The Research Of Key Techniques In Passive MMW Array Detecting And Imaging

The millimeter wave (MMW) is between the microwave and IR in the electromagneticspectrum. Compared with the two latter, the developing of the MMW technology is slower.However, in the view of utilizing the whole electromagnetic spectrum, making greaterefforts to develop the MMW technology is the trend. Actually, just because the wavelengthof MMW is between those of the microwave and IR, some of its characteristic is betweenof them. For example, the MMW has the moderate spatial resolution and penetrability ofthe smoke or fog. So in some case the MMW can complete the missions which themicrowave and IR can't. On the other hand, from the point of view of work manner, thedetecting systems can be classified two kinds: the active and the passive systems. Althoughthe passive detecting system can't get so much information as the active one, it has itsspecial characteristic. For instance, the passive system is immune to the radar clutter. It issecreting and has no electromagnetic pollution due to none of radialization. The passivesystem also has excellent capability of detecting the target covered with the stealth material.In one word, the detecting system with difference working frequency and manner can't besubstitutable each other completely. This paper is about the pivotal techniques research ofthe passive MMW detecting and imaging and the main work includes following aspects:1) The measurement of radiometric characteristic of some kinds of objects. Because thedetecting of the metal object is important in both military and civil applications, wefocused on the aim and do lots of measurement of the radiometric characteristic ofseveral objects correlating to the metal detecting and got the datum. We also completedthe inversion algorithm of retrieving the brightness temperature from the measureddatum.2) The radiometer is the apparatus of incepting the MMW radialization and is the key partof all passive MMW detecting and imaging system. Our emphasis of radiometerresearch was on a kind of AC radiometer, we discussed its principium, composing andthe recovery of its distorted output signal. Finally we gave out the design of the ACradiometer.3) The focal plane system is the main passive MMW detecting and imaging system atpresent. So in the paper we design two kinds of MMW focal plane system for thedifferent applications. The first one was designed for bomb-borne application and ouremphasis was the Cassegrain antenna. We completed the design, making andmeasuring. Then we discussed the target center aiming and identifying of the system. The other was designed for passive MMW imaging application. We emphaticallydiscussed the design of feed antenna and its feed methods, completed the making andmeasuring. We also discussed the arrangement of the feed array and the problem ofsampling by scanning.4) As a beforehand research, we discussed the application of phased array in passiveMMW imaging. Due to the difficulty of using phasers in a great deal at MMW band,we chose a novel inter-injection-locked oscillator array to realized the phase control.The method needs few or no phaser. We discussed the theory of such phased arrayfirstly, then gave out the system design scheme and completed the design of theantenna array and the coupling network.5) At present the resolution of passive MMW image is poor, so the image process is theindispensable step of any significative application. In the paper, we followed up theexistent super-resolution algorithms and brought forward the Lorentzian algorithmassisted with blind deconvolution as the processing method of passive MMW images.The result showed the method was effectual.To sum up, the above aspects of the passive MMW detecting and imaging is frombriefness to complexity and from single detector to multi-detectors, include the apparatus,system and the signal processing. All of them will establish fine foundation for the finalpassive MMW imaging applications.