CN104993220B - Rotating field formula omnidirectional antenna, low altitude short range radar system and signal processing method - Google Patents
Rotating field formula omnidirectional antenna, low altitude short range radar system and signal processing method Download PDFInfo
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Abstract
The present invention relates to radio detection technical field, a kind of rotating field formula omnidirectional antenna, low altitude short range radar system and signal processing method are disclosed.The rotating field formula omnidirectional antenna includes intersecting the two pairs of symmetrical dipoles placed；Wherein, the feed amplitude of each dipole is identical, and the angle between adjacent dipole is 90 °, and the spacing of each pair of symmetrical dipole is radar operation wavelength；The antenna radiation pattern of each dipole is cosine form, and the directional diagram after the combination of each pair of symmetrical dipole is the figure of eight, and the directional diagram when omnidirectional antenna stable state is circle.The present invention realizes the portability of radar system, while omnidirectional's detection rapidly and efficiently may be implemented, and substantially increases the mobility and reliability of low altitude short range radar system.
Description
Technical Field
The invention relates to the technical field of radio detection, in particular to a rotating field type omnidirectional antenna, a low-altitude short-range radar system and a corresponding signal processing method.
Background
In the 70 s of the 20 th century, mechanically scanned planar array antennas have been widely used in three-coordinate radar and airborne radar. Phased array antennas of the electronically scanned regime, which was the most widely used but at the same time the most expensive and complex of all regimes, began to find application in some military radar applications since the mid-to-late 60 s. (described in "introduction to Radar System", electronic Industrial Press, 3 rd edition, 2006, 7 months and 1 day)
In the prior art, both the mechanical scanning system antenna and the phased array system antenna are narrow beam directional antennas with certain directivity. The antenna has low side lobe and high angle measurement precision, so that multi-target resolution can be realized. The existing low-altitude short-range radar with the detection distance of 20km to 30km mostly works in an L wave band or an S wave band, adopts an antenna of a mechanical scanning or phased array system, and is erected on a vehicle-mounted mobile or fixed array.
The main disadvantages of the prior art described above are: most of the traditional low-altitude short-range radars adopt a matrix-plane directional antenna and a mechanical scanning or a mechanical scanning-phase scanning combined system, the structural design is complex, and particularly the requirement on the processing technology of a phased array phase scanning system antenna is high, so that the complexity, the weight and the cost of the system design are increased; the omnidirectional detection technology adopting a multi-area array and circular array system still needs digital beam scanning in azimuth, and the system has multiple beams and multiple channels, so that the system design and processing are complex. Due to the above disadvantages, the existing low-altitude short-range radar cannot be portable.
Disclosure of Invention
Aiming at the defects of the traditional system radar system and aiming at realizing the portability of the radar system, the invention provides a rotating field type omnidirectional antenna, a low-altitude short-range radar system and a corresponding signal processing method.
In a first aspect of the invention, a rotating field omni-directional antenna comprises two pairs of symmetric dipoles placed crosswise; the feeding amplitudes of the dipoles are the same, the included angle between every two adjacent dipoles is 90 degrees, and the distance between each pair of symmetrical dipoles is the radar working wavelength; the antenna directional diagram of each dipole is in a cosine form, the directional diagram formed by combining each pair of symmetrical dipoles is in an 8 shape, and the directional diagram of the omnidirectional antenna in a steady state is circular.
Preferably, the omnidirectional antennas are arranged in a vertical plane array mode and/or work in a pitching phase scanning mode.
Preferably, the omni-directional antenna is configured with multiple layers within a straight barrel-shaped housing.
Preferably, the omnidirectional antenna is arranged on the ground or a carrier by means of a tripod.
In another aspect of the present invention, a low-altitude short-range radar system is also provided, the system includes the rotating field omnidirectional antenna as described above, and a radio frequency processor and a display and control terminal; the rotating field type omnidirectional antenna is coupled with the radio frequency processor, and radiates radio frequency signals to a full airspace under the control of the radio frequency processor and receives echo signals of the full airspace; the radio frequency processor generates a radio frequency signal and processes the radio frequency signal according to the received echo signal to obtain trace point information of a full airspace; the display control terminal is also coupled with the radio frequency processor and is used for displaying the trace point information to a user and receiving a system control command of the user and sending the system control command to the radio frequency processor.
Preferably, the radio frequency processor comprises a transmitting and receiving module, a preamplifier, a receiver, a signal source and a signal processor.
Preferably, the radio frequency signals in the system operate in the L-band.
In a further aspect of the present invention, there is also provided a signal processing method, which processes four intermediate frequency signals in the system as described above, including the steps of:
respectively carrying out analog-to-digital conversion and digital down-conversion processing on the four paths of intermediate frequency signals to obtain four paths of baseband signals;
synthesizing the four paths of baseband signals into dual-channel data of an L channel and an R channel through channel synthesis;
respectively carrying out pulse compression, coherent accumulation and constant false alarm rate detection processing on the data of the L channel and the data of the R channel, and carrying out point trace matching on the point traces obtained after the constant false alarm rate detection processing by adopting a template matching method;
for the point traces on the match, the azimuth of the target is found by the ratio.
Preferably, the method further comprises the step of:
and carrying out frequency mixing and filtering processing on the echo signals of each dipole by a receiver to obtain the four paths of intermediate frequency signals.
Preferably, the intermediate frequency signal is a 60MHz intermediate frequency signal.
The omnidirectional antenna provided by the technical scheme of the invention has small volume and light weight, realizes the portability of the radar system, can realize quick and efficient omnidirectional detection, and greatly improves the maneuverability and reliability of the low-altitude short-range radar system.
Drawings
FIG. 1 is a schematic structural diagram of a low altitude short range radar system in one embodiment of the present invention;
fig. 2 is a schematic structural diagram of a rotating field omni-directional antenna according to another embodiment of the present invention;
figure 3 is a schematic illustration of the directivity pattern in an omnidirectional antenna in another embodiment of the invention;
FIG. 4 is a diagram illustrating the out-of-roundness test effect of the horizontal pattern of the omnidirectional antenna in the present invention;
FIG. 5 is a graph of the vertical (elevation) pattern test effect of the omni-directional antenna of the present invention;
FIG. 6 is a diagram illustrating the test effect of the two-channel horizontal phase pattern of the omnidirectional antenna of the present invention;
FIG. 7 is a flow chart illustrating a signal processing method according to still another embodiment of the present invention;
fig. 8 is a diagram illustrating the effect of the angle measurement test of the signal processing method of the present invention.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the embodiments described are presently preferred modes of carrying out the invention, and that the description is made for the purpose of illustrating the general principles of the invention and not for the purpose of limiting the scope of the invention. The protection scope of the present invention shall be defined by the appended claims, and all other embodiments obtained by those skilled in the art without any inventive work shall fall within the protection scope of the present invention. Wherein, the following related partial abbreviations correspond to: AD: an analog-to-digital signal converter; DDC: digital down conversion; PC: pulse compression; MTD: phase-coherent accumulation; CFAR: detecting a constant false alarm; LPF: and (4) low-pass filtering.
1. Low-altitude short-range portable radar system
Embodiment 1 of the present invention provides a low-altitude short-range radar system of a new system, which can achieve portability. As shown in the structural diagram of fig. 1, the low-altitude short-range radar system includes a rotating field type omnidirectional antenna 1, a radio frequency processor 2 and a display and control terminal 3; the rotating field type omnidirectional antenna 1 is coupled with the radio frequency processor 2, and radiates radio frequency signals to a full airspace under the control of the radio frequency processor 2 and receives echo signals of the full airspace; the radio frequency processor 2 comprises a T/R (Transmit/Receive) module, a preamplifier, a receiver, a signal source and a signal processor, generates an L-band radio frequency signal and processes the L-band radio frequency signal according to a received echo signal to obtain point trace information of a full airspace; the display and control terminal 3 is also coupled to the radio frequency processor 2, and is used for displaying the trace point information to the user and receiving the system control command of the user and sending the system control command to the radio frequency processor 2. Through the integrated structure design, the portability of the system is improved. In fig. 1, a rotating field omni directional antenna 1 is arranged on the ground or a carrier by means of a tripod 11.
The low-altitude short-range portable radar system can work in an L wave band, adopts the rotating field type omnidirectional antenna, can realize omnidirectional detection of the direction without mechanical servo or phased array wave beam control, reduces corresponding processing hardware, saves cost, reduces the weight of the antenna, reduces the installation space and improves the reliability of the system. Therefore, the technical scheme of the invention can realize the quick erection and withdrawal of the system and has strong maneuverability; the system can realize long-time accumulation of the target echo, which greatly improves the frequency spectrum resolution of the target echo signal, thereby improving the signal-to-noise ratio improvement factor.
The T/R, preamplifier, multichannel receiver and signal source referred to herein all employ currently mature design techniques, and therefore the following focuses on the rotating field omni-directional antenna and corresponding signal processing mechanisms. The radar system of the invention adopts the rotating field type omnidirectional antenna, cancels a servo rotating device of the antenna of the traditional scanning system, and can reduce the system volume, reduce the system cost and improve the system reliability.
2. Rotating field type omnidirectional antenna
Since the system of the radar antenna determines the system of the radar system to a great extent, in order to improve the disadvantages of the radar system of the conventional system described in the background of the invention, embodiment 2 of the present invention further provides a rotating field type omnidirectional antenna, which can achieve higher reliability and portability when applied to the low-altitude short-range portable radar system.
In embodiment 2 of the present invention, the rotating field type omnidirectional antenna includes two pairs of symmetric dipoles (a first dipole 201, a second dipole 202, a third dipole 203, and a fourth dipole 204) which are arranged in a crossed manner, where the first dipole 201 and the third dipole 203 are a pair of symmetric dipoles, and the second dipole 202 and the fourth dipole 204 are a pair of symmetric dipoles. As shown in FIG. 2, the feeding amplitudes of the dipoles 201-204 are the same, the included angle between the adjacent dipoles is 90 degrees, and the distance between each pair of symmetric dipoles is the radar working wavelength (considering the portability of the antenna and the realizability of the feeder line, the value range is 0.25-0.4 m). As further shown in fig. 3, the antenna pattern of each dipole is in cos form, the combined antenna pattern of each pair of symmetric dipoles is "8" shaped at any time, and the steady-state pattern is a circle.
Furthermore, the antenna gain can be improved in a vertical plane array mode, and the radar action distance is increased; in addition, certain low-altitude airspace coverage can be realized through pitching phase scanning.
Therefore, the diameter range of the rotating field type omnidirectional antenna provided by the invention is 0.3-0.45 m (considering the thickness of the skin of the antenna), the height of the antenna can be comprehensively considered according to the factors such as the portability, the weight requirement, the gain of the antenna and the like of the system, the antenna can be configured into different heights (such as four layers, six layers, eight layers and the like), the distance between the layers can be half of the working wavelength of the radar (the value range is 0.125-0.2 m), and the appearance of the system antenna can be in a straight barrel shape and is easy to carry; the antenna is small and light, and can be placed on a tripod.
According to the design concept of the rotating field type omnidirectional antenna provided by the invention, a novel omnidirectional antenna can be designed, and fig. 4-6 show the test results of the antenna performance. From the out-of-roundness test result of the horizontal directional diagram in fig. 4, the out-of-roundness of the horizontal directional diagram is less than 0.5 dB; as can be seen from the vertical pattern test result in fig. 5, the vertical beam width is 14 °, and the beam tilts up by 10 °; as can be seen from the antenna two-channel horizontal phase pattern shown in fig. 6, the phase of the two channels changes linearly.
3. Signal processing method
The prior rotating field system antenna applied to civil broadcast communication is only omnidirectional transmission or omnidirectional reception; the system antenna is applied to the field of radar detection to realize transmission and reception, and omnidirectional angle measurement is required to be realized. However, the existing system antenna has no azimuth resolution capability, the traditional angle measurement mode cannot be suitable for the system antenna, and the angle can only be solved by adopting a phase comparison method after a series of transformations in the signal processing stage, so that the antenna response speed becomes slow.
The rotating field type omnidirectional antenna provided by the invention has portability, and can realize omnidirectional detection of the direction through rapid signal processing to obtain point trace information of a full airspace. The invention further provides a processing method of the novel signal processor, aiming at the characteristics that the rotating field type omnidirectional antenna has no azimuth resolution, the phase difference between the oscillators is fixed and the directional diagram of a single oscillator is in a cos shape.
In embodiment 3 of the present invention, in order to implement echo signal processing of multiple dipoles and obtain trace point information of a full space domain from the echo signal processing, a signal processing method is also provided. Wherein, echo signals of n dipoles (n is 1,2,3,4) are processed by a receiver through frequency mixing, filtering, and the like, and then the corresponding signals are n (n is 1,2,3,4)60MHz intermediate frequency signals, fig. 7 is a flow chart of the signal processing method provided by the present invention, and the method includes the steps of:
1) respectively carrying out AD and DDC processing on the four paths of signals to obtain four paths of baseband signals;
2) synthesizing the four paths of baseband signals into dual-channel data of an L channel and an R channel through channel synthesis;
3) respectively carrying out PC, MTD, CFAR and other processing on the data of the L channel and the R channel, and carrying out trace point matching on traces obtained after CFAR of the data of the L channel and the R channel by adopting a template matching method;
4) for the point traces on the match, the azimuth of the target can be found by the ratio.
Fig. 8 is a diagram of the angle measurement effect by adopting the processing method under the ideal condition. As can be seen from fig. 8, when the target incident angle is increased by 10 °, the calculated angle is also increased by 10 °, i.e., the signal processing method of the present invention can realize omnidirectional angle measurement. The signal processing algorithm provided by the invention has simple principle and small calculation amount, and can be realized by the existing hardware platform.
The omnidirectional antenna provided by the technical scheme of the invention has small volume and light weight, realizes the portability of the radar system, can realize quick and efficient omnidirectional detection, and greatly improves the maneuverability and reliability of the low-altitude short-range radar system.
Although the present invention has been described in connection with preferred embodiments, it will be understood by those skilled in the art that the methods and systems of the present invention are not limited to the embodiments described in the detailed description, and various modifications, additions, and substitutions are possible, without departing from the spirit and scope of the invention as defined in the accompanying claims.
Claims (6)
1. A rotating field omnidirectional antenna, characterized in that the omnidirectional antenna comprises two pairs of symmetrical dipoles which are arranged in a crossed manner; wherein,
the feeding amplitudes of the dipoles are the same, the included angle between every two adjacent dipoles is 90 degrees, the distance between every two symmetrical dipoles is the radar working wavelength, and the value range of the radar working wavelength is 0.25-0.4 m;
the antenna directional diagram of each dipole is in a cosine form, the directional diagram after each pair of symmetrical dipoles are combined is in an 8 shape, and the directional diagram of the omnidirectional antenna in a steady state is circular;
the omnidirectional antenna is of a multilayer structure, and the distances between adjacent layers are equal and are half of the working wavelength of the radar.
2. An omnidirectional antenna according to claim 1, wherein the omnidirectional antenna is arranged in a vertical plane array and/or operates in a swept elevation manner.
3. The omni directional antenna according to claim 1, wherein the omni directional antenna is configured with multiple layers within a straight barrel housing.
4. An omnidirectional antenna according to claim 1, wherein the omnidirectional antenna is disposed on the ground or a carrier by means of a tripod mount.
5. A low-altitude short-range radar system, characterized in that it comprises a rotating field omnidirectional antenna according to any one of claims 1 to 4, as well as a radio frequency processor and a display and control terminal; wherein,
the rotating field type omnidirectional antenna is coupled with the radio frequency processor, and radiates radio frequency signals to a full airspace under the control of the radio frequency processor and receives echo signals of the full airspace;
the radio frequency processor generates a radio frequency signal and processes the radio frequency signal according to the received echo signal to obtain trace point information of a full airspace;
the display control terminal is also coupled with the radio frequency processor and is used for displaying the trace point information to a user and receiving a system control command of the user and sending the system control command to the radio frequency processor;
the radio frequency processor comprises a sending and receiving module, a preamplifier, a receiver, a signal source and a signal processor;
the radio frequency signals in the system operate in the L-band.
6. A signal processing method for processing the four if signals in the system of claim 5, comprising the steps of:
respectively carrying out analog-to-digital conversion and digital down-conversion processing on the four paths of intermediate frequency signals to obtain four paths of baseband signals;
synthesizing the four paths of baseband signals into dual-channel data of an L channel and an R channel through channel synthesis;
respectively carrying out pulse compression, coherent accumulation and constant false alarm rate detection processing on the data of the L channel and the data of the R channel, and carrying out point trace matching on the point traces obtained after the constant false alarm rate detection processing by adopting a template matching method;
for the point traces on the matching, the azimuth angle of the target is obtained through phase comparison;
the four paths of intermediate frequency signals are obtained by the echo signals of each dipole through the frequency mixing and filtering processing of a receiver
The intermediate frequency signal is a 60MHz intermediate frequency signal;
the omnidirectional antenna is of a multilayer structure, and the distances between adjacent layers are equal and are half of the working wavelength of the radar.
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| CN107247256A (en) * | 2017-07-19 | 2017-10-13 | 南京全信光电系统有限公司 | A kind of rf integration detector and method |
| CN110208754B (en) * | 2019-04-26 | 2024-03-26 | 四川九洲防控科技有限责任公司 | Rotary field type omni-directional antenna, omni-directional detection radar system and signal processing method |
| CN111682303B (en) * | 2020-05-09 | 2022-03-22 | 四川九洲电器集团有限责任公司 | Common-aperture full-airspace coverage antenna |
| CN111509370B (en) * | 2020-05-25 | 2024-06-07 | 中科智远信息科技有限公司 | Video wireless microwave transmission method and transmission device |
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| WO2005070022A2 (en) * | 2004-01-22 | 2005-08-04 | Hans Gregory Schantz | Broadband electric-magnetic antenna apparatus and system |
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