So far, INVAP’s most demanding venture in radar technology is its participation in the electronics of Argentina’s space-based Synthetic Aperture Radars (SAR). These systems are under current development as a joint undertaking of INVAP and the National Commission for Space Activities (CONAE), the Argentine Radioastronomics Institute (IAR) and INVAP. They are designed to fit the future SAOCOM satellites.
Nowadays, only a small group of countries in the world have the Earth observation capacity that a Synthetic Aperture Radar provides, including the United States, Canada, Japan, Germany, Italy and the UK.
In the shared responsibilities of the SAOCOM undertaking, INVAP’s task is twofold. On the one hand, we are developing the core-electronics of the SAR-L radar, pulse generation and the definition of high-speed operational modes. On the other hand, we are also constructing the satellite platform able to house large components in a relatively low-weight (under 2 ton).
SAOCOM is the first Argentine space vehicle to use extensively carbon-fiber reinforced plastic, combined with aluminum honeycomb. This type of satellite has proven to be one of the biggest challenges ever to INVAP’s space engineering so far.
SAR have three distinctive features:
• They use microwave radiation.
• They emit moving RF beams, though they have fixed antennae.
• Beams sweep their target in slanting angles, generating alternatively illuminated and dark areas.
The SAR resolution depends on the microwave length and the size of the antenna. The SAOCOM SAR operates in the L band (23 cm micro wavelength) and its antenna has an area of 25 square meters. This combination limits the size of discernable objects to 10 meters, and is therefore of little military value but very useful for environmental applications.
The radioelectric design of these antennae was done by the Argentine Radioastronomy Institute (IAR), and the construction and deployment is executed by CONAE.
To power such large antennae calls for a big surface of high efficiency and long-lasting photovoltaic cells, developed by CNEA, as well as a heavy energy storage battery bank. Due to the technical difficulties involved, only two countries have faced the development of Space SAR radars in L band: Japan, with an experimental academic satellite, already in orbit, and Argentina, with two satellites under construction.