An ultra-wideband tightly coupled wide-angle scanning array antenna

Abstract

The present invention discloses an ultra-wideband tightly coupled wide-angle scanning array antenna, which belongs to the technical field of phased array antennas. The array antenna of the present invention is composed of a plurality of unit antennas arranged in a rectangular shape, and the unit antennas include a metal floor, a metal short-circuit column, a dielectric substrate, a microstrip feeder, a metal strip, a coaxial connector, a gradient radiation slot and a narrow long slot; the array antenna of the present invention adopts the design concept of integrating the matching layer into the array surface, which can achieve ultra-wideband wide-angle scanning without adding extra weight and can meet the requirements of low profile, light weight and low cost; the array antenna of the present invention uses a tightly coupled long slot array, avoids the complex decoupling network design, and introduces a long narrow slot, which enhances the coupling between the units and reduces the input impedance, so that the antenna can be better matched with the coaxial feed; the array antenna of the present invention adopts the design of unequal spacing between the E-plane and H-plane array elements, which can improve the impedance matching performance when scanning different planes.

Description

Technical Field

[0001] The present invention belongs to the technical field of phased array antennas, and in particular relates to an ultra-wideband tightly coupled wide-angle scanning array antenna, which can be used in wireless communication systems and satellite communication systems. Background Art

[0002] Modern wireless systems need to take into account multiple functions such as communication, navigation, detection and perception, which rely on electromagnetic waves in different frequency bands. In previous applications, multiple antennas were often used to cover these electromagnetic wave frequency bands, which made the entire system bulky and too expensive to implement. In recent years, RF systems that integrate multiple functions have gradually replaced the original single-function systems and have been widely used in various wireless devices. They use ultra-wideband array technology to achieve coverage of various functional frequency bands under a single radiation aperture, thereby greatly reducing the cost of the system. Phased array antennas have the characteristics of fast beam scanning and precise pointing, and can realize beamforming, multi-beam scanning, anti-interference and other functions. They have played a huge role in the fields of multi-target tracking and long-distance point-to-point communication for a long time.

[0003] The rapid development of electronic information technology and the explosive growth of communication capacity have prompted phased array research to move beyond beam scanning functions and toward ultra-wideband coverage to meet the needs of multifunctional electronic systems. At the same time, in order to save limited space and payload, phased arrays are required to have a lower profile height and lighter weight while achieving ultra-wideband performance.

[0004] Wideband angular scanning phased array antennas have been widely studied due to their advantages such as wide frequency band and large communication capacity. However, the coupling effect between the array elements of existing wideband array antennas has a great influence on the performance of the antenna array. If the design is not appropriate, it will have a great impact on the bandwidth and other performance of the antenna. Therefore, more complex technologies are used in the design process of existing wideband array antennas, which will lead to some disadvantages, such as high cost, large size, and inconvenient debugging and maintenance.

[0005] In order to solve the above problems, broadband array technology based on tightly coupled structure came into being. The antenna using this technology is called tightly coupled array antenna (TCA). Tightly coupled array antenna, unlike the existing idea of ​​avoiding coupling, makes use of the coupling effect between elements. By adopting the array formation method of closely arranged array elements and eliminating the adverse effects of mutual coupling effect between array elements on antenna performance without using some complex decoupling technology, the size of the entire array antenna is reduced, the structure is simplified, and it is easy to conform.

[0006] The tightly coupled dipole array and the connecting slot array respectively realize the ideal model proposed by H. Wheeler: infinite current sheet and infinite magnetic flux sheet. The research on tightly coupled dipole array is quite extensive, including feeding balun, wide angle matching layer, impedance matching, etc. As the physical realization of infinite magnetic flux sheet, the connecting slot array can achieve ultra-wide impedance bandwidth in free space without balanced feeding. It also has a planar array surface form, which is more suitable for low-profile and conformal application scenarios. However, its research is very few compared with the tightly coupled dipole array. The reflective floor of the tightly coupled dipole array and the connecting slot array has a greater impact on the input impedance, which brings challenges to improving broadband matching and wide-angle matching. Summary of the invention

[0007] The purpose of the present invention is to provide an ultra-wideband tightly coupled wide-angle scanning array antenna in view of the above-mentioned deficiencies in the prior art, which can expand the working bandwidth and scanning angle, and has a simple design, low cost, light weight and planarity.

[0008] The technical problem proposed by the present invention is solved in this way:

[0009] An ultra-wideband tightly coupled wide-angle scanning array antenna, which is composed of multiple unit antennas arranged in an M×N rectangular shape, where M and N are positive integers, and the unit antenna includes a metal floor 1, a metal short-circuit column 2, a dielectric substrate 3, a microstrip feed line 4, a metal strip 5, a coaxial connector 6, a gradient radiation slot 7 and a narrow long slot 8;

[0010] The metal floor 1 and the dielectric substrate 3 are rectangular, of the same size and shape, and are placed in parallel with a gap in between; a plurality of metal short-circuit posts 2 are located between the metal floor 1 and the dielectric substrate 3, perpendicular to the dielectric substrate 3, and connected at both ends to the lower surface of the metal floor 1 and the dielectric substrate 3 respectively; a microstrip feed line 4 and a metal strip 5 are located on the upper surface of the dielectric substrate 3; the lower surface of the dielectric substrate 3 is fully covered with metal, and then etched with a gradient radiation groove 7 and a narrow long slit 8;

[0011] The gradient radiation slot 7 is a central axis symmetrical structure, the central axis coincides with the symmetry axis of the dielectric substrate 3, and both ends extend to the edge of the dielectric substrate 3; the narrow long slit 8 is parallel to the central axis of the gradient radiation slot 7 and is located on both sides of the gradient radiation slot 7;

[0012] Several metal strips 5 are arranged in parallel along the direction of the gradient radiation slot 7, and are symmetrical about the central axis of the gradient radiation slot 7; each metal strip 5 is respectively a first sub-metal strip 51, a second sub-metal strip 52 and a third sub-metal strip 53 from the middle to the two ends; the metal strip 5 located at the center of the gradient radiation slot 7 only retains the third sub-metal strip 53, and the first sub-metal strip 51 and the second sub-metal strip 52 are missing, which is used to place the microstrip feed line 4, and the microstrip feed line 4 is parallel to the metal strip 5; the lengths and widths of the three sub-metal strips are different, and there is a gap between adjacent sub-metal strips;

[0013] The dielectric substrate 3 has two vias at both ends of the microstrip feed line 4; the outer conductor of the coaxial connector 6 is connected to the metal floor 1 and the metal plate on the lower surface of the dielectric substrate 3 respectively, and the inner conductor passes through the metal floor 1 and the via 10 to connect to the microstrip feed line 4; the microstrip feed line 4 is connected to the metal plate on the lower surface of the dielectric substrate 3 through a short-circuit metallized via 9.

[0014] Furthermore, a portion of the metal short-circuit posts 2 is arranged along the narrow and long slot 8 close to the inner side of the coaxial connector 6 , and another portion of the metal short-circuit posts is arranged half around the coaxial connector 6 .

[0015] Furthermore, the period of adjacent unit antennas along the direction of the tapered radiation slot 7 is 22 mm, and the period perpendicular to the direction of the tapered radiation slot 7 is 20 mm.

[0016] Furthermore, the distance between the metal floor 1 and the dielectric substrate 3 is 11 mm, and the thickness of the dielectric substrate 3 is 2 mm.

[0017] Furthermore, the length lf of the microstrip feed line 4 is 8 mm, and the width w5 is 0.9 mm.

[0018] Furthermore, the gradient radiation slot 7 is in a bow tie shape, the slot width in the middle section is smaller than the slot width at both end sections, and there is a gradient structure between the middle section and the end sections; the slot width w1 of the end sections is 4.2 mm, the slot length w2 of the end sections is 3.5 mm, the slot width w3 of the middle section is 0.5 mm, and the slot length w4 of the middle section is 4 mm.

[0019] Furthermore, the width of the narrow long slit 8 is 0.1 mm, and the distance between its axis and the axis of the gradient radiation groove 7 is 7.5 mm.

[0020] Furthermore, the length of the first sub-metal strip 51 is 6.8 mm and the width is 0.7 mm; the length of the second sub-metal strip 52 is 2 mm and the width is 0.8 mm; the length of the third sub-metal strip 53 is 3.8 mm and the width is 0.8 mm; and the interval between adjacent sub-metal strips is 0.1 mm.

[0021] The beneficial effects of the present invention are:

[0022] The array antenna of the present invention adopts the design concept of integrating the matching layer into the array surface, which can achieve ultra-wideband large-angle scanning without adding extra weight and can meet the requirements of low profile, light weight and low cost, thus overcoming the technical problem of high profile of the existing matching layer.

[0023] The array antenna of the present invention uses a tightly coupled long slot array, avoids complex decoupling network design, and introduces a long narrow slot to enhance the coupling between units and reduce input impedance, so that the antenna can better match the 50 ohm coaxial feed, avoiding complex feed design and impedance transformation;

[0024] The array antenna of the present invention adopts a design in which the spacing between array elements on the E plane and the H plane is unequal, which can improve the impedance matching performance when scanning different planes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of the overall structure of the antenna unit in the array antenna of the present invention;

[0026] Figure 2 This is a schematic diagram of the lower surface structure of the dielectric substrate in the array antenna of the present invention;

[0027] Figure 3 This is a schematic diagram of the upper surface structure of a dielectric substrate in the array antenna of the present invention;

[0028] Figure 4 A schematic diagram of active standing wave ratio scanning along the E-plane and H-plane in an infinite array environment of an embodiment;

[0029] Figure 5 is the far-field gain pattern of the 16×∞ array scanned along the E plane at 1.6 GHz in Example 1;

[0030] Figure 6 is the far-field gain pattern of the ∞×16 array of the embodiment scanned along the H plane at 1.6 GHz;

[0031] Figure 7 is the far-field gain pattern of the 16×∞ array scanned along the E plane at 2.5 GHz in Example 1;

[0032] Figure 8 is the far-field gain pattern of the ∞×16 array of the embodiment scanned along the H plane at 2.5 GHz;

[0033] Fig. 9 is the far-field gain pattern of the 16×∞ array scanned along the E plane at 3.3 GHz in Example 1;

[0034] Fig.10 is the far-field gain pattern of the ∞×16 array of the embodiment scanned along the H plane at 3.3 GHz;

[0035] Fig.11 It is a schematic diagram of the overall structure of the array antenna described in the embodiment. DETAILED DESCRIPTION

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

[0037] This embodiment provides an ultra-wideband tightly coupled wide-angle scanning array antenna, and its overall structural diagram is shown in FIG. Fig.11 As shown, multiple unit antennas are arranged in an M×N rectangular shape; the period of adjacent unit antennas along the gradient radiation slot 7 is 22 mm, and the period perpendicular to the gradient radiation slot 7 is 20 mm. Unequal spacing in different directions can make it easier to match the impedance when scanning in different directions.

[0038] The overall structure diagram of the antenna unit is as follows: Figure 1 As shown, it includes a metal floor 1, a metal short-circuit column 2, a dielectric substrate 3, a microstrip feed line 4, a metal strip 5, a coaxial connector 6, a gradient radiation slot 7 and a narrow long slot 8;

[0039] The metal floor 1 and the dielectric substrate 3 are rectangular, of the same size and shape, and are placed in parallel with a gap in between. In this embodiment, the gap between the metal floor 1 and the dielectric substrate 3 is 11 mm. The dielectric substrate 3 uses RogersRT / duroid 5880 (tm) with a dielectric constant of 2.2 and a thickness of 2 mm. Seven metal short-circuit columns 2 are located between the metal floor 1 and the dielectric substrate 3, perpendicular to the dielectric substrate 3, and connected at both ends to the lower surface of the metal floor 1 and the dielectric substrate 3 respectively. Three of the metal short-circuit columns 2 are arranged along the narrow long gap 8 close to the inner side of the coaxial connector 6, and four of the metal short-circuit columns are arranged semi-surrounding the coaxial connector 6.

[0040] like Figure 3 As shown, the microstrip feed line 4 and the metal strip 5 are located on the upper surface of the dielectric substrate 3; Figure 2 As shown, the lower surface of the dielectric substrate 3 is fully covered with metal, and then etched with a gradient radiation groove 7 and a narrow long slit 8; the length lf of the microstrip feed line 4 is 8 mm, and the width w5 is 0.9 mm.

[0041] The gradient radiation slot 7 is a central axis symmetrical structure, the central axis coincides with the symmetry axis of the dielectric substrate 3, and the two ends extend to the edge of the dielectric substrate 3; the narrow long slit 8 is parallel to the central axis of the gradient radiation slot 7 and is located on both sides of the gradient radiation slot 7; the gradient radiation slot 7 is a bow tie shape, the slot width of the middle section is smaller than the slot width of the two end sections, and the middle section and the two end sections are in a gradient structure; the slot width w1 of the two end sections is 4.2mm, the slot length w2 of the two end sections is 3.5mm, the slot width w3 of the middle section is 0.5mm, and the slot length w4 of the middle section is 4mm. The width of the narrow long slit 8 is 0.1mm, and the distance between the central axis and the central axis of the gradient radiation slot 7 is 7.5mm.

[0042] Several metal strips 5 are arranged in parallel and at equal intervals along the direction of the gradient radiation slot 7, and are bilaterally symmetrical about the central axis of the gradient radiation slot 7; each metal strip 5 serves as a wide-angle matching layer, and from the middle to the two ends are the first sub-metal strip 51, the second sub-metal strip 52 and the third sub-metal strip 53; the metal strip 5 located at the center of the gradient radiation slot 7 only retains the third sub-metal strip 53, and the first sub-metal strip 51 and the second sub-metal strip 52 are missing, which is used to place the microstrip feed line 4, and the microstrip feed line 4 is parallel to the metal strip 5; the adjacent metal strips 5 are arranged in parallel with the metal strips 5; There are gaps between the sub-metal strips, and the lengths and widths of the three sub-metal strips are different, which can provide more different inductance and capacitance values, and can greatly improve the deterioration of the active standing wave ratio during large-angle scanning to achieve better matching; the first sub-metal strip 51 is 6.8mm long and 0.7mm wide; the second sub-metal strip 52 is 2mm long and 0.8mm wide; the third sub-metal strip 53 is 3.8mm long and 0.8mm wide; the interval between adjacent sub-metal strips is 0.1mm.

[0043] The dielectric substrate 3 has two vias at both ends of the microstrip feed line 4; the outer conductor of the coaxial connector 6 is connected to the metal floor 1, and the inner conductor passes through the metal floor 1 and the via 10 to connect to the microstrip feed line 4; the microstrip feed line 4 is connected to the metal plate on the lower surface of the dielectric substrate 3 through the short-circuit metallized via 9.

[0044] The gradient radiation slot 7 is in a bow tie shape, which can improve the matching performance; the gradient radiation slot 7 is connected to the gradient radiation slot 7 branches of the surrounding units to form a long slot array; the narrow long slot 8 is used to provide capacitive impedance, which can offset the influence of the metal floor on the input impedance, reduce the drastic degree of input impedance change with frequency, and also reduce the unit input impedance. A 50-ohm coaxial connector can be used directly for feeding, avoiding the use of complex baluns, reducing the complexity of antenna design, and making it easier to match.

[0045] Seven metal short-circuit posts 2 connect the lower surface of the dielectric substrate with the metal floor 1, which can eliminate the common mode introduced by unbalanced feeding, move the common mode resonant frequency out of the working frequency band, and expand the bandwidth.

[0046] The array antenna described in this embodiment adopts the design concept of integrating the matching layer into the array surface, and integrates the long slot radiation unit, the matching layer, and the microstrip feeder on the same dielectric substrate. Compared with the existing dielectric matching layer, the antenna array can ensure the ultra-wide bandwidth angle scanning performance without increasing the cross section, and achieves the lightweight, low-cost, and low-profile of the antenna array, which has strong engineering practicality.

[0047] Figure 4 FIG. 1 is a schematic diagram of the active standing wave ratio of the embodiment of the present invention when scanning along the E-plane and the H-plane in an infinite array environment. Figure 4It can be seen that when the active standing wave ratio is less than 3, the array can achieve a beam scanning range of ±60° in the frequency band of 1.6-3.3.

[0048] Figure 5 is the far-field gain pattern of the 16×∞ array scanning along the E plane at 1.6GHz. Figure 5 It can be seen that when scanning to 60 degrees, the gain drops by 5.5dB.

[0049] Figure 6 is the far-field gain pattern of the ∞×16 array scanning along the H plane at 1.6GHz. Figure 6 It can be seen that when scanning to 60 degrees, the gain drops by 3.7dB.

[0050] Figure 7 This is the far-field gain pattern of the 16×∞ array scanning along the E plane at 2.5GHz. Figure 7 It can be seen that when scanning to 60 degrees, the gain drops by 7dB.

[0051] Figure 8 This is the far-field gain pattern of the ∞×16 array scanning along the H plane at 2.5GHz. Figure 8 It can be seen that when scanning to 60 degrees, the gain drops by 2.4dB.

[0052] Fig. 9 This is the far-field gain pattern of the 16×∞ array scanning along the E plane at 3.3GHz. Fig. 9 It can be seen that when scanning to 60 degrees, the gain drops by 7.5dB.

[0053] Fig.10 This is the far-field gain pattern of the ∞×16 array scanning along the H plane at 3.3GHz. Fig.10 It can be seen that when scanning to 60 degrees, the gain drops by 1.6dB.

Claims

1. An ultra-wideband tightly coupled wide-angle scanning array antenna, characterized in that: The device is composed of a plurality of unit antennas arranged in an M×N rectangular shape, where M and N are positive integers, and the unit antennas include a metal floor (1), a metal short-circuit column (2), a dielectric substrate (3), a microstrip feed line (4), a metal strip (5), a coaxial connector (6), a gradient radiation slot (7) and a narrow and long slot (8); The metal floor (1) and the dielectric substrate (3) are rectangular, of the same size and shape, and are placed in parallel with a gap in between; a plurality of metal short-circuit columns (2) are located between the metal floor (1) and the dielectric substrate (3), are perpendicular to the dielectric substrate (3), and have their two ends connected to the lower surface of the metal floor (1) and the dielectric substrate (3), respectively; and a microstrip feed line (4) and a metal strip (5) are located on the upper surface of the dielectric substrate (3); The lower surface of the dielectric substrate (3) is fully covered with metal, and a gradient radiation groove (7) and a narrow and long slit (8) are etched thereon; The gradient radiation slot (7) is a central axis symmetrical structure, the central axis coincides with the symmetry axis of the dielectric substrate (3), and both ends extend to the edges of the dielectric substrate (3); the narrow long slit (8) is parallel to the central axis of the gradient radiation slot (7) and is located on both sides of the gradient radiation slot (7); A plurality of metal strips (5) are arranged in parallel along the direction of the gradient radiation slot (7) and are bilaterally symmetrical about the central axis of the gradient radiation slot (7); each metal strip (5) comprises a first sub-metal strip (51), a second sub-metal strip (52) and a third sub-metal strip (53) from the middle to the two ends; the metal strip (5) located at the center of the gradient radiation slot (7) only retains the third sub-metal strip (53), and the first sub-metal strip (51) and the second sub-metal strip (52) are missing, and are used to place a microstrip feeder (4), and the microstrip feeder (4) is parallel to the metal strip (5); the lengths and widths of the three sub-metal strips are different, and a gap is left between adjacent sub-metal strips; The dielectric substrate (3) has two vias at both ends of the microstrip feeder (4); the outer conductor of the coaxial connector (6) is connected to the metal floor (1) and the metal plate on the lower surface of the dielectric substrate (3), respectively, and the inner conductor passes through the metal floor (1) and the via (10) to be connected to the microstrip feeder (4); the microstrip feeder (4) is connected to the metal plate on the lower surface of the dielectric substrate (3) via a short-circuit metallized via (9); Seven metal short-circuit posts (2) are located between the metal floor (1) and the dielectric substrate (3), are perpendicular to the dielectric substrate (3), and have their two ends connected to the lower surfaces of the metal floor (1) and the dielectric substrate (3), respectively; three of the metal short-circuit posts (2) are arranged along the narrow long slit (8) close to the inner side of the coaxial connector (6), and four of the metal short-circuit posts are arranged semi-surrounding the coaxial connector (6).

2. The ultra-wideband tightly coupled wide-angle scanning array antenna according to claim 1, characterized in that: The period of adjacent unit antennas along the direction of the gradient radiation slot (7) is 22 mm, and the period of adjacent unit antennas in the direction perpendicular to the gradient radiation slot (7) is 20 mm.

3. The ultra-wideband tightly coupled wide-angle scanning array antenna according to claim 1, characterized in that: The distance between the metal floor (1) and the dielectric substrate (3) is 11 mm, and the thickness of the dielectric substrate (3) is 2 mm.

4. The ultra-wideband tightly coupled wide-angle scanning array antenna according to claim 1, characterized in that: The length lf of the microstrip feed line (4) is 8 mm, and the width w5 is 0.9 mm.

5. The ultra-wideband tightly coupled wide-angle scanning array antenna according to claim 1, characterized in that: The gradient radiation slot (7) is in a bow tie shape, the slot width of the middle section is smaller than the slot width of the two end sections, and the middle section and the two end sections are in a gradient structure; the slot width w1 of the two end sections is 4.2 mm, the slot length w2 of the two end sections is 3.5 mm, the slot width w3 of the middle section is 0.5 mm, and the slot length w4 of the middle section is 4 mm.

6. The ultra-wideband tightly coupled wide-angle scanning array antenna according to claim 1, characterized in that: The width of the narrow long slit (8) is 0.1 mm, and the distance between its axis and the axis of the gradient radiation groove (7) is 7.5 mm.

7. The ultra-wideband tightly coupled wide-angle scanning array antenna according to claim 1, characterized in that: The first sub-metal strip (51) is 6.8 mm long and 0.7 mm wide; the second sub-metal strip (52) is 2 mm long and 0.8 mm wide; the third sub-metal strip (53) is 3.8 mm long and 0.8 mm wide; and the interval between adjacent sub-metal strips is 0.1 mm.

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