Terahertz folded reflective array passive phased array

Abstract

This invention discloses a terahertz folded reflective passive phased array, comprising a main reflector, a feed antenna, and a polarized metal grid. The feed antenna is positioned behind the main reflector and is used to transmit X-polarized spherical waves to the polarized metal grid. The polarized metal grid is positioned between the feed antenna and the main reflector and is used to reflect X-polarized electromagnetic waves and transmit Y-polarized electromagnetic waves. The main reflector employs a metasurface architecture with multiple polarization conversion chips disposed thereon. These chips convert the incident X-polarized electromagnetic waves into Y-polarized electromagnetic waves and reflect them, while simultaneously providing phase compensation for the reflected electromagnetic waves to form plane waves or achieve beam deflection. The X-polarized spherical waves emitted from the feed antenna are reflected by the polarized metal grid to the main reflector. After polarization conversion and phase compensation by the main reflector, they are converted into Y-polarized plane waves and radiated forward through the polarized metal grid. This invention significantly improves the performance and integration of terahertz band antennas.

Description

Technical Field

[0001] This invention relates to terahertz technology, specifically to a passive phased array of terahertz folded reflection arrays. Background Technology

[0002] With the rise of microstrip antennas and the widespread application of PCB manufacturing technology, traditional rotating curved surface reflectors are gradually being replaced by planar structures to avoid the processing difficulties of complex rotating curved surface reflectors. Reflective array antennas with microstrip elements forming the main reflector are a relatively mature and highly engineering-feasible solution. By introducing different phase compensation methods, the microstrip elements on the reflector can equivalently simulate the phase distribution of a rotating parabolic surface, thereby converting the spherical wave generated by the feed source into a plane wave, while simultaneously enabling the planarization of the antenna's main reflector structure.

[0003] However, this type of reflective array antenna still integrates the feed structure of a self-rotating parabolic antenna in its feeding method, which means that the feed source is usually arranged above the reflective array. This not only results in a large overall profile height of the antenna system, making it difficult to meet the requirements of low profile integration for passive phased arrays in the terahertz band, but also introduces additional waveguide or free space propagation loss in the terahertz band. It also inevitably produces aperture blocking effect caused by the feed source and its supporting structure, thereby reducing the antenna's radiation efficiency and aperture utilization, and failing to meet the requirements of low profile, low loss, and no blocking effect. Summary of the Invention

[0004] The purpose of this invention is to provide a passive phased array for terahertz folded reflection.

[0005] The technical solution to achieve the purpose of this invention is: a terahertz folded reflective passive phased array, comprising a main reflector, a feed antenna, and a polarized metal grid, wherein:

[0006] The feed antenna is positioned behind the main reflector and is used to transmit X-polarized spherical waves into the polarized metal grid.

[0007] The polarized metal grid is disposed between the feed antenna and the main reflector, and is used to reflect X-polarized electromagnetic waves and transmit Y-polarized electromagnetic waves.

[0008] The main reflector adopts a metasurface architecture, on which multiple polarization chips are set to convert the incident X-polarized electromagnetic wave into a Y-polarized electromagnetic wave and reflect it. At the same time, it provides phase compensation for the reflected electromagnetic wave to form a plane wave or realize beam deflection.

[0009] The X-polarized spherical wave emitted from the feed antenna is reflected by the polarized metal grid to the main reflector. After polarization conversion and phase compensation by the main reflector, it is converted into a Y-polarized plane wave and radiates forward through the polarized metal grid.

[0010] Furthermore, the main reflector is a circular substrate with a feed hole at its center, and the feed antenna is mounted on the feed hole; the plurality of polarization switching chips include at least three different sizes of chips, which are arranged in concentric rings around the feed hole.

[0011] Furthermore, the feed antenna is a horn antenna, with a waveguide connection port at the bottom and a square opening at the top.

[0012] Furthermore, the feed antenna forms a virtual mirror feed in front of the polarized metal grid with the polarized metal grid as the mirror center; the electromagnetic waves irradiated to the main reflector are equivalent to those emitted by the virtual mirror feed.

[0013] Furthermore, the distance between the polarized metal grid and the main reflector is half of the architecture focal length F; the focal length F is determined by the ratio of the center energy to the edge energy radiated from the feed antenna to the main reflector.

[0014] Furthermore, the ratio is 10 dB.

[0015] Compared with existing technologies, the significant advantages of this invention are: 1) Placing the feed antenna behind the array avoids the additional propagation path and energy leakage introduced by the feedforward, significantly reducing feed path loss and improving the radiation efficiency of the system. 2) Using a planar polarized metal grid as a sub-reflector, after the feed antenna emits X-polarized electromagnetic waves, they are reflected by the polarized metal grid onto the main reflector. Through a specially designed main reflector, the phase of the emitted electromagnetic waves can be controlled while completing the polarization conversion, forming beam deflection. At this time, the electromagnetic waves will be converted to Y-polarization and pass through the polarized metal grid, thereby achieving the effect of unobstructed and low profile. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the architecture of a terahertz folded reflective array passive phased array.

[0017] Figure 2 This is a diagram showing the chip layout of the main reflector array.

[0018] Figure 3 This is a model diagram of a feed antenna. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] This invention discloses a passive phased array with terahertz folded reflection, the overall structure of which is as follows: Figure 1 As shown, the architecture mainly consists of three core parts: the main reflector 1, the feed antenna 2, and the polarized metal grid 3.

[0021] 1. System Composition and Structure

[0022] (1) Main reflecting surface 1

[0023] The main reflector 1 has the following structure: Figure 2 As shown, a circular substrate 1.5 is used. A feed hole 1.1 is machined in the center of the substrate for mounting and fixing the feed antenna 2.

[0024] On substrate 1.5, polarization switching chips of different sizes are integrated. For example... Figure 2 As shown, these chips mainly include three specifications: specification 1 chip 1.2, specification 2 chip 1.3, and specification 3 chip 1.4. They are designed according to the required phase compensation amount and arranged in concentric rings around the feed aperture 1.1, forming a reflective array capable of simultaneously achieving polarization conversion and wavefront modulation. The diameter of the substrate 1.5 can be adjusted according to actual needs. By designing different size specifications for different polarization conversion chips, the reflection phase of each chip on the incident X-polarized wave is independently controlled, thereby converting it into a Y-polarized wave of different phase for reflection.

[0025] (2) Feed antenna 2

[0026] Feed antenna 2 adopts a standard rectangular horn antenna, the model of which is as follows: Figure 3 As shown. The antenna has a standard waveguide connection port 2.1 at the bottom for connecting to an external terahertz signal source. The top has a square opening 2.2, which serves as the radiation aperture for electromagnetic waves. The antenna is fixed to the feed aperture 1.1 of the main reflector 1 via its waveguide connection port 2.1, so that its radiation direction is towards the polarized metal grid 3.

[0027] (3) Polarized metal grid 3

[0028] The polarized metal grid 3 is composed of a series of parallel, equally spaced metal lines, which are placed in parallel in front of the main reflector 1. When the electric field direction of the incident electromagnetic wave is parallel to the metal lines (i.e., X-polarization), it will be strongly reflected; when the electric field direction is perpendicular to the metal lines (i.e., Y-polarization), it can pass through with basically no obstruction.

[0029] 2. Signal Transmission and Working Process

[0030] The architecture employs a folded reflective array, and the specific process is as follows:

[0031] Initial reflection: The signal generated by the terahertz signal source is fed into the feed antenna 2 through the waveguide, and an X-polarized spherical wave is radiated outward from its square opening 2.2. This spherical wave first reaches the polarized metal grid 3. Since the polarization direction of the wave (X-polarization) is parallel to the direction of the grid metal lines, according to its characteristics, the wave is almost completely reflected, and after changing its propagation direction, it is directed toward the main reflector 1.

[0032] Polarization Conversion and Phase Compensation: The X-polarized wave incident on the main reflecting surface 1 is received by the polarization conversion chips integrated on its surface. Each chip, according to its own design, efficiently converts the incident X-polarized wave into a Y-polarized wave, while giving it a specific reflection phase determined by the chip size. Through the synergistic effect of the entire chip array, the incident spherical wave is converted into a Y-polarized plane wave with a specific directionality.

[0033] Final radiation: The plane wave, which has been converted to Y-polarization and reflected back from the main reflector 1, propagates again to the polarized metal grid 3. At this time, since the polarization direction (Y-polarization) of the wave is perpendicular to the direction of the grid metal lines, according to its characteristics, the wave is almost completely transmitted and radiates outward into free space without obstruction, forming the final antenna beam.

[0034] In actual design, the conversion efficiency of the polarization conversion chip is not 100%, and a small amount of unconverted X-polarized waves will be reflected by the main reflector. When this residual X-polarized wave encounters the polarization metal grid 3, it will be reflected back to the main reflector 1 again, undergoing a second or even multiple polarization conversions.

[0035] 3. Key Design Parameters and Equivalent Principle

[0036] Virtual mirror feed 4 and architectural focal length F: such as Figure 1 As shown, the polarized metal grid 3 serves as a sub-reflector, and the feed antenna 2 uses it as a mirror to form a virtual mirror feed 4 on its other side (the side of the main reflector 1). Therefore, the electromagnetic waves received by the main reflector can be equivalent to those directly radiated from this virtual feed 4. This principle enables this folded reflector passive phased array architecture to achieve the same illumination effect as a planar reflector array architecture while reducing the overall height.

[0037] The theoretical distance from the virtual feed 4 to the center of the main reflector 1 is defined as the structural focal length F of the reflector array. To achieve optimal illumination uniformity and phase compensation, the physical distance between the polarized metal grid 3 and the main reflector 1 is set to half of the structural focal length F (i.e., F / 2). The structural focal length F is determined by the ratio of the center energy to the edge energy radiated from the feed antenna to the main reflector 1, and can be adjusted according to actual needs. In a typical design of this invention, the distance between the feed antenna 2 and the main reflector 1 when the ratio is 10 dB is referred to as the structural focal length F.

[0038] In summary, by actively controlling or mechanically adjusting the position of the feed antenna 2, the present invention can change the equivalent position of the virtual mirror feed 4. Combined with the reconfigurable polarization chip design on the main reflector 1, the radiation beam can be scanned in space without moving the main reflector.

[0039] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A terahertz folded reflection array passive phased array, characterized in that, It includes a main reflector (1), a feed antenna (2), and a polarized metal grid (3), wherein: The feed antenna (2) is positioned behind the main reflector (1) and is used to transmit X-polarized spherical waves to the polarized metal grid (3). The polarized metal grid (3) is disposed between the feed antenna (2) and the main reflector (1) to reflect X-polarized electromagnetic waves and transmit Y-polarized electromagnetic waves. The main reflector (1) adopts a metasurface architecture, on which multiple polarization chips are provided to convert the incident X-polarized electromagnetic wave into Y-polarized electromagnetic wave and reflect it, while providing phase compensation for the reflected electromagnetic wave to form a plane wave or realize beam deflection. Among them, the X-polarized spherical wave emitted from the feed antenna (2) is reflected by the polarized metal grid (3) to the main reflector (1). After polarization conversion and phase compensation by the main reflector (1), it is converted into a Y-polarized plane wave and radiates forward through the polarized metal grid (3).

2. The terahertz folded reflection array passive phased array according to claim 1, characterized in that, The main reflector (1) is a circular substrate (1.5), and a feed hole (1.1) is provided in the center of the substrate. The feed antenna (2) is assembled in the feed hole (1.1). The multiple polarization chips include at least three different sizes of chips, which are arranged in concentric rings around the feed hole (1.1).

3. The terahertz folded reflection array passive phased array according to claim 1, characterized in that, The feed antenna (2) is a horn antenna with a waveguide connection port (2.1) at the bottom and a square opening (2.2) at the top.

4. The terahertz folded reflection array passive phased array according to claim 1, characterized in that, The feed antenna (2) forms a virtual mirror feed (4) in front of the polarized metal grid (3) with the polarized metal grid (3) as the mirror center; the electromagnetic waves irradiated to the main reflector (1) are equivalent to those emitted by the virtual mirror feed (4).

5. The terahertz folded reflection array passive phased array according to claim 1, characterized in that, The distance between the polarized metal grid (3) and the main reflector (1) is half of the architecture focal length F; the focal length F is determined by the ratio of the center energy to the edge energy radiated from the feed antenna (2) to the main reflector (1).

6. The terahertz folded reflection array passive phased array according to claim 5, characterized in that, The ratio is 10 dB.

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