Gathering border guard authorities’ needs and requirements concerning the most-used migration routes

According to the latest FRONTEX report (2019 Risk Analysis) on illegal crossings of the EU’s external borders, Eastern Mediterranean, Western Mediterranean and Western Balkans are the three major illegal migration routes.

For 2019 the total number of the reported detections of illegal border crossings into the EU was 141.741. A number lower than the year before (2018) however still a significant one.

These routes are characterized by large mountainous and forested environments with difficult terrains causing difficulties in daily monitoring processes conducted by border guard authorities. The report however does not feature any statistics on undetected border crossings.

Do undetected border crossings are more likely to happen in difficult terrains due to surveillance gaps? This seems like a reality since border and law enforcement agencies face critical issues in detecting persons and vehicles illegally crossing EU borders in such regions.

Foliage penetration is one of the most challenging obstacles to overcome in border surveillance especially in the 3 abovementioned routes. Initial work for foliage penetration radar systems dates back to the late 1960 to mid-1970 with poor results due to foliage attenuation that limited the systems to short-to-medium range operation.

In the late 1980s, the development of radars and wideband data links enabling image processing/interpretation on the ground started to provide acceptable and useful detection and characterization of forested regions.

When we talk about radar-based surveillance equipment, a fundamental trade-off between resolution and penetration capability exists: high resolution demands a high centre frequency, but high penetration demands a wavelength long enough to propagate through tree cover.