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Analysis on spectral regrowth of chirp bandwidth expansion technique in high‐resolution SAR system
Author(s) -
Kim Se Young,
Sung Jin Bong
Publication year - 2014
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.28096
Subject(s) - intermodulation , chirp , bandwidth (computing) , sideband , wideband , physics , waveform , optics , electronic engineering , microwave , telecommunications , radar , engineering , amplifier , laser
This article presents an analysis of the root causes of the spectral regrowth due to the higher‐order intermodulation in a chirp bandwidth expansion scheme using a single‐sideband modulator and frequency multipliers. The spectral regrowth of synthetic aperture radar waveform was reduced by minimizing the gain and phase imbalances between the I and the Q channels. Further, the gain and phase imbalance requirements were defined on the basis of the evaluation of the impulse response function. The 150‐MHz bandwidth of a chirp signal at 2.4 GHz was expanded to 600 MHz at 9.6 GHz. By adjusting the dc offset and the gain imbalance between the I and the Q channels, the carrier level was reduced from −28.7 to −53.4 dBm and the sidelobe levels caused by the spectral regrowth were reduced by approximately 8–9 dB. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:400–404, 2014