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In this study, when developing a phased array feeder for the verification of dual reflector antennas for satellite synthetic aperture radar (SAR) applications, the main component test and performance verification of the feeder were considered. The performance was verified at the level of the component radiator, radiofrequency/control board, and integrated phased array feeder with specifications, including the bandwidth, polarization, directivity, beam width, and side lobe, required for the feeder. Accordingly, it was confirmed that the bandwidth was 19.18 % (H) and 16.07 % (V), directivity was 38.42 dBi (H), 38.32 dBi (V), HPBW Az/El 2.064° (H)/2.187° (H), 2.083° (V)/2.202° (V), and the side lobe was under −12.84 dB (H), −13.05 dB (V). Therefore, we verified that it can be adopted as a phased array feeder for the verification of dual reflector antennas for satellite SAR applications. [ABSTRACT FROM AUTHOR]

It is essential to analyze the electrical characteristics of composite materials, such as Carbon Fiber Reinforced Polymer(CFRP), as their electromagnetic properties change according to the method of fabrication. However, the conventional method cannot be applied to paraboloid-shaped deployable reflector antenna panel. In this paper, we analyze the effect of errors generated by waveguide to coaxial adapter while measuring the reflection characteristics of a curved specimen. Using the proposed structure of the adapter, it is confirmed that the reflection characteristics of a curved specimen can be measured by compensating the effect of error that occurs at the interface between the curved surface and the vertical flange waveguide. [ABSTRACT FROM AUTHOR]

With the development of active phased array radar technology in recent years, active phased array antennas, which digitally combine signals received from subarray units using dozens of digital receiver, have been developed. The beam characteristics are greatly affected by the shape of the subarray structure as well as the weight of subarray in digital beamforming. So in this paper, the method to generate subarray structures by using recursive element exchanging method and the method to optimize subarray structures that can minimize sidelobes of operating beams are proposed. Additionally it presents the result to find the optimized subarray structure to minimize the maximum sidelobe of monopulse beam and pencil multi-beam respectively or simultaneously which are commonly used for digital beamforming by applying the algorithm propsed in this paper. [ABSTRACT FROM AUTHOR]

In this paper, the method is proposed that the equivalent result can be obtained by compensating the variation of gain and phase in the comparison with the result of near-field measurement which is obtained in the steady state, although the gain and phase variation of rx-channels occurred in the near-field rx-measurement of digital active phased array antenna. The proposed concept has the time section for monitoring the state of the rx-channels through the calibration path in the measurement timeline, and is the method for compensating the variation of state. For validating the proposed method, the fabricated X-band digital active phased array antenna and the planar near-field measurement facility is utilized. The proposed method is validated in the comparison with the compensated pattern which the unstable state of rx-channels is calibrated and the reference pattern obtained under the steady state of the rx-channels. [ABSTRACT FROM AUTHOR]