Millimeter wave frequency scanning imager based on optical filtering
A technology of frequency scanning and optical filtering, applied in the field of wave signals, can solve the problems of high power, slow imaging speed, and low precision
Inactive Publication Date: 2011-10-26
BEIHANG UNIV
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Problems solved by technology
The traditional scanning imaging technology uses mechanical rotation to scan, but there are many problems: the scanning speed is very low due to mechanical rotation, and the imaging speed is slow; and the mechanical rotation has problems of low precision and high noise; in addition, it takes a long time in the field of security inspection. work, mechanical scanning will generate heat and even cause failure, and its mechanical drive requires a lot of power, and the cost of use is very high
However, for a broadband millimeter-wave signal, to extract the signals of each frequency one by one, it is necessary to design a very complicated millimeter-wave filter circuit, resulting in low efficiency, poor circuit stability, and serious electromagnetic interference and crosstalk.
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[0021] According to the optical filtering millimeter-wave frequency scanning imager proposed by the present invention, in a specific embodiment, the millimeter-wave frequency scanning antenna 1 selects a microstrip antenna array structure using a dielectric waveguide structure, and its working frequency f scanning range is 34GHz~ 44GHz and a total of 10GHz bandwidth, the corresponding direction angle is -20°~20°, a total of 40° scanning range, and it has a frequency-direction angle function that is linear, that is
[0022] θ(f)=-20°+(f-34GHz)×40°÷10GHz
[0023] f 1 = 34GHz, f 2 = 44GHz; θ 1 = -20°, θ 2 = 20°
[0024] The unit of f in the above formula is GHz.
[0025] Millimeter-wave bidirectional selector switch 2 can choose WiseWave Technologiesd Inc. model CPD-39102020-XX millimeter-wave bidirectional selector switch, its working center frequency is 39GHz, bandwidth is 10GHz, insertion loss and isolation reach 1.0dB and 20.0dB respectively, Fully meet the requirements...
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The invention provides a novel millimeter wave imager based on the optical filtering technology and the frequency scan antenna technology and the imager can be used in the fields such as remote sensing, reconnaissance, security inspection and detection of dangerous goods. In the imager, a millimeter wave frequency scanning antenna is used to receive radiated and scattered signals of the millimeter wave from a detected region, the millimeter wave signals amplified and output by a low noise amplifier pass through an electrooptical modulator to modulate the optical signals output by a laser performing continuous wave frequency scanning; after the modulated optical signals pass through an optical fiber filter for filtering, and a photoelectric detector is used for detection. By means of the step and periodic changes of the frequency of the laser, the photoelectric detector finally detects the millimeter wave signals respectively which are from different directions, have different frequencies and are received by the frequency scan antenna and forms an one-dimensional image; and an two-dimensional image can be obtained by forming a frequency scan antenna array or scanning in another direction.
Description
technical field [0001] The present invention mainly relates to the imaging technology based on optical filtering and millimeter-wave frequency scanning antenna, which uses millimeter-wave frequency to scan the world to receive the millimeter-wave signal radiated and scattered by the target, and obtains different frequencies from different directions through the method of continuous laser frequency tuning and optical filtering. A millimeter-wave imager that finally forms a one-dimensional image of the millimeter-wave signal. Background technique [0002] Any object above absolute zero will radiate electromagnetic waves of various bands. Passive imaging detection is to detect the electromagnetic radiation and scattering of the target, and use various signal processing techniques to recover the temperature distribution map or scattering characteristic map of the target. Passive millimeter-wave imaging systems are widely used in radio astronomy research, remote sensing, military...
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IPC IPC(8): G01J5/00
Inventor 何云涛江月松张跃东欧军
Owner BEIHANG UNIV