Beam Pattern for Ultrawide-Band Impulse Signal of Linear Array in the Near Field

The beam pattern of ultrawide-band (UWB) impulse array in the near field is discussed in this paper. The basic principle of beamforming of linear array in the near field for UWB pulse is presented. Computer plots of beam patterns, such as peak amplitude pattern, peak power pattern and energy pattern are presented. The UWB nearfield array beamforming results in a directivity beam pattern having a narrow mainlobe and practically no sidelobes. The influence of every parameters, such as array length, interelement spacing, number of array elements and time duration of the pulse, to the beam patterns of a linear array for UWB Gaussian pulse is analyzed, which is useful to design a practical system. The difference of the beam patterns steering different positions in the near field is analyzed as well. According to the results, improved beam width can be achieved by either increasing the array length or decreasing the time duration of the Gaussian pulse. A reduction of the restlobe level can be achieved by either decreasing the array length or increasing the number of the array elements. However, the restlobe level in the near field beam pattern is higher than that in the far field, and it increases as the range between the source and the array decreases, which is a disadvantage to suppress the noise and interference in the near field.