Novel broadband simulation multiple correlation type microwave radiometer

Abstract

The invention provides a novel broadband simulation multiple correlation type microwave radiometer, and relates to the technical field of passive remote sensing detection. The system comprises a double-path correlation radio frequency front-end unit, an intermediate-frequency filtering and amplifying unit and an analog multiple correlation unit, wherein the analog multiple correlation unit comprises two analog multiple correlation channels, each analog multiple correlation channel comprises a broadband multiplication unit and an active differential filtering unit, and the broadband multiplication units are used for carrying out differential conversion on input same signals and orthogonal signals and carrying out correlation operation; and performing active differential filtering processing on the signal after the correlation operation through an active differential filtering unit, and outputting two paths of orthogonal differential parameters. The analog multiple correlation unit designed by the invention adopts a full-link differential design, including differential passive / active filtering, amplification and transmission, the design can provide amplitude twice as large as that of a single-ended signal and better linearity under the same power supply voltage, and meanwhile, the problems of direct-current drift and common-mode interference suppression are solved.

Description

Technical Field

[0001] The invention relates to the technical field of passive remote sensing detection, and in particular to a novel broadband analog complex correlation type microwave radiometer. Background Art

[0002] As a passive microwave detection device, the microwave radiometer does not rely on the sun as an illumination source and is not affected by weather. It can realize all-day and all-weather ground / sea reconnaissance and observation, and has developed into an important means of intelligence collection.

[0003] The core of microwave radiometer detection is to characterize the characteristics of the target by passively receiving the weak microwave radiation energy amplitude difference between the observed target and the background. The use of complex correlation system can avoid the influence of internal phase drift of the radiometer channel on the test stability, so complex correlation radiometer is the mainstream form of interferometric microwave radiometer. Existing complex correlation radiometers include digital complex correlation system radiometers and analog complex correlation system radiometers. Compared with digital complex correlation system radiometers, analog complex correlation system radiometers have the advantages of larger processing bandwidth and smaller size.

[0004] However, in existing engineering designs, the analog complex correlator of the analog complex correlation system radiometer has the problem of poor common-mode interference suppression, which has an adverse effect on system stability and measurement accuracy. Summary of the invention

[0005] 1. Technical issues to be resolved In view of the deficiencies of the prior art, the present invention provides a novel broadband analog complex correlation type microwave radiometer, which solves the technical problem of poor common mode interference suppression of the prior analog complex correlation type radiometer.

[0006] (II) Technical solution To achieve the above objectives, the present invention is implemented through the following technical solutions: The present invention provides a novel broadband analog complex correlation type microwave radiometer, comprising a dual-path correlation radio frequency front end unit, an intermediate frequency filtering and amplifying unit and an analog complex correlation unit; in, The input of the dual-path related RF front-end unit is connected to the dual-path antenna, and is used to perform low noise amplification and filtering processing on the target weak radiation signal received by the dual-path antenna, and respectively perform two power division processing on the processed two-path radiation signal to form four-path output signals, and the four-path signals are mixed and then filtered to obtain four-path broadband intermediate frequency signals; The intermediate frequency filtering and amplifying unit comprises four intermediate frequency filtering and amplifying channels cross-connected with four broadband intermediate frequency signals, and the four intermediate frequency filtering and amplifying channels are respectively used for amplifying, filtering and gain adjusting the broadband intermediate frequency signals to obtain the first, second, third and fourth intermediate frequency filtering and amplifying signals; wherein the first and third intermediate frequency filtering and amplifying signals are the same signals, and the second and fourth intermediate frequency filtering and amplifying signals are orthogonal signals; The analog complex correlation unit includes two analog complex correlation channels, and the two analog complex correlation channels both include a broadband multiplication unit and an active differential filtering unit. The two analog complex correlation channels respectively perform differential conversion on the input identical signal and orthogonal signal through the broadband multiplication unit, and perform correlation operation, and perform active differential filtering processing on the signal after the correlation operation through the active differential filtering unit, and output two orthogonal differential parameters.

[0007] Preferably, the dual-channel related RF front-end unit includes two low-noise amplifier filter circuits, two two-power splitter circuits, four mixers, four filters, two power splitter phase-shift amplifier circuits and one amplifier power splitter; in, The two-channel low-noise amplifier and filter circuit is used for low-noise amplification of two-channel target weak radiation signals and filtering out-of-band interference signals; The two-way two-power division circuit converts the two-way radio frequency signals after amplification and filtering into four-way in-phase power division signals, and the four-way in-phase power division signals are respectively input into four mixers; The amplifier power divider is used to amplify the point frequency local oscillator input and divide it into two local oscillator signals, and input the two local oscillator signals into the power division phase shift amplifier circuit respectively; The two power division and phase shift amplifier circuits respectively distribute, amplify and phase shift the two local oscillator signals to obtain four point-frequency local oscillators, which are respectively input into four mixers; The four mixers respectively use a zero intermediate frequency conversion system to fold and move the energy of the radio frequency signal with a bandwidth of N GHz to DC to N / 2 GHz; The four filters filter the outputs of the four mixers respectively.

[0008] Preferably, the two low noise amplifier filter circuits each include a first low noise amplifier, a radio frequency anti-interference filter and a second low noise amplifier connected in sequence; Wherein, the first low noise amplifier and the second low noise amplifier are used for low noise amplification of the target weak radiation signal; The radio frequency anti-interference filter is used to provide frequency selectivity of the radio frequency channel.

[0009] Preferably, the power division and phase shift amplifier circuit comprises a local oscillator power divider, a first local oscillator amplifier, a first phase shifter, a second local oscillator amplifier, a third local oscillator amplifier, a second phase shifter, and a fourth local oscillator amplifier; The local oscillator power divider divides the local oscillator signal into two paths with the same phase, wherein the first path is connected in sequence to the first local oscillator amplifier, the second phase shifter, and the second local oscillator amplifier; The second path is connected in sequence to the third local oscillator amplifier, the second phase shifter, and the fourth local oscillator amplifier.

[0010] Preferably, the first local oscillator amplifier and the third local oscillator amplifier are used to amplify the local oscillator signal while providing reverse isolation of the local oscillator.

[0011] Preferably, the dual-path related RF front-end unit also includes 8 attenuators, which are connected to the input ends and input ends of four mixers in groups of two. Specifically, the outputs of the two power division circuits are input into the mixers via the attenuators, and the outputs of the mixers are input into the filters via the attenuators.

[0012] Preferably, the intermediate frequency filtering and amplifying channel includes a first intermediate frequency amplifier, a bandpass filter and a first intermediate frequency amplifier.

[0013] Preferably, the broadband multiplication unit comprises: a first broadband balun, a second broadband balun, a broadband high-performance multiplier and a passive differential filter; Among them, the first broadband balun and the second broadband balun convert the two intermediate frequency filtered and amplified signals into differential signals and output them to the broadband high-performance multiplier. The broadband high-performance multiplier multiplies the input signals and outputs them to the passive differential filter; the output impedance of the broadband high-performance multiplier and the input impedance of the differential passive low-pass filter are matched through the first matching network.

[0014] Preferably, the active differential filter unit comprises: a feedback network, a first operational amplifier, and a second operational amplifier, wherein: The first operational amplifier achieves impedance matching with the device in the broadband multiplication unit through a second matching network; Inter-stage matching is achieved between the first operational amplifier and the second operational amplifier through a third matching network; A feedback network is connected between the compensation ports of the first operational amplifier and the second operational amplifier, and the feedback network realizes negative feedback and filtering of the operational amplifiers of the first operational amplifier and the second operational amplifier.

[0015] (III) Beneficial effects The present invention provides a novel broadband analog complex correlation type microwave radiometer. Compared with the prior art, it has the following beneficial effects: The analog complex correlation unit designed in the present invention adopts a full-link differential design, including differential passive / active filtering, amplification, and transmission. The design can provide twice the amplitude of a single-ended signal and better linearity under the same power supply voltage, while solving the problems of DC drift and common-mode interference suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of the existing analog complex correlation radiometer composition; Figure 2 It is a structural schematic diagram of a novel broadband analog complex correlation type microwave radiometer according to an embodiment of the present invention; Figure 3 Schematic diagram of the composition of the dual-channel related RF front-end unit; Figure 4 Schematic diagram of the composition of the intermediate frequency filter amplifier unit; Figure 5 Schematic diagram of the composition of the analog complex correlator unit. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The embodiment of the present application solves the technical problem of poor common-mode interference suppression of existing analog complex correlation type radiometers by providing a new broadband analog complex correlation type microwave radiometer. The link input, output and internal processing in the analog complex correlation unit of the embodiment of the present invention all adopt a differential design to maximize the suppression of common-mode interference that may be introduced.

[0020] The technical solution in the embodiment of the present application is to solve the above technical problems, and the overall idea is as follows: The block diagram of the existing analog complex correlation microwave radiometer system is as follows: Figure 1 As shown in the figure, the function consists of three parts: microwave front end part, intermediate frequency filtering and amplification part and analog complex correlation processing part. The existing analog complex correlation microwave radiometer has the following problems: the analog complex correlator has DC drift and poor common mode interference suppression problems, and also has poor amplitude and phase characteristics within the broadband intermediate frequency phase shift band, which affects the system stability and measurement accuracy.

[0021] To solve the above problems, the embodiment of the present invention proposes a novel broadband analog complex correlation type microwave radiometer, based on the characteristic that the microwave radiometer processes the noise power spectrum as the processing target, and utilizes the characteristic that the radio frequency N GHz bandwidth noise will be folded into the intermediate frequency DC ~ N / 2 GHz bandwidth during the zero intermediate frequency conversion process, so as to realize the expansion of the instantaneous processable bandwidth of the radiometer; utilizes the linear multiplication principle of the mixing process, designs a point frequency local oscillator, and indirectly realizes broadband intermediate frequency phase shifting by changing the initial phase of the point frequency local oscillator, which has the characteristics of high phase shifting accuracy, good stability and easy realization; at the same time, since the point frequency local oscillator phase shift is adopted, the additional phase fluctuation of the broadband phase shift will not be introduced; in addition, after the point frequency local oscillator phase shift is traversed, the optimal in-phase path I (detection voltage maximum value) and orthogonal path Q (detection voltage minimum value) are obtained through complex correlation detection, which overcomes the disadvantages of many parasitic parameters and poor orthogonality of traditional broadband intermediate frequency phase shift, and indirectly realizes the improvement of orthogonality. Different from the existing analog complex correlation unit that adopts a single-ended circuit design, the analog complex correlation unit designed in the embodiment of the present invention adopts a full-link differential design, including differential passive / active filtering, amplification, and transmission. This design can provide twice the amplitude of a single-ended signal and better linearity under the same power supply voltage, while solving the problems of DC drift and common-mode interference suppression.

[0022] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0023] The embodiment of the present invention provides a novel broadband analog complex correlation type microwave radiometer, such as Figure 2 As shown, it includes: a dual-path correlation radio frequency front-end unit, an intermediate frequency filtering and amplifying unit and an analog complex correlation unit; The input of the dual-path related RF front-end unit is connected to the dual-path antenna. The dual-path related RF front-end unit is used to perform low noise amplification and filtering processing on the target weak radiation signal received by the dual-path antenna, and respectively perform two-power division processing on the processed two-path radiation signal to form four-path output signals. After the four-path signals are mixed, four-path broadband intermediate frequency signals are obtained after filtering. The intermediate frequency filtering and amplifying unit comprises four intermediate frequency filtering and amplifying channels, which are cross-connected with four broadband intermediate frequency signals, and the four intermediate frequency filtering and amplifying channels are respectively used for amplifying, filtering and gain adjusting the broadband intermediate frequency signals to obtain a first intermediate frequency filtering and amplifying signal, a second intermediate frequency filtering and amplifying signal, a third intermediate frequency filtering and amplifying signal and a fourth intermediate frequency filtering and amplifying signal; wherein the first intermediate frequency filtering and amplifying signal and the third intermediate frequency filtering and amplifying signal are the same signal, and the second intermediate frequency filtering and amplifying signal and the fourth intermediate frequency filtering and amplifying signal are orthogonal signals, which are input into the analog complex correlation unit in a manner of the same signals as one group and the orthogonal signals as one group; The analog complex correlation unit comprises two analog complex correlation channels, and the two analog complex correlation channels respectively comprise a broadband multiplication unit and an active differential filtering unit. The two analog complex correlation channels respectively perform differential conversion on the input identical signal and orthogonal signal through the broadband multiplication unit, and perform correlation operation, and perform active differential filtering processing on the signal after the correlation operation through the active differential filtering unit, and output two orthogonal differential parameters.

[0024] The analog complex correlation unit designed in the embodiment of the present invention adopts a full-link differential design, including differential passive / active filtering, amplification, and transmission. This design can provide twice the amplitude of a single-ended signal and better linearity under the same power supply voltage, while solving the problems of DC drift and common-mode interference suppression.

[0025] Combine the following Figure 2~Figure 5 A detailed description of each unit: like Figure 2 As shown, the dual-channel related RF front-end unit includes two low-noise amplifier filter circuits, two two-power division circuits, four mixers, four filters, two power division phase shift amplifier circuits and an amplifier power divider; Two-way low-noise amplifier and filter circuits are used for low-noise amplification of weak target radiation signals and filtering out-of-band interference signals; The two-way two-power division circuit converts the two-way RF signals after amplification and filtering into four-way in-phase power division signals, and the four-way in-phase power division signals are respectively input into four mixers; The amplifier power divider is used to amplify the point frequency local oscillator input and divide it into two local oscillator signals, and input the two local oscillator signals into the power division phase shift amplifier circuit respectively; The two power division and phase shift amplifier circuits respectively distribute, amplify and phase shift the two local oscillator signals to obtain four point-frequency local oscillators, which are input into four mixers respectively. The four mixers use a zero intermediate frequency conversion system to fold and move the energy of the RF signal with a bandwidth of N GHz to DC ~ N / 2 GHz; The four filters filter the outputs of the four mixers respectively to filter out the local oscillator leakage signal.

[0026] Figure 3The principle block diagram of the dual-path related RF front-end unit is given, and the channel A and channel B described in the figure are exactly the same. The embodiment of the present invention describes in detail the channel A, the low noise amplifier N1, the RF anti-interference filter Z1, the low noise amplifier N2, and the power divider N3 connected in sequence. The power divider N3 divides the signal into two paths in phase, one of which is connected in sequence to the attenuator N4, the mixer N5, the attenuator N6 and the low-pass filter Z3, and the other is connected in sequence to the attenuator N7, the mixer N8, the attenuator N9 and the low-pass filter Z4. Among them, N1 and N2 realize low-noise amplification of the target weak radiation signal (such as the target radiation weak energy signal), and have the characteristics of high gain and low noise coefficient. Z1 is a bandpass filter that provides RF channel frequency selectivity to avoid interference of external active radiation on the radiometer in complex electromagnetic environments. Z3 and Z4 are low-pass filters to suppress the leaked local oscillator signal. N4 and N7 are fixed attenuators that provide good high-frequency matching and optimize the fluctuation within the band. The input local oscillator signal is connected to the power divider N34 in sequence, and the power divider N34 splits the local oscillator signal into two paths in phase, one of which is sent to the local oscillator power divider N33 of the echo 2 channel, and the other is connected in sequence to the local oscillator amplifier N25 and the local oscillator power divider N24. The power divider N24 again splits the local oscillator signal into two paths in phase, one of which is connected in sequence to the first local oscillator amplifier N20, the first phase shifter N19, the second local oscillator amplifier N18 and the local oscillator port of the mixer N5, and the other is connected in sequence to the third local oscillator amplifier N21, the second phase shifter N22, the fourth local oscillator amplifier N23 and the local oscillator port of the mixer N8. N20, N21, and N25 are local oscillator drive amplifiers. They and the power divider N24 realize the active power division amplification of the local oscillator after the frequency doubling filter. N20 and N21 also provide reverse isolation of the local oscillator to prevent the standing wave traction caused by the phase shifter phase shifting action, which affects the accuracy of the local oscillator phase shifting. N19 and N22 are digitally controlled phase shifters that can traverse the phase shift range from 0° to 360°.

[0027] like Figure 2 As shown, the intermediate frequency filter amplification unit includes four intermediate frequency filter amplification channels, each intermediate frequency filter amplification channel includes an amplification filter circuit and a gain adjustment circuit. It should be noted that in the specific implementation process, the amplification filter circuit and the gain adjustment circuit can be swapped. The amplification filter circuit amplifies the broadband intermediate frequency signal after mixing and filters out the DC component generated by the zero intermediate frequency mixing. The gain adjustment circuit can adjust the link gain of each branch according to the system's instructions to balance the amplitude inconsistency between channels. In the specific implementation process, the intermediate frequency filter amplification unit includes four completely consistent amplification filter channels, which further filter and amplify the phase-shifted mixing output signal of the dual-channel related RF front-end unit after removing the DC to meet the requirements of the subsequent complex correlator for the input signal frequency and power range.

[0028] Figure 4The principle block diagram of the intermediate frequency filter amplifier unit is given. The intermediate frequency channel 1, intermediate frequency channel 2, intermediate frequency channel 3 and intermediate frequency channel 4 described in the figure are exactly the same. Only intermediate frequency channel 1 is described here. Taking intermediate frequency channel 1 as an example, the intermediate frequency amplifier N41, filter Z41 and intermediate frequency amplifier N42 are connected in sequence. The input and output of N41 and N42 are all AC coupled to avoid the interference of the subsequent analog complex correlation unit operation after the components near the DC generated by zero intermediate frequency mixing are amplified. The signal bandwidth of the bandpass filter Z41 is 0.1 GHz to N / 2 GHz. The additional local oscillator noise introduced by the intermediate frequency signal in this band due to mixing can be ignored.

[0029] like Figure 2 As shown, the analog complex correlation unit includes two analog complex correlation channels, each analog complex correlation channel includes a broadband multiplication unit and an active differential filtering unit, the broadband multiplication unit completes the differential conversion of the input single-ended intermediate frequency signal, performs correlation operation, and outputs a DC signal proportional to the target radiation intensity. The active differential filtering unit is used to further perform active differential filtering on the signal after the correlation operation, retain the bandwidth matching the requirements of the post-stage processing, and further adjust the level of the differential signal after the correlation processing to meet the interface level requirements of the post-stage analog-to-digital converter.

[0030] Each analog complex correlation channel performs correlation operations on an in-phase intermediate frequency signal with a bandwidth of DC to N / 2 GHz and an orthogonal intermediate frequency signal with a bandwidth of DC to N / 2 GHz, and outputs a pair of orthogonal IQ signals after active differential filtering. After the signal passes through the broadband analog multiplier, the energy is distributed to the frequency range of DC to N / 2 GHz, so a low-pass filter with the lowest possible cutoff frequency is required to filter out the channel noise to the maximum extent, retaining only the bandwidth that matches the signal change. The link input, output and internal processing in the analog complex correlation unit are all differentially designed to minimize the common-mode interference that may be introduced. Under the same power supply voltage, it can provide twice the amplitude of the single-ended signal and better linearity, solving the problems of DC drift and common-mode interference suppression.

[0031] In the embodiment of the present invention, by phase shifting of the local oscillator inside the dual-channel related RF front-end unit, the signals of the two channels are correlated by a broadband high-performance multiplier, and then the in-phase and quadrature output signals are indirectly formed according to the output voltage detection. The voltage amount after the modulus value of the in-phase and quadrature signals corresponds to the amplitude signal of the target temperature detection. The advantage of such processing is that the output voltage modulus value is independent of the phase of the I and Q channels, and such processing eliminates the influence of the internal phase error of the system.

[0032] Figure 5The schematic diagram of the analog complex correlator is given. The in-phase path and the quadrature path described in the figure are completely consistent in hardware composition. Only the in-phase path is described here. The broadband baluns N51 and N55, broadband high-performance multiplier N52, matching network 1, passive differential filter Z51, matching network 2, operational amplifier N53, matching network 3, operational amplifier N54 and feedback network are connected in sequence.

[0033] N51 and N55 are broadband baluns, which convert the two intermediate frequency filtered amplified signals into differential signals and output them to the subsequent broadband high-performance multiplier N52. N52 multiplies the input signals and has the characteristics of broadband operation and high consistency. Matching network 1 realizes the matching of the output impedance of N52 with the input impedance of the differential passive low-pass filter Z51. N53 and N54 are operational amplifiers, and matching network 2 realizes the matching of the output impedance of the differential passive low-pass filter Z51 with the input impedance of N53. Matching network 3 realizes the inter-stage matching of operational amplifiers N53 and N54. The feedback network realizes the negative feedback and filtering of the operational amplifier, and together with N53 and N54, it forms an active differential low-pass filter.

[0034] In summary, compared with the prior art, the present invention has the following beneficial effects: 1. The analog complex correlation unit designed in the embodiment of the present invention adopts a full-link differential design, including differential passive / active filtering, amplification, and transmission. This design can provide twice the amplitude of a single-ended signal and better linearity under the same power supply voltage, while solving the problems of DC drift and common-mode interference suppression.

[0035] 2. The embodiment of the present invention is based on the characteristic that the microwave radiometer processes the noise power spectrum, and utilizes the characteristic that the RF N GHz bandwidth noise will be folded into the intermediate frequency DC ~ N / 2 GHz bandwidth during the zero intermediate frequency conversion process, so as to achieve the expansion of the instantaneous processable bandwidth of the radiometer.

[0036] 3. The embodiment of the present invention utilizes the linear multiplication principle of the frequency mixing process to design a point-frequency local oscillator, and indirectly realizes broadband intermediate frequency phase shifting by changing the initial phase of the point-frequency local oscillator, which has the characteristics of high phase shifting accuracy, good stability, and easy implementation. At the same time, since the point-frequency local oscillator phase shift is adopted, no additional phase fluctuation of broadband phase shifting is introduced.

[0037] 4. The embodiment of the present invention uses point-frequency local oscillator phase shifting to traverse, and then obtains the best in-phase path I (detection voltage maximum) and orthogonal path Q (detection voltage minimum) through complex correlation detection, which overcomes the shortcomings of traditional broadband intermediate frequency phase shifting, such as many parasitic parameters and poor orthogonality, and indirectly achieves the improvement of orthogonality.

[0038] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A novel broadband analog complex correlation microwave radiometer, characterized in that: It includes a dual-path correlation RF front-end unit, an intermediate frequency filter amplifier unit and an analog complex correlation unit; in, The input of the dual-path related RF front-end unit is connected to the dual-path antenna, and is used to perform low noise amplification and filtering processing on the target weak radiation signal received by the dual-path antenna, and respectively perform two power division processing on the processed two-path radiation signal to form four-path output signals, and the four-path signals are mixed and then filtered to obtain four-path broadband intermediate frequency signals; The intermediate frequency filtering and amplifying unit comprises four intermediate frequency filtering and amplifying channels cross-connected with four broadband intermediate frequency signals, and the four intermediate frequency filtering and amplifying channels are respectively used for amplifying, filtering and gain adjusting the broadband intermediate frequency signals to obtain the first, second, third and fourth intermediate frequency filtering and amplifying signals; wherein the first and third intermediate frequency filtering and amplifying signals are the same signals, and the second and fourth intermediate frequency filtering and amplifying signals are orthogonal signals; The analog complex correlation unit includes two analog complex correlation channels, and the two analog complex correlation channels both include a broadband multiplication unit and an active differential filtering unit. The two analog complex correlation channels respectively perform differential conversion on the input identical signal and orthogonal signal through the broadband multiplication unit, and perform correlation operation, and perform active differential filtering processing on the signal after the correlation operation through the active differential filtering unit, and output two orthogonal differential parameters.

2. The novel broadband analog complex correlation type microwave radiometer as claimed in claim 1, characterized in that: The dual-channel related RF front-end unit includes two low-noise amplifier filter circuits, two two-power splitter circuits, four mixers, four filters, two power splitter phase-shift amplifier circuits and an amplifier power splitter; in, The two-channel low-noise amplifier and filter circuit is used for low-noise amplification of two-channel target weak radiation signals and filtering out-of-band interference signals; The two-way two-power division circuit converts the two-way radio frequency signals after amplification and filtering into four-way in-phase power division signals, and the four-way in-phase power division signals are respectively input into four mixers; The amplifier power divider is used to amplify the point frequency local oscillator input and divide it into two local oscillator signals, and input the two local oscillator signals into the power division phase shift amplifier circuit respectively; The two power division and phase shift amplifier circuits respectively distribute, amplify and phase shift the two local oscillator signals to obtain four point-frequency local oscillators, which are respectively input into four mixers; The four mixers respectively use a zero intermediate frequency conversion system to fold and move the energy of the radio frequency signal with a bandwidth of N GHz to DC to N / 2 GHz; The four filters filter the outputs of the four mixers respectively.

3. The novel broadband analog complex correlation type microwave radiometer as claimed in claim 2, characterized in that: The two-way low noise amplifier filter circuits each include a first low noise amplifier, a radio frequency anti-interference filter and a second low noise amplifier connected in sequence; Wherein, the first low noise amplifier and the second low noise amplifier are used for low noise amplification of the target weak radiation signal; The radio frequency anti-interference filter is used to provide frequency selectivity of the radio frequency channel.

4. The novel broadband analog complex correlation type microwave radiometer as claimed in claim 2, characterized in that: The power division and phase shift amplifier circuit comprises a local oscillator power divider, a first local oscillator amplifier, a first phase shifter, a second local oscillator amplifier, a third local oscillator amplifier, a second phase shifter, and a fourth local oscillator amplifier; The local oscillator power divider divides the local oscillator signal into two paths with the same phase, wherein the first path is connected in sequence to the first local oscillator amplifier, the second phase shifter, and the second local oscillator amplifier; The second path is connected in sequence to the third local oscillator amplifier, the second phase shifter, and the fourth local oscillator amplifier.

5. The novel broadband analog complex correlation type microwave radiometer as claimed in claim 4, characterized in that: The first local oscillator amplifier and the third local oscillator amplifier are used to amplify the local oscillator signal and provide reverse isolation of the local oscillator.

6. The novel broadband analog complex correlation type microwave radiometer as claimed in claim 2, characterized in that: The dual-path related RF front-end unit also includes 8 attenuators, which are connected to the input and output ends of four mixers in groups of two. Specifically, the outputs of the two power division circuits are input into the mixers via the attenuators, and the outputs of the mixers are input into the filters via the attenuators.

7. The novel broadband analog complex correlation microwave radiometer according to any one of claims 1 to 6, characterized in that: The intermediate frequency filtering and amplifying channel includes a first intermediate frequency amplifier, a bandpass filter and a first intermediate frequency amplifier.

8. The novel broadband analog complex correlation microwave radiometer according to any one of claims 1 to 6, characterized in that: The broadband multiplication unit includes: a first broadband balun, a second broadband balun, a broadband high-performance multiplier and a passive differential filter; Among them, the first broadband balun and the second broadband balun convert the two intermediate frequency filtered and amplified signals into differential signals and output them to the broadband high-performance multiplier. The broadband high-performance multiplier multiplies the input signals and outputs them to the passive differential filter; the output impedance of the broadband high-performance multiplier and the input impedance of the differential passive low-pass filter are matched through the first matching network.

9. The novel broadband analog complex correlation type microwave radiometer according to any one of claims 1 to 6, characterized in that: The active differential filter unit includes: a feedback network, a first operational amplifier, and a second operational amplifier, wherein: The first operational amplifier achieves impedance matching with the device in the broadband multiplication unit through a second matching network; Inter-stage matching is achieved between the first operational amplifier and the second operational amplifier through a third matching network; A feedback network is connected between the compensation ports of the first operational amplifier and the second operational amplifier, and the feedback network realizes negative feedback and filtering of the operational amplifiers of the first operational amplifier and the second operational amplifier.

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