Micro Audio Directional System Phase Array Research

According to dolph-chebyshef synthesis and phased focused method, a research on micro audio directional loudspeaker array is made to improve the directivity of MEMS transducer array. This thesis analyzes the existing parametric array sound source theory and the theory of directional transducer array, after testing the micro audio directional loudspeaker, the defects of the existing transducer model is found, then a complete model which considers the array element impedance differences is proposed, after verifying the validity of the model, the aim to test phase array is achieve eventually.During the time developing the micro audio directional loudspeaker, the hardware DSB modulation is selected because of the MEMS resonance frequency, power consumption and the size of loudspeaker. Firstly, a second-order matching circuit is carried out for the MEMS transducer. Secondly, the whole hardware circuit and software is designed. Then, the sound pressure level as well as the directivity of the micro audio directional loudspeaker is measured. Finally, an assumption that the impedance difference affects the directivity of the MEMS array is proposed to explain the phenomenon of the experiment.After explanation for the model of line source array and rectangular matrix source array, this thesis put forward a complete model for the MEMS transducer array. The model is based on line source array and rectangular matrix source array model. This model considers the phase and impedance difference of element of array and then it is tested with Matlab program. The simulation result shows it is better than the two models before.Then, the complete model is applied to simulate the behavior of the array antenna theory. Dolph-chebyshef synthesis method and phase focus method are used. When dolph-chebyshef synthesis method is used we find the amplitude and number of the grating lobes is reduced but the width main lobe grows. When phase focus method is conducted the result shows the amplitude of the grating lobes is reduce somehow. The simulation result shows that using those two methods could reduce the number of grating lobes and inhibits the amplitude of the grating lobe.Finally, the actual parameters of the MEMS transducer are introduced into the complete model. Then the simulation of compensating for the MEMS transducer is conducted. Besides, the simulation of dolph-chebyshef synthesis method and phase focus method is also conducted. The simulation results shows the compensate method, dolph-chebyshef synthesis method and phase focus method could improve the directivity of the MEMS transducer array.