Ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning

Abstract

The present invention relates to an ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning, comprising a plurality of antenna units; the antenna unit comprises a tightly coupled dipole radiating unit, a reconfigurable layer, a wide angle impedance matching structure, a feeding structure and a metal floor; the wide angle impedance matching structure, the tightly coupled dipole radiating unit and the feeding structure are sequentially arranged on a first dielectric plate from top to bottom, and the first dielectric plate is placed vertically to a horizontal plane; the reconfigurable layer and the metal floor are placed vertically intersecting with the first dielectric plate, and the reconfigurable layer is located above the metal floor. The present invention proposes a reconfigurable layer and a double-layer double-sided capacitor-loaded ring structure for realizing the frequency reconfigurable function of an ultra-wideband array, while effectively ensuring its high radiation efficiency and wide angle scanning capability. In addition, the present invention also designs a feeding structure containing a capacitor-loaded short-circuit pin to ensure that there is no common mode resonance within its ultra-wideband operating frequency band.

Description

Technical Field

[0001] The invention relates to the technical field of microwave antennas, and in particular to an ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning. Background Art

[0002] As modern communication systems have increasing requirements for data transmission, related terminal devices need to cover a variety of wireless devices, provide fast network connections, and maintain stable and reliable network connections. These requirements pose new challenges to antenna array design, such as supporting multi-band operation and performing wide-angle beam scanning to expand service coverage. In this context, ultra-wideband (UWB) phased arrays have become an effective solution to the above problems with their wide-angle scanning capabilities.

[0003] Tightly coupled dipole arrays are based on the Wheeler current sheet theory and have attracted widespread attention for their wide bandwidth, compact size, low profile, and excellent cross-polarization performance. A typical tightly coupled dipole array can achieve a bandwidth of 5:1, mainly through coupling between elements. However, the short-circuit effect of the ground plane limits further bandwidth expansion. To overcome this limitation, researchers have tried to insert resistive cards between the dipole and the ground plane as absorbers to offset the short-circuit effect, thereby increasing the bandwidth to more than 10:1 times, but this design reduces the radiation efficiency of the array. Another bandwidth extension method is to use a polarization conversion floor, which increases the bandwidth to more than 15:1, but due to the deterioration of cross-polarization discrimination, this solution is only suitable for polarization-insensitive usage scenarios.

[0004] Large spatial coverage is also a key aspect of practical phased arrays. Wide-angle impedance matching (WAIM) structures have been introduced as a useful method to reduce impedance variations associated with beam scanning and expand the scanning range. For example, simple and effective WAIM designs use single or multi-layer dielectric cover layers with a scanning range of up to 60°. However, these designs increase the cost and weight of the system. Other printed circuit board-based wide-angle impedance matching structure designs are lighter, with impedance matching structure layouts in the form of frequency selective surfaces printed on the same circuit board as dipoles, covering a scanning range of {±75°, ±70°, ±60°}, a bandwidth of 6.1:1 and a VSWR of less than 3.2. However, as the operating bandwidth increases to 9:1 or higher, the H-plane scanning performance decreases significantly, that is, the VSWR exceeds 6. Wide-angle impedance matching structure designs using metasurfaces have been used to achieve a maximum scanning angle of 70° in a specific plane, while having advantages such as low profile, low cost or easy processing. However, their bandwidths are all less than 10:1. Despite significant progress in the design of various wide-angle impedance matching structures, most research focuses on a range of less than ten times the bandwidth. Summary of the invention

[0005] The technical problems to be solved by the present invention are:

[0006] In order to overcome the problems of wide-angle scanning standing waves, reduced radiation efficiency or deteriorated cross-polarization discrimination when expanding the array bandwidth in the prior art, the present invention proposes an ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning, which can not only expand the array operating bandwidth without sacrificing radiation efficiency and cross-polarization discrimination, but also be suitable for wide-angle impedance matching structures above 10:1 frequency doubling operating bandwidth to ensure good wide-angle scanning standing waves.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] An ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning, characterized in that it comprises a plurality of antenna units; the antenna units comprise tightly coupled dipole radiating units, a reconfigurable layer, a wide angle impedance matching structure, a feeding structure and a metal floor;

[0009] The wide-angle impedance matching structure, the tightly coupled dipole radiating unit, and the feeding structure are sequentially located on a first dielectric plate from top to bottom, and the first dielectric plate is placed vertically on a horizontal plane;

[0010] The reconfigurable layer, the metal floor and the first dielectric plate are arranged to intersect each other vertically, and the reconfigurable layer is located above the metal floor.

[0011] A further technical solution of the present invention: the wide-angle impedance matching structure includes two layers of double-sided capacitor loading rings, wherein the upper double-sided capacitor loading rings are symmetrically arranged on the front and back sides of the first dielectric plate; the lower double-sided capacitor loading rings are symmetrically arranged on the front and back sides of the first dielectric plate.

[0012] A further technical solution of the present invention is as follows: the lower opening of the double-sided capacitor loading ring is used to introduce capacitors.

[0013] A further technical solution of the present invention is as follows: the tightly coupled dipole radiation unit comprises a pair of dipole arms printed on the reverse side of a first dielectric plate, a first pair of coupling plates printed on the front side of the first dielectric plate, and a second pair of coupling plates printed on the reverse side of a second dielectric plate; wherein the front side of the second dielectric plate is overlapped with the reverse side of the first dielectric plate, and the first pair of coupling plates and the second pair of coupling plates are symmetrically distributed.

[0014] A further technical solution of the present invention is as follows: the feeding structure includes a short-circuit probe and a tapered balun, the upper end of the short-circuit probe is connected to the first pair of coupling plates, and the lower end is connected to the metal floor; the short-circuit probe passes through a capacitor structure in the form of a coplanar strip line designed at a position below the reconfigurable layer; the upper end of the tapered balun is connected to the center point of the dipole arm, and the lower end is connected to the SMA connector.

[0015] A further technical solution of the present invention is as follows: the tapered balun is composed of metal coatings printed on both sides of a first dielectric plate, and is used for balanced-unbalanced feeding structure transformation; the metal on one side below is wide and the metal on one side is narrow, which is an unbalanced microstrip line structure; the metal coatings on both sides above have the same width, which is a balanced stripline structure; the metal coating of the balun gradually narrows from bottom to top, and is used to gradually match the characteristic impedance of 50Ω to the feeding point of the dipole.

[0016] A further technical solution of the present invention is as follows: the reconfigurable layer includes a third dielectric plate and four metal patches printed with a cross-digital structure and a bias circuit located on the third dielectric plate; PIN diodes are designed between adjacent patches along the direction of the dipole arms to control the reconfigurable layer to adjust the phase response of the reflected wave; adjacent metal patches provide a bias voltage through the bias circuit to control the on and off of the PIN diode.

[0017] A further technical solution of the present invention is as follows: a slot which is wide in the middle and narrow at both sides is arranged in the middle of the metal floor, so that the feeding structure can pass through the slot without affecting the feeding performance.

[0018] A further technical solution of the present invention also includes a strength support layer, which is located below the metal floor and is used to fix the first dielectric plate.

[0019] A debugging method for an ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning, characterized by comprising:

[0020] By adjusting the electrical size, number, and longitudinal position of the double-sided capacitive loading loops, the wide-angle impedance matching characteristics of the array over a 14:1 frequency octave range covered in two reconfigurable states can be optimized;

[0021] The impedance matching characteristics of the array are optimized by adjusting the electrical width of the dipole arms and the electrical size of the coupling patch;

[0022] The reconfigurable state switching of the reconfigurable layer is controlled by adjusting the on-off state of the diode on the reconfigurable layer.

[0023] The beneficial effects of the present invention are:

[0024] The present invention proposes an ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning capability, which innovatively proposes a reconfigurable layer and a double-layer double-sided capacitor-loaded ring structure to realize the frequency reconfiguration function of the ultra-wideband array, while effectively ensuring its high radiation efficiency and wide angle scanning capability. In addition, the present invention also innovatively designs a feeding structure containing a capacitor-loaded short-circuit pin to ensure no common-mode resonance within its ultra-wideband operating frequency band.

[0025] In an ultra-wideband tightly coupled dipole array, the electromagnetic waves radiated upward by the oscillator (direct electromagnetic waves) and the energy radiated downward and reflected by the floor (reflected electromagnetic waves) are superimposed in anti-phase in a specific frequency band, which will lead to the generation of a short-circuit frequency band and thus affect the working bandwidth of the ultra-wideband array. By innovatively introducing a reconfigurable layer, the phase relationship between the direct electromagnetic wave and the reflected electromagnetic wave is regulated so that they are always kept in phase, thereby reconstructing and expanding the working bandwidth of the array.

[0026] The double-layer double-sided capacitive loading ring can improve the beam scanning performance of the array in both states, effectively reduce the impedance change during wide-angle scanning, and improve the impedance matching performance. It is coplanar with the dipole arm, with a lightweight design and easy to manufacture. The operating frequency band of single-layer double-sided capacitive loading rings (CLLs) is narrow, and it is impossible to optimize the wide-angle scanning and impedance matching characteristics of two frequency bands at the same time. The introduction of the second layer can effectively solve this problem. In addition, by introducing a double-layer capacitive loading ring of the same size in a mirrored manner on the other side of the dielectric plate, the bandwidth of the two reconfigurable states can be further expanded.

[0027] A short-circuit probe with capacitor loading is innovatively introduced into the feeding structure, which effectively solves the common-mode resonance problem in the two reconfigurable states. Although ordinary probes can play a certain tuning role in the common-mode resonance generated in the high-frequency state, they will introduce loop resonance in the low-frequency state, destroying the impedance matching characteristics of the array. The innovative introduction of capacitor structure in the short-circuit probe can effectively suppress the common-mode resonance generated in the low-frequency state. Therefore, this innovative short-circuit probe structure can effectively suppress the common-mode resonance generated in the two reconfigurable states and will not generate new loop resonances within the working frequency band. In addition, the capacitor loading is designed below the reconfigurable layer, so that the structure will not affect the high-frequency state common-mode resonance suppression capability brought by the traditional short-circuit probe. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0029] Figure 1 It is a schematic diagram of the arrangement of 3×3 ultra-wideband frequency reconfigurable tightly coupled dipole array units of the present invention.

[0030] Figure 2 It is a front view of the 1×3 linear array of the present invention.

[0031] Figure 3 The following are structural diagrams of the array unit of the present invention: (a) overall structural diagram; (b) exploded diagram of vertically placed components; (c) exploded diagram of horizontally placed components.

[0032] Figure 4The structural diagram of the reconfigurable layer of the present invention is as follows: (a) top view; (b) bias feed network topology diagram.

[0033] Figure 5 It is a simplified model of the working principle of the reconfigurable layer of the present invention.

[0034] Figure 6 The results of the reconfigurable state control of the present invention are: (a) the reflected wave response of the simplified model when the diode is turned off; (c) the reflected wave response of the simplified model when the diode is turned on; (d) the VSWR and radiation efficiency of the array unit when the forward beam is pointed when the diode is turned off; (e) the VSWR and radiation efficiency of the array unit when the forward beam is pointed when the diode is turned on.

[0035] Figure 7 There are three patch types with different edges according to the present invention.

[0036] Figure 8 (a) is the reflection phase of the three models in the high-frequency state (HS); Figure 8 (b) is the reflection phase of the three models in the low-frequency state (LS).

[0037] Fig. 9 It is the design process of the wide-angle scanning impedance matching layer of the present invention and the optimization result of impedance matching.

[0038] Fig.10 Schematic diagram of loop resonance generated in the low-frequency state of the present invention and elimination of loop resonance using capacitor loading technology: (a) when using a normal short-circuit pin; (b) when using a capacitor to load the short-circuit pin.

[0039] Fig.11 The following are the actual pictures of the present invention: (a) overall structure diagram; (b) reconfigurable layer; (c) microwave darkroom test diagram.

[0040] 1-impedance matching layer; 2-dipole arm; 3-coupling plate; 4-reconfigurable layer; 5-short-circuit probe; 6-metal floor; 7-tapered balun; 8-strength support layer; 9-feeding port; 10-first dielectric plate; 11-second dielectric plate; 41-metal patch; 42-third dielectric plate; 43-Floquet port; 41a-first patch (connected to positive DC voltage); 41b-second patch (connected to DC ground); 41c-first bias circuit feed line (connected to positive DC voltage); 41d-second bias circuit feed line (connected to DC ground); 41e-PIN diode; 41f-RF choke. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] The present invention provides an ultra-wideband frequency reconfigurable tightly coupled dipole array, comprising a plurality of antenna units arranged in an array, wherein the spacing between the antenna units is less than 0.5 times of the wavelength corresponding to the highest frequency of the operating frequency band.

[0043] like Figure 1 As shown, a specific embodiment of the present invention is a 3×3 array. On the basis of this embodiment, the number of array antenna units can be arbitrarily expanded in the horizontal and vertical directions. Taking normal radiation as an example, the optional operating frequency bands corresponding to the two reconfigurable states of the above array are 0.37-0.93GHz and 0.85-5.85GHz respectively. The voltage standing wave ratio in the operating frequency band is better than 3, and the radiation efficiency is better than 95%. The total bandwidth after combining two continuous bandwidths is 15.8:1 (0.37-5.85GHz). The present invention is not limited to these specific frequency bands and can be used in other multi-band configurations. The operating frequency bands corresponding to the two reconfigurable states can also be adjusted to a certain extent according to demand.

[0044] From the perspective of functional modules, the antenna unit includes a tightly coupled dipole radiating unit, a wide-angle impedance matching structure covering two reconfigurable frequency bands, a reconfigurable layer, a feeding structure, a metal floor, and a strength support layer. This structural design can effectively expand and improve the array's operating bandwidth and beam scanning performance while ensuring high radiation efficiency of the array.

[0045] From the perspective of structural components, the antenna unit includes two dielectric substrates placed vertically and three metal coatings printed thereon, a dielectric substrate placed horizontally and a metal coating printed thereon, a metal floor placed horizontally and a strength support layer. The functional modules of the components placed vertically are: tightly coupled dipole radiation unit, wide-angle matching layer structure and feeding structure with capacitor-loaded short-circuit probe; the functional modules of the components placed horizontally are: reconfigurable layer, metal floor and strength support layer.

[0046] like Figure 3As shown, it is a schematic diagram of the overall structure of the array unit, the vertically placed components and the horizontally placed components. Specifically, the wide-angle impedance matching structure covering two reconfigurable frequency bands is an impedance matching layer 1 located on the first dielectric plate 10, and the impedance matching layer 1 is a wide-angle impedance matching structure based on a double-layer double-sided capacitor loading ring design, which is located above the dipole; the wide-angle impedance matching structure includes two layers of double-sided capacitor loading rings, wherein the upper double-sided capacitor loading ring is symmetrically arranged on the front and back sides of the first dielectric plate 10; the lower double-sided capacitor loading ring is symmetrically arranged on the front and back sides of the first dielectric plate 10. Each layer contains four double-sided capacitor loading rings, and the capacitor loading rings of the upper and lower layers have different sizes; the bottom of the capacitor loading ring is opened for introducing capacitance to reduce the size of the capacitor loading ring. By adjusting the electrical size, number and longitudinal position of the capacitor loading ring, the wide-angle impedance matching characteristics of the array in the range of more than 14:1 frequency doubling covered in two reconfigurable states can be optimized. It should be noted that the wide-angle matching layer described in the present invention is also applicable to other arrays with wide-angle impedance matching requirements.

[0047] The tightly coupled dipole radiating unit comprises a pair of dipole arms 2 and four coupling plates 3; the center position of the dipole radiating unit reserves an interface for the feeding structure; the electrical length of the dipole radiating unit is less than the half wavelength corresponding to the highest frequency point of the array working frequency band; the electrical width of the dipole arm and the electrical size of the coupling plate can be used to optimize the impedance matching characteristics of the array. Wherein, the dipole arm 2 is printed on the reverse side of the first dielectric plate 10, two coupling plates form a first pair of coupling plates printed on the front side of the first dielectric plate 10, and the other two coupling plates form a second pair of coupling plates printed on the reverse side of the second dielectric plate 11, wherein the front side of the second dielectric plate 11 is overlapped with the reverse side of the first dielectric plate 10, because only the coupling plate 4 is printed on the second dielectric plate, the width of the second dielectric plate 11 is the same as that of the first dielectric plate 10, the length of the second dielectric plate 11 is less than that of the first dielectric plate 10, and the first pair of coupling plates and the second pair of coupling plates are symmetrically distributed. The dipole arm 2, the first pair of coupling plates, and the second pair of coupling plates are on a horizontal line.

[0048] The reconfigurable layer 4 includes a third dielectric plate 42 and four metal patches 41 printed with a co-digital structure and a bias circuit on the third dielectric plate 42. Each antenna unit includes four metal patches; PIN diodes are designed between adjacent patches along the dipole direction to control the reconfigurable layer to adjust the phase response of the reflected wave; adjacent metal patches provide a bias voltage through the bias circuit to control the on and off (i.e., state switching) of the PIN diode. A gap is provided in the middle area of ​​the reconfigurable layer 4 unit to ensure the smooth passage of the first dielectric plate 10 placed longitudinally. It should be noted that the reconfigurable method proposed in the present invention can be used for any antenna array with limited bandwidth due to the influence of floor reflection waves.

[0049] The feeding structure is composed of a short-circuit probe 5 with capacitor loading and a tapered balun 7; the short-circuit probe 5 is connected to the coupling plate 3 of the dipole radiating unit at the top, and the short-circuit probe 5 passes through a capacitor structure in the form of a coplanar strip line designed at the position below the reconfigurable layer, and the short-circuit probe 5 is connected to the metal floor at the bottom; the ultra-wideband tightly coupled dipole array will generate common-mode resonance and longitudinal current between the feed lines of adjacent units, thereby affecting the impedance matching and radiation characteristics of the array, and the short-circuit probe without capacitor loading can suppress the common-mode resonance generated in the working frequency band of the high-frequency state, but will introduce new common-mode resonance in the working frequency band of the low-frequency state; by innovatively loading capacitors, the common-mode resonance in the working frequency bands corresponding to the two reconfigurable states of high and low frequencies can be successfully suppressed. The tapered balun 7 is composed of metal coatings printed on both sides of the first dielectric plate 10, and is used for balanced-unbalanced feeding structure transformation; the metal on one side below is wide and the metal on the other side is narrow, which belongs to an unbalanced microstrip line structure, and the feeding port 9 at the lower end can be directly connected to the SMA connector; the metal coatings on both sides above the tapered balun 7 have the same width, which belongs to a balanced stripline structure, and is used for balanced feeding of the dipole arm 2; the metal coating of the tapered balun 7 gradually narrows from bottom to top, and can gradually match the characteristic impedance of 50Ω to the feeding point of the dipole.

[0050] The metal floor 6 is used to reflect the electromagnetic waves radiated downward by the dipole to improve the directionality of the array. A slot that is wide in the middle and narrow on both sides is provided in the middle of the floor for the feeding structure to pass through without affecting the feeding performance.

[0051] In order to ensure the stability of the array assembly, the present invention provides a strength support layer 8 at the feeding area below the array, and a groove is also reserved in the central area for the feeding structure to pass through smoothly without affecting the feeding performance; this design can ensure the stability of the SMA connector when welding with the feeding structure, and ensure that the feeding structure will not be deformed, thereby maximizing the performance of the entire array.

[0052] The wide-angle scanning impedance matching layer optimizes the impedance matching performance of the array during wide-angle scanning by changing the equivalent dielectric properties above the radiator, i.e., the dipole arm. The dipole arm and the coupling plate are the main structures for radiating electromagnetic waves. The coupling plate can also provide additional capacitance loading to offset the inductance brought by the metal floor, thereby expanding the working bandwidth of the array. The reconfigurable layer is used to adjust the phase relationship between the electromagnetic waves radiated upward by the dipole arm and the electromagnetic waves radiated downward and reflected by the floor, ensuring that the phase relationship is always maintained within the in-phase state of ±90° in the current reconfigurable state. The short-circuit probe with capacitance loading is used to suppress the common-mode resonance in the two reconfigurable states, ensuring that the array is not affected by the common-mode resonance in the working frequency band. The short-circuit probe is connected to the coupling plate of the dipole radiating unit above, and the short-circuit probe is designed with a coplanar stripline capacitor structure through its position below the reconfigurable layer, and the short-circuit probe is connected to the metal floor below. The metal floor is used to reflect the electromagnetic waves radiated downward by the dipole arm to improve the directional radiation capability of the array. The tapered balun has the function of balancing current and impedance transformation. The unbalanced structure at the lower end is connected to the RF connector, and the balanced structure at the upper end is used to feed the dipole in a balanced manner. The strength support layer is used to ensure the stability of the array assembly. It should be noted that a special slot structure is reserved in the center of the reconfigurable layer, metal floor, and strength support layer for the smooth installation of the tapered balun, which not only ensures the structural strength of the array, but also does not affect the electrical performance of the tapered balun.

[0053] Figure 4 The top view of the reconfigurable layer and the topology of the bias feed network are given. The reconfigurable layer 4 is printed with a first patch 41a with a cross-shaped structure, a second patch 41b, a first bias circuit feed line 41c, and a second bias circuit feed line 41d. Each array unit contains four metal patches; a PIN diode 41e is designed between adjacent patches along the dipole direction to control the reconfigurable layer 4 to adjust the phase response of the reflected wave; the first patch 41a and the second patch 41b provide a bias voltage through the bias circuit to control the on and off of the PIN diode (i.e., state switching), and the RF choke 41f is used to connect the DC source and the bias circuit feed line. The custom cross-shaped edge on the reconfigurable layer 4 provides additional design freedom for adjusting the bandwidth of the low-frequency state and helps to expand the total bandwidth of the two reconfigurable states. Its initial size can be determined by the in-phase bandwidth obtained by the simplified model, and the final size is determined when the impedance matching design of the array is performed.

[0054] Figure 5 A simplified model of the working principle of the reconfigurable layer is given. The Floquet port 43 is used to generate plane wave excitation, and the diode 41e is used to control the reconfigurable state switching of the reconfigurable layer. Figure 6(a) and 6(b) show the reflection amplitude and phase of the simplified model when the diode is turned off and on. Referring to the ±90° in-phase reflection band, this shows that when the diode is turned off, the in-phase reflection band appears in the low frequency band, while when the diode is turned on, the reflection band moves to the high frequency band. This shift of the in-phase band realizes the band reconstruction of the developed array. The results show that by switching the reconfigurable state, the array can switch between two operating frequency bands. Figure 6 (a) and 6(b) show that the working frequency band of the array is effectively regulated by switching the state of the reconfigurable layer, which greatly expands the total working bandwidth of the array consisting of two reconfigurable states. Taking normal radiation as an example, the optional working frequency bands corresponding to the two reconfigurable states of the above array are 0.37-0.93GHz and 0.85-5.85GHz, respectively. The voltage standing wave ratio in the working frequency band is better than 3, and the radiation efficiency is better than 95%. The total bandwidth after the combination of two continuous bandwidths exceeds 15.8:1 (0.37-5.85GHz).

[0055] Figure 7-8 The influence of reconfigurable layer patches with different edge shapes on the reflection phase is given. As the gap becomes narrower and the interdigital structure is added, the ±90° in-phase bandwidth of the reflection phase (especially in the low-frequency state) is effectively expanded. This means that the working frequency band in the low-frequency state is also effectively expanded.

[0056] It should be noted that the reconfigurable method proposed in the present invention can be used for any antenna array that is affected by floor reflected waves and has limited bandwidth.

[0057] Fig. 9 The design process of the wide-angle scanning impedance matching layer and the optimization results of the impedance matching are given. By increasing the number of faces and layers of the capacitor loading ring, the curve on the circular graph continuously moves toward the center of the circular graph, which represents that it can continuously optimize the impedance matching characteristics of the array. It should be noted that the wide-angle matching layer described in the present invention is also applicable to other arrays with wide-angle impedance matching requirements.

[0058] Fig.10 This is a schematic diagram of the loop resonance generated in the low-frequency state and the elimination of the loop resonance using capacitor loading technology. The ultra-wideband tightly coupled dipole array will generate common-mode resonance and longitudinal current between the feed lines of adjacent units, thus affecting the impedance matching and radiation characteristics of the array. The short-circuit probe without capacitor loading can suppress the common-mode resonance generated in the working frequency band of the high-frequency state, but will introduce new loop resonance in the working frequency band of the low-frequency state, limiting the working bandwidth of the array; by innovatively loading capacitors, the common-mode resonance in the working frequency band corresponding to the two reconfigurable states of high and low frequencies can be successfully suppressed, and no new loop resonance is generated.

[0059] Fig.10(a) shows the loop resonance in the low-frequency state. The mirror structure caused by the floor and the feeding structure of the array itself form a loop resonance, which destroys the impedance matching characteristics of this frequency band. The loop resonance frequency is related to the loop path length and the capacitance generated by the dipole coupling plate. Since the size of the coupling plate is determined before the integrated feeding part, it is necessary to adjust the loop length to tune this loop resonance out of the operating frequency band. Fig.10 (b) shows that after the introduction of the capacitor structure, the loop resonance in the low-frequency state is well suppressed. When the capacitor is not loaded on the short-circuit probe, there is a strong current on the short-circuit probe, and obvious loop resonance can be observed on the antenna structure; after the capacitor is loaded, the current on the short-circuit probe is effectively suppressed, causing the loop resonance to disappear, thereby ensuring the working bandwidth of the array.

[0060] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be included in the protection scope of the present invention.

Claims

1. An ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning, characterized in that: The invention comprises a plurality of antenna units; the antenna unit comprises a tightly coupled dipole radiation unit, a reconfigurable layer, a wide-angle impedance matching structure, a feeding structure and a metal floor; The wide-angle impedance matching structure, the tightly coupled dipole radiating unit, and the feeding structure are sequentially located on a first dielectric plate from top to bottom, and the first dielectric plate is placed vertically on a horizontal plane; The reconfigurable layer, the metal floor and the first dielectric plate are placed perpendicularly to each other, and the reconfigurable layer is located above the metal floor; The wide-angle impedance matching structure comprises two layers of double-sided capacitor loading rings, wherein the upper double-sided capacitor loading rings are symmetrically arranged on the front and back sides of the first dielectric plate; the lower double-sided capacitor loading rings are symmetrically arranged on the front and back sides of the first dielectric plate; The tightly coupled dipole radiation unit comprises a pair of dipole arms printed on the reverse side of a first dielectric plate, a first pair of coupling plates printed on the front side of the first dielectric plate, and a second pair of coupling plates printed on the reverse side of a second dielectric plate; wherein the front side of the second dielectric plate is superimposed on the reverse side of the first dielectric plate, and the first pair of coupling plates and the second pair of coupling plates are symmetrically distributed; The feeding structure includes a short-circuit probe and a tapered balun, wherein the upper end of the short-circuit probe is connected to the first pair of coupling plates, and the lower end is connected to the metal floor; the short-circuit probe passes through a capacitor structure in the form of a coplanar strip line at a position below the reconfigurable layer; the upper end of the tapered balun is connected to the center point of the dipole arm, and the lower end is connected to the SMA connector; The reconfigurable layer includes a third dielectric plate and four metal patches printed with a cross-digital structure and a bias circuit located on the third dielectric plate; a PIN diode is designed between adjacent patches along the direction of the dipole arm to control the reconfigurable layer to adjust the phase response of the reflected wave; the adjacent metal patches provide a bias voltage through the bias circuit to control the on and off of the PIN diode; A slot that is wide in the middle and narrow at both sides is arranged in the middle of the metal floor, so that the feeding structure can pass through the slot without affecting the feeding performance.

2. The ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning according to claim 1, characterized in that: The lower opening of the double-sided capacitor loading ring is used for introducing capacitors.

3. The ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning according to claim 1, characterized in that: The tapered balun is composed of metal coatings printed on both sides of a first dielectric plate and is used for balanced-unbalanced feed structure transformation; The metal on one side at the bottom is wide and the metal on the other side is narrow, which is an unbalanced microstrip line structure; the metal coatings on both sides at the top have the same width, which is a balanced stripline structure; the metal coating of the balun gradually narrows from bottom to top, which is used to gradually match the characteristic impedance of 50Ω to the feeding point of the dipole.

4. The ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning according to claim 1, characterized in that: The invention also comprises a strength support layer, which is located below the metal floor and is used for fixing the first dielectric plate.

5. The debugging method of the ultra-wideband frequency reconfigurable tightly coupled dipole array with wide beam scanning according to claim 1, characterized in that: include: By adjusting the electrical size, number, and longitudinal position of the double-sided capacitive loading loops, the wide-angle impedance matching characteristics of the array over a 14:1 frequency octave range covered in two reconfigurable states can be optimized; The impedance matching characteristics of the array are optimized by adjusting the electrical width of the dipole arms and the electrical size of the coupling patch; The reconfigurable state switching of the reconfigurable layer is controlled by adjusting the on-off state of the diode on the reconfigurable layer.

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