mm.

[0020] In this embodiment, the thickness H of the dielectric substrate is 3.8 mm; its relative permittivity is... ɛ r The value is 3.55, and the loss tangent is approximately 0.0035 mm.

[0021] In practical implementation, the radiating metal patch consists of two large rectangular metal sheets. An interdigitated structure is introduced on each adjacent side, extending along the x and -x directions. A pair of open-circuit quarter-wavelength co-occurring branches are introduced on each drive patch, and an open annular groove is etched on each drive patch. The interdigitated structure formed by the drive patches extending in the x and -x directions serves to reduce TM (transformation time). 1,0 TM 1,2 TM 1,4 and inverted TM 2,0 The antenna operates at four resonant modes. The open annular slots on the drive patch are designed to broaden the bandwidth and improve filtering performance. Symbiotic open-circuit stubs introduced at both ends of the drive patch enhance the selectivity of the intermediate frequency (IF) and the isolation level between the IF and high frequencies. The parasitic component is a metallic parasitic radiating patch 2 with via 4; the via enables quarter-wavelength half-mode resonant operation. The antenna configuration is almost perfectly symmetrical with respect to the X and Y axes, a measure designed to achieve a high common-mode rejection level.

[0022] The dielectric substrate 6 is a 3.8mm thick RO4003 substrate with a dielectric constant of [missing information]. ɛ r =3.55, loss tangent δ= 0.0035. Other parameters: Lg = 70.0 mm.

[0023] Reference Figure 5 As can be seen, under differential signal excitation, the antenna exhibits a -10dB impedance bandwidth across a frequency range of 2.4-2.487GHz (low frequency), 3.72-3.93GHz (mid frequency), and 5.57-5.88GHz (high frequency), and its gain curve demonstrates good frequency selectivity and out-of-band rejection capabilities. (Refer to...) Figure 6 It can be seen that under common-mode signal excitation, the antenna's reflection coefficient |S cc11 | is close to 0, meaning the common-mode signal is almost completely reflected, and the achievable gain is also very low, indicating that the antenna has good common-mode rejection capability.

[0024] Reference Figures 7-9 As can be seen, this antenna exhibits good and stable radiation performance. It demonstrates stable, unidirectional wide-side radiation performance with consistent X-polarization across all three frequency bands. It should be noted that most reported tri-band antennas are implemented using stacked radiating patches, which is difficult to achieve in a simple, low-cost single-layer structure. The results above show that the antenna of this invention has excellent filtering response, exhibiting a sharp roll-off rate and high out-of-band rejection level in all three frequency bands. Furthermore, due to the use of differential feeding, it achieves excellent common-mode rejection and low cross-polarization level.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A single-layer differential-fed tri-band filter antenna, characterized in that: It includes a dielectric substrate, on which a main radiating patch, four parasitic radiating patches and a power supply cable are provided, and a ground plane is provided below the dielectric substrate; The main radiating patch consists of two mirror-symmetrical driving patches. The adjacent ends of the two driving patches are provided with staggered open-circuit stubs, thereby forming an interdigital coupling structure. Each driving patch is provided with an open annular groove and a row of short-circuit vias, and a pair of open-circuit quarter-wavelength co-occurring stubs are introduced at both ends of each driving patch. The four parasitic radiation patches are L-shaped and distributed at the four corners of the main radiation patch. The parasitic radiation patches are provided with vias. The feed cable includes two ports powered by a coaxial cable, which are excited in a manner with equal amplitude but opposite phase to achieve differential feeding; The feed cable passes through the ground plane, dielectric substrate, and via before connecting to the main radiating patch.

2. The single-layer differential-fed tri-band filter antenna according to claim 1, characterized in that: The main radiating patch, parasitic radiating patch, and grounding plate are all made of copper with a thickness of 0.010mm to 0.025mm.

3. The single-layer differential-fed tri-band filter antenna according to claim 1, characterized in that: The insertion length L2 of the interdigitated structure of the main radiating patch is 1.7mm~2.7mm, the width W2 of the insertion portion is 0.1mm~1.4mm, the spacing G2 between the insertion portion and the driving patch is 0.15mm~0.45mm, and the spacing G3 between the insertion portions is 0.17mm~0.97mm; the distance L1 from the feed point to the edge of the driving patch is 9.5mm~10.5mm, and the distance D1 between the centers of the two feed points is 1.3mm~2.3mm; the outward extension length L3 of the quarter-wavelength co-occurring open-circuit stubs at both ends of the driving patch is 3.9mm~4.9mm, the width W3 is 0.7mm~1.7mm, and the length L4 of the quarter-wavelength co-occurring open-circuit stubs at both ends of the driving patch is 4.0mm~5.0mm, and the width W4 is 0.1mm~1. 1mm; the length S1 of the etched annular groove of the driver patch is 13.9mm~14.9mm, the shorter side length S3 of the annular groove is 1.7mm~2.7mm, the width W6 is 0.1mm~0.3mm, the distance Sx between the annular groove and the interdigitated structure of the driver patch is 7.5mm~8.5mm; the spacing D2 between the shorting posts on the driver patch is 2.18mm~3.18mm, and the distance D3 between the shorting posts of the driver patch and the feed hole is 2.7mm~3.7mm.

4. The single-layer differential-fed tri-band filter antenna according to claim 1, characterized in that: The L-shaped metal parasitic radiation patch has a length L5 of 13.8 mm, an L6 of 7.5 mm, and a width W5 of 3.6 mm; the distance G4 from the parasitic radiation patch to the driving patch is 0.5 mm; the spacing D5 between the metallized vias on the parasitic radiation patch is 0.6 mm to 1.6 mm, and the diameter D6 of the vias is 0.3 mm to 1.3 mm.

5. The single-layer differential-fed tri-band filter antenna according to claim 1, characterized in that: The thickness H of the dielectric substrate is 3mm~4mm; its relative permittivity is... ɛ r Between 3 and 4, the loss tangent is 0.0035.

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