Beside the fact that array antenna design and array processing have experienced five decades of research; they are still an active and open topic in the field of radar. In fact the recent technological advances have made the realization of array systems (ground/air/space borne) and real time processing possible.

Riding on the wave of electronic hardware and computer systems advances, the scientific interest in the realization of complex systems such as array antenna and real time signal processing has grown enormously in the recent years.

So far, array antenna design as well as array signal processing has obtained fruitful achievements in theory, algorithm and hardware. However the need for faster and more accurate signal processing routines as well as the need for more efficient and miniaturized antenna and sensors still continues.

The purpose of this special issue is to publish high-quality contributions and reviews that investigate the most relevant research activities on array antenna subsystems and array signal processing for radar applications, as well as addressing challenges and opportunities ahead.

Potential topics include but are not limited to the following:

• Advances in array antennas technologies
• Array system design, measurements, and experimental validations
• Source localization and direction of arrival (DOA) estimation
• Beamforming, interference mitigation, jammer rejection, and pattern synthesis
• Adaptive array processing
• Space-time adaptive processing (STAP) and its applications
• Array signal processing for MIMO radar
• Phased array and smart antenna design in radar applications
• New applications of sensor array signal processing
• SAR/ISAR modeling and simulation and measurements
• Passive radars and passive imaging
• Circularly polarized phased array antenna for satellite system