Study Of Algorithm Of Time-domain Near-field Antenna Measurement

Some key techniques of a new antenna measurement technique, time-domain near-field antenna measurement technique, are presented in this paper.As the basis of this paper, the definition and parameters of pulse are given. Fourier series and Fourier transform of periodic signal are introduced. With the help of the plane-wave spectrum representations for frequency-domain fields, plane-wave theory of time-domain field for near-field scanning applications are studied. Green's function representations, plane-wave spectrum representations, far-field expressions in time-domain are derived. Time-domain and frequency-domain computation schemes of far-field pattern in terms of sampling theorems are given. On the basis of the presented no probe-corrected formulas, the time-domain probe-corrected planar near-field representations are obtained, which express the desired field in terms of the output of a known no ideal probe in the scan plane.The principle of system of time-domain near-field antenna measurement is analyzed. In order to introduce direct time-domain algorithm, near-field to far-field transformation in time domain of sound-field is particular studied. The connection between angle of observed and scanning plane, the application of time gate in the direct time-domain algorithm and the synchronization of system are studied.