Circularly polarized transceiver isolation terahertz quasi-optical and differential comparator

Abstract

This application discloses a circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator, including a sum input port D1, a difference input port D2, a sum receiving port D3, a polarization selection grating C1, a circular polarizer J1, a circularly polarized beam splitter S1, and plane mirrors M1, M2, and M3. The polarization selection grating C1 is parallel to and spaced apart from the circular polarizer J1. The plane mirror M3 is perpendicular to the circular polarizer J1. The circularly polarized beam splitter S1 is parallel to and spaced apart from the circular polarizer J1. The plane mirrors M1 and M2 are respectively disposed on both sides of the circularly polarized beam splitter S1. The plane mirror M1 is parallel to the circularly polarized beam splitter S1, and the plane mirror M2 is perpendicular to the circularly polarized beam splitter S1. By setting up a circular polarizer J1 and a circular polarization beam splitter S1 that can generate transmitted and reflected beams from any polarization beam, the quasi-optical sum and difference comparator can perform sum and difference operations on incident beams with arbitrary polarization directions. Moreover, the invention is easy to manufacture and has low cost, making it easy to apply widely.

Description

Technical Field

[0001] This invention relates to the field of quasi-optical single-pulse antenna technology, and more particularly to a circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator. Background Technology

[0002] Monopulse technology is a relatively mature and widely used tracking radar technology, and the sum-difference comparator is a key component of monopulse technology. Existing monopulse sum-difference comparator configurations suitable for lower frequency bands include waveguides, microstrip lines, and substrate integrated waveguides (SIW). However, these structures face challenges at high frequencies due to increased losses, reduced power capacity, and increased fabrication difficulty caused by the reduction in structural size. Beamguide technology based on quasi-optical theory utilizes the focused propagation of a beam in free space to achieve waveguide functionality, exhibiting naturally low insertion loss at high frequencies. This provides a theoretical foundation and technical support for the research and design of monopulse sum-difference networks.

[0003] Currently, the dual-polarized beam splitter used in dual-polarized quasi-optical sum-difference comparators is a quartz substrate with a double-sided grating structure. It can achieve power equalization for two incident waves with orthogonal polarization directions, but the phase shifting effect is different. When a vertically polarized wave is incident, the phase of the transmitted wave leads the phase of the reflected wave by 90°; when a parallelly polarized wave is incident, the phase of the reflected wave leads the phase of the transmitted wave by 90°. This results in different sum-difference ports for incident beams with different polarization directions, making it impossible for sum-difference comparators designed based on this dual-polarized beam splitter to achieve sum-difference calculation for incident beams with arbitrary polarization directions. Summary of the Invention

[0004] To address the above-mentioned problems, this invention overcomes at least one of them by proposing a circularly polarized, isolated terahertz quasi-optical sum and difference comparator.

[0005] The technical solution adopted in this invention is as follows:

[0006] This application provides a circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator, including a sum input port D1, a difference input port D2, a sum receiving port D3, a polarization selection grating C1, a circular polarizer J1, a circularly polarized beam splitter S1, a plane mirror M1, a plane mirror M2, and a plane mirror M3.

[0007] The sum input port D1 and the difference input port D2 are used to input the polarized beam, and the input polarized beam is a linearly polarized beam.

[0008] The circular polarization beam splitter S1 is used to divide the power of an arbitrary polarization beam equally and generate a 90° phase difference, thereby generating a transmitted beam and a reflected beam. The amplitudes of the transmitted beam and the reflected beam are equal, and the phase of the transmitted beam is the phase of the reflected beam plus 90°.

[0009] The receiving port D3 is used to receive the reflected echo generated when the polarized beam input from the sum input port D1 encounters an obstacle outside the sum-difference comparator. The initially reflected echo is a circularly polarized beam.

[0010] The circular polarizer J1 is used to convert the input linearly polarized beam into a circularly polarized beam, and to convert the reflected echo from a circularly polarized beam to a linearly polarized beam.

[0011] The polarization selection grating C1 is used to achieve the transmission and reflection effects of the input polarized beam and the reflected echo;

[0012] The polarization selection grating C1 is parallel to and spaced apart from the circular polarizer J1;

[0013] The plane mirror M3 is arranged perpendicularly to the circular polarizer J1;

[0014] The circular polarization beam splitter S1 is parallel to and spaced apart from the circular polarization J1, and the circular polarization beam splitter S1 is arranged side by side with the polarization selection grating C1;

[0015] The plane mirror M1 and the plane mirror M2 are respectively disposed on both sides of the circularly polarized beam splitter S1. The plane mirror M2 is disposed on the side closer to the plane mirror M3, and the plane mirror M2 and the circularly polarized beam splitter J1 are respectively disposed on both sides of the plane mirror M3.

[0016] The plane mirror M1 is arranged parallel to the circularly polarized beam splitter S1, and the plane mirror M2 is arranged perpendicular to the circularly polarized beam splitter S1;

[0017] When the linearly polarized beam is input through the input port D1, the polarization direction of the linearly polarized beam is orthogonal to the polarization selection grating C1. The linearly polarized beam passes through the polarization selection grating C1, and is then converted into a circularly polarized beam by the circular polarizer J1 and reflected to the circularly polarized beam splitter S1. After passing through the circularly polarized beam splitter S1, the circularly polarized beam is equally divided into a reflected beam and a transmitted beam. At this time, the reflected beam and the transmitted beam have the same circular polarization rotation direction and the same amplitude, and the phase of the transmitted beam leads the reflected beam by 90°. The transmitted beam is output after being reflected by the plane mirror M1, and the reflected beam is output after being reflected twice by the plane mirrors M2 and M3. The output reflected beam has the same amplitude and the same phase as the transmitted beam, realizing the summation effect of the summation comparator.

[0018] When the linearly polarized beam is input through the difference input port D2, the linearly polarized beam passes directly through the circularly polarized beam splitter S1 and is equally divided into a reflected beam and a transmitted beam. At this time, the polarization direction of the reflected beam and the transmitted beam are the same, the amplitude is equal, and the phase of the transmitted beam leads the reflected beam by 90°. The transmitted beam is output after being reflected twice by plane mirrors M2 and M3, and the reflected beam is output after being reflected by plane mirror M1. The two output beams have the same amplitude but opposite phase, realizing the difference effect of the sum-difference comparator.

[0019] When the polarized beam input from the input port D1 is reflected and output as a reflected beam and a transmitted beam, and the reflected echoes generated by the output reflected beam and the transmitted beam are respectively fed into the sum-difference comparator, the reflected echoes generated by the reflected beam and the reflected echoes generated by the transmitted beam have the same rotation direction and phase, and are opposite to the rotation direction of the output reflected beam and transmitted beam, respectively. The reflected echoes generated by the reflected beam and the reflected echoes generated by the transmitted beam reach the circularly polarized beam splitter S1 through optical path processes opposite to those when the reflected beam and the transmitted beam are output. The echo and the reflected echo generated by the transmitted beam are combined into a single reflected echo. This reflected echo is reflected back to the circular polarizer J1. After passing through the circular polarizer J1, the synthesized reflected echo is transformed from a circularly polarized reflected echo into a linearly polarized reflected echo. Since the reflected echo generated by the reflected beam and the reflected echo generated by the transmitted beam have opposite rotation directions to the output reflected beam and transmitted beam, respectively, and their polarization directions are orthogonal to the polarization direction of the polarized beam input from the input port D1, the synthesized reflected echo is reflected by the polarization selection grating C1 to the receiving port D3, thus realizing the transmit / receive isolation function of the receiving port.

[0020] By setting up a circular polarizer J1 and a circular polarization beam splitter S1 that can divide the power of an arbitrary polarized beam equally and generate a 90° phase difference to produce a transmitted beam and a reflected beam, the quasi-optical sum-difference comparator is realized to perform sum-difference operations on incident beams of arbitrary polarization directions. Moreover, the quasi-optical sum-difference comparator provided by this invention has low manufacturing difficulty and cost, and is easy to widely apply.

[0021] Existing technologies use ferrite circulators or duplexers independent of the sum-difference comparator to achieve transmit-receive isolation. However, ferrite circulators or duplexers suffer from high dielectric loss in the terahertz band, and further increase system losses by extending the optical path. This invention employs a polarization-selective grating and a circular polarizer to achieve high-isolation transmit-receive isolation, resulting in a compact sum-difference comparator structure and significantly reduced losses.

[0022] Furthermore, the distance between the plane mirror M2 and the circularly polarized beam splitter S1 is h; the distance between the plane mirror M1 and the circularly polarized beam splitter S1 is L, where L = h - λ / 4, and λ is the operating wavelength.

[0023] The path where the distance from the plane mirror M1 to the circularly polarized beam splitter S1 is reduced by λ / 4 compared to the distance from the periphery of the plane mirror M2 to the circularly polarized beam splitter S1 will cause the beam passing through this path to be 90 degrees ahead in phase.

[0024] In this invention, the distance between the plane mirror M2 and the circularly polarized beam splitter S1 refers to the length between the center of the plane mirror M2 and the center of the circularly polarized beam splitter S1, which is also the distance the beam travels between the plane mirror M2 and the circularly polarized beam splitter S1.

[0025] In this invention, the distance between the plane mirror M1 and the circularly polarized beam splitter S1 refers to the length between the center of the plane mirror M1 and the center of the circularly polarized beam splitter S1, which is also the distance the beam travels between the plane mirror M1 and the circularly polarized beam splitter S1.

[0026] Furthermore, both the sum input port D1 and the difference input port D2 are located on the side of the polarization selection grating C1 away from the circular polarizer J1;

[0027] The receiving port D3 is located on the side of the polarization selection grating C1 near the circular polarizer J1;

[0028] The sum-difference comparator also includes output port D4 and output port D5;

[0029] The output port D4 is located on the side of the plane mirror M3 away from the circular polarizer J1;

[0030] The output port D5 is located on the side of the plane mirror M1 away from the differential input port D2.

[0031] The output port D4 and the output port D5 are respectively used to output the transmitted beam and the reflected beam generated by the circularly polarized beam splitter S1.

[0032] Furthermore, the circular polarization beam splitter S1 and the polarization selection grating C1 are disposed on the same side of the circular polarizer J1;

[0033] The circular polarization beam splitter S1 and the polarization selection grating C1 are disposed on the same side of the circular polarizer J1;

[0034] The distance between the polarization selection grating C1 and the circular polarizer J1 is h;

[0035] The distance between the circular polarizer J1 and the circular polarization beam splitter S1 is h;

[0036] The distance between the circularly polarized beam splitter S1 and the plane mirror M2 is h;

[0037] The distance between the plane mirror M2 and the plane mirror M3 is h.

[0038] In this invention, the distance between the polarization selection grating C1 and the circular polarizer J1 refers to the length between the center of the polarization selection grating C1 and the center of the circular polarizer J1, which is the distance the beam travels between the polarization selection grating C1 and the circular polarizer J1.

[0039] In this invention, the distance between the circular polarizer J1 and the circular polarization beam splitter S1 refers to the length between the center of the circular polarizer J1 and the center of the circular polarization beam splitter S1, which is the distance the beam travels between the circular polarizer J1 and the circular polarization beam splitter S1.

[0040] In this invention, the distance between the circularly polarized beam splitter S1 and the plane mirror M2 refers to the length between the center of the circularly polarized beam splitter S1 and the center of the plane mirror M2, which is also the distance the beam travels between the circularly polarized beam splitter S1 and the plane mirror M2.

[0041] In this invention, the distance between plane mirror M2 and plane mirror M3 refers to the length between the center of plane mirror M2 and the center of plane mirror M3, which is also the distance the beam travels between plane mirror M2 and plane mirror M3.

[0042] Furthermore, the plane mirrors M1, M2, and M3 are all plane reflecting mirrors.

[0043] The plane mirrors M1, M2, and M3 are used to control the propagation direction of the beam.

[0044] Furthermore, the beam reflections in the sum and difference comparators are all 90° reflections.

[0045] The 90° reflection in this invention refers to the sum of the incident angle and the reflection angle being 90°.

[0046] Furthermore, the polarized beams input to the sum input port D1 and the difference input port D2 are Gaussian beams, which are generated by a Gaussian feed horn.

[0047] Furthermore, the polarization selection grating C1 includes periodically arranged metal wires, the radius of the metal wires of the polarization selection grating C1 is R1, and the arrangement period of the metal wires of the polarization selection grating C1 is P1.

[0048] Furthermore, the circular polarizer J1 includes a plane mirror M4 and a metal wire grid, the metal wire grid being disposed outside the plane mirror M4, and the metal wire grid including periodically arranged wires;

[0049] The radius of the metal wire grid conductor is R2, the arrangement period of the metal wire grid conductor is P2, the spacing distance between the wire grid plane of the metal wire grid and the plane mirror M4 is t, and the angle between the arrangement direction of the metal wire grid conductor and the beam plane entering and exiting the circular polarizer J1 is α.

[0050] Furthermore, the circularly polarized beam splitter S1 includes a quartz dielectric substrate and a metal grating. The metal grating includes periodically arranged metal wires. The metal grating is disposed on both sides of the quartz dielectric substrate and is symmetrically arranged along the quartz dielectric substrate.

[0051] The thickness of the quartz substrate is d, the radius of the metal wire of the metal grating is R3, the arrangement period of the metal wire of the metal grating is P3, and the rotation angle of the metal wire of the metal grating relative to the incident surface around the central axis of the circularly polarized beam splitter S1 is φ.

[0052] In the prior art, dual-polarized beam splitters are manufactured by etching metal strips onto the surface, which is costly and difficult to produce. The circularly polarized beam splitter S1 provided by the present invention includes a quartz dielectric substrate and a metal grating, which is inexpensive and easy to manufacture.

[0053] This application also provides a monopulse antenna, including the circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator described above.

[0054] This application also provides a monopulse radar, including the circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator described above.

[0055] The beneficial effects of this invention are:

[0056] By setting up a circular polarizer J1 and a circular polarization beam splitter S1 that can divide the power of an arbitrary polarized beam equally and generate a 90° phase difference to produce a transmitted beam and a reflected beam, the quasi-optical sum-difference comparator is realized to perform sum-difference operations on incident beams of arbitrary polarization directions. Moreover, the quasi-optical sum-difference comparator provided by this invention has low manufacturing difficulty and cost, and is easy to widely apply.

[0057] In this invention, a polarization selection grating and a circular polarizer are used to achieve high isolation for transmission and reception, making the sum and difference comparator structure compact and greatly reducing losses.

[0058] The circularly polarized beam splitter S1 provided by the present invention includes a quartz dielectric substrate and a metal grating, and its production cost is low and the manufacturing difficulty is low. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the structural principle of the sum-difference comparator in an embodiment of the present invention, viewed from above.

[0060] Figure 2 This is a schematic diagram of the structural principle of the sum-difference comparator in the axial direction according to an embodiment of the present invention;

[0061] Figure 3 This is a schematic diagram of the propagation path of the beam and reflected echo input at input port D1 in the sum-difference comparator according to an embodiment of the present invention;

[0062] Figure 4 This is a schematic diagram of the propagation path of the beam input at the difference input port D2 in the sum-difference comparator according to an embodiment of the present invention;

[0063] Figure 5 This is a simplified diagram of the propagation path of the beam input at input port D1 in the sum-difference comparator according to an embodiment of the present invention;

[0064] Figure 6 This is a simplified diagram of the propagation path of the beam input at the difference input port D2 in the sum-difference comparator according to an embodiment of the present invention;

[0065] Figure 7 This is a simplified diagram of the propagation path of the reflected echo within the sum-difference comparator according to an embodiment of the present invention;

[0066] Figure 8 This is a schematic diagram of the structural principle of the circular polarizer J1 in an embodiment of the present invention;

[0067] Figure 9 yes Figure 8 A schematic diagram of the local structure in the E direction (rotated 90° clockwise);

[0068] Figure 10 This is a schematic diagram illustrating the structural principle of the polarization selection grating C1 in an embodiment of the present invention;

[0069] Figure 11 This is a schematic diagram of the structural principle of the circularly polarized beam splitter S1 in the axial direction according to an embodiment of the present invention;

[0070] Figure 12 This is a schematic diagram of the structural principle of the circularly polarized beam splitter S1 in the side view of an embodiment of the present invention. Detailed Implementation

[0071] The present invention will now be described in detail with reference to the accompanying drawings.

[0072] like Figure 1 , Figure 2As shown, this application provides a circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator, including a sum input port D1, a difference input port D2, a sum receiving port D3, a polarization selection grating C1, a circular polarizer J1, a circularly polarized beam splitter S1, a plane mirror M1, a plane mirror M2, and a plane mirror M3.

[0073] Input port D1 and differential input port D2 are used to input the polarized beam, which is a linearly polarized beam.

[0074] The circular polarization beam splitter S1 is used to divide the power of an arbitrary polarization beam equally and generate a 90° phase difference, producing a transmitted beam and a reflected beam. The amplitudes of the transmitted beam and the reflected beam are equal, and the phase of the transmitted beam is the phase of the reflected beam plus 90°.

[0075] The receiving port D3 is used to receive the reflected echo generated after the polarized beam input from the sum input port D1 encounters an obstacle outside the sum and difference comparator. The initial reflected echo is a circularly polarized beam.

[0076] Circular polarizer J1 is used to convert the input linearly polarized beam into a circularly polarized beam, and to convert the reflected echo from a circularly polarized beam to a linearly polarized beam.

[0077] The polarization selection grating C1 is used to achieve the transmission and reflection effects of the input polarized beam and the reflected echo;

[0078] The polarization selection grating C1 is parallel to and spaced apart from the circular polarizer J1;

[0079] The plane mirror M3 is positioned perpendicularly to the circular polarizer J1;

[0080] Circular polarization beam splitter S1 is arranged parallel to and spaced apart from circular polarization J1, and circular polarization beam splitter S1 is arranged side by side with polarization selection grating C1;

[0081] Plane mirrors M1 and M2 are respectively located on both sides of circularly polarized beam splitter S1. Plane mirror M2 is located on the side closer to plane mirror M3, and plane mirror M2 and circularly polarized beam splitter J1 are respectively located on both sides of plane mirror M3.

[0082] Plane mirror M1 is set parallel to circularly polarized beam splitter S1, and plane mirror M2 is set perpendicular to circularly polarized beam splitter S1;

[0083] like Figure 3 , Figure 5As shown, when the linearly polarized beam A is input through the input port D1, the polarization direction of the linearly polarized beam A is orthogonal to the polarization selection grating C1. The linearly polarized beam A passes through the polarization selection grating C1, and is then converted into a circularly polarized beam by the circular polarizer J1 and reflected to the circularly polarized beam splitter S1. After passing through the circularly polarized beam splitter S1, the circularly polarized beam is equally divided into a reflected beam A1 and a transmitted beam A2. At this time, the reflected beam A1 and the transmitted beam A2 have the same circular polarization rotation direction and the same amplitude. The phase of the transmitted beam A2 leads the reflected beam A1 by 90°. The transmitted beam A2 is output after being reflected by the plane mirror M1. The reflected beam A1 is output after being reflected twice by the plane mirrors M2 and M3. The output reflected beam A1 and the transmitted beam A2 have the same amplitude and the same phase, realizing the summation effect of the summation comparator.

[0084] like Figure 4 , Figure 6 As shown, when the linearly polarized beam B is input through the difference input port D2, the linearly polarized beam B passes directly through the circularly polarized beam splitter S1 and is equally divided into the reflected beam B1 and the transmitted beam B2. At this time, the reflected beam B1 and the transmitted beam B2 have the same polarization direction and the same amplitude, and the phase of the transmitted beam B2 leads the reflected beam B1 by 90°. The transmitted beam B2 is output after being reflected twice by the plane mirrors M2 and M3, and the reflected beam B1 is output after being reflected by the plane mirror M1. The two output beams have the same amplitude but opposite phase, realizing the difference effect of the sum-difference comparator.

[0085] In actual use, the beam output from the sum-difference comparator will generate a reflected echo after encountering an obstacle, and the reflected echo will be fed back into the sum-difference comparator.

[0086] like Figure 3 , Figure 5 and Figure 7As shown, when the linearly polarized beam A input from input port D1 is reflected, it outputs reflected beam A1 and transmitted beam A2. The reflected beam A1 and transmitted beam A2 encounter obstacles outside the sum-difference comparator, generating reflected echoes F1 and F2 respectively. These reflected echoes F1 and F2 are fed into the sum-difference comparator. The reflected echoes F1 and F2 have the same rotation direction and phase, and are opposite in rotation and propagation direction to the output reflected beam A1 and transmitted beam A2, respectively. The reflected echoes F1 and F2 are transmitted through paths opposite to those of the reflected beam A1 and transmitted beam A2 at the output. The optical path reaches the circularly polarized beam splitter S1, where the reflected echo F1 and reflected echo F2 are combined to form reflected echo F. Reflected echo F continues to be reflected back to the circularly polarized beam splitter J1. After passing through the circularly polarized beam splitter J1, reflected echo F is transformed from a circularly polarized reflected echo into a linearly polarized reflected echo. Since reflected echo F1 and reflected echo F2 have opposite rotation directions to the output reflected beam A1 and the transmitted beam A2, respectively, and the polarization direction of reflected echo F is orthogonal to the polarization direction of the linearly polarized beam A input from the input port D1, reflected echo F is reflected by the polarization selection grating C1 to the receiving port D3, realizing the transmit and receive isolation function of the port.

[0087] By setting up a circular polarizer J1 and a circular polarization beam splitter S1 that can divide the power of an arbitrary polarized beam equally and generate a 90° phase difference to produce a transmitted beam and a reflected beam, the quasi-optical sum-difference comparator is realized to perform sum-difference operations on incident beams of arbitrary polarization directions. Moreover, the quasi-optical sum-difference comparator provided by this invention has low manufacturing difficulty and cost, and is easy to widely apply.

[0088] Existing technologies use ferrite circulators or duplexers independent of the sum-difference comparator to achieve transmit-receive isolation. However, ferrite circulators or duplexers suffer from high dielectric loss in the terahertz band, and further increase system losses by extending the optical path. This invention employs a polarization-selective grating and a circular polarizer to achieve high-isolation transmit-receive isolation, resulting in a compact sum-difference comparator structure and significantly reduced losses.

[0089] In this embodiment, the distance between the plane mirror M2 and the circularly polarized beam splitter S1 is h; the distance between the plane mirror M1 and the circularly polarized beam splitter S1 is L, where L = h - λ / 4, and λ is the operating wavelength.

[0090] In this embodiment, h = 25 mm; L = 24.78 mm.

[0091] The path where the distance from plane mirror M1 to circularly polarized beam splitter S1 is reduced by λ / 4 compared to the distance from the periphery of plane mirror M2 to circularly polarized beam splitter S1 will cause the beam passing through this path to be 90 degrees ahead in phase.

[0092] In this invention, the distance between the plane mirror M2 and the circularly polarized beam splitter S1 refers to the length between the center of the plane mirror M2 and the center of the circularly polarized beam splitter S1, which is also the distance the beam travels between the plane mirror M2 and the circularly polarized beam splitter S1.

[0093] In this invention, the distance between the plane mirror M1 and the circularly polarized beam splitter S1 refers to the length between the center of the plane mirror M1 and the center of the circularly polarized beam splitter S1, which is also the distance the beam travels between the plane mirror M1 and the circularly polarized beam splitter S1.

[0094] In this embodiment, both the sum input port D1 and the difference input port D2 are located on the side of the polarization selection grating C1 away from the circular polarizer J1;

[0095] The receiving port D3 is located on the side of the polarization selection grating C1 near the circular polarizer J1;

[0096] The sum-difference comparator also includes output port D4 and output port D5;

[0097] Output port D4 is located on the side of plane mirror M3 away from circular polarizer J1;

[0098] Output port D5 is located on the side of plane mirror M1 away from differential input port D2.

[0099] Output ports D4 and D5 are used to output the transmitted beam and reflected beam generated by the circularly polarized beam splitter S1, respectively.

[0100] In this embodiment, the circular polarization beam splitter S1 and the polarization selection grating C1 are disposed on the same side of the circular polarizer J1;

[0101] The circular polarization beam splitter S1 and the polarization selection grating C1 are located on the same side of the circular polarizer J1;

[0102] The distance between the polarization selection grating C1 and the circular polarizer J1 is h;

[0103] The distance between circular polarizer J1 and circular polarizer S1 is h;

[0104] The distance between the circularly polarized beam splitter S1 and the plane mirror M2 is h;

[0105] The distance between plane mirror M2 and plane mirror M3 is h.

[0106] In this invention, the distance between the polarization selection grating C1 and the circular polarizer J1 refers to the length between the center of the polarization selection grating C1 and the center of the circular polarizer J1, which is the distance the beam travels between the polarization selection grating C1 and the circular polarizer J1.

[0107] In this invention, the distance between the circular polarizer J1 and the circular polarization beam splitter S1 refers to the length between the center of the circular polarizer J1 and the center of the circular polarization beam splitter S1, which is the distance the beam travels between the circular polarizer J1 and the circular polarization beam splitter S1.

[0108] In this invention, the distance between the circularly polarized beam splitter S1 and the plane mirror M2 refers to the length between the center of the circularly polarized beam splitter S1 and the center of the plane mirror M2, which is also the distance the beam travels between the circularly polarized beam splitter S1 and the plane mirror M2.

[0109] In this invention, the distance between plane mirror M2 and plane mirror M3 refers to the length between the center of plane mirror M2 and the center of plane mirror M3, which is also the distance the beam travels between plane mirror M2 and plane mirror M3.

[0110] In this embodiment, plane mirrors M1, M2, and M3 are all plane reflecting mirrors.

[0111] Plane mirrors M1, M2, and M3 are used to control the direction of beam propagation.

[0112] In this embodiment, the beam is reflected at 90° in the sum and difference comparator.

[0113] The 90° reflection in this invention refers to the sum of the incident angle and the reflection angle being 90°.

[0114] In this embodiment, the polarization beams input to input port D1 and input port D2 are Gaussian beams, which are generated by a Gaussian feed horn.

[0115] In practical use, the center operating frequency of the sum-difference comparator of this invention is 340GHz, the operating frequency of the Gaussian feed horn is 340Hz, and the waist radius of the generated Gaussian beam is 4.5mm.

[0116] like Figure 10 As shown, in this embodiment, the polarization selection grating C1 includes periodically arranged metal wires, the radius of the metal wires of the polarization selection grating C1 is R1, and the arrangement period of the metal wires of the polarization selection grating C1 is P1.

[0117] In this embodiment, R1 = 0.1 mm and P1 = 0.47 mm.

[0118] like Figure 8 , Figure 9 As shown, in this embodiment, the circular polarizer J1 includes a plane mirror M4 and a metal wire grid. The metal wire grid is disposed on the outside of the plane mirror M4 and includes periodically arranged wires.

[0119] The radius of the metal wire grid conductor is R2, the arrangement period of the metal wire grid conductor is P2, the spacing between the wire grid plane and the plane mirror M4 is t, and the angle between the arrangement direction of the metal wire grid conductor and the beam plane entering and exiting the circular polarizer J1 is α.

[0120] In this embodiment, R2 = 0.1 mm, P2 = 0.67 mm, t = 0.46 mm, and α = 34°.

[0121] like Figure 11 , Figure 12 As shown, in this embodiment, the circularly polarized beam splitter S1 includes a quartz dielectric substrate and a metal grating. The metal grating includes periodically arranged metal wires and is disposed on both sides of the quartz dielectric substrate and symmetrically arranged along the quartz dielectric substrate.

[0122] The thickness of the quartz substrate is d, the radius of the metal wire of the metal grating is R3, the arrangement period of the metal wire of the metal grating is P3, and the rotation angle of the metal wire of the metal grating relative to the incident surface around the central axis of the circularly polarized beam splitter S1 is φ.

[0123] In this embodiment, d = 0.11 mm, R3 = 0.05 mm, P3 = 1.5 mm, and φ = 33°.

[0124] In the prior art, dual-polarized beam splitters are manufactured by etching metal strips onto the surface, which is costly and difficult to produce. The circularly polarized beam splitter S1 provided by this invention includes a quartz dielectric substrate and a metal grating, which is inexpensive and easy to produce.

[0125] This application also provides a monopulse antenna, including the circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator described above.

[0126] This application also provides a monopulse radar, including the circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator described above.

[0127] The above description is merely a preferred embodiment of the present invention and does not limit the scope of patent protection of the present invention. Any equivalent structural transformations made based on the description and drawings of the present invention, whether directly or indirectly applied to other related technical fields, are similarly included within the scope of protection of the present invention.

Claims

1. A circularly polarized, isolated terahertz quasi-optical sum and difference comparator, characterized in that, It includes an input port D1, a differential input port D2, an output receiving port D3, a polarization selection grating C1, a circular polarizer J1, a circular polarization beam splitter S1, a plane mirror M1, a plane mirror M2, and a plane mirror M3; The sum input port D1 and the difference input port D2 are used to input the polarized beam, and the input polarized beam is a linearly polarized beam. The circular polarization beam splitter S1 is used to divide the power of an arbitrary polarization beam equally and generate a 90° phase difference, thereby generating a transmitted beam and a reflected beam. The amplitudes of the transmitted beam and the reflected beam are equal, and the phase of the transmitted beam is the phase of the reflected beam plus 90°. The receiving port D3 is used to receive the reflected echo of the polarized beam input from the input port D1, and the initially reflected echo is a circularly polarized beam. The circular polarizer J1 is used to convert the input linearly polarized beam into a circularly polarized beam, and to convert the reflected echo from a circularly polarized beam to a linearly polarized beam. The polarization selection grating C1 is used to achieve the transmission and reflection effects of the input polarized beam and the reflected echo; The polarization selection grating C1 is parallel to and spaced apart from the circular polarizer J1; The plane mirror M3 is arranged perpendicularly to the circular polarizer J1; The circular polarization beam splitter S1 is parallel to and spaced apart from the circular polarization J1, and the circular polarization beam splitter S1 is arranged side by side with the polarization selection grating C1; The plane mirror M1 and the plane mirror M2 are respectively disposed on both sides of the circularly polarized beam splitter S1. The plane mirror M2 is disposed on the side closer to the plane mirror M3, and the plane mirror M2 and the circularly polarized beam splitter J1 are respectively disposed on both sides of the plane mirror M3. The plane mirror M1 is arranged parallel to the circularly polarized beam splitter S1, and the plane mirror M2 is arranged perpendicular to the circularly polarized beam splitter S1; When the linearly polarized beam is input through the input port D1, the polarization direction of the linearly polarized beam is orthogonal to the polarization selection grating C1. The linearly polarized beam passes through the polarization selection grating C1, and is then converted into a circularly polarized beam by the circular polarizer J1 and reflected to the circularly polarized beam splitter S1. After passing through the circularly polarized beam splitter S1, the circularly polarized beam is equally divided into a reflected beam and a transmitted beam. At this time, the reflected beam and the transmitted beam have the same circular polarization rotation direction and the same amplitude, and the phase of the transmitted beam leads the reflected beam by 90°. The transmitted beam is output after being reflected by the plane mirror M1, and the reflected beam is output after being reflected twice by the plane mirrors M2 and M3. The output reflected beam has the same amplitude and the same phase as the transmitted beam, realizing the summation effect of the summation comparator. When the linearly polarized beam is input through the difference input port D2, the linearly polarized beam passes directly through the circularly polarized beam splitter S1 and is equally divided into a reflected beam and a transmitted beam. At this time, the polarization direction of the reflected beam and the transmitted beam are the same, the amplitude is equal, and the phase of the transmitted beam leads the reflected beam by 90°. The transmitted beam is output after being reflected twice by plane mirrors M2 and M3, and the reflected beam is output after being reflected by plane mirror M1. The two output beams have the same amplitude but opposite phase, realizing the difference effect of the sum-difference comparator. When the polarized beam input from the input port D1 is reflected and output as a reflected beam and a transmitted beam, and the reflected echoes generated by the output reflected beam and the transmitted beam are respectively fed into the sum-difference comparator, the reflected echoes generated by the reflected beam and the reflected echoes generated by the transmitted beam have the same rotation direction and phase, and are opposite to the rotation direction of the output reflected beam and transmitted beam, respectively. The reflected echoes generated by the reflected beam and the reflected echoes generated by the transmitted beam reach the circularly polarized beam splitter S1 through optical path processes opposite to those when the reflected beam and the transmitted beam are output. The wave and the reflected echo generated by the transmitted wave beam are combined into a single reflected echo. This reflected echo is reflected back to the circular polarizer J1. After passing through the circular polarizer J1, the synthesized reflected echo is transformed from a circularly polarized reflected echo into a linearly polarized reflected echo. Since the reflected echo generated by the reflected wave beam and the reflected echo generated by the transmitted wave beam have opposite rotation directions to the output reflected and transmitted wave beams, respectively, and their polarization directions are orthogonal to the polarization direction of the polarized beam input from the input port D1, the synthesized reflected echo is reflected by the polarization selection grating C1 to the receiving port D3, thus realizing the transmit and receive isolation function of the receiving port.

2. The circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator as described in claim 1, characterized in that, The distance between the plane mirror M2 and the circularly polarized beam splitter S1 is h; the distance between the plane mirror M1 and the circularly polarized beam splitter S1 is L, where L = h - λ / 4, and λ is the operating wavelength.

3. The circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator as described in claim 1, characterized in that, Both the sum input port D1 and the difference input port D2 are located on the side of the polarization selection grating C1 away from the circular polarizer J1; The receiving port D3 is located on the side of the polarization selection grating C1 near the circular polarizer J1; The sum-difference comparator also includes output port D4 and output port D5; The output port D4 is located on the side of the plane mirror M3 away from the circular polarizer J1; The output port D5 is located on the side of the plane mirror M1 away from the differential input port D2.

4. The circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator as described in claim 1, characterized in that, The circular polarization beam splitter S1 and the polarization selection grating C1 are disposed on the same side of the circular polarizer J1; The distance between the polarization selection grating C1 and the circular polarizer J1 is h; The distance between the circular polarizer J1 and the circular polarization beam splitter S1 is h; The distance between the circularly polarized beam splitter S1 and the plane mirror M2 is h; The distance between the plane mirror M2 and the plane mirror M3 is h.

5. The circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator as described in claim 1, characterized in that, The plane mirrors M1, M2, and M3 are all plane reflecting mirrors.

6. The circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator as described in claim 1, characterized in that, The beam is reflected at 90° in the sum and difference comparator.

7. The circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator as described in claim 1, characterized in that, The polarized beams input to the sum input port D1 and the difference input port D2 are Gaussian beams, which are generated by a Gaussian feed horn.

8. The circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator as described in claim 1, characterized in that, The polarization selection grating C1 includes periodically arranged metal wires.

9. A circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator as described in claim 1, characterized in that, The circular polarizer J1 includes a plane mirror M4 and a metal wire grid. The metal wire grid is disposed outside the plane mirror M4 and includes periodically arranged wires.

10. A circularly polarized transceiver isolated terahertz quasi-optical sum and difference comparator as described in claim 1, characterized in that, The circularly polarized beam splitter S1 includes a quartz dielectric substrate and a metal grating. The metal grating includes periodically arranged metal wires and is disposed on both sides of the quartz dielectric substrate and symmetrically arranged along the quartz dielectric substrate.

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