Low-Cost Radars Integrated into a Landslide Early Warning System - New Contributions in Information Systems and Technologies - page 14

Fig. 3. Example of accurate target detection with SDRadar

C-Band SFCW Radar

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A C-band SFCW radar has been realized by adopting a compact Vector Network
Analyzer (VNA), controlled by a Visual Basic interface ,which leads to set the
frequency measurement range and the output power, also showing other related
parameters, such as slant range resolution. The VNA is connected through a switch
module and a Butler matrix to a transmitting antenna and receiving microstrip array
antennas, in order to realize an azimuthal scanning capability able to select a specific
investigation area. Both receiving antenna (2x4 elements), and transmitting antenna
(2x2 elements) have been placed in the same plexiglass shelter, while two different
metallic boxes have been employed for the switch device and the scatterometer
(VNA, MXE, amplifiers). A photograph of the C-band radar system is illustrated in
Fig. 4(a), while the software interface is reported in Fig. 4(b). Experimental tests have
been performed to validate the maximum radar range resolution, equal to 30 cm for a
bandwidth operation of 500 MHz (Fig. 4(b)). An experimental validation of the entire
system, trough accurate position identification of two test targets, has been carried out
in the anechoic chamber at University of Calabria (Italy). In particular, a metal sheet
has been placed 5 meters away from the device, with a smaller one at a distance of 4.2
meters, like shown in Fig. 5(a). Two amplitude peaks of the processed signal (Fig.
5(b)) are located at the correct distance intervals (4.2m - 4.5m and 4.8m - 5.1m),
while other lower peaks are mainly due to other objects in the scenario and to multiple
paths of the radar signal between the two targets. Since peaks due to the target
detection are predominant with respect to the other ones (little differences between
the two higher values are only related to the different cross section of the sheets), also
in this case both effectiveness of the system and expected radar resolution are
experimentally validated.