Chapter 3: Vehicle-Mounted GPR System for Landmine Detection
Chapter 3: Vehicle-Mounted GPR System for Landmine Detection
Chapter 3: Vehicle-Mounted GPR System for Landmine Detection
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34 3. <strong>Vehicle</strong>-<strong>Mounted</strong> <strong>GPR</strong> <strong>System</strong> <strong>for</strong> <strong>Landmine</strong> <strong>Detection</strong><br />
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Fig. 3.7: Power spectra of 100 ground reflections measured by VNA #1 (a), VNA<br />
#2 (b), and VNA #3 (c) with offset frequency of 300 kHz <strong>for</strong> VNA #2 and 1.25<br />
MHz <strong>for</strong> VNA #3, and an IF bandwidth of 3 kHz.<br />
3.2.3 Antennas<br />
Vivaldi antennas are employed in this system. It is a kind of microstrip antenna,<br />
which possesses a wide bandwidth and a high cross-polarization ratio (Guillanton et<br />
al., 1998). Since it can be made on a thin and lightweight circuit board, it has<br />
advantages, <strong>for</strong> example easy to be manufactured and to be configured as an array.<br />
For SAR-<strong>GPR</strong>, the antenna shown in Fig. 3.8(a) has been designed and<br />
manufactured. The size is 19×20 cm, and the antennas are aligned with a spacing of<br />
6 cm as shown in Fig. 3.8(b). Return loss of the antennas with the array<br />
configuration is shown in Fig. 3.9.