High aperture efficiency integrated two-dimensional digital holographic antenna and beam steering method

Abstract

The application discloses a high-aperture-efficiency integrated two-dimensional digital holographic antenna and a beam control method, which comprises a holographic radiation structure, a waveguide structure, a holographic control structure and a packaging connection structure, wherein the holographic radiation structure, the waveguide structure and the holographic control structure are arranged from top to bottom, and the packaging connection structure is used for connecting the holographic radiation structure, the waveguide structure and the holographic control structure; the holographic radiation structure is composed of adjustable holographic radiation units, the phase characteristics of the holographic radiation units are quantified by using adjustable devices, and the scanning of different beams is realized; and the application has the characteristics of a scannable pencil beam, high gain, high aperture efficiency, simple antenna structure and integration.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, specifically to a high-aperture-efficiency integrated two-dimensional digital holographic antenna and a beam control method. Background Technology

[0002] Digital holographic antenna arrays, employing the principle of holographic interference, can obtain electromagnetic beams pointing to the desired beam direction by setting different holographic patterns, thus achieving beam scanning functionality. Digital holographic antenna arrays can utilize low-cost / low-power active devices to achieve electromagnetic wave modulation, enabling high gain, wide bandwidth, and beam controllability. They also possess low power consumption and low cost characteristics, making them widely applicable in millimeter-wave base station and satellite terminal fields.

[0003] However, existing domestic digital holographic antenna designs primarily rely on holographic principles to determine whether antenna elements radiate, thereby achieving beam scanning. When the antenna element's decision value is less than a threshold, the antenna element will be modulated into a non-radiating state. This results in at least half of the holographic antenna elements in the antenna array not contributing to far-field radiation in practical applications, leading to low antenna aperture utilization. Furthermore, to achieve broadband digital holographic antenna designs, air is often used as the propagation medium to reduce dispersion effects, thus requiring the use of metal components for waveguide design. This further reduces the antenna's weight and integration density, necessitating the design of low-profile and easily integrated air waveguides. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of this invention is to provide a high-aperture efficiency integrated two-dimensional digital holographic antenna and a beam control method.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A high-aperture-efficiency integrated two-dimensional digital holographic antenna includes a holographic radiation structure, a waveguide structure, a holographic control structure, and a packaging and connection structure. The holographic radiation structure, waveguide structure, and holographic control structure are arranged from top to bottom, and the packaging and connection structure is used to connect the holographic radiation structure, waveguide structure, and holographic control structure.

[0007] Furthermore, the holographic radiation structure includes N adjustable holographic radiation units arranged in an array, where N is a natural number. Each adjustable holographic radiation unit includes a coupling probe, a control circuit, a radiation patch, a bias circuit, a short-circuit metal hole, a clearance hole ring, and a three-layer dielectric substrate, which are a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate, respectively.

[0008] The coupling probe is a metal circular hole that penetrates the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate;

[0009] The control circuit and the radiation patch are disposed on the upper surface of the first dielectric substrate, and the control circuit is connected to the coupling probe.

[0010] The bias circuit is disposed on the upper surface of the second dielectric substrate; the upper surface of the third dielectric substrate is coated with copper as a common ground; the short-circuit metal via penetrates the first dielectric substrate and the second dielectric substrate, and one end of the short-circuit metal via is connected to the radiating patch, and the other end is connected to the common ground; the clearance ring is disposed on the common ground, located at the projection position of the coupling probe, to prevent the coupling probe from being connected to the common ground.

[0011] Furthermore, the control circuit includes two radio frequency control devices and a feed pad. The feed pad includes a common negative rectangular pad and two positive rectangular pads. The center of the common negative rectangular pad is connected to a coupling probe. The two short sides of the common negative rectangular pad are respectively connected to the negative terminals of the two radio frequency control devices. One short side of the positive rectangular pad is connected to the positive terminal of the radio frequency control device and is connected to the bias circuit on the second dielectric substrate through a short-circuit metal via.

[0012] Furthermore, the radiating patch includes four rectangular metal patches of the same size, the long side of which is parallel to the long side of the power supply pad, and they are arranged symmetrically around the control circuit with the coupling probe as the center point. Each rectangular metal patch is connected to the common ground through a short-circuit metal hole.

[0013] Furthermore, the bias circuit includes a bias line and a fan-shaped patch, with one end of the bias line connected to the positive rectangular pad and the other end connected to the center of the fan-shaped patch.

[0014] Furthermore, the waveguide structure includes a waveguide dielectric substrate, with a central square region cut out. Air is used as the electromagnetic wave propagation medium to reduce propagation dispersion and loss. Several metal through holes are provided around the square region to prevent electromagnetic wave leakage.

[0015] Furthermore, the holographic control structure includes a holographic dielectric substrate, the upper surface of which is coated with copper as a waveguide metal ground, the lower surface of which is designed with an FPGA control circuit module, and a circular through hole in the center of the holographic dielectric substrate for connecting the inner core of the RF coaxial interface, the outer core of which is connected to the holographic control structure.

[0016] Furthermore, the encapsulation connection structure includes a metal connection through-hole and a circular metal pad, with the circular metal pad disposed at both ends of the metal connection through-hole.

[0017] A beam control method for the high-aperture efficiency integrated two-dimensional digital holographic antenna, as described above, achieves linearly polarized beam scanning by quantizing the phase characteristics of the holographic radiation structure and adjusting the phase characteristics of the holographic radiation structure using radio frequency control devices, as detailed below:

[0018] Using the geometric center of the holographic radiation structure as the origin, a Cartesian coordinate system is constructed by establishing an x-axis along the horizontal direction and a y-axis along the vertical direction. Based on the position coordinates of each adjustable holographic radiation unit in the coordinate system and the preset beam pointing parameters, the normalized decision value of the radiation intensity to be controlled for each adjustable holographic radiation unit is calculated.

[0019]

[0020] in Here, represents the wavenumber in free space, and the vector direction represents the desired beam direction. ρ is the waveguide wavenumber within the waveguide cavity, with the vector direction being the radial direction from the origin to the radiating element. g is the radius vector from the origin to the radiation element, and the vector direction is the radial direction from the origin to the adjustable holographic radiation element. E is the normalized decision value of the radiation intensity of each adjustable holographic radiation element.

[0021] It also includes threshold determination of the normalized decision value of the radiation intensity:

[0022] When the normalized decision value is greater than the set threshold, the phase decision of the adjustable holographic radiation unit is assigned a value of 1.

[0023] When the normalized decision value is less than the set threshold, the phase decision of the adjustable holographic radiation unit is assigned a value of -1;

[0024] The phase decision assignment is used to control the bias state of the radio frequency modulation device of the adjustable holographic radiation unit.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] The design method and beam control method of the high-aperture efficiency integrated two-dimensional digital holographic antenna provided by this invention can realize dynamic adjustment of the scanning angle of the digital holographic antenna, improve antenna gain and enhance aperture efficiency by using phase control.

[0027] This invention also employs an air cavity as a waveguide transmission structure to reduce dispersion spread bandwidth, and further adopts an integrated packaging structure for the control module and antenna structure design, resulting in high antenna integration and a thinner antenna. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the holographic radiation structure of the high-aperture efficiency integrated two-dimensional digital holographic antenna in Embodiment 1 of the present invention.

[0029] Figure 2 This is a schematic diagram of the adjustable holographic radiation element of the high-aperture efficiency integrated two-dimensional digital holographic antenna in Embodiment 1 of the present invention.

[0030] Figure 3 This is a schematic diagram of the waveguide structure of the high-aperture efficiency integrated two-dimensional digital holographic antenna in Embodiment 1 of the present invention.

[0031] Figure 4 This is a schematic diagram of the holographic control structure of the high-aperture efficiency integrated two-dimensional digital holographic antenna in Embodiment 1 of the present invention.

[0032] Figure 5 This is a schematic diagram of the packaging and connection structure of the high-aperture efficiency integrated two-dimensional digital holographic antenna in Embodiment 1 of the present invention.

[0033] Figure 6 This is a schematic cross-sectional view of the high-aperture efficiency integrated two-dimensional digital holographic antenna packaged in Embodiment 1 of the present invention.

[0034] Figure 7 The diagram shows the current distribution of the adjustable holographic radiation unit under different modulation states in Embodiment 2 of the present invention. (a) and (b) are the current distribution diagrams of state 1 and state -1, respectively.

[0035] Figure 8 This is the gain pattern of the high-aperture efficiency integrated two-dimensional digital holographic antenna in Embodiment 2 of the present invention at different scanning angles in the horizontal and vertical planes when it operates at 26 GHz.

[0036] Figure 9 The S-parameter diagram and gain curve of the high-aperture efficiency integrated two-dimensional digital holographic antenna in Embodiment 2 of the present invention are shown in the frequency band of 24.5-27.5 GHz when the beam pointing Theta=0°. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0038] Example 1

[0039] This embodiment provides a high-aperture-efficiency integrated two-dimensional digital holographic antenna. The holographic antenna includes a holographic radiation structure 1, a waveguide structure 2, a holographic control structure 3, and a packaging and connection structure 4. The holographic radiation structure 1 is designed on the waveguide structure 2, the holographic control structure 1 is disposed below the waveguide structure 3, and the packaging and connection structure 4 is designed around the holographic radiation structure 1, the waveguide structure 2, and the holographic control structure 3 to connect these three structures.

[0040] like Figure 1As shown, the holographic radiation structure 1 includes several adjustable holographic radiation units 5. In this embodiment, 16×16 adjustable holographic radiation units 5 are arranged in a square array. Figure 2 The diagram shows a schematic of the adjustable holographic radiation unit structure provided in this embodiment. The adjustable holographic radiation unit 5 includes a coupling probe 501, a control circuit 502, a radiation patch 503, a bias circuit 504, a short-circuit metal via 505, a clearance ring 506, and a three-layer dielectric substrate. The three-layer dielectric substrate includes a first dielectric substrate 507, a second dielectric substrate 508, and a third dielectric substrate 509. The coupling probe 501 is a circular metal via that penetrates the first dielectric substrate 507, the second dielectric substrate 508, and the third dielectric substrate 509. The diameter of the circular metal via is d1 = 0.4 mm. The control circuit 502 and the radiation patch 503 are designed on the upper surface of the first dielectric substrate 507. The control circuit 502 includes two radio frequency control devices 5021 and a feed pad. The feed pad includes a common negative rectangular pad 5022 and two positive rectangular pads 5023. In this embodiment, the radio frequency control device 5021 selected is a PIN diode, which is equivalent to an inductor L when forward biased. b =0.1nH and resistance R b =5.2Ω series, equivalent to inductance L when reverse biased. u =0.1nH and capacitance C u =42fF series. The center of the common negative rectangular pad 5022 is connected to the coupling probe 501. The two short sides of the common negative rectangular pad 5022 are respectively connected to the negative terminals of the two RF control devices 5021. One short side of each positive rectangular pad 5023 is connected to the positive terminal of the corresponding RF control device 5021. The specific dimensions are: L1=0.6mm, L2=1.6mm, W1=0.6mm. The bias circuit 504 is designed on the upper surface of the second dielectric substrate 508 and includes a bias line 5041 and a fan-shaped patch 5042. One end of the bias line 5041 is connected to the positive rectangular pad 5023 through a metal hole with a diameter of d2=0.4mm, and the other end is connected to the center of the fan-shaped patch 5042 with a radius of r1=1.2mm. The upper surface of the third dielectric substrate 509 is coated with copper as a common ground, and a clearance ring 506 with a diameter d3=1.1mm is designed at the position of the coupling probe 501 to prevent the coupling probe 501 from being connected to the common ground.

[0041] The radiating patch 503 comprises four rectangular metal patches of the same size, specifically L3 = 2.2 mm and W2 = 1.4 mm. Their long sides are parallel to the long side of the feed pad and are arranged symmetrically around the control circuit with the coupling probe 501 as the center point. They receive power from the coupling probe to form an electric dipole. Each rectangular metal patch is connected to a common ground through three short-circuit metal holes 505 with a diameter of d2 = 0.4 mm to receive power from the coupling probe to form a magnetic dipole.

[0042] In this embodiment, the first dielectric substrate 507, the second dielectric substrate 508, and the third dielectric substrate 509 are made of RO4003C with a dielectric constant of 3.48, a loss tangent of 0.0027, and board thicknesses of 0.305mm, 0.305mm, and 0.762mm, respectively.

[0043] Figure 3 The waveguide structure 2 provided in this embodiment is shown. The waveguide structure includes a waveguide dielectric substrate 201. A square area in the center of the waveguide dielectric substrate 201 is cut out, and the cut-out area is a square with a side length of W3 = 92 mm. The holographic antenna uses air 202 as the electromagnetic wave propagation medium to reduce propagation dispersion and loss. Several metal vias 203 with a diameter of d2 = 0.4 mm are arranged around the cut-out area to prevent electromagnetic wave leakage. The waveguide dielectric substrate 201 is made of FR-4 material with a dielectric constant of 4.0, a loss tangent of 0.02, and a thickness of 2.5 mm.

[0044] Figure 4 The diagram shows the holographic control structure 3 provided in this embodiment. The holographic control structure 3 consists of a square copper metal with a side length of W4 = 95 mm etched on the upper surface of a holographic dielectric substrate 301 as a waveguide ground metal 302. An FPGA control circuit module is designed on the lower surface. A circular through-hole 303 with a radius of r = 1.25 mm is designed at the center of the dielectric to connect to an RF coaxial interface. The holographic dielectric substrate 301 is made of FR-4 material with a dielectric constant of 4.0, a loss tangent of 0.02, and a thickness of 1 mm.

[0045] Figure 5The image shows the encapsulation connection structure 4 provided in this embodiment. The encapsulation connection structure 4 includes several metal connection vias 401 and circular metal pads 402. The diameter of the metal connection vias 401 is d2 = 0.4 mm, and they are arranged around the edges of the dielectric substrate where the holographic radiation structure 1, waveguide structure 2, and holographic control structure 3 are located, with corresponding positions on different structures. The diameter of the circular metal pads 402 is d3 = 1.0 mm, and they are disposed at both ends of each metal connection via in each structure. The spacing between each circular metal pad is p = 2 mm. In actual processing, solder is first applied to the circular metal pads 402 of each structure, and reflow soldering is used to connect the circular metal pads 402 on the three structures to achieve a waveguide structure based on air 202 as the transmission medium.

[0046] Figure 6 The diagram shows a cross-sectional view of the packaged holographic antenna. In holographic radiation structure 1, the RF control device 5021 of the adjustable holographic radiation unit is connected to the metal connection via 401 via a bias circuit 504. In holographic control structure 3, the control lines of the FPGA control circuit module are connected to the metal connection via 401 on the substrate. The FPGA in the control structure outputs several control signals, which are transmitted to the metal connection via 401 in the packaged structure via control lines. Further control signals are then transmitted through the metal connection via 401 to the RF control device 5021 in holographic radiation structure 1 for modulation. The outer core of the RF coaxial interface is connected to holographic control structure 3, and the inner core is inserted into a waveguide through a circular via 303, converting the TEM mode electromagnetic wave in the coaxial line into a TM00 cylindrical wave in the air waveguide. The coupling probe 501 in the radiation structure couples the energy of the cylindrical wave, and the phase excitation radiation patch is radiated in free space by the control circuit.

[0047] Example 2

[0048] A beam control method for a high-aperture-efficiency integrated two-dimensional digital holographic antenna is proposed. By quantifying the phase characteristics of the holographic radiation structure, the phase characteristics of several adjustable holographic radiation elements are adjusted using a control circuit to achieve linearly polarized beam scanning.

[0049] Figure 7Figures (a) and (b) show the current distribution of the adjustable holographic radiation unit under different modulation states. A Cartesian coordinate system is constructed with the geometric center of the holographic radiation structure as the origin, establishing an x-axis along the horizontal direction and a y-axis along the vertical direction. The radio frequency control device 5021, named in the positive and negative directions of the x-axis, includes a first radio frequency control device 50211 and a second radio frequency control device 50212. When the first radio frequency control device is in a positive bias state and the second radio frequency control device is in a reverse bias state, the current flows in the positive x-axis direction, which is state 1. When the first radio frequency control device is in a reverse bias state and the second radio frequency control device is in a positive bias state, the current flows in the negative x-axis direction, which is state -1. The induced currents in the two states are opposite, and the unit radiation phase differs by 180°. A beam control method is designed based on this.

[0050] The beam control method includes the following steps: Calculating the normalized decision value to be controlled for each adjustable holographic radiation unit based on its position coordinates in the coordinate system and preset beam pointing parameters.

[0051]

[0052] in Here, represents the wavenumber in free space, and the vector direction represents the desired beam direction. ρ is the waveguide wavenumber within the waveguide cavity, with the vector direction being the radial direction from the origin to the adjustable holographic radiation element. g is the radius vector from the origin to the adjustable holographic radiation element, and the vector direction is the radial direction from the origin to the adjustable holographic radiation element. E is the normalized radiation intensity decision value of each element.

[0053] Furthermore, a threshold determination is performed on the normalized decision value of the radiation intensity:

[0054] When the normalized decision value of the adjustable holographic radiation unit is greater than the set threshold, the phase decision value of the holographic radiation unit is assigned to 1.

[0055] When the normalized decision value of the adjustable holographic radiation unit is less than the set threshold, the phase decision value of the holographic radiation unit is assigned to -1.

[0056] In this embodiment, the threshold value selected is 0, corresponding to an angle range of -60° to 60°, meaning the phase decision A of the adjustable holographic radiation unit is:

[0057]

[0058] like Figure 8As shown, this embodiment provides a gain pattern for a holographic antenna with a scale of 16×16 elements. The holographic antenna achieves beam scanning of ±60° in the horizontal plane and ±45° in the vertical plane at a frequency of 26 GHz, with a maximum gain of 22.5 dB and a beam pointing Theta = 0°, an aperture efficiency of 22%, a scanning gain loss of less than 3 dB, and a 3 dB beamwidth of less than 10°.

[0059] like Figure 9 As shown, this embodiment provides a maximum gain curve and S-parameter graph of a 16×16 element holographic antenna with the beam pointing at Theta=0°. The holographic antenna achieves a gain greater than 16.5dB and an S11 less than -10dB within its operating bandwidth of 24.5-27.5GHz.

[0060] Those skilled in the art will readily understand that the above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-aperture-efficiency integrated two-dimensional digital holographic antenna, characterized in that, It includes a holographic radiation structure, a waveguide structure, a holographic control structure, and a packaging and connection structure. The holographic radiation structure, waveguide structure, and holographic control structure are arranged from top to bottom, and the packaging and connection structure is used to connect the holographic radiation structure, waveguide structure, and holographic control structure.

2. The high-aperture efficiency integrated two-dimensional digital holographic antenna according to claim 1, characterized in that, The holographic radiation structure includes N adjustable holographic radiation units arranged in an array. Each adjustable holographic radiation unit includes a coupling probe, a control circuit, a radiation patch, a bias circuit, a short-circuit metal hole, a clearance hole ring, and a three-layer dielectric substrate. The three-layer dielectric substrates are a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate. The coupling probe is a metal circular hole that penetrates the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate; The control circuit and the radiation patch are disposed on the upper surface of the first dielectric substrate, and the control circuit is connected to the coupling probe. The bias circuit is disposed on the upper surface of the second dielectric substrate; The upper surface of the third dielectric substrate is coated with copper as a common ground; the short-circuit metal via penetrates the first dielectric substrate and the second dielectric substrate, and one end of the short-circuit metal via is connected to the radiating patch, and the other end is connected to the common ground; the clearance ring is disposed on the common ground, located at the projection position of the coupling probe, to prevent the coupling probe from being connected to the common ground.

3. The high-aperture efficiency integrated two-dimensional digital holographic antenna according to claim 2, characterized in that, The control circuit includes two radio frequency control devices and a feed pad. The feed pad includes a common negative rectangular pad and two positive rectangular pads. The center of the common negative rectangular pad is connected to a coupling probe. The two short sides of the common negative rectangular pad are respectively connected to the negative terminals of the two radio frequency control devices. One short side of the positive rectangular pad is connected to the positive terminal of the radio frequency control device and is connected to the bias circuit on the second dielectric substrate through a short-circuit metal via.

4. The high-aperture efficiency integrated two-dimensional digital holographic antenna according to claim 3, characterized in that, The radiating patch includes four rectangular metal patches of the same size. The long side of the rectangular metal patches is parallel to the long side of the feed pad and they are arranged symmetrically around the control circuit with the coupling probe as the center point. Each rectangular metal patch is connected to the common ground through a short-circuit metal hole.

5. The high-aperture efficiency integrated two-dimensional digital holographic antenna according to claim 3, characterized in that, The bias circuit includes a bias line and a fan-shaped patch. One end of the bias line is connected to the positive rectangular pad, and the other end is connected to the center of the fan-shaped patch.

6. The high-aperture efficiency integrated two-dimensional digital holographic antenna according to any one of claims 1-5, characterized in that, The waveguide structure includes a waveguide dielectric substrate with a central square area cut out. Air is used as the electromagnetic wave propagation medium to reduce propagation dispersion and loss. Several metal through holes are arranged around the square area to prevent electromagnetic wave leakage.

7. The high-aperture efficiency integrated two-dimensional digital holographic antenna according to any one of claims 1-5, characterized in that, The holographic control structure includes a holographic dielectric substrate, with copper plating on the upper surface of the holographic dielectric substrate serving as a waveguide metal ground. An FPGA control circuit module is designed on the lower surface of the holographic dielectric substrate. A circular through-hole is provided in the center of the holographic dielectric substrate for connecting the inner core of the RF coaxial interface. The outer core of the RF coaxial interface is connected to the holographic control structure.

8. The high-aperture efficiency integrated two-dimensional digital holographic antenna according to claim 1, characterized in that, The encapsulation connection structure includes a metal connection through-hole and a circular metal pad, with the circular metal pad disposed at both ends of the metal connection through-hole.

9. A beam control method for a high-aperture efficiency integrated two-dimensional digital holographic antenna as described in claim 3, characterized in that, By quantifying the phase characteristics of the holographic radiation structure and using radio frequency control devices to adjust the phase characteristics of the holographic radiation structure, linearly polarized beam scanning can be achieved, as follows: Using the geometric center of the holographic radiation structure as the origin, a Cartesian coordinate system is constructed by establishing an x-axis along the horizontal direction and a y-axis along the vertical direction. Based on the position coordinates of each adjustable holographic radiation unit in the coordinate system and the preset beam pointing parameters, the normalized decision value of the radiation intensity to be controlled for each adjustable holographic radiation unit is calculated. in Here, represents the wavenumber in free space, and the vector direction represents the desired beam direction. ρ is the waveguide wavenumber within the waveguide cavity, with the vector direction being the radial direction from the origin to the radiating element. g is the radius vector from the origin to the radiation element, and the vector direction is the radial direction from the origin to the adjustable holographic radiation element. E is the normalized decision value of the radiation intensity of each adjustable holographic radiation element.

10. The beam control method according to claim 9, characterized in that, Also includes: A threshold determination is performed on the normalized decision value of the radiation intensity: When the normalized decision value is greater than the set threshold, the phase decision of the adjustable holographic radiation unit is assigned a value of 1. When the normalized decision value is less than the set threshold, the phase decision of the adjustable holographic radiation unit is assigned a value of -1; The phase decision assignment is used to control the bias state of the radio frequency modulation device of the adjustable holographic radiation unit.

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