Broadband Analog Complex-Correlation Microwave Radiometer

Abstract

The present invention provides a broadband analog complex correlation type microwave radiometer, which relates to the field of passive remote sensing detection technology. The present invention includes a dual-channel correlation RF front-end unit, an intermediate frequency filtering and amplifying unit, and an analog complex correlation unit; wherein, the analog complex correlation unit includes two analog complex correlation channels, and both of the two analog complex correlation channels include a broadband multiplication unit and an active differential filtering unit. The differential conversion of the input same-signal and quadrature-signal is performed through the broadband multiplication unit and then the multiplication process is carried out. The signal after the multiplication process is subjected to active differential filtering through the active differential filtering unit, and two orthogonal differential parameters are output. The designed analog complex correlation unit 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 the single-ended signal and better linearity under the same power supply voltage, and at the same time solve the problems of DC drift and common-mode interference suppression.

Description

Technical Field

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

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

[0003] The core connotation 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 a complex correlation system can avoid the influence of phase drift inside the radiometer channel on the test stability. Therefore, the complex correlation type radiometer is the mainstream form of the current interferometric microwave radiometer. The existing complex correlation type radiometers include digital complex correlation system radiometers and analog complex correlation system radiometers. Compared with the digital complex correlation system radiometer, the analog complex correlation system radiometer has the advantages of larger processing bandwidth and smaller volume.

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

[0005] (1) Technical Problems to be Solved

[0006] Aiming at the deficiencies of the existing technology, the present invention provides a broadband analog complex correlation type microwave radiometer, which solves the technical problem of poor common-mode interference suppression of the existing analog complex correlation system radiometer.

[0007] (2) Technical Solutions

[0008] To achieve the above object, the present invention is realized through the following technical solutions:

[0009] The present invention provides a broadband analog complex correlation type microwave radiometer, including a dual-channel correlation RF front-end unit, an intermediate frequency filtering and amplifying unit, and an analog complex correlation unit;

[0010] Wherein,

[0011] The input of the dual-channel correlation RF front-end unit is connected to the dual-channel antenna, and is used for performing low-noise amplification and filtering processing on the weak radiation signals of the target received by the antenna, and respectively performing two-way power splitting processing on the two processed radiation signals to form four output signals. After the four signals are subjected to mixing processing and then filtering, four broadband intermediate frequency signals are obtained;

[0012] The intermediate frequency filtering and amplifying unit includes four intermediate frequency filtering and amplifying channels cross-connected to four broadband intermediate frequency signals. The four intermediate frequency filtering and amplifying channels are respectively used to amplify, filter, and adjust the gain of the broadband intermediate frequency signals to obtain the first, second, third, and fourth intermediate frequency filtered and amplified signals. Among them, the first and third intermediate frequency filtered and amplified signals are the same signal, and the second and fourth intermediate frequency filtered and amplified signals are orthogonal signals;

[0013] The analog complex correlation unit includes two analog complex correlation channels. Both of the two analog complex correlation channels include a broadband multiplication unit and an active differential filtering unit. The two analog complex correlation channels respectively perform differential conversion on the input same-signal and orthogonal-signal through the broadband multiplication unit, and perform multiplication processing, and perform active differential filtering processing on the signal after the multiplication processing through the active differential filtering unit to output two orthogonal differential parameters.

[0014] Preferably, the dual-channel correlation RF front-end unit includes two low-noise amplifier and filter circuits, two two-way power dividers, four mixers, four filters, two power divider and phase shifter and amplifier circuits, and an amplifier and power divider;

[0015] Among them,

[0016] The two low-noise amplifier and filter circuits are used for low-noise amplification of two target weak radiation signals and filtering of out-of-band interference signals;

[0017] The two two-way power dividers divide the two amplified and filtered RF signals into four in-phase power-divided signals, and the four in-phase power-divided signals are respectively input into the four mixers;

[0018] The amplifier and power divider is used to amplify the input point-frequency local oscillator, divide it into two local oscillator signals, and respectively input the two local oscillator signals into the power divider and phase shifter and amplifier circuits;

[0019] The two power divider and phase shifter and amplifier circuits respectively distribute, amplify, and phase-shift the two local oscillator signals to obtain 4-way point-frequency local oscillators, and input the 4-way point-frequency local oscillators into the four mixers respectively;

[0020] The four mixers respectively adopt the zero-intermediate frequency frequency conversion system to fold and shift the energy of the RF signal with a bandwidth of N gigahertz to DC~N / 2 gigahertz;

[0021] The four filters respectively filter the outputs of the four mixers.

[0022] Preferably, both of the two low-noise amplifier and filter circuits include a first low-noise amplifier, a RF anti-interference filter, and a second low-noise amplifier connected in sequence;

[0023] Among them, the first low-noise amplifier and the second low-noise amplifier are used for low-noise amplification of the target weak radiation signal;

[0024] The radio frequency anti-interference filter is used to provide frequency selectivity for the radio frequency channel.

[0025] Preferably, the power splitter phase shifter amplifier circuit includes a local oscillator power splitter, 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;

[0026] The local oscillator power splitter in-phase splits the local oscillator signal into two paths, where the first path is sequentially connected to the first local oscillator amplifier, the second phase shifter, and the second local oscillator amplifier;

[0027] The second path is sequentially connected to the third local oscillator amplifier, the second phase shifter, and the fourth local oscillator amplifier.

[0028] Preferably, 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 at the same time.

[0029] Preferably, the dual-channel correlated radio frequency front-end unit further includes 8 attenuators, which are grouped in pairs and connected to the input ends of the four mixers respectively. Specifically, the outputs of the two power splitter circuits are input to the mixers via the attenuators, and the outputs of the mixers are input to the filter via the attenuators.

[0030] Preferably, the intermediate frequency filter amplification channel includes a first intermediate frequency amplifier, a band-pass filter, and a first intermediate frequency amplifier.

[0031] Preferably, the broadband multiplication unit includes: a first broadband balun, a second broadband balun, a broadband high-performance multiplier, and a passive differential filter;

[0032] Among them, the first broadband balun and the second broadband balun convert the two intermediate frequency filter amplification signals into differential signals and output them to the broadband high-performance multiplier. The broadband high-performance multiplier multiplies the input signals and then outputs them to the passive differential filter; the output impedance of the broadband high-performance multiplier is matched with the input impedance of the differential passive low-pass filter through a first matching network.

[0033] Preferably, the active differential filtering unit includes: a feedback network, a first operational amplifier, and a second operational amplifier. Among them,

[0034] The first operational amplifier is impedance-matched with the components in the broadband multiplication unit through a second matching network;

[0035] The first operational amplifier and the second operational amplifier are cascaded and matched through a third matching network;

[0036] A feedback network is connected between the compensation ports of the first operational amplifier and the second operational amplifier, and the feedback network realizes the negative feedback and filtering of the operational amplifiers of the first operational amplifier and the second operational amplifier.

[0037] (III) Beneficial effects

[0038] The present invention provides a broadband analog complex correlation type microwave radiometer. Compared with the prior art, it has the following beneficial effects:

[0039] The analog complex correlation unit designed in 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 the 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

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 It is a schematic diagram of the composition of an existing analog complex correlation type radiometer;

[0042] Figure 2 It is a schematic diagram of the structure of the broadband analog complex correlation type microwave radiometer according to the embodiment of the present invention;

[0043] Figure 3 Schematic diagram of the composition principle of the dual-channel correlation RF front-end unit;

[0044] Figure 4 Schematic diagram of the composition principle of the intermediate frequency filtering and amplification unit;

[0045] Figure 5 Schematic diagram of the composition principle of the analog complex correlator unit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] To make the objectives, 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 below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0047] By providing a broadband analog complex correlation type microwave radiometer in the embodiments of the present application, the technical problem of poor common-mode interference suppression of the existing analog complex correlation system radiometer is solved. In the analog complex correlation unit of the embodiments of the present invention, the input, output, and internal processing of the internal link all adopt differential design to maximize the suppression of possible introduced common-mode interference.

[0048] The technical solutions in the embodiments of the present application for solving the above technical problems have the following general idea:

[0049] The block diagram of the existing analog complex correlation microwave radiometer system is as Figure 1 shown, and its functions are composed of three parts: the microwave front-end part, the intermediate-frequency filtering and amplifying part, and the analog complex correlation processing part. Problems existing in the existing analog complex correlation microwave radiometer: The analog complex correlator has problems such as DC drift and poor common-mode interference suppression, and at the same time has poor amplitude-phase characteristics in the broadband intermediate-frequency phase shift band, affecting the system stability and measurement accuracy.

[0050] To solve the above problems, the embodiments of the present invention propose a broadband analog complex correlation type microwave radiometer. Based on the characteristic that the processing target of the microwave radiometer is the noise power spectrum, and using the characteristic that the radio frequency N gigahertz bandwidth noise will fold into the intermediate-frequency DC~N / 2 gigahertz bandwidth during the zero-intermediate-frequency frequency conversion process, the expansion of the instantaneous processable bandwidth of the radiometer is realized; using the linear multiplication principle of the mixing process, a point-frequency local oscillator is designed, and by changing the initial phase of the point-frequency local oscillator, the broadband intermediate-frequency phase shift is indirectly realized, which has the characteristics of high phase shift accuracy, good stability and easy implementation; at the same time, because the point-frequency local oscillator phase shift is adopted, no broadband phase shift additional phase fluctuation will be introduced; in addition, after traversing with the point-frequency local oscillator phase shift, the best in-phase path I (the maximum value of the detection voltage) and the quadrature path Q (the minimum value of the detection voltage) are obtained through complex correlation detection, overcoming the disadvantages of many parasitic parameters and poor orthogonality of the traditional broadband intermediate-frequency phase shift, and indirectly realizing the improvement of orthogonality. Different from the existing analog complex correlation unit using a single-ended circuit design, the analog complex correlation unit designed in the embodiments 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 the single-ended signal and better linearity under the same power supply voltage, and at the same time solve the problems of DC drift and common-mode interference suppression.

[0051] To better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with the accompanying drawings of the specification and specific implementation manners.

[0052] The embodiments of the present invention provide a broadband analog complex correlation type microwave radiometer, as Figure 2 shown, including: a dual-channel correlation radio frequency front-end unit, an intermediate-frequency filtering and amplifying unit, and an analog complex correlation unit;

[0053] Among them, the input of the dual-channel correlation radio frequency front-end unit is connected to the dual-channel antenna. The dual-channel correlation radio frequency front-end unit is used to perform low-noise amplification and filtering processing on the target weak radiation signals received by the dual-channel antenna, and perform two-way power splitting processing on the two processed radiation signals respectively to form four output signals. After the four signals are subjected to mixing processing and then filtered, four broadband intermediate-frequency signals are obtained;

[0054] The intermediate-frequency filtering and amplifying unit includes four intermediate-frequency filtering and amplifying channels, which are cross-connected to four broadband intermediate-frequency signals. The four intermediate-frequency filtering and amplifying channels are respectively used to amplify, filter, and adjust the gain of the broadband intermediate-frequency signals to obtain the first intermediate-frequency filtered and amplified signal, the second intermediate-frequency filtered and amplified signal, the third intermediate-frequency filtered and amplified signal, and the fourth intermediate-frequency filtered and amplified signal. Among them, the first intermediate-frequency filtered and amplified signal and the third intermediate-frequency filtered and amplified signal are the same signal, and the second intermediate-frequency filtered and amplified signal and the fourth intermediate-frequency filtered and amplified signal are orthogonal signals, which are input into the analog complex correlation unit in the way of taking the same signal as a group and the orthogonal signal as a group.

[0055] The analog complex correlation unit includes two analog complex correlation channels. Each of the two analog complex correlation channels includes a broadband multiplication unit and an active differential filtering unit. The two analog complex correlation channels respectively perform differential conversion on the input same signal and orthogonal signal through the broadband multiplication unit and perform multiplication processing, and perform active differential filtering processing on the signal after the multiplication processing through the active differential filtering unit to output two orthogonal differential parameters.

[0056] 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 the single-ended signal and better linearity under the same power supply voltage, and at the same time solve the problems of DC drift and common-mode interference suppression.

[0057] The following will Figures 2 to 5 describe each unit in detail:

[0058] As Figure 2 shown, the dual-channel correlation RF front-end unit includes two low-noise amplifier filtering circuits, two two-way power dividers, four mixers, four filters, two power divider phase-shifting and amplifying circuits, and one amplified power divider;

[0059] The two low-noise amplifier filtering circuits are used for low-noise amplification of the target weak radiation signal and filtering of out-of-band interference signals;

[0060] The two two-way power dividers divide the two amplified and filtered RF signals into four in-phase power-divided signals, and the four in-phase power-divided signals are respectively input into the four mixers;

[0061] The amplified power divider is used to amplify the input point-frequency local oscillator, divide it into two local oscillator signals, and respectively input the two local oscillator signals into the power divider phase-shifting and amplifying circuits;

[0062] The two power divider phase-shifting and amplifying circuits respectively distribute, amplify, and phase-shift the two local oscillator signals to obtain 4-way point-frequency local oscillators, and input the 4-way point-frequency local oscillators into the four mixers respectively;

[0063] Four mixers respectively adopt a zero - intermediate - frequency frequency - conversion system to fold and shift the energy of a radio - frequency signal with a bandwidth of N gigahertz to the frequency range from DC to N / 2 gigahertz;

[0064] Four filters respectively filter the outputs of the four mixers to achieve the filtering of the local - oscillator leakage signals.

[0065] Figure 3 The principle block diagram of the dual - channel correlated radio - frequency front - end unit is given. The channel A and channel B described in the figure are exactly the same. In the embodiment of the present invention, channel A is described in detail. The low - noise amplifier N1, radio - frequency anti - interference filter Z1, low - noise amplifier N2, and power splitter N3 are connected in sequence. The power splitter N3 splits the signal in - phase into two paths. One path is connected in sequence to the attenuator N4, mixer N5, attenuator N6, and low - pass filter Z3, and the other path is connected in sequence to the attenuator N7, mixer N8, attenuator N9, and low - pass filter Z4. Among them, N1 and N2 achieve 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 provides radio - frequency channel frequency selectivity for the band - pass filter to avoid the interference of external active radiation to the radiometer in a complex electromagnetic environment. Z3 and Z4 are low - pass filters to suppress the leaked local - oscillator signals. N4 and N7 are fixed attenuators, providing good high - frequency matching and optimizing the in - band fluctuations. The input local - oscillator signal is connected to the power splitter N34 in sequence. The power splitter N34 splits the local - oscillator signal in - phase into two paths. One path passes through the amplifier N33 and is sent to the local - oscillator power splitter N32 of the echo channel, and the other path is connected in sequence to the local - oscillator amplifier N25, local - oscillator power splitter N24. The power splitter N24 splits the local - oscillator signal in - phase into two paths again. One path is connected in sequence to the first local - oscillator amplifier N20, first phase shifter N19, second local - oscillator amplifier N18, and the local - oscillator port of the mixer N5, and the other path is connected in sequence to the third local - oscillator amplifier N21, second phase shifter N22, fourth local - oscillator amplifier N23, and the local - oscillator port of the mixer N8. N20, N21, and N25 are local - oscillator driver amplifiers. They and the power splitter N24 achieve active power splitting and amplification of the local - oscillator after frequency doubling and filtering. N20 and N21 also provide reverse isolation of the local - oscillator to prevent the standing - wave traction caused by the phase - shifting action of the phase shifter, which affects the accuracy of local - oscillator phase shifting. N19 and N22 are numerically - controlled phase shifters that can traverse phase shifting from 0° to 360°.

[0066] As Figure 2As shown in the figure, the intermediate frequency filtering and amplifying unit includes four intermediate frequency filtering and amplifying channels. Each intermediate frequency filtering and amplifying channel includes an amplifying and filtering circuit and a gain adjustment circuit. It should be noted that in the specific implementation process, the positions of the amplifying and filtering circuit and the gain adjustment circuit can be swapped. The amplifying and filtering circuit amplifies the broadband intermediate frequency signal after mixing and filters out the DC component generated by 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 filtering and amplifying unit contains four completely identical amplifying and filtering channels, which further filter and amplify the output signal of the double-channel related RF front-end unit after removing the DC to meet the requirements of the input signal frequency and power range of the subsequent complex correlator.

[0067] Figure 4 The principle block diagram of the intermediate frequency filtering and amplifying 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 completely identical. Here, only intermediate frequency channel 1 is described. 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 inputs and outputs of N41 and N42 adopt AC coupling to avoid interference with the operation of the subsequent analog complex correlator unit caused by the amplification of the components near the DC generated by zero intermediate frequency mixing. The signal bandwidth of the band-pass filter Z41 is 0.1 GHz to N / 2 GHz. The additional local oscillator noise introduced by the intermediate frequency signal in this band can be ignored.

[0068] As Figure 2 shown, the analog complex correlator unit includes two analog complex correlator channels. Each analog complex correlator 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 multiplication processing, and outputs a DC signal proportional to the target radiation intensity. The active differential filtering unit is used to further perform active differential filtering processing on the signal after multiplication processing, retain the bandwidth matching the requirements of the subsequent processing, and at the same time further condition the level of the differential signal after correlation processing to meet the interface level requirements of the subsequent analog-to-digital converter.

[0069] For each analog complex correlation channel, a multiplication process is performed on an in-phase intermediate frequency signal with a bandwidth of DC to N / 2 GHz and a quadrature intermediate frequency signal with a bandwidth of DC to N / 2 GHz. After active differential filtering, a pair of quadrature IQ signals are output. After passing through a broadband analog multiplier, the energy of the signal is distributed in the frequency range of DC to N / 2 GHz. Therefore, a low-pass filter with as low a cut-off frequency as possible is required to filter out the channel noise to the greatest extent, and only the bandwidth matching the signal variation needs to be retained. The input, output, and internal processing of the links within the analog complex correlation unit all adopt differential design to suppress the possible introduced common-mode interference to the greatest extent. It can provide twice the amplitude of the single-ended signal and better linearity under the same power supply voltage, and solve the problems of DC drift and common-mode interference suppression.

[0070] In the embodiment of the present invention, through the phase shift of the local oscillator inside the dual-channel correlation RF front-end unit, after the signals of the two channels are subjected to correlation operation by a broadband high-performance multiplier, according to the output voltage detection, in-phase and quadrature output signals are indirectly formed. The voltage values after taking the modulus of the in-phase and quadrature signals correspond to the amplitude signals for target temperature detection. The advantage of such processing is that the modulus value of the output voltage is independent of the phases of the I channel and the Q channel, and this processing eliminates the influence of the internal phase error of the system.

[0071] Figure 5 The composition schematic diagram of the analog complex correlator is given. The in-phase path and the quadrature path described in the figure are completely the same in terms of hardware composition. Only the in-phase path is described here. The in-phase path includes broadband baluns N51 and N55, a broadband high-performance multiplier N52, matching network 1, a passive differential filter Z51, matching network 2, an operational amplifier N53, matching network 3, an operational amplifier N54, and a feedback network. N51 and N55 are broadband baluns, and their function is to convert the two-channel intermediate frequency filtered and amplified signals into differential signals and output them to the subsequent broadband high-performance multiplier N52. N52 performs a multiplication process on the input signals and has the characteristics of broadband operation and high consistency. Matching network 1 realizes the impedance matching between the output impedance of N52 and the input impedance of the differential passive low-pass filter Z51. N53 and N54 are operational amplifiers. Matching network 2 realizes the impedance matching between the output impedance of the differential passive low-pass filter Z51 and the input impedance of N53. The function of matching network 3 is to realize the inter-stage matching between operational amplifiers N53 and N54. The feedback network realizes the negative feedback and filtering of the operational amplifier, and together with N53 and N54, constitutes an active differential low-pass filter.

[0072] In summary, compared with the prior art, the following beneficial effects are achieved:

[0073] 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 the single-ended signal and better linearity under the same power supply voltage, and at the same time solve the problems of DC drift and common-mode interference suppression.

[0074] 2. Based on the characteristic that the processing target of the embodiment of the present invention is the noise power spectrum, and by using the characteristic that the radio frequency N gigahertz bandwidth noise will fold into the intermediate frequency DC to N / 2 gigahertz bandwidth during the zero intermediate frequency frequency conversion process, the expansion of the instantaneous processable bandwidth of the radiometer is realized.

[0075] 3. By using the linear multiplication principle of the mixing process, the embodiment of the present invention designs a point frequency local oscillator. By changing the initial phase of the point frequency local oscillator, the broadband intermediate frequency phase shift is indirectly realized, which has the characteristics of high phase shift 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 the broadband phase shift will be introduced.

[0076] 4. After the point frequency local oscillator phase shift traversal is adopted in the embodiment of the present invention, the best in-phase path I (the maximum value of the detection voltage) and the quadrature path Q (the minimum value of the detection voltage) are obtained through complex correlation detection, overcoming the disadvantages of many parasitic parameters and poor orthogonality in the traditional broadband intermediate frequency phase shift, and indirectly realizing the improvement of the orthogonality.

[0077] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A broadband analog complex correlation type 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 the orthogonal signal through the broadband multiplication unit, and perform multiplication processing, and perform active differential filtering processing on the multiplied signal through the active differential filtering unit, and output two orthogonal differential parameters; Wherein, 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 divides 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.

2. The broadband analog complex correlation type microwave radiometer according to claim 1, 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.

3. The broadband analog complex correlation type microwave radiometer according to claim 1, 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.

4. The broadband analog complex correlation type microwave radiometer according to claim 3, 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.

5. The broadband analog complex correlation type microwave radiometer according to claim 1, 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.

6. The broadband analog complex correlation type microwave radiometer according to any one of claims 1 to 5, 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.

7. The broadband analog complex correlation type microwave radiometer according to any one of claims 1 to 5, 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.

8. The broadband analog complex correlation type microwave radiometer according to any one of claims 1 to 5, 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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