CN112599973B - Non-contact variable capacitance loaded frequency tunable microstrip patch antenna - Google Patents
Non-contact variable capacitance loaded frequency tunable microstrip patch antenna Download PDFInfo
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- CN112599973B CN112599973B CN202011408461.4A CN202011408461A CN112599973B CN 112599973 B CN112599973 B CN 112599973B CN 202011408461 A CN202011408461 A CN 202011408461A CN 112599973 B CN112599973 B CN 112599973B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
- H01Q1/38—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith formed by a conductive layer on an insulating support
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/50—Structural association of antennas with earthing switches, lead-in devices or lightning protectors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
- H01Q13/08—Radiating ends of two-conductor microwave transmission lines, e.g. of coaxial lines, of microstrip lines
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Abstract
The invention relates to a frequency tunable microstrip patch antenna loaded by a non-contact variable capacitor, which comprises a bottom substrate, a microstrip patch resonator and a microstrip feeder line, wherein the microstrip patch resonator and the microstrip feeder line are respectively arranged on the upper surface and the lower surface of the bottom substrate, the microstrip patch resonator comprises a metal reflecting floor, a middle layer substrate, a top layer substrate and a microstrip patch which are sequentially stacked from bottom to top, a pair of microstrip lines for frequency tuning are arranged between the middle layer substrate and the top layer substrate, the microstrip lines for frequency tuning are overlapped with the microstrip patch in a non-contact way through the top layer substrate, the outer ends of the microstrip lines for frequency tuning are electrically connected with the inner end of the variable capacitor loaded on the upper surface of the top layer substrate, the outer ends of the variable capacitor are grounded, and the microstrip lines for frequency tuning and the corresponding variable capacitor form a non-contact frequency tuning structure for continuously tuning the frequency of the antenna. The invention firstly provides a novel non-contact variable capacitance loading scheme to design a frequency-reconfigurable microstrip patch antenna working under a main mode TM 10.
Description
Technical Field
The invention relates to the technical field of wireless communication, in particular to a frequency-tunable microstrip patch antenna loaded by a non-contact variable capacitor.
Background
In order to meet the development requirements of wireless communication systems, multifunctional antennas have been extensively studied in recent years. Among them, the excellent performance of the reconfigurable antenna becomes a research hotspot. The reconfigurable antenna has the excellent characteristics of small size, flexible function and the like, and can replace a plurality of antennas. The reconfigurable resonator is the core element of the reconfigurable antenna, which directly affects the performance of the reconfigurable antenna. In recent years, research on reconfigurable resonators has focused on the operating frequency, radiation pattern, and polarization, which play an important role in modern wireless communication systems. Of these, frequency reconfigurable resonators are of interest for use in cognitive radio systems that perform both sensing frequency and communication functions. Such resonators can be realized by loading tunable elements, for example, using pin diodes to switch between a plurality of discrete states, or loading variable capacitances to continuously tune the operating state. In addition, reconfigurable performance can also be achieved using radio frequency micro-electromechanical systems (MEMS) or liquid metals.
The microstrip patch antenna has the advantages of low section, high gain, easy loading of variable capacitance and the like, so that the microstrip patch antenna is widely applied to reconfigurable antennas, particularly to the design of frequency reconfigurable antennas. Typically, the variable capacitance is loaded directly on the microstrip patch. In the document "Frequency-configurable low-profile monolithic patch antenna" (l. Ge and k. Luk, IEEE Trans Antennas pro. vol. 62, No. 7, pp. 3443-3449, July 2014), a Frequency-reconfigurable stacked patch antenna is proposed, which consists of two stacked square patches, each of which is divided into two rectangular parts by a gap, and a variable capacitor is loaded directly on the gap in the middle of the microstrip patch. The document "universal-side mounted patch antenna with independent frequency reconfiguration" (l. Ge, m. Li, j. Wang and h. Gu, IEEE Antennas Wireless performance testing, vol. 16, pp. 113-.
However, the tunable structure is directly connected with the radiation patch, so that the radiation performance of the resonator is greatly influenced by the variable capacitor, therefore, the invention firstly provides a novel non-contact variable capacitor loading scheme to design the frequency reconfigurable antenna working in the main mode TM10 mode.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a frequency-tunable microstrip patch antenna loaded by a non-contact variable capacitor.
In order to achieve the purpose of the invention, the frequency tunable microstrip patch antenna provided by the invention comprises a bottom substrate, a microstrip patch resonator and a microstrip feeder line, wherein the microstrip patch resonator and the microstrip feeder line are respectively arranged on the upper surface and the lower surface of the bottom substrate, the microstrip patch resonator comprises a metal reflection floor, a middle substrate, a top substrate and a microstrip patch which are sequentially stacked from bottom to top, and the frequency tunable microstrip patch antenna is characterized in that: a pair of symmetrical microstrip lines for frequency tuning, which are arranged along the center line of the microstrip patch, is arranged between the middle layer substrate and the top layer substrate, the microstrip lines for frequency tuning and the microstrip patch are intersected in projection on the middle layer substrate, the outer end of each microstrip line for frequency tuning is electrically connected with a first end of a variable capacitor loaded on the upper surface of the top layer substrate, a second end of the variable capacitor is electrically connected with the metal reflection floor, and the microstrip lines for frequency tuning and the corresponding variable capacitors form a non-contact frequency tuning structure; the metal reflection floor is provided with a coupling gap corresponding to the microstrip feeder line, and the microstrip feeder line excites the microstrip patch resonator through the coupling gap.
The invention relates to a frequency tunable microstrip patch antenna loaded by a non-contact variable capacitor, which consists of a bottom substrate and a microstrip patch resonator, wherein a non-contact frequency tunable structure is introduced into the resonator, the frequency tunable structure consists of a microstrip line for non-contact frequency tuning and a corresponding variable capacitor, which are positioned in a middle layer, the microstrip line for frequency tuning and the microstrip patch are projected and intersected on the substrate of the middle layer and are used for tuning the frequency of the microstrip patch resonator, and the variable capacitor is loaded at the tail end of the microstrip line for frequency tuning and is used for realizing the continuous tuning of the frequency of the resonator. The top substrate is arranged between the microstrip line and the microstrip patch for non-contact frequency tuning, so that the influence of the loading tunable structure on the radiation performance of the resonator is reduced, and the design freedom is improved. The present frequency tunable microstrip patch antenna may be used in the base film TM10 mode.
Drawings
The invention will be further described with reference to the accompanying drawings;
fig. 1 is a perspective view of a contactless frequency-tunable microstrip patch antenna according to the present invention.
Figure 2 is a side view of a non-contact frequency tunable microstrip patch antenna of the present invention.
Fig. 3 is a schematic diagram of a non-contact frequency tunable microstrip patch antenna structure according to the present invention.
Fig. 4 is an equivalent circuit diagram of the tunable structure of the non-contact frequency tunable microstrip patch antenna of the present invention.
Fig. 5 is a simulation reflection coefficient of the non-contact frequency tunable microstrip patch antenna of the present invention under different capacitance values.
Fig. 6 is a simulated directional diagram of the non-contact frequency tunable microstrip patch antenna of the present invention at 3.54 GHz with a variable capacitance of 0.1 pF.
Fig. 7 is a simulated directional diagram of the non-contact frequency-tunable microstrip patch antenna of the present invention at 3.24 GHz with a variable capacitance of 0.9 pF.
The numbers in the figures are as follows: 1-microstrip patch, 2-variable capacitor, 3-metalized through hole, 4-metalized through hole, 5-top substrate, 6-microstrip line for frequency tuning, 7-middle substrate, 8-metal reflective floor, 9-coupling gap, 10-bottom substrate and 11-microstrip feeder line.
Detailed Description
The invention is further described with reference to the following figures and specific embodiments.
As shown in fig. 1 to fig. 3, the frequency tunable microstrip antenna loaded with the non-contact variable capacitance of the present embodiment includes an underlying substrate 10 and a microstrip patch resonator. The microstrip patch resonator comprises a metal reflection floor 8, a middle layer substrate 7, a top layer substrate 5 and a microstrip patch 1 which are sequentially stacked from bottom to top. The microstrip patch 1 is a rectangular microstrip patch and is arranged in the center of the top substrate 5. A pair of microstrip lines 6 for frequency tuning is provided between the top substrate 5 and the middle substrate 7, and the microstrip lines 6 for frequency tuning are arranged along the center line of the microstrip patch 1 and symmetrically arranged with respect to the microstrip patch. The microstrip line 6 for frequency tuning overlaps the microstrip patch 1 in a non-contact manner via the top substrate 5 (the projection of the microstrip line 6 for frequency tuning on the intermediate substrate 7 intersects with the projection of the microstrip patch 1 on the intermediate substrate 7, i.e., the two projections partially overlap), and the outer end of the microstrip line 6 for frequency tuning is connected to the variable capacitor (variable capacitor) 2 loaded on the upper surface of the top substrate via a pair of metalized through holes 4And the outer end of the variable capacitor 2 is grounded (electrically connected with the metal reflecting floor 8) through a through hole of the metallization 3. The microstrip line 6 for frequency tuning and the variable capacitor 2 constitute a non-contact frequency tuning structure of the resonator, and the capacitance value C of the variable capacitor is adjusted v To tune the frequency of the microstrip patch resonator. The lower surface of the bottom substrate 10 is provided with a microstrip feed line 11 which is arranged along the polarization direction of the antenna and used for coupling feed, the metal reflection floor 8 is provided with a coupling slot 9 corresponding to the microstrip feed line 11, the projection of the microstrip feed line 11 on the metal reflection floor 8 is vertically intersected with the coupling slot 9, and the coupling slot 9 is symmetrically arranged along the central line of the microstrip feed line 11. The microstrip feed line 11 excites the microstrip patch resonator through the coupling slot 9.
The embodiment of the invention optimizes the sizes of all parts of the antenna, and the specific parameters of the antenna are shown in the following table:
| parameter(s) | h 1 | h 2 | l p | w | l | l i | l f | w c | l s | w f | l g |
| Value (mm) | 0.508 | 0.813 | 20 | 2 | 9 | 3 | 7.5 | 0.9 | 8 | 1.8 | 60 |
In the table, the contents of the contents,h 1 the height of the top substrate 5 and the intermediate substrate 7,h 2 is the height of the underlying substrate 10,l p for the length of the microstrip patch 1, win order to the width of the microstrip line 6 for frequency tuning,lin order to be the length of the microstrip line for frequency tuning,l i the microstrip line 6 for frequency tuning is overlapped with the microstrip patch 1 in a non-contact manner via the top substrate 5,l p the side length of the microstrip patch 1 is equal to the area of the microstrip patch 1l p ×l p ，l s In order to couple the length of the slot,w c in order to couple the width of the slot,l f in order for the microstrip feed line to exceed the length of the coupling slot,w f being the width of the microstrip feed line 11,l g the side lengths of the top substrate 5, the middle substrate 7 and the bottom substrate 10. In this embodiment, Rogers is used for the top substrate 5, the middle substrate 7 and the bottom substrate 10RO4003Having a dielectric constant ofε r = 3.38, loss tangent tanδ= 2.7×10 -3 The volume of the top substrate 5 and the intermediate substrate 7 isl g ×l g ×h 1 The volume of the underlying substrate 10 isl g ×l g ×h 2 The intermediate layer substrate 7 is a double-sided printed circuit board, the upper surface of the double-sided printed circuit board 7 is a microstrip line 6 for frequency tuning, and the lower surface is a metal reflection floor 8.
In the embodiment, a pair of microstrip lines which are not in contact with the microstrip patch and loaded with variable capacitance is used as a tuning structure to realize the function of reconfigurable antenna frequency. Through eigenmode simulation, the polarization direction of the main mode TM10 is found to be parallel to the x-axis, and in order to conform to the polarization direction of the TM10 mode, the tuning structures are placed along the x-axis and symmetrically distributed on both sides of the microstrip patch 1. The frequency tunable structure is composed of a microstrip line for frequency tuning, the middle layer of which is connected with a variable capacitor 2, the inner end of the variable capacitor 2 is connected with a microstrip line 6 in the middle layer through a metalized through hole 4, and the outer end of the variable capacitor is connected with a metal reflection floor 8 through a metalized through hole 3. By adjusting the variable capacitance 2And controlling the overlapping area of the microstrip line 6 for frequency tuning and the microstrip patch 1 to realize the reconfiguration of the resonator frequency. The microstrip line 6 for frequency tuning and the microstrip patch 1 are separated by a top substrate 5, thereby reducing the influence of a loading tunable structure on the radiation performance of the resonator and improving the degree of freedom of design. Simulation results show that the introduction of the tuning structure hardly changes the polarization direction of the TM10 mode, which is very advantageous for maintaining a stable radiation pattern in antenna applications. Definition of the overlapping length of the microstrip line 6 for frequency tuningl i 。
In the resonator of the antenna of the present embodiment, the equivalent circuit of the tuning structure can be represented as a capacitor C i And C v Are connected in series. Wherein, C i Representing the coupling capacitance between the microstrip line for frequency tuning and the microstrip patch resonator, C v Representing the capacitance value of the variable capacitance. In the present design, the downward shift in the resonance frequency is due to the capacitive effect (corresponding to C) caused by the coupling between the microstrip line overlap for tuning and the microstrip patch resonator i ). Meanwhile, in order to realize the function of continuously tuning the frequency, a variable capacitor is loaded on the upper surface of the top substrate and is connected with the tail end of a microstrip line for frequency tuning through a metalized through hole, and the capacitance value C of the variable capacitor is adjusted v To dynamically adjust the electrical length of the microstrip line. As shown in fig. 4, the capacitance C due to the variable capacitance v And a coupling capacitor C i Are in series so that they will collectively affect the operating frequency of the resonator.
Fig. 5 shows simulated reflection coefficients of the frequency-tunable microstrip patch antenna loaded with the non-contact variable capacitor under different capacitance values. The frequency adjustment range is 9%, as can be seen from the figure: the frequency of the main mode TM10 is varied with C v Increasing and moving down.
Fig. 6-7 are simulated E-plane and H-plane radiation patterns at different variable capacitance values of 0.1pF, 0.9 pF. As can be seen from the figure: the cross polarization of the antenna is at least 20dB lower than the main polarization, while it is presumed that the antenna exhibits a stable broadside radiation pattern throughout the frequency tuning range.
In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.
Claims (9)
1. The utility model provides a tunable microstrip patch antenna of frequency, includes bottom substrate (10), divides microstrip patch resonator and microstrip feeder (11) of locating bottom substrate (10) upper surface and lower surface, microstrip patch resonator contains metal reflection floor (8), intermediate layer base plate (7), top layer base plate (5) and microstrip patch (1) that stack gradually the setting from bottom to top, its characterized in that: a pair of symmetrical frequency tuning microstrip lines (6) arranged along the center line of the microstrip patch (1) is arranged between the middle layer substrate (7) and the top layer substrate (5), the top layer substrate (5) is separated between the frequency tuning microstrip lines (6) and the microstrip patch (1), the frequency tuning microstrip lines (6) and the microstrip patch (1) are intersected in projection on the middle layer substrate (7), the outer end of the frequency tuning microstrip lines (6) is electrically connected with the first end of the variable capacitor (2) loaded on the upper surface of the top layer substrate (5), the second end of the variable capacitor (2) is electrically connected with the metal reflective floor (8), and the frequency tuning microstrip lines (6) and the corresponding variable capacitors (2) form a non-contact frequency tuning structure; the metal reflection floor (8) is provided with a coupling gap (9) corresponding to the microstrip feeder line (11), and the microstrip feeder line (11) excites the microstrip patch resonator through the coupling gap (9).
2. The frequency tunable microstrip patch antenna of claim 1, wherein: the outer end of the microstrip line (6) for frequency tuning is electrically connected with the first end of the variable capacitor (2) through a first metalized through hole (4) penetrating through the top substrate (5).
3. The frequency tunable microstrip patch antenna of claim 1, wherein: the second end of the variable capacitor (2) is electrically connected with the metal reflecting floor (8) through a second metalized through hole (3) penetrating through the top layer substrate (5) and the middle layer substrate (7).
4. The frequency tunable microstrip patch antenna of claim 1, wherein: the inner end of the variable capacitor (2) is the first end, and the outer end of the variable capacitor (2) surrounds the second end.
5. The frequency tunable microstrip patch antenna of claim 1, wherein: the microstrip patch (1) is a rectangular microstrip patch and is arranged in the center of the top substrate (5).
6. The frequency tunable microstrip patch antenna of claim 1, wherein: the variable capacitor (2) is arranged on the central line of the microstrip patch (1) and symmetrically arranged on two sides of the microstrip patch (1).
7. The frequency tunable microstrip patch antenna of claim 1, wherein: the bottom substrate (10) is a double-sided printed circuit board, the top layer of the double-sided printed circuit board is the microstrip line (6) for frequency tuning, and the bottom layer of the double-sided printed circuit board is the metal reflection floor (8).
8. The frequency tunable microstrip patch antenna according to claim 1, wherein: the projection of the microstrip feed line (11) on the metal reflective floor (8) is vertically intersected with the coupling slot (9), and the coupling slot (9) is symmetrically arranged along the center line of the microstrip feed line (11).
9. The frequency tunable microstrip patch antenna of claim 1, wherein: the microstrip feeder (11) and the frequency tuning microstrip line (6) are arranged along the polarization direction of the antenna.
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| CN202011408461.4A CN112599973B (en) | 2020-12-04 | 2020-12-04 | Non-contact variable capacitance loaded frequency tunable microstrip patch antenna |
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| US6636414B2 (en) * | 2002-01-08 | 2003-10-21 | Raytheon Company | High power variable slide RF tuner |
| TWI280687B (en) * | 2002-08-09 | 2007-05-01 | Wistron Neweb Corp | Multi-patch antenna which can transmit radio signals with two frequencies |
| KR100542830B1 (en) * | 2003-11-17 | 2006-01-20 | 한국전자통신연구원 | Broadband/Multiband Antenna using Floating Radiation Patch or/and Micro Electro Mechanical SystemMEMS Switches |
| CN205452542U (en) * | 2015-12-30 | 2016-08-10 | 瑞声精密制造科技(常州)有限公司 | Tunable antenna structure |
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| CN111969289B (en) * | 2020-08-19 | 2021-10-08 | 南通大学 | Low-profile frequency reconfigurable dielectric patch resonator |
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