Broadband high-gain circularly polarized microstrip antenna

[0027] The present invention will be further described below in conjunction with the drawings.

[0028] figure 1 Shown is a schematic diagram of the layered structure of the antenna of the present invention. It can be seen from the figure that the broadband high-gain circularly polarized microstrip antenna proposed by the present invention includes: floor 1, feed coaxial 2, bottom dielectric substrate 3, cut corners U-shaped groove microstrip 4, top dielectric substrate 5, substrate integrated waveguide square cavity 6, microstrip radiation unit 7; the microstrip antenna of the present invention can be processed by a common double-layer microstrip printed board process, or LTCC Process realization.

[0029] Among them, the structural floor (1) is located at the bottom of the antenna and is made of metal. The bottom dielectric substrate 3 is located on the upper layer of the floor 1 and is in close contact. The top dielectric substrate 5 is located on the upper layer of the bottom dielectric substrate 3. The floor 1, the bottom dielectric substrate 3 and the top dielectric substrate 5 are closely attached to form the antenna body; the bottom of the bottom dielectric substrate 3 has a through hole in the center of the bottom floor, so that the feed coaxial 2 can pass through the floor.

[0030] The bottom dielectric substrate 3 and the top dielectric substrate 5 are in close contact, the same microwave dielectric material can be used, and the impedance bandwidth of the antenna can be adjusted by selecting the thickness of different dielectric substrates.

[0031] The substrate integrated waveguide square cavity 6 is processed on the top dielectric substrate 5. The microstrip radiation unit 7 and the cut corner U-shaped groove microstrip 4 are all located in the substrate integrated waveguide square cavity 6, and the feed coaxial 2 passes through the floor 1 Connected to the corner-cut U-shaped groove microstrip 4 for antenna feeding.

[0032] The cut corner U-shaped groove microstrip 4 is located at the bottom of the top dielectric substrate 5, and the geometric center of the patch is connected to the feeding coaxial 2. The corner-cut U-shaped groove microstrip 4 is a square microstrip patch with corners, which is composed of a square microstrip patch with diagonal cut corners and a U-shaped groove in the center. The antenna's work can be changed by adjusting the length of the four sides of the U-shaped groove. Frequency, adjust the size of the cut corner to change the axial ratio of the antenna, and adjust the size of the U-shaped groove to change the standing wave ratio of the antenna.

[0033] The microstrip radiation unit 7 is coplanar with the top-shaped microstrip line 10. The cut corner U-shaped groove microstrip 4 is coplanar with the bottom layer loop-shaped microstrip line 8. The 2×2 microstrip radiating unit 7 includes 4 square microstrip patches with cut corners, which are distributed in a Tian shape at equal intervals and coplanar. The projection of the geometric center in the vertical direction is the same as the geometric center of the cut corner U-shaped groove microstrip 4 The projections in the vertical direction coincide. The size of the four square microstrip patches with cut corners in the microstrip radiating unit 7 and the size of the substrate integrated waveguide square cavity 6 are adjusted to change the antenna pattern and gain value. Adjusting the cut corner size can change the axial ratio of the antenna.

[0034] When the antenna is processed by the microstrip printed board process, the feed coaxial 2 can be realized by coaxial. If the LTCC process is used for processing, the probe of the feed coaxial 2 can be replaced by a metal column. The coaxial probe of the feeding coaxial 2 passes through the floor and connects to the geometric center of the microstrip 4 with a cut corner U-shaped groove.

[0035] Such as figure 2 , 3 As shown, the substrate integrated waveguide square cavity 6 is in the shape of a round shape or a rectangle, and includes a bottom layer round microstrip line 8, a metal cylindrical array 9 and a top layer round microstrip line 10;

[0036] Among them, the projections of the bottom layer loop microstrip line 8 and the top layer loop microstrip line 10 in the vertical direction completely overlap, that is, the sizes of the bottom layer loop microstrip line 8 and the top layer loop microstrip line 10 are exactly the same. The bottom loop microstrip line 8 and the top loop microstrip line 10 are connected by a metal cylindrical array 9.

[0037] The metal cylinder array 9 is perpendicular to the bottom layer loop-shaped microstrip line 8 and the top layer loop-shaped microstrip line 10. The metal cylinder array 9 includes a plurality of evenly arranged metal cylinders (distributed in a zigzag pattern), one of two adjacent metal cylinders The distance between them is not more than 1/80 wavelength. Adjusting the size of the integrated waveguide square cavity 6 can change the antenna pattern and gain value.

[0038] Furthermore, the present invention also provides a phased array antenna, including a plurality of phased array units, the phased array units are implemented by using the wide-band high-gain circularly polarized microstrip antenna.

[0039] Such as figure 1 As shown, in this case, the size of the structural floor 1 is: 6.7mm×6.7mm×0.2mm, the thickness of the bottom dielectric substrate 3 is 0.094mm, and the thickness of the top dielectric substrate 5 is 0.47mm. A microwave dielectric plate with a dielectric constant of 5.9 is used. The cut corner U-shaped groove microstrip 4 adopts a square microstrip patch with a side length of 2 mm, and the two corners cut off from the patch are isosceles right triangles with a waist length of 0.6 mm. The width of the U-shaped groove in the center of the patch is 0.245mm, the total length of the groove is 2.75mm, and the center length of the bottom of the groove is 0.715mm. The 2×2 microstrip radiating unit 7 is composed of four square microstrip patches with a side length of 1.9 mm, the spacing of the square patches is 2.3 mm, and each patch is cut into an isosceles right triangle with a waist length of 0.33 mm. The circular microstrip line 8 constituting the substrate integrated multimode waveguide 6 has an outer side length of 5.4 mm, an inner side length of 4.6 mm, a metal cylindrical hole diameter of 0.1 mm, and a hole-to-hole center distance of 0.212 mm. The antenna working indexes of this embodiment are as follows:

[0040] Frequency: Ka band (23GHz-27GHz);

[0041] Standing wave ratio: ≤2.0;

[0042] Circular polarization axis ratio: ≤3dB;

[0043] Gain value: ≥5.9dB;

[0044] The voltage standing wave ratio of the wideband circularly polarized microstrip antenna of the Ka band of the present invention varies with frequency as follows Figure 4 As shown, the simulated gain and axial ratio of the antenna at different frequencies are shown in Table 1.

[0045] Table 1 The simulated gain and axial ratio of the antenna at different frequencies

[0046] Frequency/GHz

[0047] It can be seen from the embodiments of the present invention that the present invention adopts a single-point-fed lower layer microstrip to excite the upper layer 2×2 microstrip radiating element through the substrate integrated waveguide square cavity, and realizes the antenna wide impedance bandwidth at the same time through Single-point feeding avoids the use of complicated feeding networks. The 2×2 microstrip radiation unit increases the area of ​​the radiation patch, makes the aperture field distribution more uniform, and improves the gain of the antenna.

[0048] The invention adopts the substrate integrated waveguide square cavity to reduce the lateral leakage of electromagnetic waves, and reduces the feed loss of the antenna compared with the common upper microstrip structure. In addition, this structure makes the antenna have the advantages of weak mutual coupling effect and good wide-angle scanning performance when used as a phased array unit. At the same time, the invention adopts the method of evenly cutting the angles on the two layers of microstrip patches to realize the circular polarization and the wide-axis ratio bandwidth of the antenna.

[0049] The above is only a specific implementation of the example of the present invention, but the protection scope of the present invention is not limited to this. Any person skilled in the art can easily extend and change within the technical scope shown in the present invention. All technical solutions should be covered within the protection scope of the present invention. The content that is not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.