CN110994185A - Microstrip line tuning circuit and base station antenna - Google Patents
Microstrip line tuning circuit and base station antenna Download PDFInfo
- Publication number
- CN110994185A CN110994185A CN201911242775.9A CN201911242775A CN110994185A CN 110994185 A CN110994185 A CN 110994185A CN 201911242775 A CN201911242775 A CN 201911242775A CN 110994185 A CN110994185 A CN 110994185A
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- CN
- China
- Prior art keywords
- microstrip line
- tuning circuit
- circuit
- base station
- station antenna
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
- H01Q5/30—Arrangements for providing operation on different wavebands
- H01Q5/307—Individual or coupled radiating elements, each element being fed in an unspecified way
- H01Q5/314—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors
- H01Q5/335—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors at the feed, e.g. for impedance matching
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/12—Supports; Mounting means
- H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
- H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
- H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
- H01Q1/246—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for base stations
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
- H01Q5/10—Resonant antennas
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
- H01Q5/20—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements characterised by the operating wavebands
- H01Q5/28—Arrangements for establishing polarisation or beam width over two or more different wavebands
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
- H01Q5/50—Feeding or matching arrangements for broad-band or multi-band operation
Abstract
The invention discloses a microstrip line tuning circuit, which consists of a single-layer PCB (printed circuit board), wherein the single-layer PCB consists of a front copper-clad microstrip line, a dielectric plate and a back copper-clad floor; the front copper-clad microstrip line comprises: the resonator comprises an input bonding pad, an output bonding pad, an input impedance conversion section, an output impedance conversion section and a resonator consisting of a plurality of open-circuit branches connected in parallel, wherein the resonator eliminates the impedance discontinuity phenomenon of the ultra-wideband radiation unit near a corresponding frequency point due to electromagnetic mode conversion by means of anti-resonance, so that the purpose of expanding the impedance bandwidth is achieved. Considering that the most widely used base station antenna radiation units basically work below a third-order mode, the microstrip line tuning circuit is theoretically adapted to almost all radiation units by optimizing to a proper resonant frequency, so that the impedance bandwidth is remarkably improved. The invention also provides a base station antenna.
Description
Technical Field
The invention relates to the technical field of radio frequency tuning circuits, in particular to a universal impedance matching circuit of a sub-6GHz radiating unit of an ultra-wideband base station antenna and an implementation method thereof.
Background
The wireless communication enters the 5G era, and with the development and utilization of new frequency spectrum resources such as n74 (1427-1518 MHz), n71 (617-698 MHz) and the like, higher requirements are put forward on the working bandwidth of a base station antenna (sub-6 GHz). Meanwhile, the miniaturization and integration of the base station antenna are the necessary ways to solve the increasingly serious problems of sector crosstalk and site resource shortage in the dense networking environment. The base station antenna has to meet the strict directional diagram indexes and circuit indexes such as standing wave, isolation, passive intermodulation and the like in the working bandwidth. On the one hand, ultra-wideband makes impedance matching of the radiating elements of the base station antenna very difficult. The impedance bandwidth can be expanded by designing multiple resonances, and the matching of a wider frequency is realized, which is a main method for designing an ultra-wideband radiating unit in the base station antenna industry at present. However, the above method has limitations: 1) it is not easy to design multiple resonances because the resonant modes do not simply correspond to the radiating surface structures and feeding modes of the antennas, and the interaction between different resonant modes is very sensitive; 2) multiple resonance is not a sufficient condition for full-band impedance matching, each resonance corresponds to a specific distribution mode of voltage/current on the vibrator, and if the conversion between different modes is discontinuous, sudden impedance change can be caused, so that the matching fails. On the other hand, more arrays are integrated within increasingly more constraining antennas and crosstalk between radiating elements will become increasingly severe. The radiation units are subjected to complex electromagnetic coupling through mechanisms such as common ground current, parasitic capacitance/parasitic inductance, scattering, secondary radiation and the like, isolation is damaged, the radiation units transmit and receive mutually, the radiation units are mutually bound, and each radiation unit is matched with each other and receives/transmits signals which are influenced by other radiation units. Not only the circuit parameters of standing waves, isolation and the like are difficult to reach the standard, but also the radiation pattern is seriously influenced, thereby causing the problems of gain reduction, waveform distortion, sidelobe suppression, front-to-back ratio variation and the like.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a microstrip line tuning circuit which can eliminate the impedance discontinuity phenomenon of an ultra-wideband radiation unit (sub-6GHz) near a corresponding frequency point due to electromagnetic mode conversion, thereby expanding the impedance bandwidth.
The invention also provides an ultra-wideband base station antenna.
In order to achieve the purpose, the invention adopts the following technical scheme.
A microstrip line tuning circuit is characterized by consisting of a single-layer PCB (printed Circuit Board), wherein the single-layer PCB consists of a front copper-clad microstrip line, a dielectric plate and a back copper-clad floor; the front copper-clad microstrip line comprises: the resonator comprises an input bonding pad, an output bonding pad, an input impedance transformation section, an output impedance transformation section and a resonator consisting of a plurality of open-circuit branches connected in parallel, wherein the resonator is connected between the input impedance transformation section and the output impedance transformation section, each open-circuit branch forms an LC resonance circuit, and each open-circuit branch is matched with the input impedance transformation section and the output impedance transformation section to realize resonance near corresponding frequency.
More preferably, the three-order intermodulation index of the single-layer PCB within the design working frequency is better than-120 dBm, the thickness of the dielectric plate is 0.5-1.5 mm, and the thickness of the copper-clad plate is 0.035 +/-0.005 mm.
More preferably, the rear copper-clad floor is electrically connected to the input pad and the output pad through a metal via.
More preferably, the number of the open branches is one, two or more.
A base station antenna comprises a plurality of radiation units, and is characterized in that each radiation unit is connected with a microstrip line tuning circuit, and resonance of the microstrip line tuning circuit near corresponding frequency is utilized to eliminate impedance mutation caused by mode conversion discontinuity; the corresponding frequency is a standing wave peak frequency of the radiation unit, and the resonance is an anti-resonance for flattening a standing wave peak.
More preferably, the microstrip tuning circuit is as described above.
More preferably, an input pad of the microstrip line tuning circuit is connected to a vibrator pin of the radiating element or a PCB feeder via a radio frequency cable, and an output pad of the microstrip line tuning circuit is connected to a phase shifter or a connector of the radiating element via a radio frequency cable.
More preferably, the number of the open-circuit branches is consistent with the number of the standing wave peaks of the radiation unit and corresponds to one another.
More preferably, the radiating element is a half-wave dipole vibrator, a full-wave folded vibrator, a metal die-cast vibrator or a PCB vibrator.
More preferably, the operating frequency band of the radiation unit includes: 1427-1518 MHz, 617-698 MHz and sub-6 GHz.
The invention has the beneficial effects that:
when the micro-strip line tuning circuit is combined with the ultra-wideband radiation unit, the impedance discontinuity phenomenon of the ultra-wideband radiation unit (sub-6GHz) near a corresponding frequency point due to electromagnetic mode conversion can be eliminated, so that the impedance bandwidth is expanded; meanwhile, the circuit adopts a common single-layer PCB microstrip line circuit, and has the advantages of simple process, low cost and easy batch implementation.
The base station antenna provided by the invention utilizes the micro-strip tuning circuit to perform anti-resonance, so that the impedance sudden change of the ultra-wideband radiation unit caused by discontinuous mode conversion is eliminated, and the aims of flattening the wave crest and improving the standing wave are achieved; the method has universality and is suitable for antenna oscillators with different frequencies, different types and different forms. Meanwhile, the anti-resonance adopts a single-layer PCB microstrip line circuit form which is easy to realize in batch, and the design period of the ultra-wideband radiation unit is effectively shortened.
The microstrip tuning circuit can be used for a multi-frequency compact antenna array, realizes in-situ matching of the radiation unit, eliminates the influence of adaptation on the power/phase distribution of the antenna array, and improves the directional diagram.
Drawings
Fig. 1 is a three-dimensional schematic diagram of a microstrip tuning circuit provided in embodiment 1 of the present invention.
Fig. 2 is a schematic front view of a microstrip tuning circuit provided in embodiment 1 of the present invention.
Fig. 3 is a schematic back view of a microstrip tuning circuit provided in embodiment 1 of the present invention.
Fig. 4 is a standing wave diagram of a base station antenna radiating unit without a microstrip line tuning circuit.
Fig. 5 shows a standing wave diagram of a base station antenna radiating unit using a microstrip line tuning circuit.
Fig. 6 is a schematic diagram of the microstrip line tuning circuit.
Description of reference numerals:
1: front copper-clad microstrip line, 2: dielectric plate, 3: back copper-clad floor, 4: metal via, 5: a radiation unit.
1-1: input pad, 1-2: output pad, 1-3: input impedance transformation section, 1-4: output impedance transformation section, 1-5: a third order resonator.
Detailed Description
The following describes the embodiments of the present invention with reference to the drawings of the specification, so that the technical solutions and the advantages thereof are more clear and clear. The embodiments described below are exemplary and are intended to be illustrative of the invention, but are not to be construed as limiting the invention.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Example 1
As shown in fig. 1, a microstrip line tuning circuit is a single-layer PCB circuit board, which is composed of three parts, namely a front copper-clad microstrip line 1, a dielectric board 2 and a back copper-clad floor 3. The three-order intermodulation index of the PCB within the designed working frequency is better than-120 dBm (two-way 43dBm carrier input), the thickness of the dielectric plate is 0.5-1.5 mm, and the thickness of the copper-clad plate is 0.035 +/-0.005 mm, so that the requirements of the base station antenna on power capacity and passive intermodulation index are met. In addition, in order to improve the consistency of mass production, the dielectric plate 2 is made of a plate with high stability and small batch difference and a manufacturing process.
Referring to fig. 2, the front-side copper-clad microstrip line 1 is composed of an input pad 1-1, an output pad 1-2, an input impedance conversion section 1-3, an output impedance conversion section 1-4, and a third-order resonator 1-5 composed of three open-circuit branches of low-frequency f1, medium-frequency f2, and high-frequency f3 connected in parallel, each open-circuit branch constitutes an LC resonance circuit, and the open-circuit branches and the input/output impedance conversion sections are optimized to realize resonance near corresponding frequencies.
The above-mentioned specific optimization process and optimization method for optimizing the open-circuit branch and the input/output impedance transformation section are all common technical knowledge known to those skilled in the art, and are not described herein again.
When the microstrip line tuning circuit is used for impedance matching of a base station antenna radiation unit, the input end is connected with a vibrator pin or a PCB feeder line through a radio frequency cable, and the output end is connected with a phase shifter or a connector through a radio frequency cable, as shown in fig. 6. Considering that the most widely used base station antenna radiation units (such as half-wave dipoles and full-wave folded oscillators) basically work below a third-order mode, the microstrip line tuning circuit is theoretically adapted to almost all radiation units after being optimized to a proper resonant frequency, so that the impedance bandwidth is remarkably improved. The antenna has definite physical significance, can be processed and realized on a single-layer PCB, and undoubtedly provides a universal and cheap solution for the increasing bandwidth requirement of the base station antenna. In addition, it should be noted that: the microstrip line tuning circuit described in this embodiment is only an exemplary form, and the microstrip line tuning circuit described in the present invention can achieve resonance of first order, second order, third order, or even higher order in principle by increasing/decreasing the number of open-circuit branches and modifying the impedance transformation section.
Referring to fig. 3, the back copper-clad floor 3 is electrically connected to the input pad 1-1 and the output pad 1-2 through the metal via 4, so as to facilitate soldering. It should be noted that: the microstrip line tuning circuit described in this patent is suitable for various welding methods of cable outer conductors, and the metal via grounding shown in fig. 3 is only one example.
To show the utility of the microstrip line tuning circuit in impedance matching of the antenna radiation unit of the base station, fig. 4 and 5 are graphs simulating the measurement result of standing waves before and after the microstrip line tuning circuit is adopted, respectively.
As can be seen from fig. 4: the standing wave value is overall larger, standing waves at the two ends of the working frequency range f1 and f3 are near 2, and the standing wave at the frequency point f2 is as high as 2.6. From the standing wave curve it can be seen that: the antenna works in a second-order resonance mode, and the peak clipping is carried out on three frequency points of f1/f2/f3 when the whole standing wave is reduced to be less than 1.5.
Fig. 5 is a standing wave after matching using the above microstrip line tuning circuit. As can be clearly seen from fig. 5: the 'anti-resonance' is realized through the microstrip line tuning circuit, standing wave curves near f2 and f3 are reduced from wave crests to wave troughs, and the 'anti-resonance' successfully eliminates the mismatch of the vibrator at the corresponding frequency caused by discontinuous mode conversion; at the same time, the standing wave at f1 also drops below 1.5. This example fully demonstrates the significant utility of the microstrip line tuning circuit of the present invention in impedance matching of the radiating elements of a base station antenna.
In practical application, as shown in fig. 6, the microstrip line tuning circuit can be used for a multi-frequency compact antenna array, so as to implement in-situ matching of the radiating element 5, eliminate the influence of adaptation on antenna array power/phase distribution, and improve a directional diagram.
It should be emphasized that: the exemplary embodiments of fig. 1-5 provide only one exemplary implementation of the microstrip line tuning circuit disclosed herein. The core principle of the invention is that anti-resonance is generated near a specific frequency through the LC tuning circuit and the impedance transformation section which are connected in parallel, thereby eliminating or improving the mismatch of the ultra-wideband antenna element in the discontinuous multi-mode conversion process. The design of the tuning circuit based on this principle, no matter how many resonance orders are, and what implementation form the circuit is implemented, should be regarded as an embodiment of the invention. The scope of the invention should be determined by the appended claims and their equivalents. The details not described in the detailed description are prior art or common general knowledge.
Claims (10)
1. A microstrip line tuning circuit is characterized by consisting of a single-layer PCB (printed Circuit Board), wherein the single-layer PCB consists of a front copper-clad microstrip line, a dielectric plate and a back copper-clad floor; the front copper-clad microstrip line comprises: the resonator comprises an input bonding pad, an output bonding pad, an input impedance transformation section, an output impedance transformation section and a resonator consisting of a plurality of open-circuit branches connected in parallel, wherein the resonator is connected between the input impedance transformation section and the output impedance transformation section, each open-circuit branch forms an LC resonance circuit, and each open-circuit branch is matched with the input impedance transformation section and the output impedance transformation section to realize resonance near corresponding frequency.
2. The microstrip line tuning circuit of claim 1, wherein the single-layer PCB has a third order intermodulation index better than-120 dBm within a design operating frequency, the dielectric plate has a thickness of 0.5-1.5 mm, and the copper-clad thickness is 0.035 ± 0.005 mm.
3. A microstrip line tuning circuit according to claim 1 wherein the back copper-clad ground is electrically connected to the input pad and the output pad by metal vias.
4. The microstrip line tuning circuit of claim 1, wherein the number of open-circuit stubs is one, two, or more than three.
5. A base station antenna comprises a plurality of radiation units, and is characterized in that each radiation unit is connected with a microstrip line tuning circuit, and resonance of the microstrip line tuning circuit near corresponding frequency is utilized to eliminate impedance mutation caused by mode conversion discontinuity; the corresponding frequency is a standing wave peak frequency of the radiation unit, and the resonance is an anti-resonance for flattening a standing wave peak.
6. A base station antenna according to claim 5, characterized in that the microstrip tuning circuit is according to any of claims 1-4.
7. The base station antenna according to claim 6, wherein the input pad of the microstrip line tuning circuit is connected to the oscillator pin of the radiating element or the PCB feeder via a radio frequency cable, and the output pad of the microstrip line tuning circuit is connected to the phase shifter or the connector of the radiating element via a radio frequency cable.
8. The base station antenna according to claim 6, wherein the number of the open-circuit branches is consistent with the number of the peaks of the standing wave of the radiating unit, and the open-circuit branches correspond to the peaks of the standing wave of the radiating unit.
9. The base station antenna of claim 5, wherein the radiating element is a half-wave dipole element, a full-wave folded element, a metal die-cast element or a PCB element.
10. The base station antenna according to claim 5, wherein the operating frequency band of the radiating element comprises: 1427-1518 MHz, 617-698 MHz and sub-6 GHz.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911242775.9A CN110994185A (en) | 2019-12-06 | 2019-12-06 | Microstrip line tuning circuit and base station antenna |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911242775.9A CN110994185A (en) | 2019-12-06 | 2019-12-06 | Microstrip line tuning circuit and base station antenna |
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| CN110994185A true CN110994185A (en) | 2020-04-10 |
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| CN201911242775.9A Pending CN110994185A (en) | 2019-12-06 | 2019-12-06 | Microstrip line tuning circuit and base station antenna |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112886242A (en) * | 2021-01-12 | 2021-06-01 | 珠海格力电器股份有限公司 | Matching circuit, on-board antenna, verification method and verification device for on-board antenna |
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2019
- 2019-12-06 CN CN201911242775.9A patent/CN110994185A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112886242A (en) * | 2021-01-12 | 2021-06-01 | 珠海格力电器股份有限公司 | Matching circuit, on-board antenna, verification method and verification device for on-board antenna |
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