A multi-band radio frequency unit combiner

Abstract

This invention discloses a multi-band RF unit combiner, relating to the field of combiner technology. It includes a combiner body with a PCB board fixedly connected inside. Precise filtering of the three frequencies is achieved through a low-pass filter, a band-pass filter, and a high-pass filter. Basic microwave microstrip combining is completed via a T-type combining microstrip node, an impedance-matching microstrip segment, and an SMA onboard RF socket. Microwave isolation and bandwidth are improved by using a resonant isolation microstrip segment and an interdigital resonant coupling unit. Low microwave intermodulation and high power are achieved by relying on a coaxial resonant filter cavity and a thickened-wall resonant tuning rod. A CT cross-coupled resonant cavity and a multi-stage impedance matching segment enhance microwave suppression and matching. An optical true-delay terahertz photonic RF combining branch is integrated. A high-resistivity silicon effective dielectric structure is introduced to solve the problems of high metal loss and broadband beam dispersion in terahertz bands. An amplitude-frequency inversion delay calibration architecture is used to uniformly correct the delay difference between microwave and terahertz links. A single device is compatible with microwave / 110~145GHz multi-band integrated RF bus.

Description

Technical Field

[0001] This invention relates to the field of combiner technology, specifically a multi-band radio frequency unit combiner. Background Technology

[0002] Multi-band RF unit combiners are passive RF devices in the field of wireless communication. Their core function is to combine two or more RF signals from different frequency bands into one output. They can also reverse the separation of multi-band signals. Through filtering design, they ensure that the signals of each frequency band do not interfere with each other. They allow multi-band signals to share the same antenna and feeder system, reducing the number of antennas and feeders used, saving hardware costs and installation space. They are widely used in indoor distribution systems, base station antennas, and multi-operator shared coverage scenarios.

[0003] Existing multi-band combiners mostly employ a single filter structure or cavity combining form, which generally suffers from poor frequency band isolation, high insertion loss, large size, and narrow impedance matching bandwidth. Moreover, most are single-ended output architectures, which cannot simultaneously achieve miniaturization, low intermodulation, and high suppression characteristics, making it difficult to adapt to the engineering requirements of indoor distributed systems for multi-frequency combining, differential compatibility, and high integration. Existing multi-band combiners generally rely on simple combining topologies, resulting in poor inter-band isolation, insufficient intermediate frequency bandwidth, weak high-frequency harmonic suppression, large signal run-through reflections, and uneven impedance matching. Furthermore, they only support single-ended output, making them unable to be efficiently adapted to differential antennas and difficult to simultaneously achieve high isolation, wideband matching, and low-interference transmission.

[0004] In addition, traditional combiners either use a pure microstrip structure, which has low power capacity and poor intermodulation suppression; or they use a pure cavity structure, which has large size and low integration. They generally suffer from inconsistent impedance matching, serious passive intermodulation interference, and cannot balance miniaturization and high power operation, making it difficult to meet the integrated high-performance requirements of modern communication systems.

[0005] Finally: Existing multi-band combiners generally have insufficient out-of-band rejection capability and limited inter-band isolation. Passive intermodulation suppression and power capacity are difficult to balance. Impedance matching is mostly a single-stage design with weak bandwidth expansion capability, and most are independent structures stacked together, failing to form a complete system of hierarchical progression and synergistic enhancement. Existing RF combiners only cover the microwave RF band and cannot be compatible with next-generation 110~145GHz terahertz photonic RF signals. Microwave and terahertz signals require two independent combining devices, resulting in large equipment stacking volume and superimposed link losses. Traditional phase-shifting RF combining topologies cannot achieve instantaneous broadband RF combining, lack a low-loss dielectric matching structure adapted for terahertz, and the high ohmic loss of metal microstrip in the terahertz band cannot meet the RF convergence requirements of high-speed terahertz communication above 8Gbps. There is no RF synchronization calibration architecture based on optical true delay, and the time delay difference between microwave and terahertz links cannot be uniformly corrected, resulting in severe intersymbol interference after combining. Summary of the Invention

[0006] Therefore, in order to overcome the above-mentioned shortcomings, the present invention provides a multi-band radio frequency unit combiner.

[0007] This invention is implemented as follows: a multi-band radio frequency unit combiner is constructed. The device includes a combiner body, with a PCB board fixedly connected inside. A low-pass filter is soldered to the right side of the top front end of the PCB board, a band-pass filter is soldered to the right side of the top front end of the PCB board, a high-pass filter is soldered to the center of the right side of the top right end of the PCB board, a T-shaped combining microstrip node is soldered to the center of the top front end of the PCB board, an impedance matching microstrip segment is soldered to the left side of the top front end of the PCB board, and an SMA onboard radio frequency socket is soldered to the rear end of the top end of the PCB board. An optical radio frequency coupling microstrip branch is integrated on the upper layer of the PCB board, and the optical radio frequency coupling microstrip branch includes an optical true time-delay coupling microstrip and an optoelectronic conversion matching pad.

[0008] Preferably, the combiner body further includes a resonant isolation microstrip segment, a resonant isolation microstrip segment is soldered to the top left end of the PCB board, an interdigital resonant coupling unit is soldered to the front side of the top left end of the PCB board, a stepped open-circuit stub filter unit is soldered to the rear side of the top right end of the PCB board, a multi-stage combining microstrip node is soldered to the front side of the top left end of the PCB board, a wideband impedance transition microstrip segment is soldered to the top left end of the PCB board, and an RF interface is soldered to the front side of the top left end of the PCB board. The optical true time delay coupling microstrip is connected in series between the wideband impedance transition microstrip segment and the multi-stage combining microstrip node. The optical true time delay coupling microstrip is equipped with a multi-frequency time delay calibration pad, and the multi-frequency time delay calibration pad is matched with the antenna amplitude-frequency inversion calibration link.

[0009] Preferably, the combiner body further includes a coaxial resonant filter cavity. The coaxial resonant filter cavity is fixed to the rear side solder at the center of the bottom of the PCB board. A thickened wall resonant tuning rod is fixed to the front right side solder at the bottom of the PCB board. A common cavity signal synthesis structure is fixed to the front right side solder at the bottom of the PCB board. A cavity impedance matching section is fixed to the front left side solder at the bottom of the PCB board. A photonic radio frequency feed window is opened on the side wall of the coaxial resonant filter cavity. The photonic radio frequency feed window is aligned and coupled with the photoelectric conversion matching pad at the end of the optical true time delay coupling microstrip. A high-resistivity silicon effective dielectric resonant thin layer is laid inside the window.

[0010] Preferably, the combiner body further includes a CT cross-coupled resonant cavity. The CT cross-coupled resonant cavity is fixed with solder at the center of the bottom left side of the PCB board. A low intermodulation resonant rod is fixed with solder at the front end of the bottom left side of the PCB board. A common cavity broadband synthesizer is fixed with solder at the front end of the bottom left side of the PCB board. A multi-level impedance matching segment is fixed with solder at the bottom of the PCB board, and the multi-level impedance matching segment is located on the right side of the CT cross-coupled resonant cavity. The photoelectric conversion matching pad of the upper optical radio frequency coupling microstrip branch on the PCB board is electrically connected to the CT cross-coupled resonant cavity for receiving 110~145GHz terahertz photonic radio frequency signals, realizing the multi-band common output of microwave radio frequency and terahertz photonic radio frequency. A dual-mode effective dielectric resonant core is added inside the CT cross-coupled resonant cavity. The dual-mode effective dielectric resonant core matches the 110~145GHz terahertz waveguide propagation constant to realize microwave and terahertz dual-frequency cross-coupling suppression.

[0011] Preferably, the bandpass filter is located to the right of the low-pass filter, the impedance matching microstrip segment is located to the left of the T-type combining microstrip node, and the fundamental mode transmission waveguide width of the optical true time delay coupling microstrip matches the effective dielectric waveguide w=600μm size parameter, forming a continuous broadband impedance link with the impedance matching microstrip segment.

[0012] Preferably, the wideband impedance transition microstrip segment is located to the right of the resonant isolation microstrip segment, the RF interface is located to the left front of the multi-stage combining microstrip node, the multi-stage combining microstrip node is located to the left of the impedance matching microstrip segment, and the multi-frequency delay calibration pads are respectively led out to the reserved calibration terminals on the side of the RF interface. The calibration terminals are connected to an external spectrum analyzer to complete the amplitude-frequency response inversion delay correction.

[0013] Preferably, the common cavity signal synthesis structure is located on the left side of the thickened wall resonant tuning rod, the low intermodulation resonant rod is located on the left side of the cavity impedance matching section, the common cavity broadband synthesizer is located on the left side of the low intermodulation resonant rod, and the common cavity broadband synthesizer has a composite metal-high resistivity silicon double-layer synthesis cavity inside, which is compatible with microwave radio frequency low intermodulation synthesis and terahertz photon low loss synthesis.

[0014] Preferably, the resonant isolation microstrip segment and the broadband impedance transition microstrip segment are arranged in series and are both located on the signal transmission path at the front end of the impedance matching microstrip segment. The input end of the multi-stage impedance matching segment is connected to the output end of the common cavity broadband synthesizer, and its output end is connected to the input end of the cavity impedance matching segment. The optical true time delay coupling microstrip segment and the resonant isolation microstrip segment are arranged in parallel and isolated. The electromagnetic transparency characteristics of optical signals are used to eliminate crosstalk in the microwave-terahertz band, and the isolation is improved to more than 60dB.

[0015] Preferably, the interdigital resonant coupling unit is coupled to the bandpass filter, the stepped open-circuit stub filter unit is coupled to the high-pass filter, and the multi-stage combining microstrip node and the T-type combining microstrip node are cascaded to form a dual-node low-reflection signal busbar structure. The dual-node low-reflection signal busbar structure adds a photonic signal busbar branch, which is connected to the output of the optical true time-delay coupling microstrip. The microwave and terahertz busbar signals are independently isolated and then synthesized.

[0016] Preferably, a method of using a multi-band radio frequency unit combiner includes the following steps:

[0017] Step 1: Basic microstrip combining; low-pass filter, band-pass filter, and high-pass filter are used for frequency division and gating, T-type combining microstrip node is connected and output through impedance matching microstrip segment; simultaneously, the optically generated terahertz coherent RF signal is connected to the optical true time delay coupling microstrip, and link time delay calibration based on antenna amplitude-frequency inversion is completed through multi-frequency time delay calibration pads;

[0018] Step 2: Isolation and matching enhancement; optimization of resonant isolation microstrip segment, interdigital resonant coupling unit, stepped open-circuit stub filter unit, multi-stage combining microstrip node, and broadband impedance transition microstrip segment calibration; optical true time delay coupling microstrip completes true time delay compensation for terahertz signals, eliminates broadband beam tilting effect, and high-resistivity silicon effective dielectric thin layer suppresses terahertz metal ohmic loss.

[0019] Step 3: Coaxial cavity enhancement; introduce a coaxial resonant filter cavity, thicken the wall resonant tuning rod for intermodulation, match the common cavity signal synthesis structure with the cavity impedance adaptation section; the photonic RF feed window of the coaxial resonant filter cavity completes the pre-filtering of terahertz and microwave signals in the cavity, and the dual-mode effective dielectric resonant core synchronously suppresses out-of-band harmonics of two frequency bands;

[0020] Step 4: CT cross-coupling integration; CT cross-coupling integration; adding CT cross-coupling resonant cavity transmission zeros, common cavity broadband synthesizer and multi-level impedance matching segments to achieve high-performance output across the entire frequency band; the CT cross-coupling resonant cavity synchronously generates independent transmission zeros for microwave and 110~145GHz terahertz signals, dual-frequency collaboratively suppresses interference, and completes microwave photonic integrated multi-band combined output.

[0021] The present invention has the following advantages: The present invention provides an improved multi-band radio frequency unit combiner, which, compared with similar devices, has the following improvements:

[0022] The multi-band RF unit combiner described in this invention achieves precise filtering of three frequencies through a low-pass filter, a band-pass filter, and a high-pass filter. Basic microwave microstrip combining is completed via a T-type combining microstrip node, an impedance-matching microstrip segment, and an SMA onboard RF socket. Microwave isolation and bandwidth are enhanced by a resonant isolation microstrip segment and an interdigital resonant coupling unit. Low microwave intermodulation and high power are achieved using a coaxial resonant filter cavity and a thickened-wall resonant tuning rod. Microwave suppression and matching are further strengthened through a CT cross-coupled resonant cavity and a multi-stage impedance matching segment. Finally, an integrated optical true-delay terahertz photonic RF combining branch is used, introducing a high-resistivity silicon effective dielectric structure to address the high loss and broadband beam dispersion issues of terahertz metals. An amplitude-frequency inversion delay calibration architecture is incorporated to uniformly correct the delay difference between microwave and terahertz links. A single device is compatible with microwave / 110~145GHz multi-band integrated RF bus. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process flow of the present invention;

[0024] Figure 2 This is a frontal structural schematic diagram of the present invention;

[0025] Figure 3 This is a rear view structural schematic diagram of the present invention;

[0026] Figure 4 This is a top-view three-dimensional structural diagram of the PCB board of the present invention;

[0027] Figure 5 This is a bottom-view three-dimensional structural diagram of the PCB board of the present invention.

[0028] The components include: combiner body-1, PCB board-2, low-pass filter-3, band-pass filter-4, high-pass filter-5, T-type combiner microstrip node-6, impedance matching microstrip segment-7, SMA onboard RF socket-8, resonant isolation microstrip segment-9, interdigital resonant coupling unit-10, stepped open-circuit stub filter unit-11, multi-stage combiner microstrip node-12, wideband impedance transition microstrip segment-13, RF interface-14, coaxial resonant filter cavity-15, thickened wall resonant tuning rod-16, common cavity signal synthesis structure-17, cavity impedance adaptation segment-18, CT cross-coupled resonant cavity-19, low intermodulation resonant rod-20, common cavity broadband synthesizer-21, and multi-stage impedance adaptation segment-22. Detailed Implementation

[0029] The following is in conjunction with the appendix Figures 1-5The principles and features of the present invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0030] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The embodiments of this invention will now be described according to its overall structure.

[0032] Example 1:

[0033] Please see Figures 1-5 This invention discloses a multi-band radio frequency unit combiner, comprising a combiner body 1, which serves as the outer casing of the entire product and protects the internal components; a PCB board 2, which is the mounting base for all components, and all radio frequency components are fixed on it; a low-pass filter 3, used to filter low-frequency signals; a band-pass filter 4, used to filter mid-frequency signals; a high-pass filter 5, used to filter high-frequency signals; a T-type combining microstrip node 6, which combines the three filtered signals together; an impedance matching microstrip segment 7, which makes signal transmission smoother and reduces reflection loss; and an SMA onboard radio frequency socket 8, used to output the combined radio frequency signal.

[0034] The combiner body 1 also includes a resonant isolation microstrip segment 9, which is used to separate signals of different frequency bands to prevent mutual interference; an interdigital resonant coupling unit 10 improves the passband width and suppression effect of intermediate frequency signals; a stepped open-circuit stub filter unit 11 enhances the harmonic filtering capability of high-frequency signals; a multi-stage combining microstrip node 12 further combines signals and reduces reflection; a wideband impedance transition microstrip segment 13 makes the impedance matching of the entire frequency band smoother; and an RF interface 14 converts single-ended signals into differential signals to improve anti-interference capability. An optical true time delay coupling microstrip is laid on the upper layer of the PCB board 2. The front end of the optical true time delay coupling microstrip is a photoelectric conversion matching pad, and the rear end is connected to the photonic signal bus branch. Multi-frequency delay calibration pads are printed in the middle section of the optical true time delay coupling microstrip, and calibration leads extend to the reserved terminals on the side of the RF interface.

[0035] The combiner body 1 also includes a coaxial resonant filter cavity 15, which improves the filtering effect and power carrying capacity; a thickened wall resonant tuning rod 16 reduces the magnetic field and current, suppressing passive intermodulation; a common cavity signal synthesis structure 17 realizes low-loss merging of multiple signals; a cavity impedance matching section 18 corrects the impedance mismatch problem caused by cavity coupling; a photonic radio frequency feed window is opened on the right side wall of the coaxial resonant filter cavity 15, and a high-resistivity silicon effective dielectric resonant thin layer is pasted on the inner wall of the window. The thickness of the thin layer matches the skin depth of electromagnetic waves from 110 to 145 GHz, which greatly reduces the terahertz metal transmission loss.

[0036] The combiner body 1 also includes a CT cross-coupled resonant cavity 19, which improves the isolation between frequency bands and out-of-band suppression; a low intermodulation resonant rod 20 further reduces system nonlinear interference; a common-cavity broadband synthesizer 21 improves power capacity and operating bandwidth; a multi-stage impedance matching section 22, in conjunction with the preceding matching structure, achieves precise impedance matching across the entire frequency band; a dual-mode effective dielectric resonant core is embedded in the center of the CT cross-coupled resonant cavity 19, which adopts a hexagonal periodic perforated high-resistivity silicon structure, based on the effective dielectric constant formula: ,in, The effective relative permittivity of the medium in the x-direction is calculated in batches by scanning the perforation diameter d and period a using CST electromagnetic simulation. Intrinsic relative permittivity of high-resistivity silicon substrate, standard value 11.7; The relative permittivity of air is a fixed value of 1. The air-fill duty cycle inside the silicon substrate is calculated from the perforation geometry. The diameter of a single hole in the hexagonal array is determined to be 180 μm based on the manufacturing process. The period length of the hexagonal lattice is constrained to 200 μm for wafer fabrication linewidth; after calculating the dielectric constant using the above formula, it is substituted into the formula for the propagation constant of the terahertz waveguide fundamental mode: ,in, : The mode propagation constant characterizes the rate of phase change of a terahertz wave propagating along a waveguide. : Silicon dielectric free space wavenumber, f is the operating frequency 110~145GHz, c is the speed of light in vacuum; The transverse and longitudinal transverse wavenumbers of the waveguide are calculated using the Maccari approximation method with a waveguide width w=600μm and a thickness h=500μm. The two sets of formulas are combined for calculation to match the 110~145GHz terahertz transmission resonance condition, while also being compatible with microwave RF resonance, thus achieving synchronous filtering and suppression in both microwave and terahertz bands.

[0037] The working principle of a multi-band radio frequency unit combiner based on Embodiment 1 is as follows:

[0038] First, when using this device, place it in the work area, and then connect it to an external power source to power the photoelectric conversion and time delay calibration auxiliary circuit on the PCB board 2 of this device.

[0039] Second, the basic combining process of the microwave link: Low-pass filter 3 accurately selects low-frequency signals, band-pass filter 4 stably selects mid-frequency signals, and high-pass filter 5 efficiently selects high-frequency signals. The three clean microwave signals are transmitted to the T-type combining microstrip node 6 to complete the convergence, and microwave reflection loss is eliminated by the impedance matching microstrip segment 7. The terahertz photonic RF link works synchronously: The optical heterodyne beat frequency generates a 110~145GHz coherent terahertz optical signal, which is connected to the optoelectronic conversion matching pad. After completing the optical-to-terahertz electrical signal conversion, it enters the optical true time-delay coupling microstrip. The traditional phase-shifting phased array beam offset formula is as follows: ,in, Frequency shift causes beam tilt angle, an inherent defect of phase-shifting architecture; The difference between the actual frequency and the center frequency of the signal; System design center operating frequency; The reference beam pointing angle, this formula proves that the beam will shift with frequency under broadband phase-shifting systems. The optical true time delay formula is: Where, T: optical signal transmission delay, which is determined only by the optical path length and is independent of the radio frequency; L: optical true-coupled microstrip equivalent optical path length, which is measured by the actual PCB wiring length; : Group velocity of light in a medium; The equivalent refractive index of the microstrip substrate is obtained from a table of PCB material parameters; this formula enables frequency-independent time delay compensation, completely eliminating terahertz beam tilt dispersion. The core phase fitting formula for link delay calibration is as follows: Where t: the actual delay difference between channels; Radio frequency phase difference at multiple frequency points, measured by connecting a spectrum analyzer to the calibration terminal. : Frequency sweep step size, customizable settings for the test instrument; linear fitting of amplitude and phase data collected from multiple frequency points to uniformly compensate for timing deviations between the microwave and terahertz links, thus avoiding inter-symbol interference after combining.

[0040] Third, the isolation matching enhancement layer: the resonant isolation microstrip segment 9 isolates microwave branch crosstalk, the interdigital resonant coupling unit 10 and the stepped open-circuit stub filter unit 11 optimize microwave out-of-band suppression, the multi-stage combining microstrip node 12 and the broadband impedance transition microstrip segment 13 smooth microwave impedance; the optical true time delay coupling microstrip and the resonant isolation microstrip segment 9 are arranged in parallel for isolation, the optical carrier has no radio frequency electromagnetic radiation, and the mutual isolation between microwave and terahertz signals exceeds 60dB; the photonic signal bus branch merges the calibrated terahertz radio frequency into the dual-node bus structure, and the microwave and terahertz physical branches are independently bused without coupling interference;

[0041] Fourth, the coaxial cavity enhancement layer: The coaxial resonant filter cavity 15 and the thickened-wall resonant tuning rod 16 optimize the low intermodulation characteristics of the microwave; the common cavity signal synthesis structure 17 and the cavity impedance matching section 18 complete the microwave cavity matching; the high-resistivity silicon effective dielectric resonant thin layer inside the photonic RF feed window is determined by the formula... , The equivalent dielectric constant of the medium is optimized, reducing the insertion loss of terahertz microstrip transmission from 3dB to 0.18dB / cm. The coaxial cavity simultaneously performs primary harmonic filtering on both microwave and terahertz signals, reducing the filtering load on the subsequent CT cavity.

[0042] Fifth, the integrated CT cross-coupling layer: CT cross-coupling resonant cavity 19, low intermodulation resonant rod 20, common cavity broadband composite 21, and multi-stage impedance matching segment 22 complete microwave full-band suppression matching; dual-mode effective dielectric resonant core combined formula. , The device is designed to match microwave and 110-145 GHz terahertz resonant propagation conditions, generating independent out-of-band transmission zeros for each frequency band. The two signals are integrated into a microwave-terahertz RF synthesis process within a common-cavity broadband synthesizer 21, ultimately outputting a hybrid multi-band RF signal via the SMA onboard RF socket 8. This single unit is compatible with both traditional mobile communication base station microwave and 110-145 GHz 8Gbps terahertz high-speed wireless communication RF convergence, resolving the shortcomings of existing discrete equipment stacking, link loss superposition, broadband beam dispersion, and inconsistent link delays.

[0043] Example 2:

[0044] Please see Figures 1-5 The multi-band radio frequency unit combiner of the present invention, compared with Embodiment 1, further includes the following steps:

[0045] Step 1: Basic microstrip combining; low-pass filter, band-pass filter, and high-pass filter are used for frequency division and gating, T-type combining microstrip node is connected and output through impedance matching microstrip segment; simultaneously, the optically generated terahertz coherent RF signal is connected to the optical true time delay coupling microstrip, and link time delay calibration based on antenna amplitude-frequency inversion is completed through multi-frequency time delay calibration pads;

[0046] Step 2: Isolation and matching enhancement; optimization of resonant isolation microstrip segment, interdigital resonant coupling unit, stepped open-circuit stub filter unit, multi-stage combining microstrip node, and broadband impedance transition microstrip segment calibration; optical true time delay coupling microstrip completes true time delay compensation for terahertz signals, eliminates broadband beam tilting effect, and high-resistivity silicon effective dielectric thin layer suppresses terahertz metal ohmic loss.

[0047] Step 3: Coaxial cavity enhancement; introduce a coaxial resonant filter cavity, thicken the wall resonant tuning rod for intermodulation, match the common cavity signal synthesis structure with the cavity impedance adaptation section; the photonic RF feed window of the coaxial resonant filter cavity completes the pre-filtering of terahertz and microwave signals in the cavity, and the dual-mode effective dielectric resonant core synchronously suppresses out-of-band harmonics of two frequency bands;

[0048] Step 4: CT cross-coupling integration; CT cross-coupling integration; adding CT cross-coupling resonant cavity transmission zeros, common cavity broadband synthesizer and multi-level impedance matching segments to achieve high-performance output across the entire frequency band; the CT cross-coupling resonant cavity synchronously generates independent transmission zeros for microwave and 110~145GHz terahertz signals, dual-frequency collaboratively suppresses interference, and completes microwave photonic integrated multi-band combined output.

[0049] This invention provides an improved multi-band RF unit combiner. It achieves precise three-band filtering through a low-pass filter 3, a band-pass filter 4, and a high-pass filter 5. Basic microwave microstrip combining is completed via a T-type combining microstrip node 6, an impedance-matching microstrip segment 7, and an SMA onboard RF socket 8. Microwave isolation and bandwidth are enhanced by a resonant isolation microstrip segment 9 and an interdigital resonant coupling unit 10. Low microwave intermodulation and high power are achieved using a coaxial resonant filter cavity 15 and a thickened-wall resonant tuning rod 16. Microwave suppression and matching are further strengthened through a CT cross-coupled resonant cavity 19 and a multi-stage impedance matching segment 22. Finally, an integrated optical true-delay terahertz photonic RF combining branch is used, introducing a high-resistivity silicon effective dielectric structure to address the high loss and broadband beam dispersion issues of terahertz metals. An amplitude-frequency inversion delay calibration architecture is incorporated to uniformly correct the delay difference between microwave and terahertz links. A single device is compatible with microwave / 110~145GHz multi-band integrated RF bus.

[0050] The above description shows and illustrates the basic principles, main features, and advantages of the present invention. Standard parts used in the present invention can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts, and equipment adopt conventional models in the prior art, and the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here.

[0051] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-band radio frequency unit combiner, characterized in that: The system includes a combiner body (1), a PCB board (2) is fixedly connected inside the combiner body (1), a low-pass filter (3) is fixed to the right side of the top front end of the PCB board (2) by solder, a band-pass filter (4) is fixed to the right side of the top front end of the PCB board (2) by solder, a high-pass filter (5) is fixed to the center of the right side of the top of the PCB board (2) by solder, a T-shaped combining microstrip node (6) is fixed to the center of the top front end of the PCB board (2) by solder, an impedance matching microstrip segment (7) is fixed to the left side of the top front end of the PCB board (2) by solder, an SMA onboard RF socket (8) is fixed to the rear end of the top of the PCB board (2), and an optical radio frequency coupling microstrip branch is integrated on the upper layer of the PCB board (2). The optical radio frequency coupling microstrip branch includes an optical true time delay coupling microstrip and an optoelectronic conversion matching pad.

2. The multi-band radio frequency unit combiner according to claim 1, characterized in that: The combiner body (1) also includes a resonant isolation microstrip segment (9). The resonant isolation microstrip segment (9) is fixed with solder on the top left end of the PCB board (2). An interdigital resonant coupling unit (10) is fixed with solder on the front side of the top left end of the PCB board (2). A stepped open-circuit stub filter unit (11) is fixed with solder on the rear side of the top right end of the PCB board (2). A multi-stage combining microstrip node (12) is fixed with solder on the front side of the top left end of the PCB board (2). A wideband impedance transition microstrip segment (13) is fixed with solder on the top left end of the PCB board (2). An RF interface (14) is fixed with solder on the front side of the top left end of the PCB board (2). The optical true time delay coupling microstrip is connected in series between the wideband impedance transition microstrip segment (13) and the multi-stage combining microstrip node (12). The optical true time delay coupling microstrip is equipped with a multi-frequency time delay calibration pad. The multi-frequency time delay calibration pad is matched with the antenna amplitude-frequency inversion calibration link.

3. The multi-band radio frequency unit combiner according to claim 2, characterized in that: The combiner body (1) also includes a coaxial resonant filter cavity (15). The coaxial resonant filter cavity (15) is fixed to the rear side of the bottom center of the PCB board (2) by solder. The thickened wall resonant tuning rod (16) is fixed to the front right side of the bottom of the PCB board (2). The common cavity signal synthesis structure (17) is fixed to the front right side of the bottom of the PCB board (2). The cavity impedance matching section (18) is fixed to the front left side of the bottom of the PCB board (2). A photonic radio frequency feed window is opened on the side wall of the coaxial resonant filter cavity (15). The photonic radio frequency feed window is aligned and coupled with the photoelectric conversion matching pad at the end of the optical true time delay coupling microstrip. A high-resistivity silicon effective dielectric resonant thin layer is laid inside the window.

4. The multi-band radio frequency unit combiner according to claim 3, characterized in that: The combiner body (1) also includes a CT cross-coupled resonant cavity (19). The CT cross-coupled resonant cavity (19) is fixed with solder on the center of the bottom left side of the PCB board (2). The low intermodulation resonant rod (20) is fixed with solder on the front end of the bottom left side of the PCB board (2). The common cavity broadband synthesizer (21) is fixed with solder on the front end of the bottom left side of the PCB board (2). The multi-stage impedance matching section (22) is fixed with solder on the bottom of the PCB board (2), and the multi-stage impedance matching section (22) is located in the CT cross-coupled resonant cavity (19). 9) On the right side, the photoelectric conversion matching pad of the upper optical radio frequency coupling microstrip branch of the PCB board (2) is electrically connected to the CT cross-coupled resonant cavity (19) to access 110~145GHz terahertz photonic radio frequency signals, so as to realize the multi-band common output of microwave radio frequency and terahertz photonic radio frequency. A dual-mode effective dielectric resonant core is added inside the CT cross-coupled resonant cavity (19). The dual-mode effective dielectric resonant core matches the 110~145GHz terahertz waveguide propagation constant to realize microwave and terahertz dual-frequency cross-coupling suppression.

5. The multi-band radio frequency unit combiner according to claim 4, characterized in that: The bandpass filter (4) is located to the right of the low-pass filter (3), and the impedance matching microstrip segment (7) is located to the left of the T-type combining microstrip node (6). The fundamental mode transmission waveguide width of the optical true time delay coupling microstrip matches the effective dielectric waveguide w=600μm size parameter, forming a continuous broadband impedance link with the impedance matching microstrip segment (7).

6. The multi-band radio frequency unit combiner according to claim 5, characterized in that: The wideband impedance transition microstrip segment (13) is located on the right side of the resonant isolation microstrip segment (9), the radio frequency interface (14) is located on the left front side of the multi-stage combining microstrip node (12), the multi-stage combining microstrip node (12) is located on the left side of the impedance matching microstrip segment (7), and the multi-frequency delay calibration pads are respectively led out to the reserved calibration terminal on the side of the radio frequency interface (14). The calibration terminal is connected to an external spectrum analyzer to complete the amplitude-frequency response inversion delay correction.

7. The multi-band radio frequency unit combiner according to claim 6, characterized in that: The common cavity signal synthesis structure (17) is located to the left of the thickened wall resonant tuning rod (16), the low intermodulation resonant rod (20) is located to the left of the cavity impedance matching section (18), the common cavity broadband synthesizer (21) is located to the left of the low intermodulation resonant rod (20), and the common cavity broadband synthesizer (21) has a composite metal-high resistivity silicon double-layer synthesis cavity inside, which is compatible with microwave radio frequency low intermodulation synthesis and terahertz photon low loss synthesis.

8. The multi-band radio frequency unit combiner according to claim 7, characterized in that: The resonant isolation microstrip segment (9) and the broadband impedance transition microstrip segment (13) are connected in series and are both located on the signal transmission path at the front end of the impedance matching microstrip segment (7). The input end of the multi-stage impedance matching segment (22) is connected to the output end of the common cavity broadband synthesizer (21), and its output end is connected to the input end of the cavity impedance matching segment (18). The optical true time delay coupling microstrip and the resonant isolation microstrip segment (9) are arranged in parallel and isolated. The electromagnetic transparency characteristics of optical signals are used to eliminate crosstalk in the microwave-terahertz band, and the isolation is improved to more than 60dB.

9. The multi-band radio frequency unit combiner according to claim 8, characterized in that: The interdigital resonant coupling unit (10) is coupled to the bandpass filter (4), the stepped open-circuit stub filter unit (11) is coupled to the high-pass filter (5), and the multi-stage combining microstrip node (12) and the T-type combining microstrip node (6) are cascaded to form a dual-node low-reflection signal busbar structure. The dual-node low-reflection signal busbar structure adds a photonic signal busbar branch, which is connected to the output terminal of the optical true time delay coupling microstrip. The microwave and terahertz busbar signals are isolated independently and then synthesized.

10. A method of using a multi-band radio frequency unit combiner, for implementing the multi-band radio frequency unit combiner as described in claim 9, characterized in that: Includes the following steps: Step 1: Basic microstrip assembly; The low-pass filter (3), band-pass filter (4), and high-pass filter (5) are frequency divided and selected, and the T-type combiner microstrip node (6) is matched and output through the impedance matching microstrip segment (7); Simultaneously, the optically generated terahertz coherent radio frequency signal is connected to the optical true time delay coupled microstrip, and the link time delay calibration based on antenna amplitude-frequency inversion is completed through multi-frequency time delay calibration pads; Step Two: Isolation and Matching Enhancement; Resonant isolation microstrip segment (9), interdigital resonant coupling unit (10), stepped open-circuit stub filter unit (11) line optimization, multi-stage combining microstrip node (12), wideband impedance transition microstrip segment (13) calibration; Optical true-delay coupled microstrip achieves true-delay compensation for terahertz signals, eliminates broadband beam tilting effects, and high-resistivity silicon effective dielectric thin layer suppresses terahertz metal ohmic loss. Step 3: Coaxial cavity enhancement; introduce a coaxial resonant filter cavity (15), thicken the wall resonant tuning rod (16) for intermodulation, and match the common cavity signal synthesis structure (17) with the cavity impedance matching section (18); the photonic radio frequency feed window of the coaxial resonant filter cavity (15) completes the pre-filtering of terahertz and microwave signals in the cavity, and the dual-mode effective dielectric resonant core synchronously suppresses the out-of-band harmonics of the two frequency bands; Step 4: CT cross-coupling integration; CT cross-coupling integration; add CT cross-coupling resonant cavity (19) transmission zero point, common cavity broadband synthesizer (21) and multi-level impedance matching segment (22) to achieve full-band high-performance output; CT cross-coupling resonant cavity (19) synchronously generates independent transmission zero points for microwave and 110~145GHz terahertz signals, dual-frequency collaboratively suppresses interference, and completes microwave photonic integrated multi-band combined output.

Images