Bandwidth enhanced circular polarization reconfigurable microstrip antenna

Abstract

The invention relates to the technical field of antennas, in particular to a bandwidth-enhanced circularly-polarized reconfigurable microstrip antenna. Comprising a dielectric substrate and a metal floor attached to the lower surface of the dielectric substrate, and an annular patch, a driving branch knot, two parasitic branch knots and a direct current bias line are attached to the upper surface of the dielectric substrate. An inner conductor and an outer conductor of the coaxial cable are connected with the driving branch knot and the metal floor respectively, the driving branch knot excites a TM11 mode of the circular ring through an electric coupling path and excites a resonant mode of the parasitic branch knot through another magnetic coupling path, and the resonant parasitic branch knot excites another TM11 mode of the circular ring through electric coupling. And the circular polarization bandwidth with two axial ratio zero points is enhanced. The bias network controls the on-off of the diode on the parasitic branch knot through the DC voltage loaded by the coaxial cable so as to realize circular polarization reconfiguration. The antenna has the advantages of being compact in structure, enhanced in bandwidth, reconfigurable in circular polarization and low in profile, and compared with a circular polarization reconfigurable antenna of the same size, the bandwidth is expanded by more than one time, and the application range is wide.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a bandwidth-enhanced circularly polarized reconfigurable microstrip antenna. Background Technology

[0002] As modern wireless systems evolve towards miniaturization and integration, the design space available for antennas is increasingly limited. As an indispensable component of wireless communication equipment, the performance of antennas directly impacts the overall communication quality. Circularly polarized antennas can receive electromagnetic waves with any polarization and exhibit excellent resistance to multipath fading and interference. To reduce the number of antennas and increase system capacity, reconfigurable circularly polarized antennas with multiple polarization orientations are used in wireless communication systems. However, antenna miniaturization often leads to a decrease in antenna gain and bandwidth performance. Small-sized reconfigurable circularly polarized patch antennas have extremely narrow bandwidths, limiting their application potential in increasingly powerful communication systems. Therefore, expanding the bandwidth of reconfigurable circularly polarized antennas while maintaining their small size has become a current research hotspot in the antenna field. Summary of the Invention

[0003] This invention discloses a bandwidth-enhanced circularly polarized reconfigurable microstrip antenna, the antenna comprising a dielectric substrate, wherein a metal ground plane is disposed on the lower surface of the dielectric substrate;

[0004] A circular patch is attached to the upper surface of the dielectric substrate. Two parasitic branches are arranged in the circular patch. The two parasitic branches are symmetrically arranged along the center line of the dielectric substrate. A driving branch is arranged outside one of the gaps between the two parasitic branches. The two parasitic branches and the driving branch are connected to each other through a DC bias line.

[0005] The antenna also includes a coaxial cable, the inner conductor of which is connected to the drive stub, and the outer conductor of which is connected to a metal ground plane.

[0006] Furthermore, the driving stub includes an arc-shaped first fan-shaped strip and a first rectangular strip. The inner center of the first fan-shaped strip is connected to one end of the first rectangular strip, and the other end of the first rectangular strip extends and passes through the center of the circular patch. The driving stub is used to electrically couple and excite a TM line polarization mode of the annular patch.

[0007] Furthermore, both parasitic segments are arc segments, symmetrically arranged about the extension line of the first rectangular strip; the one on the right is the second fan-shaped strip, and the one on the left is the third fan-shaped strip;

[0008] The inner center of the second sector strip is connected to one end of the second rectangular strip. The other end of the second rectangular strip extends to one side of the first rectangular strip without contacting it. A first metal post is provided at one end of the second rectangular strip near the first rectangular strip. A first switching diode is provided on the second rectangular strip.

[0009] The inner center of the third sector strip is connected to one end of the third rectangular strip. The other end of the third rectangular strip extends to one side of the first rectangular strip without contacting it. A second metal post is provided at one end of the third rectangular strip near the first rectangular strip. A second switching diode is provided on the third rectangular strip.

[0010] Furthermore, the DC bias line includes a first L-shaped strip and a second L-shaped strip;

[0011] The short side of the first L-shaped strip is connected to the center of the second rectangular strip, and the long side of the first L-shaped strip is connected to the first rectangular strip; a first inductor is provided on the short side of the first L-shaped strip, and a second inductor is provided on the long side of the first L-shaped strip.

[0012] The short side of the second L-shaped strip is connected to the center of the third rectangular strip, and the long side of the first L-shaped strip is connected to the first rectangular strip; a fourth inductor is provided on the short side of the second L-shaped strip, and a third inductor is provided on the long side of the second L-shaped strip.

[0013] Furthermore, the dielectric substrate material is Rogers RT / duroid, with a relative permittivity of , a loss tangent of , a length and width L of mm, and a thickness H of mm.

[0014] Furthermore, the outer radius R of the annular patch is .mm, and the inner radius R is .mm.

[0015] The bandwidth-enhanced circularly polarized reconfigurable microstrip antenna as described in claim 1, characterized in that the diameter d of the inner conductor of the coaxial cable is mm, and the distance l to the annular patch is... d It is in .mm format.

[0016] Furthermore, the width w of the first rectangular strip is .mm; the inner radius R of the first fan-shaped strip is .mm, the width w is .mm, the angle θ is deg, and the gap distance g between it and the annular patch is mm.

[0017] Furthermore, the width w of the second and third rectangular strips is .mm; the inner radius R of the fan-shaped strip is .mm, the width w is .mm, the angle θ is deg, the gap distance g between it and the annular patch is .mm, the diameter d of the first and second metal pillars is .mm, and the lateral spacing d between it and the inner conductor of the coaxial cable is .mm. The distance l from the first and second switching diodes to the nearest metal pillar is .mm.

[0018] Furthermore, the widths w of the first L-shaped strip and the second L-shaped strip are mm, l is mm, and l is mm.

[0019] Because of the adoption of the above technical solution, the present invention has the following advantages:

[0020] 1. This invention excites a pair of annular patches™ with equal amplitude, a 90° phase difference, and spatial orthogonality through electromagnetic coupling between parasitic and driving branches. 11 This mode enables bandwidth expansion for circular polarization. Reconfigurable circular polarization is achieved by integrating bias lines to control the operating state of parasitic stubs.

[0021] 2. Compared with traditional circularly polarized reconfigurable microstrip antennas, the antenna of this invention maintains a smaller lateral dimension while exhibiting significant bandwidth expansion. The lateral dimension is 0.072λ0. 2 With a profile height of 0.033λ0, a bandwidth of 3.9%, and a peak gain of 6.6dBi, it exhibits excellent side-firing radiation characteristics and can be applied to a wider range of antenna communication devices.

[0022] 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

[0023] The accompanying drawings of this invention are described below.

[0024] Figure 1 This is a three-dimensional schematic diagram of the antenna of the present invention.

[0025] Figure 2 This is a top view of the antenna of the present invention.

[0026] Figure 3 This is a dimensional diagram of the antenna of the present invention.

[0027] Figure 4 This is a top view of the parasitic stub in the antenna of the present invention.

[0028] Figure 5This is a top view of the driving stub in the antenna of the present invention.

[0029] Figure 6 The reflection coefficient (|S) of the antenna in this embodiment of the invention. 11 |) A schematic diagram of the curve as a function of frequency.

[0030] Figure 7 This is a schematic diagram of the antenna gain curve in an embodiment of the present invention.

[0031] Figure 8 This is a schematic diagram of the antenna efficiency curve in an embodiment of the present invention.

[0032] Figure 9 This is a schematic diagram of the axial ratio curve of the antenna in an embodiment of the present invention.

[0033] Figure 10 This is a two-dimensional horizontal radiation pattern of the antenna in the left-hand circular polarization operating state at 2.45 GHz in an embodiment of the present invention.

[0034] Figure 11 This is a two-dimensional horizontal radiation pattern of the antenna in the right-hand circular polarization operating state at 2.45 GHz in an embodiment of the present invention.

[0035] In the figure: 1-Dielectric substrate; 2-Metal ground plane; 3-Annular patch; 4-Drive branch; 41-First rectangular strip; 42-First fan-shaped strip; 5-Parasitic branch; 5301-Second rectangular strip; 5302-Third rectangular strip; 5401-First fan-shaped strip; 5402-Second fan-shaped strip; 5101-First metal pillar; 5102-Second metal pillar; 5201-First switching diode; 5202-Second... Switching diode; 5301 - Second rectangular strip; 5302 - Third rectangular strip; 5401 - Second sector strip; 5402 - Third sector strip; 6 - DC bias line; 6101 - First L-shaped strip; 6102 - Second L-shaped strip; 6201 - First inductor; 6202 - Second inductor; 6203 - Third inductor; 6204 - Fourth inductor; 6101 - First L-shaped strip; 6102 - Second L-shaped strip. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] A bandwidth-enhanced circularly polarized reconfigurable microstrip antenna, such as Figures 1 to 5 As shown, the antenna includes a dielectric substrate 1, and a metal ground plane 2 is disposed on the lower surface of the dielectric substrate;

[0038] A circular patch 3 is attached to the upper surface of the dielectric substrate 1. Two parasitic branches 5 are arranged in the circular patch 3. The two parasitic branches 5 are symmetrically arranged along the center line of the dielectric substrate 1. A driving branch 4 is arranged outside one of the gaps between the two parasitic branches 5. The two parasitic branches 5 and the driving branch 4 are connected to each other through a DC bias line 6.

[0039] The antenna also includes a coaxial cable 7, the inner conductor of which is connected to the drive stub 4, and the outer conductor of which is connected to the metal ground plane 2.

[0040] The driving branch 4 includes an arc-shaped first fan-shaped strip 42 and a first rectangular strip 41. The inner center of the first fan-shaped strip 42 is connected to one end of the first rectangular strip 41. The other end of the first rectangular strip 41 extends and passes through the center of the circular patch 3. The driving branch 4 is used for electrically coupling and exciting one TM of the annular patch 3. 11 Linear polarization mode.

[0041] Both parasitic segments 5 are arc segments, symmetrically arranged about the extension line of the first rectangular strip 41; the one on the right is the second fan-shaped strip 5401, and the one on the left is the third fan-shaped strip 5402;

[0042] The inner center of the second sector strip 5401 is connected to one end of the second rectangular strip 5301. The other end of the second rectangular strip 5301 extends to one side of the first rectangular strip 41 without contacting the first rectangular strip 41. A first metal post 5101 is provided at one end of the second rectangular strip 5301 near the first rectangular strip 41. A first switching diode 5201 is provided on the second rectangular strip 5301.

[0043] The inner center of the third sector strip 5402 is connected to one end of the third rectangular strip 5302. The other end of the third rectangular strip 5302 extends to one side of the first rectangular strip 41 without contacting the first rectangular strip 41. A second metal post 5102 is provided at one end of the third rectangular strip 5302 near the first rectangular strip 41. A second switching diode 5202 is provided on the third rectangular strip 5302.

[0044] The DC bias line 6 includes a first L-shaped strip 6101 and a second L-shaped strip 6102;

[0045] The short side of the first L-shaped strip 6101 is connected to the center of the second rectangular strip 5301, and the long side of the first L-shaped strip 6101 is connected to the first rectangular strip 41; a first inductor 6201 is provided on the short side of the first L-shaped strip 6101, and a second inductor 6202 is provided on the long side of the first L-shaped strip 6101.

[0046] The short side of the second L-shaped strip 6102 is connected to the center of the third rectangular strip 5302, and the long side of the first L-shaped strip 6102 is connected to the first rectangular strip 41; a fourth inductor 6204 is provided on the short side of the second L-shaped strip 6102, and a third inductor 6203 is provided on the long side of the second L-shaped strip 6102.

[0047] The dielectric substrate 1 is made of Rogers RT / duroid 5880 material, with a relative permittivity of 2.2, a loss tangent of 0.0009, a length and width L of 60 mm, and a thickness H of 4 mm.

[0048] The outer radius R1 of the annular patch 3 is 18.6 mm, and the inner radius R2 is 10.6 mm.

[0049] The diameter d2 of the inner conductor of the coaxial cable 7 is 0.3 mm, and the distance l to the annular patch 3 is... d It is 0.95mm.

[0050] The width w2 of the first rectangular strip 41 is 0.1 mm; the inner radius R4 of the first fan-shaped strip 42 is 8.3 mm, the width w4 is 1.3 mm, the angle θ2 is 52 degrees, and the gap distance g1 between it and the annular patch 3 is 1 mm.

[0051] The width w1 of the second rectangular strip 5301 and the third rectangular strip 5302 is 0.2 mm; the inner radius R3 of the fan-shaped strip 54 is 5.65 mm, the width w3 is 2.2 mm, the angle θ1 is 121 degrees, the gap distance g2 between it and the annular patch 3 is 2.75 mm, the diameter d1 of the first metal post 5101 and the second metal post 5102 is 0.3 mm, and the lateral spacing d between it and the inner conductor of the coaxial cable 7 is 0.4 mm. The distance l1 from the first switching diode 5201 and the second switching diode 5202 to the nearest metal post is 1.4 mm.

[0052] The widths w5 of the first L-shaped strip 6101 and the second L-shaped strip 6102 are 0.5 mm, l2 is 2 mm, and l3 is 1 mm.

[0053] In this embodiment, the antenna polarization state is controlled by applying a DC bias to the inner and outer conductors of the coaxial cable 7. The positive terminals of the two switching diodes 52 are on the left and the negative terminals are on the right, with the same orientation. When a positive voltage is applied to the inner conductor of the coaxial cable, the first switching diode 5201 is turned off and the second switching diode 5202 is turned on, and the antenna operates in state I, with left-hand circular polarization. When a negative voltage is applied to the inner conductor of the coaxial cable, the first switching diode 5201 is turned on and the second switching diode 5202 is turned off, and the antenna operates in state II, with right-hand circular polarization.

[0054] The two operating states of the antenna described in this embodiment are shown in Table 1:

[0055] Table 1. Switch on / off combinations under the two operating states of the antenna

[0056] state 5201 5202 Polarization Ⅰ disconnect Conductivity Left-hand circular polarization Ⅱ Conductivity disconnect Right-hand circular polarization

[0057] Based on the above parameters, the high-frequency electromagnetic simulation software HFSS was used to simulate and analyze the reflection coefficient, gain, efficiency, and radiation pattern of the designed compact, bandwidth-enhanced, circularly polarized, reconfigurable microstrip antenna under various states. The analysis results are as follows:

[0058] Due to the structural symmetry of this embodiment, the reflection coefficient, efficiency, and gain value are the same in all states. The simulation results below are presented separately for each state.

[0059] like Figure 6 As shown, the simulated reflection curves of this embodiment of the invention are shown in various states, with impedance bandwidths of 4.9% and 2.39-2.51 GHz in each state.

[0060] like Figure 7 As shown, the simulated gain of this embodiment of the invention has a stable gain value of 6-6.6 dBi within the band, and the antenna has a high gain value.

[0061] like Figure 8 As shown, the simulation efficiency of this embodiment of the invention is as high as 90%.

[0062] like Figure 9 As shown in the figure, the axial ratio characteristic curve of the embodiment of the present invention shows that the circular polarization bandwidth range is 2.39 to 2.485 GHz, and the overlap range with the linear polarization impedance bandwidth is 2.39 to 2.485 GHz. The antenna operating bandwidth is 4.9%, and it has two axial ratio zero points. Compared with the traditional circular polarization reconfigurable microstrip antenna, the antenna bandwidth is extended by more than 1 times.

[0063] like Figure 10 As shown, the two-dimensional radiation pattern of state I in the xz plane in this embodiment is given, which shows good side-firing radiation characteristics. The antenna polarization is left-hand circular polarization.

[0064] like Figure 11 As shown, the two-dimensional radiation pattern of state II in the xz plane in this embodiment is given, which shows good side-firing radiation characteristics. The antenna polarization is right-hand circular polarization.

[0065] In summary, the present invention provides a compact, bandwidth-enhanced, circularly polarized reconfigurable microstrip antenna that, while possessing excellent radiation characteristics, also has the advantages of compact size, simple structure, and enhanced bandwidth.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A bandwidth-enhanced circularly polarized reconfigurable microstrip antenna, characterized in that, The antenna includes a dielectric substrate (1) and a metal ground plane (2) is disposed on the lower surface of the dielectric substrate; A circular patch (3) is attached to the upper surface of the dielectric substrate (1). Two parasitic branches (5) are arranged inside the circular patch (3). The two parasitic branches (5) are symmetrically arranged along the center line of the dielectric substrate (1). A driving branch (4) is arranged outside one of the gaps between the two parasitic branches (5). The two parasitic branches (5) and the driving branch (4) are connected to each other through a DC bias line (6). The antenna also includes a coaxial cable (7), the inner conductor of which is connected to the drive stub (4), and the outer conductor of which is connected to the metal ground plane (2).

2. The bandwidth-enhanced circularly polarized reconfigurable microstrip antenna as described in claim 1, characterized in that, The driving stub (4) includes an arc-shaped first fan-shaped strip (42) and a first rectangular strip (41). The inner center of the first fan-shaped strip (42) is connected to one end of the first rectangular strip (41). The other end of the first rectangular strip (41) extends and passes through the center of the circular patch (3). The driving stub (4) is used to electrically couple and excite one TM of the annular patch (3). 11 Linear polarization mode.

3. The bandwidth-enhanced circularly polarized reconfigurable microstrip antenna as described in claim 2, characterized in that, Both parasitic segments (5) are arc segments, symmetrically arranged about the extension line of the first rectangular strip (41); the one on the right is the second fan-shaped strip (5401), and the one on the left is the third fan-shaped strip (5402); The inner center of the second sector strip (5401) is connected to one end of the second rectangular strip (5301). The other end of the second rectangular strip (5301) extends to one side of the first rectangular strip (41) without contacting the first rectangular strip (41). A first metal post (5101) is provided at one end of the second rectangular strip (5301) near the first rectangular strip (41). A first switching diode (5201) is provided on the second rectangular strip (5301). The inner center of the third sector strip (5402) is connected to one end of the third rectangular strip (5302). The other end of the third rectangular strip (5302) extends to one side of the first rectangular strip (41) without contacting the first rectangular strip (41). A second metal post (5102) is provided at one end of the third rectangular strip (5302) near the first rectangular strip (41). A second switching diode (5202) is provided on the third rectangular strip (5302).

4. The bandwidth-enhanced circularly polarized reconfigurable microstrip antenna as described in claim 3, characterized in that, The DC bias line (6) includes a first L-shaped strip (6101) and a second L-shaped strip (6102); The short side of the first L-shaped strip (6101) is connected to the center of the second rectangular strip (5301), and the long side of the first L-shaped strip (6101) is connected to the first rectangular strip (41); a first inductor (6201) is provided on the short side of the first L-shaped strip (6101), and a second inductor (6202) is provided on the long side of the first L-shaped strip (6101); The short side of the second L-shaped strip (6102) is connected to the center of the third rectangular strip (5302), and the long side of the first L-shaped strip (6102) is connected to the first rectangular strip (41); a fourth inductor (6204) is provided on the short side of the second L-shaped strip (6102), and a third inductor (6203) is provided on the long side of the second L-shaped strip (6102).

5. The bandwidth-enhanced circularly polarized reconfigurable microstrip antenna as described in claim 4, characterized in that, The dielectric substrate (1) is made of Rogers RT / duroid 5880, with a relative permittivity of 2.2, a loss tangent of 0.0009, a length and width L of 60 mm, and a thickness H of 4 mm.

6. The bandwidth-enhanced circularly polarized reconfigurable microstrip antenna as described in claim 4, characterized in that, The outer radius R1 of the annular patch (3) is 18.6 mm, and the inner radius R2 is 10.6 mm.

7. The bandwidth-enhanced circularly polarized reconfigurable microstrip antenna as described in claim 4, characterized in that, The inner conductor of the coaxial cable (7) has a diameter d2 of 0.3 mm and a distance l from the annular patch (3). d It is 0.95mm.

8. The bandwidth-enhanced circularly polarized reconfigurable microstrip antenna as described in claim 4, characterized in that, The width w2 of the first rectangular strip (41) is 0.1 mm; the inner radius R4 of the first fan-shaped strip (42) is 8.3 mm, the width w4 is 1.3 mm, the angle θ2 is 52 degrees, and the gap distance g1 between it and the annular patch (3) is 1 mm.

9. The bandwidth-enhanced circularly polarized reconfigurable microstrip antenna as described in claim 4, characterized in that, The width w1 of the second rectangular strip (5301) and the third rectangular strip (5302) is 0.2 mm; the inner radius R3 of the fan-shaped strip (54) is 5.65 mm, the width w3 is 2.2 mm, the angle θ1 is 121 degrees, the gap distance g2 between it and the annular patch (3) is 2.75 mm, the diameter d1 of the first metal post (5101) and the second metal post (5102) is 0.3 mm, and the lateral spacing d between it and the inner conductor of the coaxial cable (7) is 0.4 mm. The distance l1 from the first switching diode (5201) and the second switching diode (5202) to the nearest metal post is 1.4 mm.

10. The bandwidth-enhanced circularly polarized reconfigurable microstrip antenna as described in claim 4, characterized in that, The widths w5 of the first L-shaped strip (6101) and the second L-shaped strip (6102) are 0.5 mm, l2 is 2 mm, and l3 is 1 mm.

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