L-Band Anti-jamming Wideband Receiver

The L-band anti-jamming wideband receiver designed in this thesis is based on point to multipoint microwave equipment. Focusing on the development of the L-band adaptive anti-jamming wideband receiver, the implementations of the receiver are analyzed in this thesis. Specially, the functional module of electrically tunable duplexer, low noise amplifier, frequency source, the mirror suppressing mixing receiving circuits and AGC are analyzed and designed. At last, the indicators of the whole receiver are tested.Firstly, the background of several applications are briefly introduced, the purpose and significance of the study are analyzed; Secondly, the main parameters of the receiver are deeply discussed and analyzed, several common design schemes of receivers are compared, from which a mirror suppressing mixing scheme suitable for this project with relatively simple circuits is chosen; Then adaptive notch and adaptive change of frequency technology is applied to adaptive anti-jamming technology, when the interference signal outside the passband, it's easy to filter out the interference signal since the electrically tunable filter bandwidth is narrow; When the interference is inside the receiver passband, spread spectrum algorithm and adaptive notch filter are combined to filter out interference; adaptive change of frequency scheme is used if it is not effectively to filter out interference signals, in accordance with prior appointment, change the frequency of the electrically tunable duplexer is applied when judgement condition is met. At last, with respect of the overall design of the receiver, the constituent of the equipment is briefly introduced and the range of the discussion in this thesis is defined. Also, from the point of view of the system, the isolation of receiving and transmitting and the distribution of the gain of receiving link is analyzed and computed.In this thesis, the main function modules are designed in anti-jamming broadband receiver. Electrically tunable duplexer is used as the RF front-end of the receiver, aiming at filtering the spurious and interference outside the work band. The electrically tunable duplexer designed in this thesis supports wide tuning range, high speed tuning, narrow passband, and with the ability of automatic frequency calibration. Low noise amplifier, adopting a classic structure with double-balanced technique, achieves high reliability and good broadband characteristics. A limiter is attached at the front-end of LNA. It can prevent the equipment from damaging in case of strong interference occurs. What's more, to meet future demands of minimization, several single-chip MMIC LNA chips are analyzed. Because of the features of the local oscillator frequency source, such as broad system bandwidth, small step and low phase noise, schemes, of fractional single loop, mixing loop and single-chip integrated frequency source are proposed. Single-chip integrated phase-locking scheme is selected since it is highly integrated and easy to apply after comparison. Classic Hartley structure of the scheme is used for suppression mirror mixer circuit, since image rejection is high. The IF section of the receiver is mainly consists of AGC amplifier. In this thesis, traditional AGC circuits, wide-dynamic-range dipolar analog cascade circuits and rapid burst digital AGC circuits are analyzed and designed.The test methods and results after each module and whole receiver are discussed. The results show that the indicators of the receiver can completely meet the requirements of the system design.