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5.2Evaluation of amplitude and phasee relative amplitude and relative phase of each radi-ating element of the antenna calculated from the REV waveform are shown in Figs.12 to 19. Each gure shows the result of antenna RX-1, RX-2, TX-1 and TX-2, respec-tively. e datasets collected on October 9, 2008, and February 6, 2017, are plotted as group 1 and group 2, re-spectively. As the results of both group 1 and group 2 almost coincide, each antenna element of the WINDS APAA works normally even aer eight and a half years of operation.e REV of the WINDS APAA was performed 19 times from October 9, 2008, to February 6, 2017. e results of evaluation of the relative amplitude and relative phase of representative element no. 1 of antenna RX-1 and element no. 1 of antenna TX-1 are shown in Figs. 20 to 23. From the results of time dependency, the variation of the ampli-tude of element no. 1 of antenna RX-1 was 3.7 dBp-p, and that of phase of the same element was 25.9°p-p. Also, the variation of the amplitude of element no. 1 of antenna TX-1 was 4.1 dBp-p, and that of phase of the same element was 23.2°p-p. From the results, we judged that although both the amount of variation of amplitude and phase shi are slightly large, this trend has not progressed. As for other elements, the same results were obtained.6Phase compensation experimentOne of the purposes of the REV method is to maximize the APAA gain by correcting the initial settings of phase. e experiment for this purpose was performed on July 23, 2012 (for RX-1), and on September 6, 2012 (for TX-2), between JAXA Tsukuba Space Center and NICT Kashima Space Technology Center. e evaluation method of the experiment is to establish the phase of the phase shier for beam settings using direction cosines of the beam directed to Kashima (normal method to determine beam direction). e receiving level for the case of adding the compensation phase to the initial phase of the REV was compared with the level obtained by the normal method. e receiving signal level of a continuous wave for one minute was measured every 40 ms while xing the phase. e averaged data was plotted to construct a graph.e results of the received signal with RX-1 at Kashima terminal are shown in Figs. 24 and 25. e former shows the case where the beam was set using direction cosines and the latter shows the case where the beam was set using phase compensation of the REV. As a result, the signal level of the former is higher than the latter by 0.13 dB. is 122.0122.2122.4122.6122.8123.0123.2123.4123.6123.8124.00100200300400500600700800900100011001200130014001500Relative Amplitude(dB)Measurement PointsAverageAmplitude ：123.56dBFiF24Relative amplitude of the beam adjusted using direction cosines (RX-1)122.0122.2122.4122.6122.8123.0123.2123.4123.6123.8124.00100200300400500600700800900100011001200130014001500AverageAmplitude：123.43dBMeasurement PointsRelative Amplitude (dB)FiF25Relative amplitude of the beam adjusted using phase compensation (RX-1)123.0123.2123.4123.6123.8124.0124.2124.4124.6124.8125.00100200300400500600700800900100011001200130014001500Relative Amplitude (dB)Measurement PointsAverage Amplitude︓124.04dBFiF26Relative amplitude of the beam adjusted using direction cosines (TX-2)FiF27Relative amplitude of the beam adjusted using phase compensation (TX-2)123.0123.2123.4123.6123.8124.0124.2124.4124.6124.8125.00100200300400500600700800900100011001200130014001500Relative Amplitude(dB)Measurement PointsAverage Amplitude︓124.27dB3 Ultra-High-Speed Satellite Communication Technology136　　　Journal of the National Institute of Information and Communications Technology Vol. 64 No. 2 (2017)