| The phased array receiving system mainly consists of the phased array receivingantenna array and the receiving array elements. The main demand for the phased arrayreceiving technology at present is to find and determine the main parameters of thetarget including the azimuth, elevation, velocity and distance etc., so as to achieveapplications of tracking, telecontrol, ranging, velocity measuring and imaging of thetarget. It’s of great significance to use the array antenna for multi-target TT&C andstudy the multi-beam TT&C system technology based on phased array, which have awide application prospect. The receiving array elements are the core components of thephased array receiving system. The requirements of the receiving assembly on lownoise, amplitude/phase consistency as well as high isolation between multiple channelsdetermine directly the beam-forming capability of the high performance adaptiveantenna.The phase/amplitude consistency between the receiving array elements is closelyrelated with the beam steering accuracy, ultra-low sidelobe of the antenna, adaptive nullcontrol and precise single-pulse angle measurement of the multi-beam TT&C system.High beam steering accuracy, ultra-low beam side lode and high adaptive null controlcapability can improve the tracking accuracy of the system, increase the TT&C distancein space and improve the anti-jamming capability of the equipment. By adopting thereceiving array element with high phase/amplitude consistency, the array scale can bereduced, equipment manufacturing cost saved and reliability improved.Based on deep understanding of the composition and operating principle of thereceiving array, the requirements for the pre-filter of the receiving assembly areanalyzed and screened. A design scheme of using dielectric filter is proposed based oncomprehensive considerations to resolve the consistency difficulty in large batchproduction. The low noise amplifier (LNA) is a key component of the receivingassembly. After a reasonable analysis of the technical specifications of the receivingsystem, the noise figure and the total gain of the LNA are obtained, based on which the circuit and the field effect transistor (FET) are selected. For the matching circuit, fieldcircuit co-simulation is made and the design is optimized again and again. Thus the keydifficulty in achieving low noise, high gain and low cost of the receiving assembly isovercome. The inconsistency of amplitude/phase within the receiving assembly isanalyzed and the design of the amplitude/phase control circuit is put forward, whichimproves the amplitude/phase control accuracy of the receiving array. The difference inbatches of components and the inconsistency in circuit processing and assembling arethe main factors that cause the inconsistency of amplitude/phase of the receiving array.After an analysis of the main factors that affect the inconsistency of amplitude/phasebetween channels, measures that should be taken in the design are put forward toimprove the consistency of amplitude/phase of the receiving array.With the engineering requirements taken into consideration, a method is designedand implemented. That is, within100MHz bandwidth in S-band, the dielectric filter isused for pre-filtering, then, after RF amplification by LNA, high-precision digital phaseshifter and balancing circuit calibration are used. The receiving array element that isdesigned and implemented has an amplitude consistency of no more than±0.75dB andphase consistency of no more than±5o. |
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