Series-fed dual-mode filtering antenna and wireless communication equipment

Abstract

The present invention discloses a series-fed dual-mode filtering antenna and communication equipment, the antenna comprises a ground plane, a feeding structure, a metal strip, a dielectric substrate, a non-resonant node and a series-fed radiator, the metal strip, the dielectric substrate, the non-resonant node and the series-fed radiator are vertically placed on the ground plane, the dielectric substrate, the non-resonant node and the series-fed radiator are aligned along the same central axis, there are two metal strips, the two metal strips are symmetrically arranged on the first surface of the dielectric substrate about the central axis, the non-resonant node and the series-fed radiator are arranged on the second surface of the dielectric substrate, the non-resonant node is fed by the feeding structure as the main radiator, the series-fed radiator is used as a parasitic radiator, and coupling is generated between the non-resonant node and the series-fed radiator and the metal strip. The present invention can suppress the interference of adjacent frequency bands, thereby maintaining the gain and omnidirectional radiation performance, and at the same time has a high level of suppression of harmonics, which can ensure that no additional insertion loss and the occupied area caused by the redundant structure are introduced.

Description

Technical Field

[0001] The invention relates to a series-fed dual-mode filtering antenna and wireless communication equipment, belonging to the technical field of wireless communication. Background Art

[0002] With the rapid development of wireless communication technology, the requirements for communication quality are getting higher and higher. Antennas, as an important component of communication systems, have a direct impact on the communication quality of the system. In communication systems, in order to pursue the effective use of space, antennas in different frequency bands are often expected to be compactly arranged. A major problem caused by compact arrangement is the serious mutual coupling between antennas in adjacent frequency bands, which will lead to the deterioration of communication quality. On the other hand, the antenna works in a complex frequency environment. It is hoped that the interference and stray signals in the environment can be suppressed to improve the signal quality and receiving sensitivity of the antenna. It is also hoped that the radiation of the antenna outside the working frequency band can be limited to reduce the interference of out-of-band radiation to other devices and systems, and meet the requirements of electromagnetic compatibility. Furthermore, considering the shortage of spectrum resources, the spectrum utilization of the system can be improved through precise frequency selectivity and high roll-off, and unnecessary frequency band overlap and interference can be avoided. Therefore, in terms of antenna performance, in addition to basic indicators such as bandwidth, gain, and directivity, the introduction of filtering performance is also an important consideration.

[0003] Adding an additional cascade filter to the antenna is a simple way to introduce filtering performance. However, the introduction of the filter will bring additional insertion loss and also increase the overall volume of the antenna, which is not conducive to miniaturization. Another solution is a filter antenna, which combines the radiating element and the filter into an integral module. The filter antenna reduces the interconnection loss that occurs when the receiving antenna is connected to the filter, suppresses unwanted signals outside the operating frequency band, and helps to achieve a more compact and lower-cost RF front-end system. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a series-fed dual-mode filtering antenna that can generate transmission zeros on the upper and lower sides of the passband to suppress interference in adjacent frequency bands, thereby maintaining gain and omnidirectional radiation performance, while having a high level of suppression of harmonics, thereby ensuring that no additional insertion loss is introduced and no area is occupied by redundant structures.

[0005] Another object of the present invention is to provide a wireless communication device including the above antenna.

[0006] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0007] A series-fed dual-mode filtering antenna comprises a ground plane, a feeding structure, a metal strip, a dielectric substrate, a non-resonant node and a series-fed radiator, wherein the metal strip, the dielectric substrate, the non-resonant node and the series-fed radiator are vertically placed on the ground plane, the dielectric substrate, the non-resonant node and the series-fed radiator are aligned along the same central axis, there are two metal strips, the two metal strips are symmetrically arranged on the first surface of the dielectric substrate about the central axis, the non-resonant node and the series-fed radiator are arranged on the second surface of the dielectric substrate, the non-resonant node is fed by the feeding structure and serves as a main radiator, the series-fed radiator serves as a parasitic radiator, and coupling is generated between the non-resonant node and the series-fed radiator and the metal strip.

[0008] Furthermore, the non-resonant node is an open-circuit transmission line or a short-circuit transmission line, and the transmission line is made equivalent to a capacitor or an inductor by adjusting the length of the transmission line.

[0009] Furthermore, the series-fed radiator includes a first metal strip, a second metal strip and a feed line, the first metal strip is connected to the second metal strip through the feed line, the width of the feed line is smaller than the first metal strip and the second metal strip, and the first metal strip and the second metal strip are excited in phase by adjusting the length of the feed line. The first metal strip and the second metal strip in phase form a dual-element array, and the length of the first metal strip and the second metal strip is adjusted to be equivalent to LC resonance within the working frequency band.

[0010] Furthermore, when the non-resonant node and the series-fed radiator are capacitively coupled, a radiation zero point is generated at a frequency point lower than the resonant frequency.

[0011] Furthermore, when the non-resonant node and the series-fed radiator are inductively coupled, a radiation zero point is generated at a frequency point greater than the resonant frequency.

[0012] Furthermore, the distance between the radiation zero point and the resonant frequency is adjusted by the coupling strength between the non-resonant node and the series-fed radiator.

[0013] Furthermore, when the two metal strips are excited by the non-resonant node in a capacitive coupling manner, they generate in-phase currents, forming a quasi-common-mode structure;

[0014] The two metal strips use the series-fed radiator as the electrical ground, and are short-circuited together with the non-resonant node and the series-fed radiator by the grounding plate. After the feeding structure feeds the non-resonant node, the magnetic field of the non-resonant node passes through the loop formed by the grounding plate, the series-fed radiator, the two metal strips and the displacement current to achieve magnetic coupling. The series-fed radiator and the two metal strips generate anti-phase current to form a quasi-differential mode structure.

[0015] Furthermore, the two metal strips are coupled with the non-resonant node to form a structure with a resonant frequency and a radiation zero point, and the resonant frequency and the radiation zero point are regulated by the coupling strength between the two metal strips and the non-resonant node and the resonant frequency of the two metal strips.

[0016] Furthermore, the feeding structure is a coaxial line, which includes an outer conductor and an inner conductor, wherein the outer conductor is connected to a ground plate, and the inner conductor is connected to a non-resonant node through a through hole of a dielectric substrate.

[0017] Another object of the present invention can be achieved by adopting the following technical solutions:

[0018] A wireless communication device comprises the above-mentioned series-fed dual-mode filtering antenna.

[0019] The present invention has the following beneficial effects compared with the prior art:

[0020] 1. The series-fed dual-mode filtering antenna of the present invention does not include an additional filtering circuit, the antenna structure is simple, and there is no additional increase in the antenna volume. It has practical engineering application value. The radiation zero point is generated by the cross-coupling structure and the dual-mode structure, and the out-of-band suppression of -14.9 dB (0.65-5 GHz), -20 dB (5-5.6GHz) and -20.56 dB (6.3-7.3 GHz) is achieved. By adjusting the specific dimensions of the cross-coupling structure and the dual-mode structure, the zero point position can be adjusted; it has a bandpass filtering effect with high roll-off and good out-of-band suppression capability out of the band. At the same time, it has good radiation performance in the passband. The way to achieve filtering performance does not bring additional processing costs and has a wide range of applications, and does not introduce additional insertion loss.

[0021] 2. The series-fed dual-mode filter antenna of the present invention operates in the 5735-6100MHz frequency band, covering the 5735-5835MHz frequency band of WIFI and the 5850-5925MHz frequency band of V2X, and can generate two adjustable radiation zero points to enhance selectivity, thereby ensuring isolation from adjacent frequency bands and achieving out-of-band suppression of -14.9 dB (0.65-5 GHz), -20 dB (5-5.6 GHz) and -20.56dB (6.3-7.3 GHz); therefore, the antenna can be used as a WIFI antenna in the 5GHz frequency band and can suppress other WIFI frequency bands; it can also be used as a vehicle-mounted V2X antenna, which can suppress adjacent WIFI frequency bands, and can suppress harmonic interference while improving communication quality, and is particularly suitable for integration with antennas of multiple frequencies. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0023] Figure 1 This is a front view structural diagram of the series-fed dual-mode filtering antenna according to an embodiment of the present invention.

[0024] Figure 2 It is a top view of the structure of the series-fed dual-mode filter antenna according to an embodiment of the present invention.

[0025] Figure 3 It is a decomposition structure diagram of the series-fed dual-mode filtering antenna according to an embodiment of the present invention.

[0026] Figure 4 It is a structural diagram of the relationship between the feeding structure, the ground plate, and the non-resonant node in the series-fed dual-mode filter antenna according to an embodiment of the present invention.

[0027] Figure 5 It is a structural diagram of a series-fed radiator in a series-fed dual-mode filter antenna according to an embodiment of the present invention.

[0028] Figure 6 This is a simulation result diagram of the reflection coefficient-frequency of the series-fed dual-mode filtering antenna according to an embodiment of the present invention.

[0029] Figure 7 It is a simulation result diagram of gain-frequency and radiation efficiency-frequency of the series-fed dual-mode filter antenna according to an embodiment of the present invention.

[0030] Figure 8 Schematic diagram of the radiation pattern of the series-fed dual-mode filtering antenna according to an embodiment of the present invention.

[0031] Among them, 1-ground plate, 2-outer conductor, 3-inner conductor, 4-first metal strip, 5-second metal strip, 6-dielectric substrate, 7-non-resonant node, 8-series-fed radiator. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] Example:

[0034] like Figure 1-Figure 3 As shown, this embodiment provides a series-fed dual-mode filtering antenna, which can be applied to various communication devices, and includes a ground plane 1, a feeding structure, a metal strip, a dielectric substrate 6, a non-resonant node 7 and a series-fed radiator 8. The metal strip, the dielectric substrate 6, the non-resonant node 7 and the series-fed radiator 8 are vertically placed on the ground plane 1, the dielectric substrate 6, the non-resonant node 7 and the series-fed radiator 8 are aligned along the same central axis, there are two metal strips, the two metal strips are a first metal strip 4 and a second metal strip 5, respectively, the first metal strip 4 and the second metal strip 5 are symmetrically arranged on the first surface (front surface) of the dielectric substrate 6 about the central axis, and the non-resonant node 7 and the series-fed radiator 8 are arranged on the second surface (rear surface) of the dielectric substrate 6.

[0035] Furthermore, if Figure 4 As shown, the non-resonant node 7 is fed by a feeding structure as a main radiator. The feeding structure is a coaxial line, which includes an outer conductor 2 and an inner conductor 3. The outer conductor 2 is connected to the ground plate 1, and the inner conductor 3 is connected to the non-resonant node 7 through a through hole of the dielectric substrate 6.

[0036] Furthermore, the non-resonant node 7 is an open transmission line or a short transmission line, which is not surrounded by metal and can radiate energy outward. By adjusting the length of the transmission line, the transmission line can be made equivalent to a capacitor or an inductor.

[0037] Furthermore, if Figure 5 As shown, the series-fed radiator 8 serves as a parasitic radiator, which includes a first metal strip 81, a second metal strip 82 and a feed line 83, wherein the first metal strip 81 and the second metal strip 82 are respectively an upper metal strip and a lower metal strip, the first metal strip 81 is connected to the second metal strip 82 via the feed line 83, the width of the feed line 83 is smaller than the first metal strip 81 and the second metal strip 82, and the length of the feed line 83 is adjusted to approximately 1 / 2 wavelength at the center frequency, so that the first metal strip 81 and the second metal strip 82 are excited in phase, and the width of the feed line 83 is narrow to suppress their radiation; the first metal strip and the second metal strip in phase form a dual-element array to improve the antenna gain, and the length of the first metal strip 81 and the second metal strip 82 is adjusted to approximately 1 / 4 wavelength at the center frequency to be equivalent to LC resonance within the working frequency band.

[0038] Furthermore, coupling is generated between the non-resonant node 7 and the series-fed radiator 8 to form a cross-coupling structure, and the series-fed radiator 8 is directly excited by the non-resonant node 7. The non-resonant node 7 and the series-fed radiator 8 radiate outward at the same time to form two radiation paths. When the two paths transmit in anti-phase, a radiation zero point will be generated. In order to enable coupling between the non-resonant node 7 and the series-fed radiator 8, a groove is opened on the second metal strip 82, and the position of the groove corresponds to the position of the non-resonant node 7. The non-resonant node 7 and the series-fed radiator 8 are coupled through the groove, and the size of the groove affects the coupling strength between the non-resonant node 7 and the series-fed radiator 8.

[0039] Furthermore, when the non-resonant node 7 and the series-fed radiator 8 are capacitively coupled, a radiation zero point is generated at a frequency point lower than the resonant frequency. The distance between the radiation zero point and the resonant frequency is adjusted by the coupling strength between the non-resonant node 7 and the series-fed radiator 8. The stronger the coupling, the farther the distance between the radiation zero point and the resonant frequency.

[0040] Furthermore, when the non-resonant node 7 and the series-fed radiator 8 are inductively coupled, a radiation zero point is generated at a frequency point greater than the resonant frequency. The distance between the radiation zero point and the resonant frequency is adjusted by the coupling strength between the non-resonant node 7 and the series-fed radiator 8. The stronger the coupling, the farther the distance between the radiation zero point and the resonant frequency.

[0041] Furthermore, the dual-mode structure includes a quasi-common mode structure and a quasi-differential mode structure. When the first metal strip 4 and the second metal strip 5 are excited by the non-resonant node 7 in a capacitive coupling manner, in-phase current is generated to form a quasi-common mode structure. At this time, the waveguide wavelength corresponding to the metal strip is not affected by the dielectric constant of the dielectric substrate 6, and its resonant frequency is higher than the antenna operating frequency. Therefore, under the quasi-common mode structure, only one resonance is generated by the series-fed radiator 8, and its response is similar to the response of the cross-coupling structure; the first metal strip 4 and the second metal strip 5 use the series-fed radiator 8 as the electrical ground to form a microstrip line structure, and are short-circuited together with the non-resonant node 7 and the series-fed radiator 8 by the ground plate 1. After the feeding structure feeds the non-resonant node 7, the magnetic field of the non-resonant node 7 passes through the loop formed by the ground plate, the series-fed radiator, the two metal strips and the displacement current to achieve magnetic coupling. The series-fed radiator 8 and the two metal strips generate anti-phase current to form a quasi-differential mode structure.

[0042] Furthermore, the waveguide wavelength of the microstrip line structure formed by the first metal strip 4, the second metal strip 5 and the series-fed radiator 8 is affected by the dielectric constant of the dielectric substrate. The lengths of the two metal strips are designed so that they resonate just within the working frequency band. The two metal strips are equivalent to a resonant circuit. After coupling with the non-resonant node 7, an opposite resonant structure is generated in the overall equivalent circuit. Therefore, the two metal strips are coupled with the non-resonant node to form a structure with a resonant frequency and a radiation zero point. The resonant frequency and the radiation zero point are regulated by the coupling strength between the two metal strips and the non-resonant node 7 and the resonant frequency of the two metal strips.

[0043] like Figure 6 As shown, the reflection coefficient (S 11 )-frequency simulation result diagram, the impedance matching in the passband is good, the impedance bandwidth is 5735-6100MHz, and the return loss is below -10dB.

[0044] like Figure 7 As shown, the simulation results of gain-frequency and radiation efficiency-frequency of the series-fed dual-mode filter antenna of this embodiment are shown. The gain in the working frequency band is about 4dBi, and the passband has high roll-off filtering characteristics on both sides, and out-of-band suppression of -14.9 dB (0.65-5 GHz), -20 dB (5-5.6 GHz) and -20.56 dB (6.3-7.3 GHz) is achieved. The antenna efficiency in the working frequency band is about -0.44dB, and no additional insertion loss is introduced, which meets the working efficiency requirements of the terminal antenna.

[0045] like Figure 8 As shown, it is the radiation pattern of the series-fed dual-mode filter antenna of this embodiment. The maximum radiation direction is the horizontal direction, and the maximum radiation gain can reach 4.62dBi, with good high-gain omnidirectional radiation performance.

[0046] In summary, the present invention can adjust the size of the relevant structure according to the needs to adapt to the receiving and transmitting equipment of the wireless communication system in different frequency bands. Due to the filtering characteristics of the present invention, it is particularly suitable for communication scenarios where the frequency band interval is small and the selectivity needs to be improved, and the frequency composition is complex and harmonics need to be suppressed. At the same time, benefiting from the integration of filtering characteristics and radiation characteristics, the present invention is also suitable for the integration and integration of wireless mobile communication system equipment.

[0047] The above is only a preferred embodiment of the present invention, but the implementation of the present invention is not limited to the above embodiment. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principle of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A series-fed dual-mode filtering antenna, characterized in that: It includes a ground plane, a feeding structure, a metal strip, a dielectric substrate, a non-resonant node and a series-fed radiator, wherein the metal strip, the dielectric substrate, the non-resonant node and the series-fed radiator are vertically placed on the ground plane, the dielectric substrate, the non-resonant node and the series-fed radiator are aligned along the same central axis, there are two metal strips, the two metal strips are symmetrically arranged on the first surface of the dielectric substrate about the central axis, the non-resonant node and the series-fed radiator are arranged on the second surface of the dielectric substrate, the non-resonant node is fed by the feeding structure and serves as a main radiator, the series-fed radiator serves as a parasitic radiator, and coupling is generated between the non-resonant node and the series-fed radiator and the metal strip.

2. The series-fed dual-mode filtering antenna according to claim 1, characterized in that: The non-resonant node is an open transmission line or a short transmission line. If the non-resonant node is an open transmission line, the length of the open transmission line is adjusted to make the open transmission line equivalent to a capacitor. If the non-resonant node is a short transmission line, the length of the short transmission line is adjusted to make the short transmission line equivalent to an inductor.

3. The series-fed dual-mode filtering antenna according to claim 1, characterized in that: The series-fed radiator includes a first metal strip, a second metal strip and a feed line, wherein the first metal strip is connected to the second metal strip via the feed line, and the width of the feed line is smaller than that of the first metal strip and the second metal strip. By adjusting the length of the feed line, the first metal strip and the second metal strip are excited in phase, and the first metal strip and the second metal strip in phase form a dual-element array. By adjusting the length of the first metal strip and the second metal strip, LC resonance within the working frequency band is achieved.

4. The series-fed dual-mode filtering antenna according to claim 1, characterized in that: When the non-resonant node and the series-fed radiator are capacitively coupled, a radiation zero point is generated at a frequency point lower than the resonant frequency.

5. The series-fed dual-mode filtering antenna according to claim 1, characterized in that: When the non-resonant node and the series-fed radiator are inductively coupled, a radiation zero point is generated at a frequency point greater than the resonant frequency.

6. The series-fed dual-mode filtering antenna according to any one of claims 4 to 5, characterized in that: The distance between the radiation zero point and the resonant frequency is adjusted by the coupling strength between the non-resonant node and the series-fed radiator.

7. The series-fed dual-mode filtering antenna according to any one of claims 1 to 5, characterized in that: When the two metal strips are excited by a non-resonant node in a capacitive coupling manner, they generate in-phase currents, forming a quasi-common-mode structure; The two metal strips use the series-fed radiator as the electrical ground, and are short-circuited together with the non-resonant node and the series-fed radiator by the grounding plate. After the feeding structure feeds the non-resonant node, the magnetic field of the non-resonant node passes through the loop formed by the grounding plate, the series-fed radiator, the two metal strips and the displacement current to achieve magnetic coupling. The series-fed radiator and the two metal strips generate anti-phase current to form a quasi-differential mode structure.

8. The series-fed dual-mode filtering antenna according to claim 7, characterized in that: The two metal strips are coupled with the non-resonant node to form a structure with a resonant frequency and a radiation zero point, wherein the resonant frequency and the radiation zero point are regulated by the coupling strength between the two metal strips and the non-resonant node and the resonant frequency of the two metal strips.

9. The series-fed dual-mode filtering antenna according to any one of claims 1 to 5, characterized in that: The feeding structure is a coaxial line, which includes an outer conductor and an inner conductor. The outer conductor is connected to a ground plate, and the inner conductor is connected to a non-resonant node through a through hole of a dielectric substrate.

10. A wireless communication device, characterized in that: It comprises the series-fed dual-mode filtering antenna as described in any one of claims 1 to 9.

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