Low-profile broadband circularly polarized array antenna based on traveling wave slot coupled feeding

Abstract

The invention discloses a low-profile broadband circularly polarized array antenna based on traveling wave slot coupling feeding. The array adopts a multi-layer structure and comprises a feed microstrip line layer, a first dielectric substrate, a metal plate with a cross recess, second to fifth dielectric substrate layers, a first metal sheet layer and a second metal sheet layer from top to bottom. The feed network realizes energy equal-amplitude in-phase and unequal-phase transmission through the first-stage T-shaped microstrip line and the second-stage unequal-length T-shaped microstrip line. The cross recess on the metal plate and the metalized through hole in the dielectric substrate work cooperatively to guide electromagnetic waves to radiate upwards and suppress transverse loss. The multiple layers of dielectric plates and the metal sheets are mixed and stacked and are arranged in a sequential rotation mode, so that the impedance bandwidth and the axial ratio bandwidth are effectively widened, and the antenna gain is improved. The antenna realizes the characteristics of high gain, wide bandwidth and low profile of 0.056 working wavelength under the center frequency of 7GHz.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of antennas, and particularly relates to a low-profile wideband circularly polarized array antenna based on a traveling wave slot coupling feed. BACKGROUND

[0002] With the rapid development of modern wireless communication technology, radar technology and satellite navigation system, the comprehensive performance requirements of antennas are significantly improved. The existing array antennas, while achieving wideband and high gain, often have problems such as complex structure, high volume, insufficient polarization performance, etc. Especially in the microwave frequency band, the traditional circularly polarized array antenna usually adopts a multi-layer metal patch or a loading cross slot form to generate circularly polarized waves, but such structure has a high profile and limited bandwidth.

[0003] On the other hand, the feed structure plays a key role in the performance of the antenna. Although the traditional standing wave type feed method has high efficiency, its frequency response is narrow and it is difficult to meet the wideband requirement. The traveling wave feed structure can transmit energy in a wider frequency band and is not sensitive to frequency changes, so it has a significant advantage in the design of wideband antennas. However, the existing traveling wave feed circularly polarized array antenna still has problems such as narrow axial ratio bandwidth, complex structure, and difficult processing.

[0004] Therefore, how to realize a circularly polarized array antenna with wide impedance bandwidth, wide axial ratio bandwidth and high gain by using a traveling wave feed method while maintaining a compact structure and low profile has become an important research direction in the field of antenna design. SUMMARY

[0005] The purpose of the present application is to provide a low-profile wideband circularly polarized array antenna based on a traveling wave slot coupling feed, which realizes high gain, wide bandwidth and low profile performance of the antenna through the comprehensive design of multi-layer dielectric and metal patch and the traveling wave slot coupling feed structure, to overcome the problems of complex structure, narrow axial ratio bandwidth and high height in the prior art.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] The application discloses a low-profile broadband circularly polarized array antenna based on a traveling wave slot coupling feed, which comprises, from bottom to top, a feed microstrip line layer (1), a first dielectric substrate layer (2), a metal plate (3), a second dielectric substrate layer (4), a third dielectric substrate layer (5), a first metal sheet layer (6), a fourth dielectric substrate layer (7), a fifth dielectric substrate layer (8) and a second metal sheet layer (9); the feed microstrip line layer (1) comprises a first-level feed microstrip line (11), a second-level feed microstrip line (12) and a third-level feed microstrip line (13); the first-level feed microstrip line (11) is designed in a T shape to realize energy equal-amplitude in-phase transmission; the second-level feed microstrip line (12) is designed in a non-equal-length T shape to realize further energy equal-amplitude non-equal-phase transmission; the third-level feed microstrip line (13) is in a rectangular ring shape and is composed of four rectangular slit rings with different orientations and the same shape, namely a first rectangular slit ring (14) oriented in a positive x direction, a second rectangular slit ring (15) oriented in a negative y direction, a third rectangular slit ring (16) oriented in a positive x direction and a fourth rectangular slit ring (17) oriented in a negative y direction; the first rectangular slit ring (14), the second rectangular slit ring (15), the third rectangular slit ring (16) and the fourth rectangular slit ring (17) are respectively designed with non-equal-width rectangular microstrip line segments to improve matching with the metal plate (3) and realize efficient transmission of electromagnetic waves; energy is input from the first-level feed microstrip line (11), transmitted through the second-level feed microstrip line (12) and the third-level microstrip line (13); the energy is transmitted along the microstrip line path direction of the feed microstrip line layer (1) and radiates electromagnetic waves in different directions at the same time; the electromagnetic wave radiation mode is not sensitive to frequency variation; the feed microstrip line layer (1) realizes array wide impedance bandwidth and wide axial ratio bandwidth through the traveling wave energy transmission mode.

[0008] Further, the first dielectric substrate (2) is rectangular, located above the feed microstrip line layer (1), and contains 14 identical and cylindrical first metal vias (21), 14 identical and cylindrical second metal vias (22), 14 identical and cylindrical third metal vias (23), and 14 identical and cylindrical fourth metal vias (24); the 14 first metal vias (21) penetrate the first dielectric substrate (2) and are distributed in a split square shape in the first rectangular split ring (14); the 14 second metal vias (22) penetrate the first dielectric substrate (2) and are distributed in a split square shape in the second rectangular split ring (15); the 14 third metal vias (23) penetrate the first dielectric substrate (2) and are distributed in a split square shape in the third rectangular split ring (16); the 14 fourth metal vias (24) penetrate the first dielectric substrate (2) and are distributed in a split square shape in the fourth rectangular split ring (17); the metal vias around the first rectangular split ring (14), the second rectangular split ring (15), the third rectangular split ring (16), and the fourth rectangular split ring (17) bind electromagnetic waves in such a way that electromagnetic waves propagate along the z-axis direction and reduce the loss of electromagnetic waves propagating along the xoy plane;

[0009] Further, the metal plate (3) is rectangular and located above the first dielectric substrate (2); the metal plate (3) comprises a first cross slot (31), a second cross slot (32), a third cross slot (33) and a fourth cross slot (34); the first cross slot (31) is etched in the positive direction of the x-axis; the second cross slot (32) is etched in the positive direction of the x-axis away from the first cross slot (31); the third cross slot (33) is etched in the positive direction of the x-axis at 45°; the fourth cross slot (34) is etched in the positive direction of the y-axis away from the first cross slot (31); the etching directions of the first cross slot (31), the second cross slot (32), the third cross slot (33) and the fourth cross slot (34) are all at an angle of 45° with the y-axis; part of the energy is transmitted on the rectangular gap ring, the initial excitation slot is the slot above the first unequal-width rectangular microstrip line segment where the current first passes; the current flows through a microstrip line of 0.25 working wavelengths to reach the second unequal-width rectangular microstrip line; the current flows through a microstrip line of 0.25 working wavelengths to reach the second unequal-width rectangular microstrip line; the phase of the current at the second unequal-width rectangular microstrip line is negative 90° different from the phase of the first unequal-width rectangular microstrip line; the current flows through a microstrip line of 0.25 working wavelengths to reach the third unequal-width rectangular microstrip line; the phase of the current at the third unequal-width rectangular microstrip line is negative 90° different from the phase of the second unequal-width rectangular microstrip line; the current flows through a microstrip line of 0.25 working wavelengths to reach the fourth unequal-width rectangular microstrip line, and the phase of the current at the fourth unequal-width rectangular microstrip line is negative 90° different from the phase of the third unequal-width rectangular microstrip line; etching the first cross slot (31), the second cross slot (32), the third cross slot (33) and the fourth cross slot (34) on the metal plate (3) controls the generation of electromagnetic waves with the same amplitude and a phase difference of negative 90° clockwise along the positive z-axis direction at each of the four slots of the first cross slot (31), the second cross slot (32), the third cross slot (33) and the fourth cross slot (34), realizing the propagation of left-handed circularly polarized electromagnetic waves along the positive z-axis direction;

[0010] Further, the second dielectric substrate layer (4) comprises a first cylindrical dielectric substrate (41), a second cylindrical dielectric substrate (42), a third cylindrical dielectric substrate (43) and a fourth cylindrical dielectric substrate (44) with the same shape; the first cylindrical dielectric substrate (41) comprises 24 fifth metal through holes (45) in the same cylindrical shape; the 24 fifth metal through holes (45) are arranged in a ring shape and penetrate the first cylindrical dielectric substrate (41) with the center of the first cylindrical dielectric substrate (41); the second cylindrical dielectric substrate (42) comprises 24 sixth metal through holes (46) in the same cylindrical shape; the 24 sixth metal through holes (46) are arranged in a ring shape and penetrate the second cylindrical dielectric substrate (42) with the center of the second cylindrical dielectric substrate (42); the third cylindrical dielectric substrate (43) comprises 24 seventh metal through holes (47) in the same cylindrical shape; the 24 seventh metal through holes (47) are arranged in a ring shape and penetrate the third cylindrical dielectric substrate (43) with the center of the third cylindrical dielectric substrate (43); the fourth cylindrical dielectric substrate (44) comprises 24 eighth metal through holes (48) in the same cylindrical shape; the 24 eighth metal through holes (48) are arranged in a ring shape and penetrate the fourth cylindrical dielectric substrate (44) with the center of the fourth cylindrical dielectric substrate (44); the fifth metal through holes (45), the sixth metal through holes (46), the seventh metal through holes (47) and the eighth metal through holes (48) bind electromagnetic waves in a ring-shaped distribution arrangement manner inside the first cylindrical dielectric substrate (41), the second cylindrical dielectric substrate (42), the third cylindrical dielectric substrate (43) and the fourth cylindrical dielectric substrate (44) respectively, realize further propagation of electromagnetic waves along the positive z-axis direction, and reduce the loss of electromagnetic wave propagation along the xoy plane;

[0011] Furthermore, the third dielectric substrate layer (5) includes a fifth cylindrical dielectric substrate (51), a sixth cylindrical dielectric substrate (52), a seventh cylindrical dielectric substrate (53), and an eighth cylindrical dielectric substrate (54); the fifth cylindrical dielectric substrate (51), the sixth cylindrical dielectric substrate (52), the seventh cylindrical dielectric substrate (53), and the eighth cylindrical dielectric substrate (54) are respectively located above the first cylindrical dielectric substrate (41), the second cylindrical dielectric substrate (42), the third cylindrical dielectric substrate (43), and the fourth cylindrical dielectric substrate (44); the first metal sheet layer (6) includes a first metal sheet (61), a second metal sheet (62), a third metal sheet (63), and a fourth metal sheet (64); the first metal sheet (61), the second metal sheet (62), the third metal sheet (63), and the fourth metal sheet (64) are respectively located above the fifth cylindrical dielectric substrate (51), the sixth cylindrical dielectric substrate (52), the seventh cylindrical dielectric substrate (53), and the eighth cylindrical dielectric substrate (54); the first metal sheet (61), the second metal sheet (62), the third metal sheet (63), and the fourth metal sheet (64) are respectively loaded with a square metal sheet (65) in the shape of "soil" and a four-slit ring (66); the center of the square metal sheet (65) in the shape of "soil" coincides with the centers of the fifth cylindrical dielectric substrate (51), the sixth cylindrical dielectric substrate (52), the seventh cylindrical dielectric substrate (53), and the eighth cylindrical dielectric substrate (s); the four-slit ring (66) surrounds the square metal sheet (65) in the shape of "soil"; the length L r1 、L r2 variation affects the axial ratio variation; the "soil"-shaped part of the square metal sheet (65) in the shape of "soil" realizes the improvement of the axial ratio of the circularly polarized electromagnetic wave; the variation of the side length r of the square metal sheet of the square metal sheet (65) in the shape of "soil" affects the gain variation; the square metal sheet of the square metal sheet (65) in the shape of "soil" realizes the gain improvement of the left-handed circularly polarized electromagnetic wave;

[0012] Further, the fourth dielectric substrate layer (7) comprises the same ninth cylindrical dielectric substrate (71), tenth cylindrical dielectric substrate (72), eleventh cylindrical dielectric substrate (73) and twelfth cylindrical dielectric substrate (74); the ninth cylindrical dielectric substrate (71), tenth cylindrical dielectric substrate (72), eleventh cylindrical dielectric substrate (73) and twelfth cylindrical dielectric substrate (74) are located above the first metal sheet (61), second metal sheet (62), third metal sheet (63) and fourth metal sheet (64) respectively; the fifth dielectric substrate layer (8) comprises the same thirteenth cylindrical dielectric substrate (81), fourteenth cylindrical dielectric substrate (82), fifteenth cylindrical dielectric substrate (83) and sixteenth cylindrical dielectric substrate (84); the thirteenth cylindrical dielectric substrate (81), fourteenth cylindrical dielectric substrate (82), fifteenth cylindrical dielectric substrate (83) and sixteenth cylindrical dielectric substrate (84) are located above the ninth cylindrical dielectric substrate (71), tenth cylindrical dielectric substrate (72), eleventh cylindrical dielectric substrate (73) and twelfth cylindrical dielectric substrate (74) respectively; the second metal sheet layer (9) comprises the same fifth metal sheet (91), sixth metal sheet (92), seventh metal sheet (93) and eighth metal sheet (94) which are different in direction and same in shape; the fifth metal sheet (91), sixth metal sheet (92), seventh metal sheet (93) and eighth metal sheet (94) are located above the thirteenth cylindrical dielectric substrate (81), fourteenth cylindrical dielectric substrate (82), fifteenth cylindrical dielectric substrate (83) and sixteenth cylindrical dielectric substrate (84) respectively; the fifth metal sheet (91), sixth metal sheet (92), seventh metal sheet (93) and eighth metal sheet (94) comprise asymmetric clover-shaped metal sheet (95), first unequal length cross-shaped metal sheet (96) and second unequal length cross-shaped metal sheet (97); the asymmetric clover-shaped metal sheet (95) is a four-piece rectangle with different outer side cut angles, and the two center-symmetric rectangles have the same cut angle size; the center of the asymmetric clover-shaped metal sheet (95) is consistent with the center of the thirteenth cylindrical dielectric substrate (81), fourteenth cylindrical dielectric substrate (82), fifteenth cylindrical dielectric substrate (83) and sixteenth cylindrical dielectric substrate (84); the first unequal length cross-shaped metal sheet (96) and the second unequal length cross-shaped metal sheet (97) are located outside the two rectangles with larger outer side cut angles of the asymmetric clover-shaped metal sheet (95); adjusting the cut edge length L t1 、L t2 of the asymmetric clover-shaped metal sheet (95) can realize the movement of the control working frequency point; the change of the cut edge length L t1 、L t2 of the asymmetric clover-shaped metal sheet (95) can realize the movement of the control working frequency point; the length Ls1 L s2 Width W s The change affects the gain of the left-hand circularly polarized electromagnetic wave; the first unequal-length cross-shaped metal plate (96) and the second unequal-length cross-shaped metal plate (97) further enhance the radiation of the left-hand circularly polarized electromagnetic wave and increase the gain.

[0013] Furthermore, the first rectangular slit ring (14), the second rectangular slit ring (15), the third rectangular slit ring (16), the fourth rectangular slit ring (17), the first cross groove (31), the second cross groove (32), the third cross groove (33), the fourth cross groove (34), the first metal plate (61), the second metal plate (62), the third metal plate (63), the fourth metal plate (64), the asymmetrical clover-shaped metal plate (95), the first unequal-length cross-shaped metal plate (96), and the second unequal-length cross-shaped metal plate (97) have different orientations and rotate from the y-axis to the x-axis, rotating 90° in sequence. This sequential rotation method combines four left-handed circularly polarized electromagnetic waves into a single left-handed circularly polarized electromagnetic wave; the sequential rotation achieves a reduction in axial ratio, a widening of axial ratio bandwidth, and an enhancement of array gain;

[0014] Furthermore, energy is input from the first-stage fed microstrip line (11), then transmitted out of the array through the second-stage fed microstrip line (12), and then through the third-stage microstrip line (13). The energy is transmitted along the path of the microstrip line in the fed microstrip line layer (1), while simultaneously radiating electromagnetic waves in different directions. This electromagnetic wave radiation method is not sensitive to frequency changes. The fed microstrip line layer (1) achieves a wide impedance bandwidth and a wide axial ratio bandwidth of the array by transmitting energy through traveling waves.

[0015] Furthermore, the first cylindrical dielectric substrate (41), the second cylindrical dielectric substrate (42), the third cylindrical dielectric substrate (43), the fourth cylindrical dielectric substrate (44), the ninth cylindrical dielectric substrate (71), the tenth cylindrical dielectric substrate (72), the eleventh cylindrical dielectric substrate (73), and the twelfth cylindrical dielectric substrate (74) have a dielectric constant of 9.3 and are thin; the low-profile broadband circularly polarized array antenna based on traveling wave slot coupling feed has an overall array height of 0.56 wavelengths at a working frequency of 7 GHz; the 9.3 dielectric constant dielectric cylindrical dielectric substrate is mixed and superimposed with the first metal sheet (61), the second metal sheet (62), the third metal sheet (63), the fourth metal sheet (64), the fifth metal sheet (91), the sixth metal sheet (92), the seventh metal sheet (93), and the eighth metal sheet (94), which reduces the overall height of the array and realizes the low-profile characteristics of the array;

[0016] Further, the low-profile wideband circularly polarized array antenna based on the traveling wave slot coupling feed realizes left-handed circularly polarized wave, 10.45dBi gain, 83.84% impedance bandwidth, 28.67% axial ratio bandwidth, and 0.056 working wavelength profile height at the center working frequency of 7GHz; the low-profile wideband circularly polarized array antenna based on the traveling wave slot coupling feed has the characteristics of high gain, wide bandwidth, and low profile;

[0017] The present application has the following advantages:

[0018] 1. The low-profile wideband circularly polarized array antenna based on the traveling wave slot coupling feed realizes efficient energy transmission in a wide frequency range through the traveling wave slot coupling feed structure, so that the array antenna realizes 83.84% impedance bandwidth and 28.67% axial ratio bandwidth at the center frequency of 7GHz;

[0019] 2. The low-profile wideband circularly polarized array antenna based on the traveling wave slot coupling feed effectively reduces the overall height of the antenna to only 0.056 working wavelengths by adopting a multi-layer thin dielectric layer and a multi-layer metal sheet superposition structure;

[0020] 3. The low-profile wideband circularly polarized array antenna based on the traveling wave slot coupling feed enhances the radiation gain by adopting a 2*2 array design, and realizes a high gain of 10.45dBi;

[0021] 4. The low-profile wideband circularly polarized array antenna based on the traveling wave slot coupling feed avoids complex feed networks and improves the degree of freedom of feed network design by adopting a design that the feed network and the radiation structure are not in direct contact;

[0022] 5. The low-profile wideband circularly polarized array antenna based on the traveling wave slot coupling feed ensures stable output of left-handed circular polarization and realizes low axial ratio by sequential rotation.

[0023] Therefore, the low-profile wideband circularly polarized array antenna based on the traveling wave slot coupling feed realizes left-handed circular polarization, 10.45dBi gain, 83.84% impedance bandwidth, 28.67% axial ratio bandwidth, and 0.056 working wavelength profile height at the center working frequency of 7GHz, and has the characteristics of high gain, wide bandwidth, and low profile;

[0024] The present application will be further described below in conjunction with the drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a layered exploded view of the overall structure of the present application;

[0026] Figure 2Top view of the feeding microstrip line layer (1) of the present application;

[0027] Figure 3 Top view of the first dielectric substrate (2) of the present application;

[0028] Figure 4 Top view of the metal plate (3) of the present application;

[0029] Figure 5 Top view of the first cylindrical dielectric substrate (41) of the present application;

[0030] Figure 6 Top view of the first metal sheet (61) of the present application;

[0031] Figure 7 Top view of the fifth metal sheet (91) of the present application;

[0032] Figure 8 Layered detail view of the first cylindrical dielectric substrate (41), the fifth cylindrical dielectric substrate (51), the first metal sheet (61), the ninth cylindrical dielectric substrate (71), the third cylindrical dielectric substrate (81), and the fifth metal sheet (91) of the present application;

[0033] Figure 9 Reflection coefficient S 11 curve of the present application working at 7 GHz;

[0034] Figure 10 Axial ratio curve of the present application working at 7 GHz;

[0035] Figure 11 Gain curve of the present application working at 7 GHz;

[0036] Figure 12 E-plane normalized pattern of the present application working at 7 GHz;

[0037] Figure 13 H-plane normalized pattern of the present application working at 7 GHz. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those of ordinary skill in the art without any creative work fall within the protection scope of the present application.

[0039] Many specific details are set forth in the following description in order to provide a thorough understanding of the application. However, the application can be practiced according to other embodiments that can not be described in detail herein, and the scope of the present application is not limited to the specific embodiments described herein.

[0040] The application provides a low profile wideband circularly polarized array antenna based on traveling wave slot coupling feed, and a specific embodiment is as follows.

[0041] In the application, the working frequency point of the low profile wideband circularly polarized array antenna based on traveling wave slot coupling feed is 7GHz, and the array size L1 is 48mm.

[0042] Referring to Figure 1 , the low profile wideband circularly polarized array antenna based on traveling wave slot coupling feed comprises, from bottom to top, a feed microstrip line layer (1), a first dielectric substrate layer (2), a metal plate (3), a second dielectric substrate layer (4), a third dielectric substrate layer (5), a first metal sheet layer (6), a fourth dielectric substrate layer (7), a fifth dielectric substrate layer (8), and a second metal sheet layer (9).

[0043] Referring to Figure 2 , the first-level feed microstrip line (11) is designed in a "T" shape to realize energy equal-amplitude and in-phase transmission, the second-level feed microstrip line (12) is designed in a non-equal-length "T" shape next to the first-level feed microstrip line (11) to realize further energy equal-amplitude and non-equal-phase transmission, the third-level feed microstrip line (13) is in a rectangular ring shape and consists of four rectangular aperture rings of the same shape but different orientations, namely, a first rectangular aperture ring (14) oriented in the positive x direction, a second rectangular aperture ring (15) oriented in the negative y direction, a third rectangular aperture ring (16) oriented in the positive x direction, and a fourth rectangular aperture ring (17) oriented in the negative y direction, the rectangular microstrip line connected between the second-level feed microstrip line (12) and the third-level feed microstrip line (13) is non-equal-length, and the length of the rectangular microstrip line is designed to cause phase delay of the transmitted current, so that when the current reaches the first rectangular aperture ring (14), the second rectangular aperture ring (15), the third rectangular aperture ring (16), and the fourth rectangular aperture ring (17), the current phase difference between the first rectangular aperture ring (14) and the second rectangular aperture ring (15) is negative 90°, the current phase difference between the second rectangular aperture ring (15) and the third rectangular aperture ring (16) is negative 90°, the current phase difference between the third rectangular aperture ring (16) and the fourth rectangular aperture ring (17) is negative 90°, and the current phase difference between the fourth rectangular aperture ring (17) and the first rectangular aperture ring (14) is negative 90°, and the current phase difference when the current is input into the fourth rectangular aperture ring (17) is adjusted by adjusting L f1 , L f2 , L f3 , L f4The length of Lf9 is achieved by adjusting the length of L f5 The length of Lf9 is achieved by adjusting the length of L f6 The length of Lf9 is achieved by adjusting the length of L f7 The length of Lf9 is achieved by adjusting the length of L f8 The length of Lf9 is achieved by adjusting the length of L f10 The design provides phase difference conditions for sequential rotation; the width of the microstrip line for phase delay is 1.2 mm; the width of the first-level feeding microstrip line (11) is 1.2 mm; the width of the second-level feeding microstrip line (12) is 0.6 mm; the width of the ring line of the first rectangular split ring (14), the second rectangular split ring (15), the third rectangular split ring (16) and the fourth rectangular split ring (17) is 0.8 mm, and the width of the unequal width part is 1.2 mm; the third-level feeding microstrip line (13) adjusts the phase delay of the current passing through the unequal width rectangular microstrip line by adjusting the side length Lh of the rectangular split ring, so as to realize the generation of negative 90° phase difference in the four unequal width rectangular microstrip line segments of the first rectangular split ring (14), the second rectangular split ring (15), the third rectangular split ring (16) and the fourth rectangular split ring (17) in sequence clockwise, and provide phase conditions for generating left-handed circularly polarized electromagnetic waves;

[0044] Referring to Figure 3 , the first dielectric substrate (2) is rectangular and located above the feeding microstrip line layer (1); the first dielectric substrate (2) comprises 14 identical cylindrical first metal through holes (21), 14 identical cylindrical second metal through holes (22), 14 identical cylindrical third metal through holes (23) and 14 identical cylindrical fourth metal through holes (24); the 14 first metal through holes (21) penetrate the first dielectric substrate (2) and are distributed in the first rectangular split ring (14) in the form of split square; the 14 second metal through holes (22) penetrate the first dielectric substrate (2) and are distributed in the second rectangular split ring (15) in the form of split square; the 14 third metal through holes (23) penetrate the first dielectric substrate (2) and are distributed in the third rectangular split ring (16) in the form of split square; the 14 fourth metal through holes (24) penetrate the first dielectric substrate (2) and are distributed in the fourth rectangular split ring (17) in the form of split square; the diameters D v of the first metal through holes (21), the second metal through holes (22), the third metal through holes (23) and the fourth metal through holes (24) are all 1 mm;

[0045] Referring to Figure 4, the metal plate (3) is rectangular, above the first dielectric substrate (2); the metal plate (3) contains the first cross slot (31), the second cross slot (32), the third cross slot (33) and the fourth cross slot (34); the first cross slot (31) is etched in the positive direction of x axis, the second cross slot (32) is etched away from the first cross slot (31) in the positive direction of x axis, the third cross slot (33) is etched in the positive direction of x axis 45°, and the fourth cross slot (34) is etched away from the first cross slot (31) in the positive direction of y axis; the etching direction of the first cross slot (31), the second cross slot (32), the third cross slot (33) and the fourth cross slot (34) is all 45° with y axis; part of the energy is transmitted on the rectangular crack ring, the initial excitation slot is the slot above which the current first passes through the first unequal width rectangular microstrip line segment; the current flows through the microstrip line of 0.25 working wavelength to reach the second unequal width rectangular microstrip line; the current flows through the microstrip line of 0.25 working wavelength to reach the second unequal width rectangular microstrip line; the phase of the current in the second unequal width rectangular microstrip line is negative 90° with the phase of the first unequal width rectangular microstrip line; the current flows through the microstrip line of 0.25 working wavelength to reach the third unequal width rectangular microstrip line; the phase of the current in the third unequal width rectangular microstrip line is negative 90° with the phase of the second unequal width rectangular microstrip line; the current flows through the microstrip line of 0.25 working wavelength to reach the fourth unequal width rectangular microstrip line, and the phase of the current in the fourth unequal width rectangular microstrip line is negative 90° with the phase of the third unequal width rectangular microstrip line; etching the first cross slot (31), the second cross slot (32), the third cross slot (33) and the fourth cross slot (34) on the metal plate (3) controls the electromagnetic wave with the same amplitude and negative 90° phase difference generated clockwise along the positive z axis direction in each of the first cross slot (31), the second cross slot (32), the third cross slot (33) and the fourth cross slot (34), so as to realize the propagation of left-handed circularly polarized electromagnetic wave along the positive z axis direction; the slot width W sc of the first cross slot (31), the second cross slot (32), the third cross slot (33) and the fourth cross slot (34) is 0.8mm, the slot length L sc is 8.6mm; the center positions of the first cross slot (31), the second cross slot (32), the third cross slot (33) and the fourth cross slot (34) are respectively away from the rectangular edge of the metal plate (3) by d=24mm;

[0046] Referring to Figure 5The first cylindrical dielectric substrate (41) comprises 24 identical cylindrical fifth metal through holes (45) arranged in a ring at the center of the first cylindrical dielectric substrate (41) and penetrating the first cylindrical dielectric substrate (41); the second cylindrical dielectric substrate (42) comprises 24 identical cylindrical sixth metal through holes (46) arranged in a ring at the center of the second cylindrical dielectric substrate (42) and penetrating the second cylindrical dielectric substrate (42); the third cylindrical dielectric substrate (43) comprises 24 identical cylindrical seventh metal through holes (47) arranged in a ring at the center of the third cylindrical dielectric substrate (43) and penetrating the third cylindrical dielectric substrate (43); the fourth cylindrical dielectric substrate (44) comprises 24 identical cylindrical eighth metal through holes (48) arranged in a ring at the center of the fourth cylindrical dielectric substrate (44) and penetrating the fourth cylindrical dielectric substrate (44); the radii R of the fifth metal through holes (45), the sixth metal through holes (46), the seventh metal through holes (47) and the eighth metal through holes (48) are 0.5 mm; the center-to-center distances R of the fifth metal through holes (45), the sixth metal through holes (46), the seventh metal through holes (47) and the eighth metal through holes (48) from the centers of the first cylindrical dielectric substrate (41), the second cylindrical dielectric substrate (42), the third cylindrical dielectric substrate (43) and the fourth cylindrical dielectric substrate (44) are 6.36 mm; the radii R1 of the first cylindrical dielectric substrate (41), the second cylindrical dielectric substrate (42), the third cylindrical dielectric substrate (43) and the fourth cylindrical dielectric substrate (44) are 7.2 mm. v2 v1

[0047] Referring to Figure 6 ​​, the first metal sheet layer (6) comprises a first metal sheet (61), a second metal sheet (62), a third metal sheet (63) and a fourth metal sheet (64); the first metal sheet (61), the second metal sheet (62), the third metal sheet (63) and the fourth metal sheet (64) are respectively located above a fifth cylindrical dielectric substrate (51), a sixth cylindrical dielectric substrate (52), a seventh cylindrical dielectric substrate (53) and an eighth cylindrical dielectric substrate (54); the first metal sheet (61), the second metal sheet (62), the third metal sheet (63) and the fourth metal sheet (64) are respectively loaded with a "earth" shaped square metal sheet (65) and a four-split circular ring (66), the center of the "earth" shaped square metal sheet (65) is consistent with the center of the fifth cylindrical dielectric substrate (51), the sixth cylindrical dielectric substrate (52), the seventh cylindrical dielectric substrate (53) and the eighth cylindrical dielectric substrate (54); the four-split circular ring (66) surrounds the "earth" shaped square metal sheet (65); the length L r1 、L r2 of the "earth" shaped part of the "earth" shaped square metal sheet (65) affects the change of the axial ratio; the "earth" shaped part of the "earth" shaped square metal sheet (65) realizes the improvement of the axial ratio of the circularly polarized electromagnetic wave; the change of the side length r of the square metal sheet of the "earth" shaped square metal sheet (65) affects the change of the gain; the square metal sheet of the "earth" shaped square metal sheet (65) realizes the gain improvement of the left-handed circularly polarized electromagnetic wave;

[0048] Referring to Figure 7, the second metal sheet layer (9) comprises fifth, sixth, seventh and eighth metal sheets (91, 92, 93, 94) which are different in direction and same in shape; the fifth, sixth, seventh and eighth metal sheets (91, 92, 93, 94) are respectively above the thirteenth, fourteenth, fifteenth and sixteenth cylindrical dielectric substrates (81, 82, 83, 84); the fifth, sixth, seventh and eighth metal sheets (91, 92, 93, 94) comprise an asymmetric clover-shaped metal sheet (95), a first unequal-length cross-shaped metal sheet (96) and a second unequal-length cross-shaped metal sheet (97); the asymmetric clover-shaped metal sheet (95) is a four-leafed rectangle with different outside corner angles, and the two center-symmetrical outside corner angles of the rectangle are same in size; the center of the asymmetric clover-shaped metal sheet (95) is consistent with the centers of the thirteenth, fourteenth, fifteenth and sixteenth cylindrical dielectric substrates (81, 82, 83, 84); the first and second unequal-length cross-shaped metal sheets (96, 97) are respectively outside the two outside corner large rectangles of the asymmetric clover-shaped metal sheet (95); the length L t1 、L t2 of the first and second unequal-length cross-shaped metal sheets (96, 97) is adjusted to realize the movement of the control working frequency point; the length L s1 、L s2 and the width W s of the first and second unequal-length cross-shaped metal sheets (96, 97) are changed to affect the gain of the left-handed circularly polarized electromagnetic wave; the first and second unequal-length cross-shaped metal sheets (96, 97) further enhance the radiation of the left-handed circularly polarized electromagnetic wave and improve the gain;

[0049] Referring to Figure 8 , the dielectric constants of the first and ninth cylindrical dielectric substrates (41, 71) are 9.3, and the thicknesses thereof are respectively t2=0.7mm and t4=2mm; the materials of the fifth and third cylindrical dielectric substrates (51, 81) are FR4, and the thicknesses thereof are respectively t3=0.2mm and t5=0.2mm;

[0050] Referring to Figures 8-13, the low profile wideband circularly polarized array antenna based on the traveling wave slot coupling feed, the main polarization of the antenna is left-handed circular polarization, and the cross polarization is right-handed circular polarization; the main radiation direction of the antenna is less than-20dB at a frequency of 7GHz; at the center working frequency of 7GHz, a left-handed circularly polarized wave is realized, the gain is 10.45dBi, the impedance bandwidth is 83.84%, and the axial ratio bandwidth is 28.67%;

[0051] The above merely provides an embodiment of the present application, but is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the scope of claims of the present application.

Claims

1. A low-profile broadband circularly polarized array antenna based on traveling wave slot coupling feed, the array comprising, from bottom to top, a feed microstrip line layer (1), a first dielectric substrate (2), a metal plate (3), a second dielectric substrate layer (4), a third dielectric substrate layer (5), a first metal sheet layer (6), a fourth dielectric substrate layer (7), a fifth dielectric substrate layer (8), and a second metal sheet layer (9); the feed microstrip line layer (1) includes a first-stage feed microstrip line (11), a second-stage feed microstrip line (12), and a third-stage feed microstrip line (13); the first-stage feed microstrip line (11) is designed with a "T" shape to achieve equal amplitude and in-phase energy transmission; the second-stage feed microstrip line (12) is immediately connected to the first-stage feed microstrip line (11). The design incorporates unequal-length "T" shapes to achieve further energy transmission with equal amplitude but unequal phase. The three-stage fed microstrip line (13) is a rectangular ring composed of four rectangular slit rings of the same shape but facing different directions: the first rectangular slit ring (14) faces the positive x direction; the second rectangular slit ring (15) faces the negative y direction; the third rectangular slit ring (16) faces the positive x direction; and the fourth rectangular slit ring (17) faces the negative y direction. By designing unequal-width rectangular microstrip line segments on the first rectangular slit ring (14), the second rectangular slit ring (15), the third rectangular slit ring (16), and the fourth rectangular slit ring (17), the matching with the metal plate (3) is improved, and the efficient transmission of electromagnetic waves is achieved. The phase delay of the microstrip line satisfies the condition that... In this case, Where ∈ eff Let be the relative permittivity of the dielectric substrate, h be the thickness of the dielectric substrate, and W be the width of the microstrip line. λ g Where λ is the equivalent wavelength, c is the speed of light, and f is the operating frequency. Where θ is the phase, L f The length of the microstrip line is given; energy is input from the first-stage fed microstrip line (11), transmitted through the second-stage fed microstrip line (12), and then through the third-stage microstrip line (13); energy is transmitted along the path of the microstrip line in the fed microstrip line layer (1), and electromagnetic waves are radiated along the positive z-axis. This electromagnetic wave radiation method is insensitive to frequency changes; the fed microstrip line layer (1) achieves a wide impedance bandwidth and a wide axial ratio bandwidth by transmitting energy through traveling waves; the third-stage fed microstrip line (13) adjusts the side length L of the rectangular slit ring. h By adjusting the phase delay of the current through the unequal-width rectangular microstrip lines, a negative 90° phase difference is generated clockwise sequentially at the four unequal-width rectangular microstrip line segments on the first rectangular gap ring (14), the second rectangular gap ring (15), the third rectangular gap ring (16), and the fourth rectangular gap ring (17), thus providing phase conditions for generating left-hand circularly polarized electromagnetic waves.

2. The low-profile broadband circularly polarized array antenna based on traveling wave slot coupling feed according to claim 1, characterized in that: the first dielectric substrate (2) is rectangular and located above the feed microstrip line layer (1); the first dielectric substrate (2) includes 14 identical cylindrical first metal vias (21), 14 identical cylindrical second metal vias (22), 14 identical cylindrical third metal vias (23), and 14 identical cylindrical fourth metal vias (24); the 14 first metal vias (21) penetrate the first dielectric substrate (2) and are distributed in a square-shaped slit ring (14); the 14 second metal vias... (22) Penetrates the first dielectric substrate (2) and is distributed in a square-shaped slit in the second rectangular slit ring (15); the 14 third metal through holes (23) penetrate the first dielectric substrate (2) and are distributed in a square-shaped slit in the third rectangular slit ring (16); the 14 fourth metal through holes (24) penetrate the first dielectric substrate (2) and are distributed in a square-shaped slit in the fourth rectangular slit ring (17); the metal through holes surround the first rectangular slit ring (14), the second rectangular slit ring (15), the third rectangular slit ring (16) and the fourth rectangular slit ring (17) to confine the electromagnetic waves, thereby realizing the propagation of the electromagnetic waves along the positive z-axis and reducing the loss of the electromagnetic waves propagating along the xoy plane.

3. The low-profile broadband circularly polarized array antenna based on traveling wave slot coupling feed according to claim 1, characterized in that: the metal plate (3) is rectangular and located above the first dielectric substrate (2); the metal plate (3) includes a first cross groove (31), a second cross groove (32), a third cross groove (33) and a fourth cross groove (34); the first cross groove (31) is etched in the positive x-axis direction; the second cross groove (32) is etched in the positive x-axis direction away from the first cross groove (31); The third cross groove (33) is etched at a positive 45° angle to the x-axis; the fourth cross groove (34) is etched in the positive y-axis direction away from the first cross groove (31); the etching directions of the first cross groove (31), the second cross groove (32), the third cross groove (33), and the fourth cross groove (34) are all at an angle of 45° to the y-axis; part of the energy is transmitted on the rectangular slit ring, and the initial excitation groove is the groove above the first unequal-width rectangular microstrip line segment when the current first passes through it; the current flows through a microstrip line with a working wavelength of 0.

25. The current reaches the second unequal-width rectangular microstrip line; the phase difference between the current in the second unequal-width rectangular microstrip line and the first unequal-width rectangular microstrip line is -90°; the current flows through a microstrip line of 0.25 operating wavelengths to reach the third unequal-width rectangular microstrip line; the phase difference between the current in the third unequal-width rectangular microstrip line and the second unequal-width rectangular microstrip line is -90°; the current flows through a microstrip line of 0.25 operating wavelengths to reach the fourth unequal-width rectangular microstrip line; the current in the fourth unequal-width rectangular microstrip line... The phase difference between the line and the third non-uniform width rectangular microstrip line is negative 90°; the first cross groove (31), the second cross groove (32), the third cross groove (33) and the fourth cross groove (34) are etched on the metal plate (3) to control the first cross groove (31), the second cross groove (32), the third cross groove (33) and the fourth cross groove (34) to generate electromagnetic waves with a phase difference of negative 90° and the same amplitude in the four groove directions clockwise, so as to realize the propagation of left-hand circularly polarized electromagnetic waves along the positive z-axis.

4. The low-profile broadband circularly polarized array antenna based on traveling wave slot coupling feed according to claim 1, characterized in that: the second dielectric substrate layer (4) comprises a first cylindrical dielectric substrate (41), a second cylindrical dielectric substrate (42), a third cylindrical dielectric substrate (43), and a fourth cylindrical dielectric substrate (44) of the same shape; the first cylindrical dielectric substrate (41) comprises 24 identical cylindrical fifth metal vias (45); the 24 fifth metal vias (45) are arranged in a ring around the center of the first cylindrical dielectric substrate (41) and penetrate the first cylindrical dielectric substrate (41); the second cylindrical dielectric substrate (42) comprises 24 identical cylindrical sixth metal vias (46); the 24 sixth metal vias (46) are arranged in a ring around the center of the second cylindrical dielectric substrate (42) and penetrate the first cylindrical dielectric substrate (42); the third cylindrical dielectric substrate (43) comprises 24 identical cylindrical seventh metal vias (47); the 24 seventh metal vias (47) are arranged in a ring around the center of the third cylindrical dielectric substrate (43) and penetrate the third cylindrical dielectric substrate (43); the fourth cylindrical dielectric substrate (44) contains 24 identical cylindrical eighth metal vias (48); the 24 eighth metal vias (48) are arranged in a ring around the center of the fourth cylindrical dielectric substrate (44) and penetrate the fourth cylindrical dielectric substrate (44); the fifth metal via (45), the sixth metal via (46), the seventh metal via (47) and the eighth metal via (48) are arranged in a ring inside the first cylindrical dielectric substrate (41), the second cylindrical dielectric substrate (42), the third cylindrical dielectric substrate (43) and the fourth cylindrical dielectric substrate (44) respectively to confine electromagnetic waves, realize further upward propagation of electromagnetic waves, and reduce the loss of electromagnetic waves propagating along the xoy plane.

5. The low-profile broadband circularly polarized array antenna based on traveling-wave slot coupling feed according to claim 1, wherein the array is characterized in that: the third dielectric substrate layer (5) includes a fifth cylindrical dielectric substrate (51), a sixth cylindrical dielectric substrate (52), a seventh cylindrical dielectric substrate (53) and an eighth cylindrical dielectric substrate (54); the fifth cylindrical dielectric substrate (51), the sixth cylindrical dielectric substrate (52), the seventh cylindrical dielectric substrate (53) and the eighth cylindrical dielectric substrate (54) are respectively located above the first cylindrical dielectric substrate (41), the second cylindrical dielectric substrate (42), the third cylindrical dielectric substrate (43) and the fourth cylindrical dielectric substrate (44); the first metal sheet layer (6) includes a first metal sheet (61), a second metal sheet (62), a third metal sheet (63) and a fourth metal sheet (64); the first metal sheet (61), the second metal sheet (62), the third metal sheet (63) and the fourth metal sheet (64) are respectively located above the fifth cylindrical dielectric substrate (51), the sixth cylindrical dielectric substrate (52), the seventh cylindrical dielectric substrate (53) and the eighth cylindrical dielectric substrate (54); the first metal sheet (61), the second metal sheet (62), the third metal sheet (63) and the fourth metal sheet (64) are respectively loaded with a square metal sheet (65) in the shape of "tu" and a four-slit ring (66); the center of the square metal sheet (65) in the shape of "tu" is consistent with the centers of the fifth cylindrical dielectric substrate (51), the sixth cylindrical dielectric substrate (52), the seventh cylindrical dielectric substrate (53) and the eighth cylindrical dielectric substrate (54); the four-slit ring (66) surrounds the square metal sheet (65) in the shape of "tu"; the length L r1 、L r2 variation affects the axial ratio variation; the "tu"-shaped part of the square metal sheet (65) in the shape of "tu" realizes the improvement of the axial ratio of circularly polarized electromagnetic waves; the variation of the side length r of the square metal sheet of the square metal sheet (65) in the shape of "tu" affects the gain variation; the square metal sheet of the square metal sheet (65) in the shape of "tu" realizes the gain improvement of left-handed circularly polarized electromagnetic waves.

6. The low-profile broadband circularly polarized array antenna based on traveling wave slot coupling feed according to claim 1, characterized in that: The fourth dielectric substrate layer (7) includes the same cylindrical ninth dielectric substrate (71), tenth cylindrical dielectric substrate (72), eleventh cylindrical dielectric substrate (73) and twelfth cylindrical dielectric substrate (74). The ninth cylindrical dielectric substrate (71), the tenth cylindrical dielectric substrate (72), the eleventh cylindrical dielectric substrate (73), and the twelfth cylindrical dielectric substrate (74) are located above the first metal sheet (61), the second metal sheet (62), the third metal sheet (63), and the fourth metal sheet (64), respectively; the fifth dielectric substrate layer (8) includes the same thirteenth cylindrical dielectric substrate (81), fourteenth cylindrical dielectric substrate (82), fifteenth cylindrical dielectric substrate (83), and sixteenth cylindrical dielectric substrate (84); The thirteenth cylindrical dielectric substrate (81), the fourteenth cylindrical dielectric substrate (82), the fifteenth cylindrical dielectric substrate (83), and the sixteenth cylindrical dielectric substrate (84) are respectively located above the ninth cylindrical dielectric substrate (71), the tenth cylindrical dielectric substrate (72), the eleventh cylindrical dielectric substrate (73), and the twelfth cylindrical dielectric substrate (74); the second metal sheet layer (9) includes a fifth metal sheet (91), a sixth metal sheet (92), a seventh metal sheet (93), and an eighth metal sheet (94) with different orientations and the same shape; the fifth metal sheet (91), the sixth metal sheet (92), the seventh metal sheet (93), and the eighth metal sheet (94) are respectively located above the thirteenth cylindrical dielectric substrate (81), the fourteenth cylindrical dielectric substrate (82), the fifteenth cylindrical dielectric substrate (83), and the sixteenth cylindrical dielectric substrate (84). 91), the sixth metal sheet (92), the seventh metal sheet (93), and the eighth metal sheet (94) include an asymmetrical clover-shaped metal sheet (95), a first unequal-length cross-shaped metal sheet (96), and a second unequal-length cross-shaped metal sheet (97); the asymmetrical clover-shaped metal sheet (95) is composed of four rectangles with different outer chamfers, and the chamfers of the two centrally symmetrical rectangles with different outer chamfers are the same size; the center of the asymmetrical clover-shaped metal sheet (95) coincides with the center of the thirteenth cylindrical dielectric substrate (81), the fourteenth cylindrical dielectric substrate (82), the fifteenth cylindrical dielectric substrate (83), and the sixteenth cylindrical dielectric substrate (84); the first unequal-length cross-shaped metal sheet (96) and the second unequal-length cross-shaped metal sheet (97) are located outside the two rectangles with larger outer chamfers of the asymmetrical clover-shaped metal sheet (95); the length L of the chamfered edge of the asymmetrical clover-shaped metal sheet (95) is... t1 L t2 The change in length L of the first unequal-length cross-shaped metal plate (96) and the second unequal-length cross-shaped metal plate (97) enables the movement of the control operating frequency point; s1 L s2 Width W s The changes affect the gain of the left-hand circularly polarized electromagnetic wave; the first unequal-length cross-shaped metal plate (96) and the second unequal-length cross-shaped metal plate (97) further enhance the radiation of the left-hand circularly polarized electromagnetic wave and increase the gain.

7. The low-profile broadband circularly polarized array antenna based on traveling wave slot coupling feed according to claims 1-6, characterized in that: the first rectangular slot ring (14), the second rectangular slot ring (15), the third rectangular slot ring (16), the fourth rectangular slot ring (17), the first cross slot (31), the second cross slot (32), the third cross slot (33), the fourth cross slot (34), the first metal plate (61), the second metal plate (62), the third metal plate (63), the fourth metal plate (64), the asymmetric clover-shaped metal plate (95), the first unequal-length cross-shaped metal plate (96) and the second unequal-length cross-shaped metal plate (97) have different orientations and rotate 90° sequentially from the y-axis to the x-axis. This sequential rotation method combines four left-handed circularly polarized electromagnetic waves into a single left-handed circularly polarized electromagnetic wave; the sequential rotation reduces the axial ratio, widens the axial ratio bandwidth, and enhances the array gain.

8. The low-profile broadband circularly polarized array antenna based on traveling wave slot coupling feed according to claims 1-7, wherein the first cylindrical dielectric substrate (41), the second cylindrical dielectric substrate (42), the third cylindrical dielectric substrate (43), the fourth cylindrical dielectric substrate (44), the ninth cylindrical dielectric substrate (71), the tenth cylindrical dielectric substrate (72), the eleventh cylindrical dielectric substrate (73), and the twelfth cylindrical dielectric substrate (74) have a dielectric constant of 9.3 and are thin; based on traveling wave... The low-profile broadband circularly polarized array antenna with slot coupling feed has an overall height of 0.56 wavelengths at a working frequency of 7 GHz. The cylindrical dielectric substrate with dielectric constant 9.3 is mixed and superimposed with the first metal sheet (61), the second metal sheet (62), the third metal sheet (63), the fourth metal sheet (64), the fifth metal sheet (91), the sixth metal sheet (92), the seventh metal sheet (93) and the eighth metal sheet (94), which reduces the overall height of the array and realizes the low profile characteristic of the array.

9. The low-profile broadband circularly polarized array antenna based on traveling wave slot coupling feed as described in claims 1-8 achieves left-hand circularly polarized wave, a gain of 10.45 dBi, an impedance bandwidth of 83.84%, an axial ratio bandwidth of 28.67%, and a profile height of 0.056 operating wavelengths at a center operating frequency of 7 GHz. The low-profile broadband circularly polarized array antenna based on traveling wave slot coupling feed has the characteristics of high gain, wide bandwidth, and low profile.

Images