Channel Imbalance Compensation with IF Signal for Chinaxe2x80x99s IDBSAR Highresolution wideswath (HRWS) synthetic aperture radar (SAR) images are valuable for disaster and environment monitoring. Digital beamforming (DBF) in elevation is a powerful technique for future HRWS SAR. However, realtime DBF processing requires massive digital resources, which are precious for spaceborne SAR. The intermediate frequency (IF) process scheme of DBF SAR is advantageous in reducing the required digital resources. Since DBF processing is performed before digital demodulation in IF DBF SAR, the channel imbalance of the system must be compensated with IF real signal. That will be quite different from the conventional scheme and has never been researched. This paper gives solution to this problem based on the IF process scheme without adding to the system complexity. Chinaxe2x80x99s next generation airborne DBF SAR (IDBSAR), operated by the Institute of Electronics, Chinese Academy of Sciences (IECAS), will serve as a test bed.

CDMbased 4Channel Digital Beamforming Transmitter Using a Single DAC In recent years, digital beamforming (DBF) is gaining more attention for next generation directional communication systems such as 5G, thanks to its flexibility for beamstearing compared with that of both analog and hybridbeamforming. However, conventional digital beamforming requires the use of independent Digital to Analog converter (DAC) and RF chain for each antenna element, which poses significant challenges in cost, power and heat management. In this work, we report for the first time a novel lowcost solution with reduced hardware complexity in DBF. Digital beamformed multiple baseband signal is designed to feed different antenna elements through a single DAC. Coding schemes were implemented in digital baseband domain, while decoding was done in analog RF domain. The decoded signals are tested before connected with antenna for proofofconcept. The demonstrated technique provides cost and size reduction of the array system, while keeping the integrity of the signals and beam pattern.