This white paper has been written with the Partnership of ECHOES Radar Technologies.
Synthetic Aperture Radar (SAR) is an active imaging sensor employed in remote sensing applications that can achieve wide areas images in every weather condition. SAR imaging uses an antenna that is mounted on a moving platform. Through the processing of received echoes, SAR permits to obtain a larger synthetic antenna aperture which improves the azimuth resolution.
Radars at a specific frequency band usually have different capabilities, characteristics and applications than radars in other frequency bands. It is well known, for instance, that penetration capabilities essentially depend on microwave frequency . Typically, penetration distance is inversely proportional to microwave frequency. The higher the frequency, the lower the penetration depth. Also, terrain characteristics affect penetration capabilities and humidity acts as a shield to microwave penetration . Emerging military and civilian applications of P- and L-band radar systems include the detection of targets concealed by foliage and/or camouflage, detection of buried objects, forestry applications, biomass measuring, archaeological and geological exploration.
On the other hand, it is easier to obtain accurate range and position measurements at the higher radar frequencies, e.g., X-, Ku- and Ka-bands, since they have broader bandwidth (which determines range accuracy and range resolution) and narrower beam antennas for a given physical size antenna (which determines angle accuracy and angle resolution) . From these considerations, it is clear the benefit that a single multi-band SAR system might produce in terms of operational flexibility and observation capabilities for different applications and end-users.
The purpose of this paper is to introduce the feasibility study of a multi-band SAR based on an emerging Teledyne e2v’s proprietary Digital to Analogue Converter (DAC) and Analogue to Digital Converter (ADC) capable of direct signal generation and direct synthesis up to Ka-band. In particular, the direct signal generation can be done via a dual-channel DAC with wide instantaneous bandwidth (up to 6 GHz with 12 GSps) and a large output analogue bandwidth (up to 25 GHz). Such a feasibility study involves the analysis of key enabling technologies, the definition of a preliminary architecture and the preliminary design of a multi-band SAR system that can indeed be mounted onboard aerial platforms. Examples of components and expected performance in terms of Noise Equivalent Sigma Zero (NESZ), received power and data-rate are discussed.