An edge loading structure for improving the truncation effect of a strongly coupled phased array

Abstract

The invention discloses an edge loading structure for improving the truncation effect of a strongly coupled phased array, belonging to the technical field of antenna engineering. The edge loading structure is composed of a dielectric substrate, a semi-butterfly metal patch, and a T-shaped metal patch with a loading resistor. The semi-butterfly metal patch connected to the array edge unit guides electromagnetic waves to radiate in the form of traveling waves in the high-frequency band of the working frequency band, and together with the dipole arm and the ground plane of the array edge unit forms a single dipole antenna in the low-frequency band; the T-shaped metal patch with a loading resistor provides a grounding loop for the semi-butterfly metal patch to absorb the excess energy that has not been radiated. The invention has the advantages of simple structure, easy processing, and light weight. In the embodiment, a 32-element strongly coupled two-column linear array is designed. By comparing the active voltage standing wave ratios of the array elements during side radiation and E-plane 60° scanning before and after loading the structure described in the invention, it can be known that the proposed structure has a significant improvement effect on the truncation effect of the strongly coupled phased array.

Description

Technical Field

[0001] The present invention belongs to the technical field of antenna engineering, relates to a strongly coupled phased array antenna, and particularly relates to an edge loading structure for improving the truncation effect of a strongly coupled phased array. This structure can significantly improve the deterioration of array scanning and matching performance caused by the truncation effect of the strongly coupled phased array, and has the characteristics of simple structure, easy processing, and light weight. Background Art

[0002] Due to its characteristics of high gain, fast scanning, and beam controllability, phased array antennas have been widely used in radar and communication systems. In practical applications, a phased array is composed of a finite number of array elements. The boundary conditions around the edge elements and the central elements of the array are different, which will cause changes in their performance, that is, the edge truncation effect of the phased array antenna.

[0003] A strongly coupled phased array cancels the inductive effect of the metal floor by introducing a capacitive effect between array elements to achieve ultra-wideband operation of the antenna array. Due to the strong mutual coupling between array elements, the edge truncation effect of a strongly coupled phased array is more obvious than that of a traditional phased array. The paper "UWB Low-Profile Tightly Coupled Dipole Array With Integrated Balun and Edge Terminations" discusses two methods for dealing with the truncation effect of a strongly coupled phased array. Method 1: Extend the dipole arm length of the edge antenna element. This method can achieve a 3-fold frequency operating bandwidth under the condition that the active standing wave ratio is less than 3 in the broadside direction when a balun is loaded. Method 2: Periodically load resistors on the edge. Although the impedance matching of the array is further optimized by this method, the low-frequency radiation efficiency of the array is only about 40%. There is no further research and discussion in the paper on the treatment of the edge truncation effect of the array under large scanning angles. Summary of the Invention

[0004] Based on the background art, the present invention proposes a novel edge loading structure for improving the truncation effect of a strongly coupled phased array, which greatly improves the deterioration of scanning and matching performance caused by the truncation effect of the strongly coupled phased array antenna. The present invention has the characteristics of simple structure, easy processing, and light weight.

[0005] The technical solution of the present invention is an edge loading structure for improving the truncation effect of a strongly coupled phased array. The edge loading structure is arranged at the ends of adjacent two rows of the array antenna. Each row of antenna patches in the array antenna is separately provided with a dielectric substrate, and each dielectric substrate is vertically arranged on the metal floor; the edge loading structure includes: a first dielectric substrate, a second dielectric substrate, a third dielectric substrate, a first half-butterfly metal patch, a second half-butterfly metal patch, a T-shaped grounding metal patch, a resistor, and a metal floor;

[0006] The first dielectric substrate is integrated with the dielectric substrate of one of two adjacent rows of the array antenna, and the second dielectric substrate is integrated with the dielectric substrate of the other of the two adjacent rows of the array antenna; the first half - butterfly metal patch is disposed on the first dielectric substrate, and one end thereof is connected to the coupling patch of the array antenna at the corresponding position; the second half - butterfly metal patch is disposed on the second dielectric substrate, and one end thereof is connected to the coupling patch of the array antenna at the corresponding position; the metal floor of the edge - loading structure is the same piece as the metal floor of the array antenna; both sides of the third dielectric substrate are connected to the first dielectric substrate and the second dielectric substrate, the third dielectric substrate is perpendicular to the metal floor, and two ends of the "-" shaped part of the T - shaped grounding metal patch are respectively connected to the other ends of the first half - butterfly metal patch and the second half - butterfly metal patch; the bottom end of the "|" shaped part of the T - shaped grounding metal patch is connected to one end of a resistor, and the other end of the resistor is connected to the metal floor.

[0007] Further, the third dielectric substrate is perpendicular to the first dielectric substrate and the second dielectric substrate.

[0008] Further, the first half - butterfly metal patch and the second half - butterfly metal patch are right - angled trapezoids, the top sides of the right - angled trapezoids are connected to the coupling patches of the array antenna, and the bottom sides are connected to the T - shaped grounding metal patch.

[0009] Further, two ends of the "-" shaped part of the T - shaped grounding metal patch protrude from the planes of the first dielectric substrate and the second dielectric substrate.

[0010] Further, the waists of the first half - butterfly metal patch and the second half - butterfly metal patch that are close to the metal floor are right - angled waists.

[0011] The half - butterfly metal patch of the present invention is connected to the coupling patch of the array edge antenna unit. In the high - frequency band of the antenna operating frequency band, the half - butterfly metal patch is equivalent to a traveling - wave structure with an electrically large size, guiding electromagnetic waves to radiate outward in the form of traveling waves. In the low - frequency part of the antenna operating frequency band, the metal patch and the edge antenna unit form a single - dipole antenna, thereby improving the edge truncation effect of the strongly - coupled array. The T - shaped grounding metal patch is orthogonally arranged and electrically connected to the half - butterfly metal patch, providing a current path to the ground for the half - butterfly metal patch, and can effectively improve the matching of the large - angle scanning and the array edge units in the low - frequency band. The resistor is loaded between the T - shaped grounding metal patch and the floor, absorbing part of the redundant un - radiated energy and improving the matching of the array edge units. Description of the Drawings

[0012] Figure 1 are the front view, side view and 3D view of the unit of the edge - loading structure of the invention, where Figure 1 (a) is the front view of the unit, Figure 1 (b) is the side view of the structural unit,Figure 1 (c) is the 3D view of the said structural unit.

[0013] Figure 2 It is a schematic diagram of a strongly coupled phased array antenna without loading the edge loading structure of the present invention.

[0014] Figure 3 It is a schematic diagram of a strongly coupled phased array antenna loaded with the edge loading structure of the present invention.

[0015] Figure 4 It is a schematic diagram of the antenna element at the edge of the array after loading the edge loading structure of the present invention.

[0016] Figure 5 It is the side radiation active VSWR (Active VSWR) curve of the antenna element in the array without loading the edge loading structure of the present invention.

[0017] Figure 6 It is the side radiation active VSWR (Active VSWR) curve of the antenna element in the array after loading the edge loading structure of the present invention.

[0018] Figure 7 It is the E-plane 60° scan active VSWR (Active VSWR) curve of the antenna element in the array without loading the edge loading structure of the present invention.

[0019] Figure 8 It is the E-plane 60° scan active VSWR (Active VSWR) curve of the antenna element in the array loaded with the edge loading structure of the present invention. Detailed implementation mode

[0020] Example 1.

[0021] In this example, the model diagram of the edge loading structure for improving the truncation effect is as shown in Figure 1 shown. The dielectric substrate material of the antenna layer is Rogers5880, with a thickness of 0.127 mm and a relative dielectric constant of 2.2. As shown in Figure 1 (c), Structure 1 is a semi-butterfly-shaped metal patch, printed on the reverse side of the dielectric substrate of the antenna layer, with the width in the z direction gradually changing from 25 mm to 58 mm and the length in the y direction being 115 mm. Structure 2 is a T-shaped grounding metal sheet, printed on the inner side of a 0.05 mm thick polyimide dielectric substrate (relative dielectric constant 3.5). The size above the T-shaped metal sheet is 100 mm * 58 mm, and the rectangular size below the T-shaped metal sheet is 10 mm * 65 mm. Structure 3 is a resistor, welded on the T-shaped metal sheet.

[0022] In order to verify the performance of the edge loading structure proposed by the present invention, a linear array of strongly coupled phased array antennas with a working bandwidth of 4:1 was designed for verification, and its schematic diagram is as shown in Figure 2As shown, there are 2 antenna elements arranged in the x - direction and 16 antenna elements arranged in the y - direction in the array, with the edges truncated. Due to the symmetry of the array structure, only antenna elements numbered 1 - 8 will be discussed and analyzed subsequently, and the spacing between elements is 75 mm.

[0023] Figure 3 It is a schematic diagram of a strongly coupled phased array after loading the edge - loading structure as shown in Figure 1 (c) on both sides of the array.

[0024] Figure 4 It is a schematic diagram of the edge antenna element of the strongly coupled phased array after loading the edge - loading structure shown in Figure 1 (c). The semi - butterfly - shaped metal patch 4 is printed on the reverse side of the dielectric substrate 5 of the antenna layer and is connected to the coupling patch 6 of the edge antenna element. The T - shaped metal patch 7 is printed on the dielectric substrate 11. The upper side of the T - shaped metal patch 7 is welded to the semi - butterfly - shaped metal patches 4 on both sides, and the lower side of the T - shaped metal patch 7 is welded to the metal floor 8. The structure 9 is a 150Ω resistor, which is welded to the T - shaped metal patch 7. The structure 10 is the dipole arm of the antenna element.

[0025] Figure 5 It is the side - radiation active standing - wave curve of the array antenna element without loading the edge - loading structure described in the present invention, where f L is the lowest operating frequency of this array. Due to the truncation effect of the array, at this time, at f L , the active voltage standing - wave ratio of the 1st antenna element of the array is close to 5.

[0026] Figure 6 The side - radiation active standing - wave curve of the array antenna element after loading the edge - loading structure described in the present invention is given. It can be seen from the figure that at this time, in the range of f L - 4f L , the active voltage standing - wave ratio of the 1st - 8th antenna elements of the array remains below 2.6.

[0027] Figure 7 It is the E - plane 60° scanning active standing - wave curve of the array antenna element without loading the edge - loading structure described in the present invention. At this time, in the range of f L - 1.5f L , the active voltage standing - wave of the 1st - 3rd antenna elements of the array deteriorates severely, and the active voltage standing - wave ratio at the low - frequency points remains above 8. For the 4th - 5th antenna elements of the array, in the range of f L - 1.5f L , there are also some frequency points where the active voltage standing - wave ratio is greater than 4.

[0028] Figure 8 The E - plane 60° scanning active standing - wave curve of the array antenna element after loading the edge - loading structure described in the present invention is given. It can be seen from the figure that in the range of f L - 4fL Within the operating frequency band, the active standing wave of all antenna elements in the array is less than 3.5.

[0029] From the above comparative analysis, it can be seen that the edge loading structure described in the present invention can effectively improve the edge truncation effect of the strongly coupled phased array antenna and optimize the impedance matching of the strongly coupled phased array antenna at broadside and when the E-plane scanning angle is 60°.

[0030] The specific embodiments given above are only preferred examples in the improvement of the edge truncation effect of the strongly coupled phased array by this edge loading structure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An edge loading structure for improving the truncation effect of a strongly coupled phased array, wherein the edge loading structure is arranged at the ends of two adjacent rows of array antennas, wherein each row of antenna patches in the array antenna is independently provided with a dielectric substrate, and each dielectric substrate is vertically arranged on a metal floor; The edge loading structure comprises: a first dielectric substrate, a second dielectric substrate, a third dielectric substrate, a first half-butterfly metal patch, a second half-butterfly metal patch, a T-shaped grounding metal patch, a resistor, and a metal floor; The first dielectric substrate is integrated with the dielectric substrate of one of the two adjacent rows of the array antenna, and the second dielectric substrate is integrated with the dielectric substrate of the other of the two adjacent rows of the array antenna; the first semi-butterfly metal patch is arranged on the first dielectric substrate, and one end is connected to the coupling patch of the array antenna at the corresponding position; the second semi-butterfly metal patch is arranged on the second dielectric substrate, and one end is connected to the coupling patch of the array antenna at the corresponding position; the metal floor of the edge loading structure is the same as the metal floor of the array antenna; the two sides of the third dielectric substrate are connected to the first dielectric substrate and the second dielectric substrate, and the third dielectric substrate is perpendicular to the metal floor, and the two ends of the "1"-shaped part of the T-shaped grounding metal patch are respectively connected to the other end of the first semi-butterfly metal patch and the second semi-butterfly metal patch; the bottom end of the "1"-shaped part of the T-shaped grounding metal patch is connected to one end of the resistor, and the other end of the resistor is connected to the metal floor.

2. The edge loading structure for improving the truncation effect of a strongly coupled phased array according to claim 1, characterized in that: The third dielectric substrate is perpendicular to the first dielectric substrate and the second dielectric substrate.

3. The edge loading structure for improving the truncation effect of a strongly coupled phased array according to claim 1, characterized in that: The first half-butterfly-shaped metal patch and the second half-butterfly-shaped metal patch are right-angled trapezoids, the top side of the right-angled trapezoids is connected to the coupling patch of the array antenna, and the bottom side is connected to the T-shaped grounding metal patch.

4. The edge loading structure for improving the truncation effect of a strongly coupled phased array according to claim 1, characterized in that: Two ends of the "I"-shaped portion of the T-shaped grounding metal patch protrude from the planes of the first dielectric substrate and the second dielectric substrate.

5. The edge loading structure for improving the truncation effect of a strongly coupled phased array according to claim 3, characterized in that: The waists of the first half-butterfly-shaped metal patch and the second half-butterfly-shaped metal patch close to the metal floor are right-angle waists.

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