A reconfigurable microstrip antenna with 360° circumferential beam coverage

Abstract

The present application provides a reconfigurable microstrip antenna with 360° circumferential beam coverage, comprising a dielectric substrate; and a metal slotted floorboard attached to the lower surface of the dielectric substrate; a circular patch and a plurality of T-shaped monopoles attached to the upper surface of the dielectric substrate, the plurality of T-shaped monopoles being connected to the metal slotted floorboard via switch assemblies, the T-shaped monopoles being used to excite equivalent magnetic flux at both ends of the circular patch, and the plurality of switch assemblies generating a tilted beam pattern of the reconfigurable microstrip antenna by controlling a combination of on and off states; a coaxial cable for exciting the circular patch and the metal slotted floorboard is also provided below the metal slotted floorboard, the inner and outer conductors of the coaxial cable being connected to the geometric centers of the circular patch and the metal slotted floorboard, respectively. The present invention has the advantages of a compact structure, linear polarization and elevation beam tilt characteristics, and a low profile, and the 360° circumferential beam coverage is achieved by switching four tilted beams with different directions.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a reconfigurable microstrip antenna with 360-degree circumferential beam coverage. Background Art

[0002] In modern communication systems, such as those on urban roads, severe multipath effects, multipath reflections, and scattering are unavoidable. Therefore, traditional antennas with a single radiation pattern are unable to meet the requirements of today's complex road environments. To improve the coverage, efficiency, and channel capacity of transmission systems, reconfigurable pattern antennas with multiple beam switching capabilities are being used in wireless communication systems. Reconfigurable pattern antennas have also been extensively studied in many application scenarios, such as wireless local area networks, cellular base station communications, and navigation link systems. Endfire antennas, on the other hand, are antennas whose maximum radiation direction is parallel to the radiator's surface and offer high gain performance. However, in some communication scenarios, such as large conference rooms, antennas are often mounted on rooftops. In these cases, endfire antennas are no longer suitable, and directional radiating antennas with tilted angles are more suitable. Therefore, reconfigurable pattern antennas with low profiles, tilted beams, and high gain have attracted widespread attention. However, existing tilted-beam antennas are rare. Common end-fire reconfigurable antennas include Yagi antennas, Huygens source antennas that combine electric and magnetic dipoles, and some switch-controlled frequency selective surface (FSS) antennas. These antennas often suffer from structural asymmetry and high profiles, making them difficult to install and integrate, making them incompatible with the miniaturization and integration trends of today's wireless communication technologies. Summary of the Invention

[0003] The object of the present invention is to provide a reconfigurable microstrip antenna with 360° circumferential beam coverage.

[0004] The object of the present invention is achieved through such a technical solution, which includes a dielectric substrate; and a metal grooved floor attached to the lower surface of the dielectric substrate;

[0005] A circular patch and a plurality of T-shaped monopoles are attached to the upper surface of the dielectric substrate. The plurality of T-shaped monopoles are respectively connected to the metal slotted floor via switch assemblies. The T-shaped monopoles are used to excite equivalent magnetic flux at both ends of the circular patch. The plurality of switch assemblies generate a tilted beam pattern of the reconfigurable microstrip antenna by controlling the combination of on and off states.

[0006] A coaxial cable for exciting the circular patch and the metal slotted floor is also provided under the metal slotted floor. The inner and outer conductors of the coaxial cable are respectively connected to the geometric centers of the circular patch and the metal slotted floor.

[0007] Furthermore, the number of the T-shaped monopoles is four;

[0008] The T-shaped monopole includes a rectangular strip and a fan-shaped strip connected to one end of the rectangular strip.

[0009] Furthermore, the circular patch is cut with four rectangular through slots arranged in an array at equal angles along the center of the circle;

[0010] The rectangular through slots are arranged along the radial direction of the circular patch, and the other ends of the four rectangular strips are respectively arranged in the four rectangular through slots. The rectangular strips are arranged parallel to the rectangular through slots to form an interdigital capacitive coupling structure for improving the impedance matching of the reconfigurable microstrip antenna.

[0011] Furthermore, the switch components each include three metal pillars, one end of each of the three metal pillars is connected to the fan-shaped strip, two metal pillars on both sides of the three metal pillars are symmetrically arranged about the rectangular strip, and the middle metal pillar is located on the center line of the rectangular strip. The metal pillars are used to excite equivalent magnetic currents at both ends of the middle circular patch that are not in contact with it, and the two equivalent magnetic currents have amplitude and phase differences, which can form a directional pattern of an inclined beam.

[0012] Furthermore, the metal grooved floor is provided with a plurality of annular grooves corresponding to the metal pillars one by one;

[0013] The annular groove divides the metal grooved floor into an inner floor and an outer floor. Each inner floor is connected to the outer floor through two rectangular switches. The other ends of the three metal columns are respectively connected to one inner floor.

[0014] Furthermore, the circular patch and the T-shaped monopole are both copper-clad films of the same thickness;

[0015] The radius R1 of the circular patch is 9 mm, the length L1 of the rectangular through-slot is 3.9 mm, and the width W1 of the rectangular through-slot is 0.6 mm;

[0016] The length L2 of the rectangular strip is 4 mm, the width W2 of the rectangular strip is 0.4 mm, the width W2 of the fan-shaped strip is 1.5 mm, and the angle A1 of the fan-shaped strip is 80 degrees;

[0017] The gap distance gap1 between the circular patch and the T-shaped monopole is 0.25 mm;

[0018] The radius R2 of the metal column is 0.25 mm, and the angle A2 between the radial line of the circular patch passing through the center of the metal column on both sides and the center line of the rectangular strip is 8 degrees.

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

[0020] 1. The present invention uses two pairs of grounded metal poles to generate two sets of equivalent magnetic currents. The two sets of equivalent magnetic currents have corresponding phase differences and amplitudes, so they can successfully offset the radiation of one side beam of the double-conical beam and produce an end-fire radiation pattern with a 30° inclination angle.

[0021] 2. Compared to traditional monopole antennas, this antenna combines the low-profile advantages of microstrip antennas, with a profile height of 0.035λg, making it easy to process and integrate. It also offers excellent directional radiation characteristics, a peak gain of 8.8dBi, and uses an ideal switch to switch beam states, achieving 360° circumferential beam coverage. Using coaxial cable center feed, the antenna has a simple structure and a radiation efficiency of up to 95%.

[0022] Other advantages, objectives, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description and claims. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] Figure 1 It is a three-dimensional schematic diagram of the reconfigurable microstrip antenna with 360° circumferential beam coverage of the present invention.

[0025] Figure 2 It is a top view of the reconfigurable microstrip antenna with 360° circumferential beam coverage of the present invention.

[0026] Figure 3 It is a top view of a circular patch in the reconfigurable microstrip antenna with 360° circumferential beam coverage of the present invention.

[0027] Figure 4 It is a top view of a T-shaped monopole in a reconfigurable microstrip antenna with 360° circumferential beam coverage according to the present invention.

[0028] Figure 5 This is a schematic diagram of the connection between the metal column, the rectangular switch and the metal slotted floor in the reconfigurable microstrip antenna with 360° circumferential beam coverage of the present invention.

[0029] Figure 6 4 is a reflection coefficient curve diagram of an embodiment of a reconfigurable microstrip antenna with 360° circumferential beam coverage according to the present invention.

[0030] Figure 7FIG. 4 is a graph showing the simulated gain variation with frequency of an embodiment of a reconfigurable microstrip antenna with 360° circumferential beam coverage according to the present invention.

[0031] Figure 8 This is a simulated efficiency curve of the reconfigurable microstrip antenna with 360° circumferential beam coverage according to the present invention.

[0032] Figure 9 The horizontal plane two-dimensional radiation pattern of the reconfigurable microstrip antenna with 360° circumferential beam coverage under different working conditions at 5.32 GHz of the present invention.

[0033] Figure 10 It is the normalized vertical plane radiation pattern of the reconfigurable microstrip antenna with 360° circumferential beam coverage in the working state I at 5.32 GHz of the present invention.

[0034] In the figure: 1-dielectric substrate; 2-metal slotted floor; 3-circular patch; 31-rectangular through-slot; 4-T-shaped monopole; 5-switch assembly; 6-coaxial cable; 21-annular groove; 22-inner floor; 23-outer floor; 31-rectangular through-slot; 41-rectangular strip; 42-fan-shaped strip; 51-metal pillar; 52-rectangular switch; 5101-first metal pillar; 5102-second metal pillar; 5103-third metal pillar; 5104-fourth metal pillar; 5105-fifth metal pillar; 5106-sixth metal pillar; 5107-seventh metal pillar; 5108-eighth metal pillar; 5109-ninth metal pillar; 5110-tenth metal pillar; 5111-eleventh metal pillar; 5112-twelfth metal pillar. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings and examples.

[0036] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention. In addition, the terms "first", "second" and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0037] like Figure 1-Figure 5 A reconfigurable microstrip antenna with 360° circumferential beam coverage is shown, characterized in that it includes a dielectric substrate 1; and a metal grooved floor 2 attached to the lower surface of the dielectric substrate 1;

[0038] A circular patch 3 and a plurality of T-shaped monopoles 4 are attached to the upper surface of the dielectric substrate 1. The plurality of T-shaped monopoles 4 are respectively connected to the metal slotted floor 2 via switch components 5. The T-shaped monopoles 4 are used to excite equivalent magnetic flux at both ends of the circular patch 3. The plurality of switch components 5 generate a tilted beam pattern of the reconfigurable microstrip antenna by controlling the combination of on and off states.

[0039] A coaxial cable 6 for exciting the circular patch 3 and the metal slotted floor 2 is also provided below the metal slotted floor 2 . The inner and outer conductors of the coaxial cable 6 are connected to the geometric centers of the circular patch 3 and the metal slotted floor 2 , respectively.

[0040] In the example of the present invention, the dielectric substrate 1 is made of Rogers 5880 with a thickness of 2 mm, a relative dielectric constant of 2.2, and a loss tangent of 0.0009. The diameter of the metal grooved floor 2 is 1.4λg.

[0041] As an embodiment of the present invention, the number of the T-shaped monopoles 4 is four;

[0042] The T-shaped monopole 4 includes a rectangular strip 41 and a fan-shaped strip 42 connected to one end of the rectangular strip 41 .

[0043] As an embodiment of the present invention, the circular patch 3 is cut with four rectangular through slots 31 arranged in an array with equal angles along the center of the circle;

[0044] The rectangular through slots 31 are arranged along the radial direction of the circular patch 3, and the other ends of the four rectangular strips 41 are respectively arranged in the four rectangular through slots 31. The rectangular strips 41 are arranged parallel to the rectangular through slots 31 to form an interdigital capacitive coupling structure, which is used to improve the impedance matching of the reconfigurable microstrip antenna.

[0045] As an embodiment of the present invention, the switch assembly 5 includes three metal pillars 51, one end of each of the three metal pillars 51 is connected to the fan-shaped strip 42, the two metal pillars 51 on both sides of the three metal pillars 51 are symmetrically arranged about the rectangular strip 41, and the middle metal pillar 51 is located on the center line of the rectangular strip 41. The metal pillar 51 is used to excite the equivalent magnetic currents at the two ends of the middle circular patch 3 that are not in contact with it, and the two equivalent magnetic currents have amplitude and phase differences, which can form a directional pattern of an inclined beam.

[0046] As an embodiment of the present invention, the metal grooved floor 2 is provided with a plurality of annular grooves 21 corresponding to the metal pillars 51 one by one;

[0047] The annular groove 21 divides the metal grooved floor 2 into an inner floor 22 and an outer floor 23 . Each inner floor 22 is connected to the outer floor 23 via two rectangular switches 52 . The other ends of the three metal columns 51 are respectively connected to one inner floor 22 .

[0048] In the present invention, the Figure 5 As shown, the 12 metal pillars include a first metal pillar 5101, a second metal pillar 5102, a third metal pillar 5103, a fourth metal pillar 5104, a fifth metal pillar 5105, a sixth metal pillar 5106, a seventh metal pillar 5107, an eighth metal pillar 5108, a ninth metal pillar 5109, a tenth metal pillar 5110, an eleventh metal pillar 5111, and a twelfth metal pillar 5112.

[0049] The first metal pillar 5101 , the second metal pillar 5102 , the fifth metal pillar 5105 , the sixth metal pillar 5106 and the corresponding eight rectangular switches 52 constitute a first switch module;

[0050] The first metal pillar 5101 , the second metal pillar 5102 , the seventh metal pillar 5107 , the eighth metal pillar 5108 and the corresponding eight rectangular switches 52 constitute a second switch module;

[0051] The third metal pillar 5103 , the fourth metal pillar 5104 , the ninth metal pillar 5109 , the tenth metal pillar 5110 and the corresponding eight rectangular switches 52 constitute a third switch module;

[0052] The third metal pillar 5103 , the fourth metal pillar 5104 , the eleventh metal pillar 5111 , the twelfth metal pillar 5112 and the corresponding eight rectangular switches 52 constitute a fourth switch module.

[0053] The above four switch modules are used to control the four states I, II, III, and IV respectively. The first switch module controls state I, which is defined as the end-fire state facing the left side.

[0054] State II is controlled by the second switch module, and state II is defined as an end-fire state facing right;

[0055] State III is controlled by a third switch module, where state III is defined as an end-fire state facing the rear side;

[0056] State IV is controlled by the fourth switch module, and state IV is defined as an end-fire state facing the front side.

[0057] Table 1 shows the on-off combinations of the switches in the four working states of the antenna in this embodiment.

[0058] Table 1 Switch on / off combinations in four antenna working states

[0059] state Switch group 1 Switch group 2 Switch group 3 Switch group 4 Ⅰ conduction disconnect disconnect disconnect Ⅱ disconnect conduction disconnect disconnect Ⅲ disconnect disconnect conduction disconnect Ⅳ disconnect disconnect disconnect conduction

[0060] As an embodiment of the present invention, the circular patch 3 and the T-shaped monopole 4 are both copper-clad films with the same thickness;

[0061] The radius R1 of the circular patch 3 is 9 mm, the length L1 of the rectangular through-slot 31 is 3.9 mm, and the width W1 of the rectangular through-slot 31 is 0.6 mm;

[0062] The length L2 of the rectangular strip 41 is 4 mm, the width W2 of the rectangular strip 41 is 0.4 mm, the width W3 of the fan-shaped strip 42 is 1.5 mm, and the angle A1 of the fan-shaped strip 42 is 80 degrees;

[0063] The gap distance gap1 between the circular patch 3 and the T-shaped monopole 4 is 0.25 mm;

[0064] The radius R2 of the metal pillar 51 is 0.25 mm, and the angle A2 between the radial line of the circular patch 3 passing through the center of the metal pillar 51 on both sides and the center line of the rectangular strip 41 is 8 degrees.

[0065] 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 reconfigurable microstrip antenna with 360° circumferential beam coverage in various states. The analysis results are as follows:

[0066] Due to the structural symmetry of this embodiment, the reflection coefficient, efficiency and gain values ​​in each state are the same. The following simulation results are placed separately for the results of one group of states.

[0067] like Figure 6 As shown in FIG. 1 , the simulated reflection curves of the embodiment of the present invention in various states have an impedance bandwidth of 2.3% (5.26-5.38 GHz) in each state.

[0068] like Figure 7 As shown, the simulation gain of the embodiment of the present invention has a stable gain value within the band: 8.4-8.8dBi, and the antenna has a relatively high gain value.

[0069] like Figure 8 As shown, the simulation efficiency value of the embodiment of the present invention is as high as 96%.

[0070] like Figure 9 As shown in the figure, the horizontal plane two-dimensional radiation pattern of each switching state in this embodiment is given. The maximum gain of state I points to the horizontal plane. State II maximum gain points to the horizontal plane State III maximum gain points to the horizontal plane State 4: Maximum gain pointing to the horizontal plane Each switching direction can cover a 3dB down-wave width of up to 125°, which also shows that the entire azimuth plane can be fully covered in the four states.

[0071] like Figure 10 As shown, the simulation results of the two-dimensional radiation pattern in the vertical plane under state I are given, and the maximum gain points to θ = 30°, indicating that the antenna designed by the present invention has tilted beam directivity and the cross-polarization level of the antenna is good, up to more than 30dB.

[0072] In summary, the reconfigurable microstrip antenna with 360° circumferential beam coverage of the present invention has the advantages of compact size, simple structure and high gain while having excellent radiation characteristics.

[0073] 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 reconfigurable microstrip antenna with 360° circumferential beam coverage, characterized in that: It comprises a dielectric substrate (1); and a metal grooved floor (2) attached to the lower surface of the dielectric substrate (1); A circular patch (3) and a plurality of T-shaped monopoles (4) are attached to the upper surface of the dielectric substrate (1); the plurality of T-shaped monopoles (4) are respectively connected to the metal slotted floor (2) via switch components (5); the T-shaped monopoles (4) are used to excite equivalent magnetic flux at both ends of the circular patch (3); and the plurality of switch components (5) generate a tilted beam pattern of the reconfigurable microstrip antenna by controlling a combination of on and off states; A coaxial cable (6) for exciting the circular patch (3) and the metal slotted floor (2) is also provided below the metal slotted floor (2), and the inner and outer conductors of the coaxial cable (6) are connected to the geometric centers of the circular patch (3) and the metal slotted floor (2), respectively. The number of the T-shaped monopoles (4) is four; The T-shaped monopole (4) comprises a rectangular strip (41) and a fan-shaped strip (42) connected to one end of the rectangular strip (41); The circular patch (3) is cut with four rectangular through slots (31) arranged in an array at equal angles along the center of the circle; The rectangular through slots (31) are arranged along the radial direction of the circular patch (3), the other ends of the four rectangular strips (41) are respectively arranged in the four rectangular through slots (31), and the rectangular strips (41) and the rectangular through slots (31) are arranged in parallel to form an interdigital capacitive coupling structure for improving the impedance matching of the reconfigurable microstrip antenna.

2. The reconfigurable microstrip antenna with 360° circumferential beam coverage according to claim 1, characterized in that: The switch assembly (5) comprises three metal pillars (51), one end of each of the three metal pillars (51) is connected to the sector strip (42), two metal pillars (51) on both sides of the three metal pillars (51) are symmetrically arranged with respect to the rectangular strip (41), and the middle metal pillar (51) is located on the center line of the rectangular strip (41), and the metal pillar (51) is used to excite equivalent magnetic currents at both ends of the middle circular patch (3) that are not in contact with it, and the two equivalent magnetic currents have an amplitude and phase difference, and can form a directional pattern of a tilted beam.

3. The reconfigurable microstrip antenna with 360° circumferential beam coverage according to claim 2, characterized in that: The metal grooved floor (2) is provided with a plurality of annular grooves (21) corresponding one to one with the metal pillars (51); The annular groove (21) divides the metal grooved floor (2) into an inner floor (22) and an outer floor (23). Each inner floor (22) is connected to the outer floor (23) via two rectangular switches (52). The other ends of the three metal columns (51) are respectively connected to one inner floor (22).

4. The reconfigurable microstrip antenna with 360° circumferential beam coverage according to claim 3, characterized in that: The circular patch (3) and the T-shaped monopole (4) are both copper-clad films of the same thickness; The radius R1 of the circular patch (3) is 9 mm, the length L1 of the rectangular through-slot (31) is 3.9 mm, and the width W1 of the rectangular through-slot (31) is 0.6 mm; The length L2 of the rectangular strip (41) is 4 mm, the width W2 of the rectangular strip (41) is 0.4 mm, the width W2 of the fan-shaped strip (42) is 1.5 mm, and the angle A1 of the fan-shaped strip (42) is 80 degrees; The gap distance gap1 between the circular patch (3) and the T-shaped monopole (4) is 0.25 mm; The radius R2 of the metal column (51) is 0.25 mm, and the angle A2 between the radial line of the circular patch (3) passing through the center of the metal column (51) on both sides and the center line of the rectangular strip (41) is 8 degrees.

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