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This paper reports on a model developed for evaluating major system performance of a spaceborne bistatic synthetic aperture radar (SAR) for remote sensing applications. The procedure accounts for formation flying aspects. It is particularly aimed at comparison of monostatic and bistatic cases, and, as a test case, it is applied to study a novel configuration, based on a small satellite equipped with a receiving-only antenna orbiting in tandem with a large, noncooperative transmitting spacecraft, the Italian COSMO-SkyMed mission. Numerical results and plots show the effectiveness of the procedure as a mission design tool and put in evidence key issues and characteristics of the proposed spaceborne bistatic formation.

This work aims to describe the characteristics and the status of development, including the results of a first preliminary testing campaign, of a low frequency airborne imaging radar developed in Italy for the Italian Space Agency.

This letter deals with the design, realization, and validation of a multimode/multifrequency airborne radar designed for both surface and subsurface prospections. The system operates in the frequency band from very high frequency (VHF) to ultrahigh frequency (UHF) and works in two different modes: 1) a nadir-looking sounder in the VHF band (carrier frequency of 163 MHz); and 2) a side-looking imager (i.e., synthetic aperture radar) in the UHF band with two channels at 450 and 860 MHz, respectively. The system validation has been carried out for the “sounder” mode due to helicopter-borne surveys carried out over an area in the Campania region, Southern Italy. The surveys have provided a first proof of system capability in obtaining useful information about the surface and shallower subsurface layers over a large scale and in a relatively short time. In particular, the data collected by the sounder have been processed by means of a microwave tomographic reconstruction approach, and features consistent with tunnels buried at a depth of 15 m have been identified.

In the recent years a new class of airborne radar system using low frequency have emerged. They are sounder working at VHF/UHF band and SAR (Synthetic Aperture Radar) that are able to provide high resolution images at P and L band. Behind these developments lie technological advances in antenna design, low noise amplifiers, band pass filters, digital receiver technology as well as new processing algorithms. The combination of low frequency and high bandwidth, creates a variety of military an civilian applications, ranging from the detection of targets concealed by foliage and/or camouflage or buried to forestry applications, biomass measuring, Archeological and geological exploration. Following these potentialities, the Italian Space Agency promoted the development of a new multi-mode and multi-band airborne radar system, that can be considered also a “proof-of-concept” for future dedicated spaceborne missions. The research consortium CO.RI.S.T.A. is in charge of the design, development and flight validation of such system, that is the first airborne radar entirely built in Italy.The radar is able to work either as nadir-looking sounder at VHF band (163 Mhz) and as side booking imager (SAR) at P band with two channels at 450 MHz and 900 MHz. The system uses a very flexible architecture due to the implementation of a direct digital synthesis(DDS) of transmitted signal and of stepped-frequency technology that allows the transmission of large bandwidth and facilitates multiple polarizations. Radar is controlled and timed by a powerful control unit based on FPGA technology that is also able to store all data with high data rate directly on SATA disks. Some flight campaigns have been performed on south Italy by using a helicopter of Aeronautica Militare. The present work presents a detailed system description, performance analysis, data processing algorithms and measurement campaign results description.