CN1163407A - Active zero-beating radar system - Google Patents
Active zero-beating radar system Download PDFInfo
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- CN1163407A CN1163407A CN 97103067 CN97103067A CN1163407A CN 1163407 A CN1163407 A CN 1163407A CN 97103067 CN97103067 CN 97103067 CN 97103067 A CN97103067 A CN 97103067A CN 1163407 A CN1163407 A CN 1163407A
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- frequency mixer
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- directional coupler
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Abstract
Monostatic homodyne radar system, in particular for continuous wave operation, in which one input port of a balanced mixer (2) is connected to an oscillator (1) and another input port of the mixer is connected to an antenna (3). The mixer has a directional coupler with a 90 DEG phase difference between the coupling arms. The load impedances of the coupling arms have a reflection factor greater than 0.3, so that coupling of the power supplied from the oscillator to the antenna ensues, which coupling is sufficient for the radiation.
Description
Radar system drops into civil area more and more, for example at commercial measurement technology (for example level gauging), at communication electronics (distance alarm, ground speed is measured) and at consumer field (mobile alarm device, door opener) etc. under the operating position, depend on that whether technical input is reduced to minimum degree, especially will see price.The radar system that is particularly suitable for this class application is used a kind of active structure, and its antenna both can be used for emission and also can be used for receiving.A kind of like this radar system is called active radar system, and it is just in time opposite with the bistatic radar system that emitting antenna and receiving antenna separate.In traditional Radar Technology, continue under the general structure situation of emission radar system, the high-frequency signal that oscillator produces not only is used as through the antenna emission and transmits, also use according to the homodyne principle, received signal changes much lower intermediate frequency (difference frequencies of two signals) in frequency mixer.A part of power of providing of oscillator is by means of the directional coupler shunting that transmits and be transported to frequency mixer for this purpose, a kind of like this system is depicted in Fig. 3, oscillator 1 provides high-frequency signal, tells a part and be sent to frequency mixer 3 from the high-frequency signal of directional coupler 11.Be implemented in separting transomission and received signal on the antenna by circulator 12.Respectively by the application difference of system, the frequency of high-frequency signal or remain unchanged (for example at radar Doppler) perhaps change (for example frequently transfer continuous wave radar, pulse frequency is transferred radar) by external modulation signal 4.Fig. 3 also paints into for the joint 4 of external modulation signal feed plate configuration be the joint 5 of intermediate frequency leading-out end configuration.
The circulator of using in this device 12 becomes makes basic obstacle simple, low cost radar system.Do not have the good structure of this circulator to transmit and receive two antennas separately and realize (being bistatic radar) the most simply by application.Be disadvantageous at first mainly in this case by the increase of the external dimensions of antenna decision.Also have, because the skew of the locus of antenna especially can not be accurately consistent at the directivity characteristic of near region.Under the active radar system situation,, also can abandon circulator as selecting the structure of Fig. 4.In this structure, directional coupler 14 also can be used for the received signal of coming from antenna is sent on the high frequency input terminal of frequency mixer 13.According to the size of the insertion of directional coupler 14 decay, different with the structure with circulator, the power of received signal also not exclusively is sent to frequency mixer.The low receiving sensitivity of the receiver that therefore causes considers that the little propagation distance (being 200 meters to the maximum) in this paper described application at the beginning can tolerate mostly.
The hypothesis frequency mixer has input end separately to local oscillator signal and high-frequency received signal in said structure.The structure of liking the band balanced mixer of usefulness in microwave technology is exactly this situation.Two kinds of high-frequency signals for the treatment of mixing are by a common joint input under non-balanced frequency mixers (for example diode mixer) situation.Replacing the directional coupler mode along separate routes when using this frequency mixer with T, is possible to the further simplification of system shown in Figure 4.The basic shortcoming of this improvement project is: because of the oscillator demodulation amplitude noise in non-balanced frequency mixers has damaged sensitivity.As if only be suitable for spread scope has only several meters detecting devices to this solution.
Task of the present invention is: propose a kind of simplification radar system, it needs a few components following of cramped construction size situation.
This task is solved by the radar system with following feature: active zero-beating radar system
A) be equipped with oscillator (1) with the generation high-frequency signal,
B) be equipped with balanced mixer (2) with two input gates and an out gate and
C) be equipped with antenna (3),
D) at this moment, an input gate of frequency mixer links to each other with oscillator, and an input gate links to each other with antenna,
E) at this moment, frequency mixer comprises the directional coupler (6) with 90 ° of phase differential between coupling arm,
F) at this moment, this directional coupler have two input ends of forming the frequency mixer input gate (P1, P2) and two output terminals (P3, P4), and
G) at this moment, this output terminal is connected on the one end with such impedance, and the reflection coefficient of its generation is so big at least, to such an extent as to the overcoupling that the power that provided between the frequency mixer input gate by oscillator is enough used for the emissive power of regulation has been provided.
Further develop by the dependent claims item and provide.
According to the described radar system of invention, it relates to the active zero-beating radar system that (for example) can be used for continuous oscillation operation.At the oscillator of the promising generation high-frequency signal of this radar system and be useful on the antenna that transmits and receives.This oscillator and antenna are usually received the input gate of frequency mixer separately, and frequency mixer has out gate in addition.Frequency mixer is the balanced mixer that comprises a directional coupler and two nonlinear organization elements.Phase differential between two coupling arms of directional coupler is 90 °.Frequency mixer is such design, and coupling arm is connected on the one end to have the loaded impedance that so obviously surpasses zero reflection coefficient, to such an extent as to the enough share overcoupling in the power that oscillator is prepared are to another input gate of frequency mixer, for the emission domination.The intermediate frequency that mixing by oscillator signal and received signal produces can tap on the out gate of frequency mixer.
Below rely on Fig. 1 and Fig. 2 to elaborate according to the described system of invention.
Fig. 1 provides according to the described apparatus structure arrangement of invention with the form of figure.
Fig. 2 has provided the graphic texture of the frequency mixer that uses in the structure of Fig. 1.
Fig. 1 has described the structure be made up of oscillator 1, frequency mixer 2 and antenna 3.And the external modulation of the high-frequency signal that oscillator produces realizes by joint 4.The intermediate frequency that frequency mixer provides is arranged for using on the out gate joint 5 of frequency mixer.Represent that by means of arrow shown in the crooked dotted line power section ground that oscillator provides is to the antenna terminal overcoupling.The local oscillator input (LO input) of frequency mixer 2 directly links to each other with oscillator 1, and the high frequency of frequency mixer input (RF input) directly links to each other with antenna 3.Under the balanced mixer situation of general version, at this moment for example used the structure of the described at the beginning Fig. 3 of this paper and Fig. 4, purpose is to make all three (two input gates, out gates) as far as possible fully decoupling.If this can cause such result under Fig. 1 structure situation, by not emission of antenna, because be absorbed in frequency mixer to the whole power of frequency mixer input gate from oscillator.Therefore, be modulation like this according to the balanced mixer of application of the present invention, the determining section overcoupling of the high-frequency signal power that is provided by oscillator is to another input gate of frequency mixer, and arrival is led on the path of antenna 3.
Fig. 2 has described the balanced mixer schematic circuit with schottky diode.This frequency mixer comprises directional coupler 6, converting network 7,8 (TN), diode 9,10 and the CLC element with joint 5 (frequency mixer out gate). Diode 9,10 is oppositely settled each other, therefore obtains desirable balancing effect on out splice going splice 5.Output terminal P3, the P4 of linear combination arrival direction coupling mechanism 6 of signal that leads to input end P1, the P2 of directional coupler.Diode is because its nonlinear characteristic curve produces signal by way of parenthesis when difference frequency, and difference frequency arrives joint 5 by the low-pass filter of being made up of the CLC element with intermediate-freuqncy signal.Converting network 7,8th, the impedance of such conversion diode 9,10, at the output terminal P3 of directional coupler, the last generation of P4 has the identical load impedance of normal reflection coefficient.If the impedance of diode directly caused desirable reflection coefficient or for example on diode in addition suitable DC voltage can cause this reflection coefficient, so this converting network also can be cancelled.Can use the semiconductor structure element that other has the nonlinear characteristic curve in balanced structure, for example transistor replaces diode.At first adjust reflection coefficient and will be higher than zero significantly; Preferred value is in and is higher than in 0.3 the scope.Though have unattenuated reflection coefficient, based on 90 ° of phase differential selecting between the coupling arm, the input gate perfect match of frequency mixer.Uncoupling is cancelled, and the power attenuation between input gate is 1/|R|
2If (for example) select | R|=2
-1/2, the power of then presenting to input gate has half to transfer another input gate to.
Claims (5)
1, active zero-beating radar system
A) be equipped with oscillator (1) with the generation high-frequency signal,
B) be equipped with balanced mixer (2) with two input gates and an out gate and
C) be equipped with antenna (3),
D) at this moment, an input gate of frequency mixer links to each other with oscillator, and an input gate links to each other with antenna,
E) at this moment, frequency mixer comprises the directional coupler (6) with 90 ° of phase differential between coupling arm,
F) at this moment, this directional coupler have two input ends of forming the frequency mixer input gate (P1, P2) and two output terminals (P3, P4), and
G) at this moment, this output terminal is connected on the one end with such impedance, and the reflection coefficient of its generation is so big at least, to such an extent as to the overcoupling that the power that provided between the frequency mixer input gate by oscillator is enough used for the emissive power of regulation has been provided.
2, according to claim item 1 described radar system, it is characterized in that having reflection coefficient and be at least 0.3.
3, according to claim item 1 or 2 described radar systems, it is characterized in that, frequency mixer comprises two converting networks (7,8), each converting network is connected respectively to an output terminal (P3 of directional coupler with one input end, P4) on, and be connected respectively on the nonlinear circuit element with the one output terminal, and
This converting network produces predetermined reflection coefficient on directional coupler.
4, according to claim item 1 or 2 described radar systems, it is characterized in that frequency mixer comprises output terminal (P3, P4) nonlinear element on that can be directly connected to directional coupler, and this nonlinear circuit element is arrangement like this and connects up the reflection coefficient that its generation is expected.
5, according to one of claim item 1 to 4 described radar system, its high-frequency signal is modulated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 97103067 CN1163407A (en) | 1996-03-19 | 1997-03-19 | Active zero-beating radar system |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19610850.0 | 1996-03-19 | ||
| CN 97103067 CN1163407A (en) | 1996-03-19 | 1997-03-19 | Active zero-beating radar system |
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| Publication Number | Publication Date |
|---|---|
| CN1163407A true CN1163407A (en) | 1997-10-29 |
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| CN 97103067 Pending CN1163407A (en) | 1996-03-19 | 1997-03-19 | Active zero-beating radar system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103560753A (en) * | 2008-07-17 | 2014-02-05 | Bea股份公司 | Mixer structure for doppler radar applications and doppler radar sensor |
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1997
- 1997-03-19 CN CN 97103067 patent/CN1163407A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103560753A (en) * | 2008-07-17 | 2014-02-05 | Bea股份公司 | Mixer structure for doppler radar applications and doppler radar sensor |
| CN103560753B (en) * | 2008-07-17 | 2017-04-12 | Bea股份公司 | Mixer structure for doppler radar applications and doppler radar sensor |
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