Flat-top end-fire microstrip antenna

Abstract

The application discloses a flat-top quasi-end-fire microstrip antenna, which is characterized in that a multi-step strip resonator is arranged obliquely above four sequentially arranged patch resonators, horizontal currents at two ends of the multi-step strip resonator and a horizontal parallel current in the middle are formed, the currents at the two ends and the current in the middle are opposite, and after the polarization currents of the four patch resonators are superposed, quasi-end-fire with a flat-top radiation effect is realized, and a quasi-end-fire surface is orthogonal to a polarization direction.

Description

Technical Field

[0001] This invention relates to a wireless communication device, and more particularly to a flat-top quasi-end-fire microstrip antenna. Background Technology

[0002] Quasi-end-fire microstrip antennas utilize the structure of microstrip antennas to achieve radiation directions that approximate the extension direction of the microstrip structure. Similar to traditional end-fire antennas, they feature planar integrability, ease of installation, and high gain. However, unlike traditional end-fire antennas, the radiation of quasi-end-fire microstrip antennas is unaffected by metallic ground planes, further enhancing their immunity to large metallic ground planes. Flat-top quasi-end-fire microstrip antennas exhibit relatively uniform radiation within a certain range along the maximum radiation direction, with low radiation fluctuations (less than 1 dB). This facilitates uniform signal coverage and stable collection, making them more suitable for short-range, high-reliability communications, indoor or complex environments, low-Earth orbit satellite-to-ground communication, and radar.

[0003] Currently, there are no flat-top quasi-end-fire microstrip antennas; only traditional quasi-end-fire microstrip antennas exist, which are mainly implemented in two ways. The first is a microstrip Yagi array antenna, which uses a director and a reflector to achieve [the desired effect]. H The first method achieves a surface-to-end radiation effect, but does not create a flat-top radiation effect in the directional end-fire direction. The second method uses a microstrip patch loaded with dual rows of vias, and achieves better results under array conditions. E It achieves the effect of quasi-end-firing, but it also fails to create a flat-top radiation effect in the quasi-end-firing direction, and cannot achieve... H Aim at the end of the line for firing. Summary of the Invention

[0004] Purpose of the invention: In view of the above-mentioned prior art, a flat-top quasi-end-fire microstrip antenna is proposed to achieve quasi-end-fire with flat-top radiation effect, and the quasi-end-fire surface is orthogonal to the polarization direction.

[0005] Technical solution: A flat-top quasi-end-fire microstrip antenna, comprising, from top to bottom, a top layer metal, an upper dielectric substrate, a middle layer metal, a lower dielectric substrate, a bottom layer metal, and a coaxial connector; an air layer is provided between the upper dielectric substrate and the lower dielectric substrate; The top metal layer is a multi-step strip, with the width gradually increasing from the top and bottom to the center, symmetrically arranged. The intermediate metal layer is located on the upper surface of the lower dielectric substrate and includes square patches 1, 2, 3 and 4 arranged from left to right along the same horizontal center line. The size of square patches 1 to 3 decreases sequentially, and square patch 4 has the same size as square patch 3. The multi-step strip is located to the right of the square patch four; The bottom metal is a metallic ground located on the lower surface of the lower dielectric substrate; the inner conductor of the coaxial connector passes through the bottom metal and the lower dielectric substrate and is connected to the second square patch, with the connection point located on the vertical symmetry line of the second square patch; the outer conductor of the coaxial connector is connected to the bottom metal.

[0006] Furthermore, the multi-step strip has two abrupt changes in linewidth. The linewidths from the top and bottom to the middle are between 0.035λ0 and 0.036λ0, 0.139λ0 and 0.143λ0, and 0.348λ0 and 0.358λ0, respectively. The line lengths from the top and bottom to the middle are between 0.209λ0 and 0.214λ0, 0.417λ0 and 0.429λ0, and 1.114λ0 and 1.147λ0, respectively. λ0 is the free space wavelength corresponding to the center frequency.

[0007] Furthermore, the spacing between the lower dielectric substrate and the upper dielectric substrate is between 0.391λ0 and 0.403λ0.

[0008] Furthermore, the horizontal center-to-center distance between the square patch four and the multi-step strip is between 0.057λ0 and 0.058λ0.

[0009] Furthermore, the side length of square patch one is between 0.331λ0 and 0.341λ0, the side length of square patch two is between 0.291λ0 and 0.300λ0, and the side lengths of square patches three and four are between 0.278λ0 and 0.286λ0; the spacing between square patch one and square patch two is between 0.017λ0 and 0.018λ0; the spacing between square patch two and square patch three is the same as the spacing between square patch three and square patch four, both being between 0.0119λ0 and 0.0122λ0.

[0010] Furthermore, the square patch 1, square patch 2, square patch 3, and square patch 4, together with the lower dielectric substrate and the bottom metal, respectively constitute patch resonators 1, 2, 3, and 4; the multi-step strip, together with the upper dielectric substrate, the lower dielectric substrate, and the bottom metal, constitutes a multi-step strip resonator; the signal is fed in from the coaxial connector, and under the combined action of the four patch resonators and the multi-step strip resonator, a flat-top quasi-end-oriented radiation is achieved, which is orthogonal to the polarization direction.

[0011] Beneficial effects: Existing quasi-end-fire microstrip antennas cannot achieve a flat-top radiation effect in the quasi-end-fire direction, and the polarization direction of some designs is not orthogonal to the quasi-end-fire surface. This invention places a multi-step strip resonator obliquely above four sequentially arranged patch resonators, forming horizontal currents at both ends and a horizontal parallel current in the middle of the multi-step strip resonator. The currents at both ends are opposite to the current in the middle. After being superimposed with the polarization currents of the four patch resonators, a quasi-end-fire with a flat-top radiation effect is achieved, and the quasi-end-fire surface is orthogonal to the polarization direction.

[0012] Specifically, the multi-step strip resonator consists of a multi-step strip, upper and lower dielectric substrates, and a bottom metal layer. When coupled with a surface-mount resonator, four currents can be generated on the multi-step strip, including horizontal currents in the same direction at both ends and a parallel current in the same direction in the middle, with the currents at both ends in opposite directions to the middle current. The overall current, superimposed with the polarization currents on the four surface-mount resonators, can form... E The flat-top radiation effect can be controlled by manipulating the multi-step strips. E The elevation angle range of the flat-top radiation coverage and the flat-top radiation effect.

[0013] The four surface-mount resonators have square patches arranged perpendicular to the polarization direction along the same center line. Except for the two square patches on the right, which are the same size, the size decreases from left to right. The superposition and radiation effect of the polarization currents on the four patches forms... H The quasi-end radiation is orthogonal to the polarization direction. Attached Figure Description

[0014] Figure 1 This is a schematic cross-sectional view of the flat-top quasi-end-fire microstrip antenna of the present invention. Figure 2 This is a schematic diagram of the top metal structure of the flat-top quasi-end-fire microstrip antenna of the present invention; Figure 3 This is a schematic diagram of the intermediate metal structure of the flat-top quasi-end-fire microstrip antenna of the present invention; Figure 4 Antenna for an embodiment of the present invention S Parametric simulation response; Figure 5 The antenna in this embodiment of the invention is located at the center frequency (1.587 GHz). H Surface simulation radiation pattern; Figure 6 In this embodiment of the invention, the antenna is positioned at the center frequency (1.587 GHz) and... H Maximum radiation point of the surface ( θ = 35°) intersecting E Directional view. Detailed Implementation

[0015] The invention will now be further explained with reference to the accompanying drawings.

[0016] A flat-top quasi-end-fire microstrip antenna, such as Figure 1 As shown, it mainly consists of a top layer metal 1, an upper dielectric substrate 2, a middle layer metal 3, a lower dielectric substrate 4, a bottom layer metal 5, a coaxial connector 6, and fixing screws 7.

[0017] The top metal layer 1 is located on the upper surface of the upper dielectric substrate 2. For example... Figure 2 As shown, the top metal 1 is a multi-step strip 101, with the linewidth gradually increasing symmetrically from the top and bottom to the center, exhibiting two abrupt changes in linewidth. The linewidths of the multi-step strip 101 range from 0.035λ0 to 0.036λ0, 0.139λ0 to 0.143λ0, and 0.348λ0 to 0.358λ0 from the top and bottom to the center, respectively. The line lengths range from 0.209λ0 to 0.214λ0, 0.417λ0 to 0.429λ0, and 1.114λ0 to 1.147λ0 from the top and bottom to the center, respectively. λ0 is the free-space wavelength corresponding to the center frequency.

[0018] The intermediate metal layer 3 is located on the upper surface of the lower dielectric substrate 4. For example... Figure 3 As shown, the intermediate metal layer 3 is composed of square patch 1 301, square patch 2 302, square patch 3 303 and square patch 4 304, which are arranged from left to right along the same horizontal center line. The size of square patch 1 301 to square patch 3 303 decreases sequentially, and square patch 4 304 has the same size as square patch 3 303.

[0019] The side length of square patch 1 (301) is between 0.331λ0 and 0.341λ0, the side length of square patch 2 (301) is between 0.291λ0 and 0.300λ0, and the side lengths of square patches 303 (303) and 4 (304) are between 0.278λ0 and 0.286λ0. The spacing between square patches 1 (301) and 2 (301) is between 0.017λ0 and 0.018λ0. The spacing between square patches 2 (302) and 3 (303) is the same as the spacing between square patches 3 (303) and 4 (304), both being between 0.0119λ0 and 0.0122λ0.

[0020] An air layer is provided between the lower dielectric substrate 4 and the upper dielectric substrate 2, and the distance between the lower dielectric substrate 4 and the upper dielectric substrate 2 is between 0.391λ0 and 0.403λ0. Specifically, the upper dielectric substrate 2 and the lower dielectric substrate 4 are fixed by fixing screws 7 that are thin at both ends and thick in the middle.

[0021] The multi-step strip 101 is located to the right of the square patch 304, and the horizontal center distance between the square patch 304 and the multi-step strip 101 is between 0.057λ0 and 0.058λ0.

[0022] The bottom metal 5 is a metal ground and is located on the lower surface of the lower dielectric substrate 4. The inner conductor of the coaxial connector 6 passes through the bottom metal 5 and the lower dielectric substrate 4 and is connected to the square patch 302. The connection point is located on the vertical symmetry line of the square patch 302. The outer conductor of the coaxial connector 6 is connected to the bottom metal 5.

[0023] In the above structure, square patch 1 301, square patch 2 302, square patch 303, and square patch 4 304, together with the lower dielectric substrate 4 and the bottom metal 5, constitute patch resonators 1, 2, 3, and 4, respectively. The multi-step strip 101, together with the upper dielectric substrate 2, the lower dielectric substrate 4, and the bottom metal 5, forms a multi-step strip resonator.

[0024] For the flat-top quasi-end-fire microstrip antenna with the above structure, the signal is fed in from the coaxial connector 6. Under the combined action of four patch resonators and multi-step strip resonators, the flat-top quasi-end-fire radiation is achieved and is orthogonal to the polarization direction.

[0025] During this process, the four patch resonators along H Surface arrangement is the formation H The basis of surface-mount resonator. A multi-step strip resonator receives a coupled signal from a surface-mount resonator and forms a specific current distribution. The narrow strips on the top and bottom sides of the multi-step strip 101 receive horizontal currents in the same direction, while the left and right edges of the wide strip in the middle receive two horizontally polarized parallel currents in the same direction, but in the opposite direction to the currents on the narrow strips. The inner region of the wide strip in the middle is a weak current region, meaning it has two parallel currents in the same direction with a certain distance between them. When the four currents of the multi-step strip resonator are superimposed with the polarization currents of the four surface-mount resonators, the effect can be weakened. E The gain in the direction of maximum radiation is increased, the gain on both sides of the direction of maximum radiation is enhanced, and the gain far away from the direction of maximum radiation is greatly reduced, thereby achieving... E The flat-top radiation effect of the surface.

[0026] Adjusting the width of the middle strip of a multi-step strip resonator is equivalent to adjusting the distance between the parallel currents on both sides. When the current distance is appropriately increased, it is possible to achieve a wider range of elevation angles. E Flat-top radiation is beneficial for reducing the distance between the multi-step strip resonator and the metal ground. Adjusting the length of the wide strip in the middle of the multi-step strip resonator is equivalent to adjusting the length ratio between the parallel current in the middle and the currents in the narrow strips on both sides. When this current-length ratio is too large, EGain fluctuations deteriorate within the flat-top radiation range, and matching bandwidth deteriorates when the current length is too small.

[0027] In this embodiment, the substrate has a relative permittivity of 2.5. Figure 4 This embodiment of the antenna demonstrates... S Parametric simulation results, from Figure 4 As can be seen, the antenna in this embodiment has two matching frequency bands, namely 1.56~1.61 GHz (3.2%) and 1.69~1.70 GHz (0.6%). Since the second frequency band does not achieve flat-top quasi-end firing, only the first frequency band is an effective working frequency band.

[0028] Figure 5 , Figure 6 The simulated radiation pattern at the antenna center frequency (1.587 GHz) of this embodiment is shown. From Figure 5 of H As can be seen from the surface simulation radiation pattern, the antenna in this embodiment achieves quasi-end-direction radiation, with the radiation direction pointing towards... H Maximum radiation point of the surface ( θ At (= 35°). From Figure 6 and H Maximum radiation point of the surface ( θ = 35°) intersecting E As can be seen from the surface simulation radiation pattern, the antenna in this embodiment achieves flat-top radiation within a range of ±30° with relatively small gain fluctuations.

[0029] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flat-top quasi-end-fire microstrip antenna, characterized in that, It includes, from top to bottom, a top layer metal (1), an upper dielectric substrate (2), a middle layer metal (3), a lower dielectric substrate (4), a bottom layer metal (5), and a coaxial connector (6); an air layer is provided between the upper dielectric substrate (2) and the lower dielectric substrate (4); The top metal (1) is a multi-step strip (101), with the width gradually increasing from the top and bottom sides towards the middle. The intermediate metal layer (3) is located on the upper surface of the lower dielectric substrate (4), including square patches one (301), square patch two (302), square patch three (303) and square patch four (304) arranged from left to right along the same horizontal center line. The size of square patches one (301) to square patch three (303) decreases sequentially, and square patch four (304) has the same size as square patch three (303). The four square patches are arranged perpendicular to the polarization direction along the same center line. The multi-step strip (101) is located to the right of the square patch four (304); The bottom metal (5) is a metal ground located on the lower surface of the lower dielectric substrate (4); the inner conductor of the coaxial connector (6) passes through the bottom metal (5) and the lower dielectric substrate (4) and is connected to the square patch two (302). The connection point is located on the vertical symmetry line of the square patch two (302), and the outer conductor of the coaxial connector (6) is connected to the bottom metal (5).

2. The flat-top quasi-end-fire microstrip antenna according to claim 1, characterized in that, The multi-step strip (101) has two linewidth abrupt changes. The linewidths from the top and bottom to the middle are between 0.035λ0 and 0.036λ0, 0.139λ0 and 0.143λ0, and 0.348λ0 and 0.358λ0, respectively. The line lengths from the top and bottom to the middle are between 0.209λ0 and 0.214λ0, 0.417λ0 and 0.429λ0, and 1.114λ0 and 1.147λ0, respectively. λ0 is the free space wavelength corresponding to the center frequency.

3. The flat-top quasi-end-fire microstrip antenna according to claim 2, characterized in that, The spacing between the lower dielectric substrate (4) and the upper dielectric substrate (2) is between 0.391λ0 and 0.403λ0.

4. The flat-top quasi-end-fire microstrip antenna according to claim 2, characterized in that, The horizontal center-to-center distance between the square patch four (304) and the multi-step strip (101) is between 0.057λ0 and 0.058λ0.

5. The flat-top quasi-end-fire microstrip antenna according to claim 2, characterized in that, The side length of square patch 1 (301) is between 0.331λ0 and 0.341λ0, the side length of square patch 2 (302) is between 0.291λ0 and 0.300λ0, and the side lengths of square patch 3 (303) and square patch 4 (304) are between 0.278λ0 and 0.286λ0. The spacing between square patch 1 (301) and square patch 2 (302) is between 0.017λ0 and 0.018λ0. The spacing between square patch 2 (302) and square patch 3 (303) is the same as the spacing between square patch 3 (303) and square patch 4 (304), both being between 0.0119λ0 and 0.0122λ0.

6. The flat-top quasi-end-fire microstrip antenna according to any one of claims 1-5, characterized in that, The square patch 1 (301), square patch 2 (302), square patch 3 (303) and square patch 4 (304) respectively form patch resonators 1, 2, 3 and 4 with the lower dielectric substrate (4) and the bottom metal (5); the multi-step strip (101) forms a multi-step strip resonator with the upper dielectric substrate (2), the lower dielectric substrate (4) and the bottom metal (5); the signal is fed in from the coaxial connector (6), and under the combined action of the four patch resonators and the multi-step strip resonator, the flat-top quasi-end-oriented radiation is realized and is orthogonal to the polarization direction.

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