There Is No Phase Calibration Measurement For The Terahertz Compact Field

Terahertz wave refers to the electromagnetic wave whose frequency is within the range of 0.1-10THz(wavelength is 3,000-30?m).It has a huge application prospect in communication,biomedicine,astronomy,safety inspection and other fields.Terahertz measurement technology is the basis of terahertz wave application,and the performance measurement of terahertz antenna plays an important role in the terahertz measurement technology.Therefore,the design of THz antenna and the measurement of THz antenna performance are one of the research focuses in the field of THz.There are many ways to realize antenna measurement,including near field measurement,far field measurement,and contraction field measurement.In terahertz band,the compact antenna test range(CATR)is the most effective method.In the finite space of the compact field system,the far-field spherical wave from a source is compressed into an approximate plane wave,and then the antenna is measured.In the construction of compact field,it is necessary to calibrate the area(quiet area)of the measuring antenna and measure the phase and amplitude distribution of the electric field in the quiet area.In the terahertz band,the phase measurement results have completely lost the reference significance because the scanning frame's moving and positioning error is close to the wavelength,but the amplitude information measured by the probe is not much different from the real value in the range of probe jitter.In this thesis,by measuring the amplitude information of two faces in the compact field static zone,a series of novel algorithms are used to restore the phase of one face,so as to restore the complete electric field information in the static zone.On the basis of comparing the traditional methods,the angular spectrum iteration method,the intensity transfer equation method(TIE)and the genetic algorithm used for the first time are applied to recover the phase information of the field of the compact field in the terahertz band.Based on the simulation data of the three-reflection tightening field system of Beijing University of Posts and Telecommunications,the phase recovery calibration of the terahertz tightening field system is carried out by using the novel algorithm mentioned above,and the comparison of these algorithms is made.The angular spectrum iteration method has the advantages of simplicity,continuous descent and so on,so as to improve the speed and precision of phase recovery.Tie-improved angular spectrum iterative algorithm and further genetic algorithm are better than other algorithms in terms of details.Compared with further genetic algorithm,tie-improved angular spectrum iterative algorithm and further genetic algorithm,the recovered phase of further genetic algorithm is closer to the standard phase.The above research provides practical measurement method for the static area calibration of terahertz contraction field of three mirrors for the key civil aerospace project of Beijing University of Posts and Telecommunications in the 13th five-year plan period,and also provides a good solution for the challenges faced by the application of terahertz contraction field measurement technology in higher frequency band.