A stacked terahertz emission front end based on electromagnetic bandgap

Abstract

The present invention relates to a stacked assembled terahertz transmitting front end based on an electromagnetic band gap. A stacked assembled terahertz transmitting front end based on an electromagnetic band gap comprises a metal base, a cover plate, and a power supply PCB board; an array of terahertz source transmitting units is arranged on the metal base, each transmitting unit comprises a three-layer laminate structure, a feed link of each transmitting unit is encapsulated in the metal base, and a radio frequency connector is provided on the side of the metal base; the power supply PCB board is installed at the bottom of the metal base. The stacked highly integrated terahertz transmitting front end of the present invention adopts three layers of laminates to realize the main functional circuits, and is arranged based on cubic block units; vertical waveguide transmission lines are adopted between the laminates of the stacked terahertz transmitting front end provided by the present invention, and a gap waveguide structure is used at the connection surface to realize non-contact connection; a high-density layout of feeding, frequency multiplication, and amplification links is realized on the metal base, and independent control of multiple transmitting units is realized, with a compact structure, which is conducive to array expansion.

Description

Technical Field

[0001] The present invention belongs to the technical field of terahertz testing, and in particular relates to a stacked assembled terahertz emission front end of an electromagnetic band gap. Background Art

[0002] The terahertz transceiver front-end, consisting of key components such as frequency multipliers, mixers, antennas, and couplers, is a critical component in terahertz test instruments. Previous broadband terahertz transceiver front-end designs employed a combination of discrete components, with each functional component encapsulated within a metal cavity. Multiple components were assembled by connecting different cavities. This design approach ensured the stability of each component's performance, but the discrete design architecture resulted in bulk, high cost, and difficulty in integration. Consequently, traditional terahertz transceiver front-ends were difficult to miniaturize, limiting the potential for miniaturization of terahertz test instrument modules.

[0003] Terahertz sources based on solid-state electronics typically use a semi-metal cavity to encapsulate the circuit. Based on the cavity structure required for mechanical processing and manufacturing, a planar layout is used to cascade the various key components. A solid-state terahertz source frequency-doubling link typically includes core components such as an RF input port, a frequency tripler, a power amplifier, an isolator, a frequency doubler, and a horn antenna. The microwave signal undergoes multiple stages of frequency multiplication and is output by the antenna. Each stage of the device is encapsulated in a metal cavity, and the devices are cascaded in one dimension. The core components are primarily connected using standard waveguide flanges, which are precisely positioned using pins and tightly secured using screws. Limited by the linear nature of the waveguide transmission line, the terahertz source link is laid out in a two-dimensional plane, and one-dimensional linear connections are used whenever possible to reduce design complexity.

[0004] Terahertz sources manufactured based on existing technologies are large in size, have high manufacturing costs, high assembly requirements, are difficult to integrate, and are not conducive to high-density array layouts. When cost, volume, and system integration are not considerations and only broadband and high performance are required, terahertz sources developed based on existing technologies are a good solution. However, for miniaturized terahertz test instruments and various terahertz application systems, such as terahertz imaging and non-destructive testing, new requirements for miniaturization, portability, and high integration are put forward, and existing design solutions are not suitable. In addition, terahertz chips that can achieve SIP have narrow bandwidth and a low upper frequency limit, and are only suitable for terahertz application systems operating in narrowband or point frequency, and cannot be used in terahertz test instruments with high broadband performance requirements. For broadband high-frequency terahertz front-ends, in the context of chip-level packaging not yet being achieved, a hybrid integration approach can be adopted to get rid of the traditional separate assembly architecture, thereby significantly reducing the size of the device and changing the device connection method, thereby avoiding the space waste caused by screw assembly, and thus improving the integration of the terahertz front-end. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention proposes a stacked, assembled terahertz emission front end based on an electromagnetic bandgap (EBG). This design integrates the various core components required for a terahertz source into a cubic space using a three-dimensional stacking process. This integrated design ensures the comprehensive performance of each component, and based on the basic cubic structure, achieves terahertz signal generation and radiation. This invention offers a compact size, low cost, high integration, and ease of expansion for large arrays, making it a preferred solution for multi-port arrayed terahertz systems.

[0006] The technical solution adopted by the present invention to solve its technical problems is: a laminated assembled terahertz transmitting front end based on electromagnetic band gap, including a metal base, a cover plate, and a power supply PCB board; the terahertz source transmitting unit array is arranged on the metal base, each transmitting unit includes a three-layer laminate structure, the feed link of each transmitting unit is encapsulated in the metal base, and a radio frequency connector is provided on the side of the metal base; the power supply PCB board is installed at the bottom of the metal base.

[0007] Furthermore, a waveguide transmission cavity is etched in the vertical direction of the three-layer laminate structure, and the laminates are connected through the waveguide openings of the waveguide transmission cavity.

[0008] Furthermore, the three-layer laminate structure includes an upper laminate, a middle laminate and a lower laminate; a low-frequency waveguide reflection cavity is provided on the lower surface of the middle laminate; the low-frequency waveguide reflection cavity is connected to the waveguide port on the upper surface of the lower laminate; the high-frequency waveguide input port on the lower surface of the middle laminate is connected to the high-frequency waveguide reflection cavity on the upper surface of the lower laminate; a frequency doubling link is printed on the microstrip circuit between the waveguide port on the lower surface of the middle laminate and the low-frequency waveguide reflection cavity.

[0009] Furthermore, a pyramidal horn antenna is etched on the upper laminate, with a waveguide input port at the lower end, a gradient structure in the middle, and a square radiation port at the upper end; the waveguide input port at the lower end is connected to the waveguide port on the upper surface of the middle laminate.

[0010] Furthermore, periodic shielding columns are etched near the waveguide opening on the upper surface of the middle laminate.

[0011] Furthermore, periodic shielding columns are etched near the waveguide opening on the lower surface of the lower laminate.

[0012] Furthermore, the feeding link includes a microstrip feeder, a frequency multiplier amplifier, a feedthrough capacitor, and a solder pad. One end of the microstrip feeder is connected to a radio frequency connector, and the other end is fed into a waveguide transmission cavity through a microstrip-waveguide probe. The frequency multiplier amplifier is connected in series in the microstrip feeder; the power supply PCB board is connected to the frequency multiplier amplifier through a feedthrough capacitor and a solder pad, and power supply control is performed.

[0013] Furthermore, a cover plate is provided above the feeder link.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) The stacked highly integrated terahertz emission front end designed by the present invention uses three layers of laminated chips to realize the main functional circuits and is arranged based on cubic block units;

[0016] (2) The stacked terahertz emission front-end designed by the present invention uses vertical waveguide transmission lines between the stacked sheets, and a gap waveguide structure is used at the connection surface to achieve non-contact connection;

[0017] (3) The terahertz frequency doubling circuit packaging cavity of the present invention is an open cavity design, and a dual-band gap waveguide is designed at the connection surface of the half cavity, which greatly reduces the volume of the frequency doubling device without deteriorating the performance of the frequency doubling device, and the frequency doubling device can be integrated into the terahertz emission front end by stacking and assembling;

[0018] (4) The present invention realizes a high-density layout of the feeding, frequency multiplication, and amplification links on a metal base, realizes independent control of multiple transmitting units, and has a compact structure, which is conducive to array expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the overall structure of a stacked and assembled terahertz emission front end based on electromagnetic band gap in an embodiment of the present invention;

[0020] Figure 2 It is a structural diagram of the metal base;

[0021] Figure 3 Feeder link diagram for each transmitting unit;

[0022] Figure 4 A perspective view of the structure of the upper laminate;

[0023] Figure 5 It is a structural perspective view of the middle layer laminate;

[0024] Figure 6 is the upper surface of the middle laminate;

[0025] Figure 7 is the lower surface of the middle laminate;

[0026] Figure 8 A perspective view of the structure of the lower laminate;

[0027] Figure 9 is the upper surface of the lower laminate;

[0028] Figure 10 is the lower surface of the lower laminate;

[0029] In the figure, 1. Metal base; 2. Cover; 3. Power supply PCB board; 4. Upper laminate; 5. Middle laminate; 6. Lower laminate; 7. Pin; 8. RF connector; 9. Microstrip feed line; 10. Frequency doubling amplifier; 11. Feedthrough capacitor; 12. Solder pad; 13. Horn antenna; 14. Shielding column; 15. First waveguide output port; 16. Frequency doubling link; 17. Low-frequency waveguide reflection cavity; 18. Second waveguide output port; 19. High-frequency waveguide reflection cavity; 20. Low-frequency waveguide input port; 21. High-frequency waveguide input port; 22. Feed link; 23. Pin hole. DETAILED DESCRIPTION

[0030] To facilitate understanding of the present invention, the present invention is described in more detail below with reference to the accompanying drawings and specific embodiments. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0031] In this embodiment, a 4×1 transmitting array is taken as an example. Figure 1 As shown, the structure of the electromagnetic bandgap-based stacked assembly terahertz transmitting front end mainly includes: a metal base 1, a cover plate 2, a power supply PCB board 3, a three-layer laminate, a pin 7, and an RF connector 8. Among them, the terahertz source array is located on the metal base 1. Each transmitting unit comprises a three-layer laminate structure, which is positioned by the cooperation of the pin 7 and the pin hole 23. The three-layer laminate realizes the frequency multiplication of the microwave signal to the terahertz signal and generates directional radiation through the horn antenna. The metal base 1 encapsulates the micro-feed link 22, which is fed by the RF connector. The terahertz signal can be generated by connecting an external microwave signal source. The cover plate 2 is located above the micro-feed link 22.

[0032] Figure 2 The structure diagram of the metal base is shown in FIG. 22. The feed link 22 of each transmitting unit is as shown in FIG. Figure 3 As shown, it includes a microstrip feed line 9, a frequency multiplier amplifier 10, a through-hole capacitor 11, and a solder pad 12. One end of the microstrip feed line 9 is connected to the RF connector 8, and the other end is fed into the waveguide transmission cavity through a microstrip-waveguide probe. The frequency multiplier amplifier 10 is connected in series with the microstrip feed line 9 to achieve the frequency multiplication and amplification function of the microwave signal. The power supply PCB board 3 on the back of the metal base 1 is connected to the frequency multiplier amplifier 10 through the through-hole capacitor 11 and the solder pad 12 and controls the power supply. This structure encapsulates the necessary basic circuits such as feeding, frequency multiplication, amplification, and power supply in the smallest possible size, generates an RF signal, and inputs it into the waveguide transmission line of the laminated structure.

[0033] The three-layer laminate structure of each emission unit is a key component of the present invention, and the structure diagram is shown in FIG. Figures 4-10 shown.

[0034] Figure 4 The upper laminate 4 has pin holes 23, screw holes and a pyramid-shaped horn antenna 13 etched in the square laminate. The lower end of the horn antenna 13 is a waveguide input port, and a square radiation port is formed on the upper surface through a gradient structure to generate directional radiation in the vertical direction.

[0035] Figure 5-7 This is a schematic diagram of the structure of the middle laminate 5. In addition to the necessary pin and screw holes, periodic shielding pillars 14 are etched near the first waveguide output port 15 on the upper surface of the middle laminate 5. This uses an electromagnetic bandgap structure to achieve contactless interconnection between the laminates, ensuring continuity of vertical waveguide transmission signals. The lower surface features a low-frequency waveguide to high-frequency waveguide conversion structure, which is achieved through a frequency doubling link 16. The low-frequency waveguide and high-frequency waveguide are connected via two waveguide-to-microstrip conversion structures. The frequency doubling link 16 is printed on a suspended microstrip circuit on a quartz substrate and includes filtering, coupling probes, and a frequency doubling chip, achieving frequency doubling, harmonic suppression, and impedance matching.

[0036] Figure 8-10 This is a schematic diagram of the structure of the lower laminate 6. The second waveguide output port 18 on the upper surface is connected to the low-frequency waveguide reflection cavity 17 on the lower surface of the middle laminate 5, and the high-frequency waveguide reflection cavity 19 is connected to the high-frequency waveguide input port 21 on the lower surface of the middle laminate 5. The combination of the middle laminate 5 and the lower laminate 6 together constitutes a terahertz frequency multiplier. The frequency multiplier is divided into two laminates due to the design of the laminated structure, which facilitates the assembly of the frequency multiplier chip and the matching filter link. For different frequency bands, square periodic shielding columns of different sizes are designed to shield the electromagnetic lateral leakage of the corresponding frequency band to ensure the performance of the frequency multiplier after the lamination is spliced. The lower surface of the lower laminate 6 is a low-frequency waveguide input port 20, which is used to connect the vertical waveguide transmission line.

[0037] In the above-mentioned embodiment, the core components of the highly integrated terahertz emission front-end are packaged in a three-layer laminate. A cavity structure is etched into the laminate to form a waveguide transmission line and a waveguide conversion structure. Each laminate contains a different functional circuit, and the laminates are connected by vertical waveguide ports. On the one hand, the design with waveguides as the primary transmission line is retained, achieving low-loss transmission of broadband terahertz signals. On the other hand, the closed cavity sealing method of traditional terahertz circuits is replaced by an open cavity sealing method, eliminating the need for screw transfer and significantly reducing the volume. The emission source adopts a cubic block unit structure, and the entire complex cavity structure and corresponding functional circuits are layered based on a stacking and segmentation method, thus achieving the integrated design of the terahertz source.

[0038] An electromagnetic bandgap structure is designed at the waveguide interface to suppress lateral electromagnetic leakage, enabling contactless connection of the waveguide transmission line, thereby ensuring the vertical interconnection and waveguide transmission characteristics during stacking. The terahertz circuit package cavity is divided into two halves, and a gap waveguide structure is designed at the dividing surface, ensuring continuity of electrical performance despite the discontinuous package cavity structure.

Claims

1. A stacked and assembled terahertz emission front end based on an electromagnetic bandgap, characterized by: The device comprises a metal base, a cover plate, and a power supply PCB board; the terahertz source transmitting unit array is arranged on the metal base, each transmitting unit comprises a three-layer laminate structure, the feed link of each transmitting unit is encapsulated in the metal base, and a radio frequency connector is provided on the side of the metal base; the power supply PCB board is installed at the bottom of the metal base; The three-layer laminate structure is etched with a waveguide transmission cavity in the vertical direction, and the laminates are connected through the waveguide openings of the waveguide transmission cavity; The three-layer laminate structure includes an upper laminate, a middle laminate, and a lower laminate; a low-frequency waveguide reflection cavity is provided on the lower surface of the middle laminate; the low-frequency waveguide reflection cavity is connected to the waveguide port on the upper surface of the lower laminate; the waveguide port on the lower surface of the middle laminate is connected to the high-frequency waveguide reflection cavity on the upper surface of the lower laminate; a frequency doubling link is printed on the microstrip circuit between the waveguide port on the lower surface of the middle laminate and the low-frequency waveguide reflection cavity; The upper laminate is etched with a pyramidal horn antenna, whose lower end is a waveguide input port, the middle is a gradient structure, and the upper end is a square radiation port; the waveguide input port at the lower end is connected to the waveguide port on the upper surface of the middle laminate.

2. The electromagnetic band gap-based stacked assembled terahertz emission front end according to claim 1, characterized in that: Periodic shielding columns are etched near the waveguide opening on the upper surface of the middle laminate.

3. The electromagnetic band gap-based stacked assembled terahertz emission front end according to claim 1, characterized in that: Periodic shielding columns are etched near the waveguide opening on the lower surface of the lower laminate.

4. The electromagnetic band gap-based stacked assembled terahertz emission front end according to any one of claims 1 to 3, characterized in that: The feeding link includes a microstrip feeder, a frequency multiplier amplifier, a feedthrough capacitor, and a solder pad. One end of the microstrip feeder is connected to a radio frequency connector, and the other end is fed into a waveguide transmission cavity through a microstrip-waveguide probe. The frequency multiplier amplifier is connected in series in the microstrip feeder; the power supply PCB board is connected to the frequency multiplier amplifier through the feedthrough capacitor and the solder pad, and power supply control is performed.

5. The electromagnetic band gap-based stacked assembled terahertz emission front end according to claim 4, characterized in that: A cover plate is provided above the feeder link.

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