Research On Fault Diagnosis Methods And Software Implementation For Phased Array Antenna

Phased array technology is originated from the late 1930 s. As the representative of electronically scanned array radar, phased array radar has been attached great importance by a majority of countries due to its excellent tactical and strategic performance such as multi-channel data processing and rich resources management methods. Thus, phased array radar is widely used in almost all kinds of military radars. As is known to all, Modern phased array antenna usually consists a large number of radiating elements, and with the fast development of the continuous deteriorating electromagnetic environment, coupled with an increasing number of radiating elements, phased array antenna in daily work will inevitably produce fault. By using diagnosis algorithm to locate the fault units and identify the failure type through measuring its radiation characteristics is still a sophisticated technical issue. Thus new requirements have been presented on antenna testing technology.In order to meet these requirements, a novel measurement and diagnosis method utilizing Walsh phase-feeding technology for phased array antenna is researched in this thesis. The proposed method is based on phase-shifted measurement method. By introducing Walsh function into phase-feeding processing, a special coefficient matrix is then produced to simplify the solution of measurement equation effectively. By measuring electromagnetic wave signals from the probe when the phase shifters altering phase simultaneously under the mid-field testing distance, the synthesis amplitude and phase information are acquired. By solving equations consist of receiving signals, amplitude and phase of each channel are determined. After that, divergence analysis between recovered incentives and channel incentives which composed of phase shifter supplementary information is been implemented by diagnosis algorithm. Finally, the detection and location of fault elements can be realized and the radiation patterns could be reconstructed. The major contributions are summarized as follows:1. The failure types of phase shifters and its influence on radiation characteristics are investigated. They are the foundations and premise for testing and diagnosis. When a few radiation elements get failure, the consequence is not fatal. However, when multiple elements have failure, especially when these failure elements correlate, the situation becomes worse. Thus, we establish an antenna module and simulate directional patterns under three typical failure types. Statistical analyses on radiation characteristic variations are given out.2. The fast identifying method for the active array pattern is explored. It will vary due to the location of elements in the array. With the numerous radiating elements, we explore a fast and approximate method to determine the active array pattern under specified planar array and provide necessary prior information for fault diagnosis. The active array pattern is used to solve each channel excitation and also useful in the pattern recovery processing. A theoretical method to determine the active array pattern is discussed and the software simulation results are displayed.3. The fault diagnosis algorithm of phased array antenna which based on Walsh function is researched. By introducing Walsh function in the process of phase-feeding and utilizing its orthogonality, a special coefficient matrix is then produced. Thus, solution of measurement equations is simplified. Compared with other phase-feeding technologies, this algorithm has several advantages as follows: minimum parameter value error, the fast phase-feeding processing, and the least time-consuming. By divergence analysis between recovered incentives and channel incentives which composed of phase shifter supplementary information, the fault diagnosis of phase shifters in each T/R module can be implemented.4. The computer simulation and verification on fault diagnosis software platform of phased array antenna is developed. The overall design conception is elaborated, and the feature of basic and advanced parameter setting modules on the platform are also presented in the beginning. In the next, we establish an antenna module and determine the necessity simulation parameters. At last, by setting three different failure modes of phase shifters on the platform, diagnosis algorithm of phased array antenna which based on Walsh phase-feeding technology is verified by computer simulation. The simulation results indicate that the location of the failure units and the type of fault elements of phased array antenna can be realized successfully.