Alternative Defense Technologies

¶ 3. Alternative Defense Technologies

¶ 3.1 Passive Coherent Location (PCL)

PCL systems do not emit their own energy but instead use existing transmitters (FM radio, DAB+, DVB-T, 5G) as "Illuminators of Opportunity." The leading system is the Hensoldt TwInvis (Hensoldt: TwInvis):

Hensoldt presented a deployable military variant in 2023 and expects over 100 orders (Defense News, 2023). The system demonstrated its capabilities at the FAA (Hensoldt: FAA) and will be certified for civil aviation from 2026 (Hensoldt: Civil Aviation).

Alpine Advantage: Switzerland's 99.9% DAB+ coverage and one of Europe's densest 5G networks provide ideal conditions. PCL systems cost 10-20% of an active AESA radar, with a TCO savings potential of 79% over 20 years. Since they emit no radiation, they are immune to Anti-Radiation Missiles. Academic foundations are documented in publications from the University of La Sapienza Rome and IET journals. Experiments with DVB-T signals on a Pilatus PC-12 demonstrate practical applicability (ResearchGate, 2022). Armasuisse conducts research with NATO PfP partners on reconnaissance technologies (Armasuisse: Joint Research; Armasuisse: RadCom).

¶ 3.2 Acoustic Drone Detection

In Ukraine, over 14,000 acoustic sensors operate in the "Sky Fortress" system, supplemented by the "Zvook" system. Each sensor consists of a parabolic reflector, microphone, Android phone, and backup battery (Zvook; United24 Media, 2025).

AI-based classification reduced the false positive rate to 1.6%. NATO has pledged funding for 15,000 additional sensors (Militarnyi, 2025; AlgorithmWatch, 2025; C-UAS Hub).

¶ 3.3 Directed Energy Weapons (DEW)

Laser Systems: The Rheinmetall Skyranger 30 HEL integrates a 30mm cannon, guided missiles, and a 20 kW high-energy laser. Germany ordered 19 systems for approximately EUR 595 million (Rheinmetall, 2022).

High-Power Microwave: The Epirus Leonidas deactivated 61 of 61 drones across five scenarios -- including a 49-drone swarm with a single pulse. Cost per "kill": a few US cents (Breaking Defense, 2025; Epirus, 2025).

Kinetic Interceptors: The Rheinmetall Skynex with AHEAD ammunition (35mm) costs approximately EUR 4,000 per engagement -- significantly cheaper than IRIS-T (EUR 300,000-500,000) or Patriot (USD 3-4 million) (Defence-UA).

¶ 3.4 The Cost Asymmetry

Annual Patriot production amounts to only ~650 missiles worldwide (Norsk Luftvern, 2025; Norsk Luftvern: Reality; Euro-SD, 2025).

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