Study Of Parameter Estimation Of Array Signal Under Mutual Couple Condition

Array antenna technology is a kind of parameter estimation technology that makes use of speciality of antenna arranged in space, and it has been widely applied in radar, sonar, mobile communications and other fields in recent years, along with the development of the third generation communication technology, array antenna technology is also widely used in it. In array signal processing theory, no faintness requires the space is no more the length of half wave between two antennas, but the frequency of hertzian waves is very high, so the space between two antennas must be very small, then mutual cuppling will be a big problem in DOA estimation algorithms, so it makes high sense to research mutual cuppling correction problems. Based on accessorial antennas and diagonal project tion methods, parameters estimation problems in the presence of mutual cuppling are investigated in this paper. The main works of the thesis are listed as follows:1. The mathematic model of mutual coupling and its correlative characteristic are researched, analysis the effect of mutual coupling to DOA algorithm for the perspective of beamforming。From experimental simulation, two common methodss of mutual coupling correction are compared, and extend Self-calibration method base on MUSIC to Y array, this method can be convergent to no error result.2. Based on the method of instrumental sensor, the mutual coupling correction problems is investigated. Utilized the two ways that is based on carry-on instrumental sensor and non-calibrated auxiliary sensor, the mutual coupling correction is realized. Based on the method of auxiliary sensor non-calibrated, the solving of the number of mutual coupling coefficients is analysised. Analysis the three ways that utilized to estimate the mutual coupling coefficients, found that the least square method with direct equation solution method is the same method essentially and the performance of the method it based on eigenvalue decomposition slightly worse.3. Based on the Toeplitz structure of UAL mutual coupling matrix, DOA of coherent signal in mutual coupling condition is investigated. Analysis the effect of mutual coupling to steer vector in coherent signal, found that the effect can be equal to the change of attenuation coefficient, so, DOA in coherent signal situation can be resolved by traditional methods when instrumental sensor exist. To the problem of aperture loss when instrumental sensor exist, combination the idea of least squares and diagonal projection methods, a method of DOA in coherent signal condition is realized, and it has the advantage of low computation, easy apply in projection and low SNR situation.