The Swarm Weapon That Cannot Be Too Broad

Introduction

High-power microwave (HPM) weapons occupy a distinctive niche within directed-energy air defence. Unlike lasers, which concentrate energy on a specific point, microwave systems are designed to disrupt or damage electronics across a wider volume of space. That characteristic makes them especially attractive against drone swarms, where dozens of aircraft may approach simultaneously and where engaging each target individually can be too slow or too expensive. At the same time, the very feature that makes HPM systems useful against groups of drones creates a governance challenge: electronics belonging to friendly forces, civilian infrastructure, or nearby systems may also be exposed if controls are inadequate. The result is a technology whose military value depends as much on rules, deconfliction and electromagnetic discipline as on raw power. [GAO]gao.govgao 23 106717Science & Tech Spotlight: Directed Energy Weapons25 May 2023 — For example, wider beam DEWs, such as high power microwave or millimete…Published: May 2023

Why Microwave Systems Suit Groups of Drones

Drone swarms create a fundamentally different defensive problem from a single aircraft. Traditional air-defence systems often engage one target at a time and consume finite ammunition or missiles. A swarm seeks to overwhelm that logic through numbers. High-power microwave weapons attempt to reverse the cost equation by affecting many electronic targets within a beam footprint at once. [DroneShield]droneshield.comA Counter to Drone Swarms: High-Power Microwave…Military forces must prioritise a counter to drone swarming tactics with wh…

The mechanism is straightforward in concept. An HPM system emits intense electromagnetic energy intended to couple into electronic components, wiring or circuits. The objective is not necessarily to burn through a structure but to disrupt, degrade or permanently damage the electronics that allow a drone to navigate and function. The US Office of Naval Research describes HPM weapons as systems that interact directly with electronics, causing disruption or damage sufficient to prevent mission completion. [Office of Naval Research]onr.navy.milOffice of Naval ResearchDirected Energy Weapons: High Power MicrowavesHPM weapons create beams of electromagnetic energy over a broad spe…

For swarm defence, several advantages stand out:

• One-to-many engagement: A sufficiently broad microwave footprint can affect multiple drones during a single engagement cycle rather than requiring separate aim points. [DroneShield]droneshield.comA Counter to Drone Swarms: High-Power Microwave…Military forces must prioritise a counter to drone swarming tactics with wh…
• Rapid response: Electronic effects occur at electromagnetic speeds, potentially allowing defenders to engage dense formations before they disperse. [Office of Naval Research]onr.navy.milOffice of Naval ResearchDirected Energy Weapons: High Power MicrowavesHPM weapons create beams of electromagnetic energy over a broad spe…
• Magazine depth: The limiting factor is typically power generation and thermal management rather than stocks of interceptors. [Defence Finance Monitor]defencefinancemonitor.comnon kinetic counter uas with highDefence Finance MonitorNon-Kinetic Counter-UAS with High Power Microwave8 Dec 2025 — This report examines the operational, technical and…
• Economics: Defenders can avoid spending costly missiles against inexpensive mass-produced drones. [DroneShield]droneshield.comA Counter to Drone Swarms: High-Power Microwave…Military forces must prioritise a counter to drone swarming tactics with wh…

Recent demonstrations illustrate the attraction. In 2025, Epirus reported that its Leonidas HPM system neutralised dozens of drones during live-fire events, including a large swarm engagement in which a single microwave pulse reportedly affected 49 drones. Independent reporting described the demonstration as evidence of the growing interest in counter-swarm microwave defence. [Epirus+2Unmanned Airspace]epirusinc.comTap to unmute.Read moreEpirusEpirus' Leonidas High-Power Microwave Defeats 49-Drone…10 Sept 2025 — Leonidas neutralized 61-of-61 drones, culminating in a 49…

The operational appeal is therefore not precision but scale. Microwave weapons are being developed because defenders increasingly face attacks in which quantity matters as much as the sophistication of any individual drone. [The War Zone]twz.comarmy puts 50m bet on next gen leonidas high power microwave counter drone techThe War ZoneArmy Puts $43M Bet On Next Gen Leonidas High Power…17 Jul 2025 — Epirus' CEO says successful tests of the company's Gen II…

How Area Effects Create Friendly-Risk Problems

The same area effects that make microwave weapons effective against swarms also create their most important limitation. Electronics do not inherently distinguish between friendly and hostile ownership.

The US Government Accountability Office has highlighted this issue directly, noting that wider-beam directed-energy systems such as high-power microwave weapons can affect all assets within an area, whether friend or foe. In practical terms, this means a commander cannot assume that only the targeted drones will experience disruption. [GAO]gao.govgao 23 106717Science & Tech Spotlight: Directed Energy Weapons25 May 2023 — For example, wider beam DEWs, such as high power microwave or millimete…Published: May 2023

Several categories of risk arise:

Friendly military systems. Modern forces rely heavily on digital communications, sensors, radios, networking equipment, navigation aids and autonomous systems. If these assets lie within the microwave engagement footprint, they may experience unintended effects unless appropriately hardened or excluded from the area. [Electronics For You]electronicsforu.comElectronics For YouDirected Energy Weapons: High Power Microwaves4 Oct 2016 — Proper planning before an HPM attack could prevent unintend…

Civil infrastructure. Military operations increasingly occur near ports, airfields, energy facilities and communications networks. The broader the microwave effect, the greater the need to understand nearby electronic dependencies before employment. [QinetiQ]qinetiq.comThe challenges of Directed Energy30 Mar 2021 — Understanding collateral effects and interoperability with infrastructure is key. –…

Uncertain damage assessment. Microwave effects are often less visually obvious than kinetic interception. A drone may lose function and fall, but evaluating whether nearby systems were also affected can be more difficult. Analysts have long noted that post-engagement assessment for HPM attacks is inherently challenging because physical destruction may not be visible. [Electronics For You]electronicsforu.comElectronics For YouDirected Energy Weapons: High Power Microwaves4 Oct 2016 — Proper planning before an HPM attack could prevent unintend…

Mixed airspace complications. Swarms may operate near friendly drones, civilian aircraft support systems or allied platforms. An engagement that successfully neutralises hostile drones could also interfere with systems operating in the same electromagnetic environment if safeguards fail. [GAO]gao.govgao 23 106717Science & Tech Spotlight: Directed Energy Weapons25 May 2023 — For example, wider beam DEWs, such as high power microwave or millimete…Published: May 2023

This is why microwave weapons are often described as counter-electronics systems rather than purely anti-drone systems. Their actual target is the electronic architecture that enables the drone, and many other systems depend on electronics as well. [Epirus]epirusinc.comEpirusEpirus Leonidas High-Power Microwave: Directed Energy…Leonidas is a solid-state, high-power HPM system, utilizing Gallium Nitrid…

The Governance Challenge Is Not Secondary

For microwave defence systems, governance is not simply a legal afterthought. It is part of the weapon’s operational effectiveness.

A laser operator generally attempts to place energy on a defined point. An HPM operator must instead think about an electromagnetic volume. The question is not merely whether the target lies within the beam but also what else lies within or near the affected area. [GAO]gao.govgao 23 106717Science & Tech Spotlight: Directed Energy Weapons25 May 2023 — For example, wider beam DEWs, such as high power microwave or millimete…Published: May 2023

This changes how military organisations approach deployment. Before fielding microwave systems, planners typically need to address:

Some modern programmes increasingly emphasise controllability rather than simply maximum power. Developers have highlighted software-defined approaches that allow operators to adjust energy output, shape engagement parameters and define protected areas, reflecting the importance of controlling collateral electromagnetic effects rather than merely expanding destructive reach. [Tectonic Defense]tectonicdefense.comexclusive epirus leonidas downs fiber optic drone during testsTectonic DefenseExclusive: Epirus' Leonidas Downs Fiber-Optic Drone…13 Jan 2026 — Leonidas is a vehicle-mounted high-power microwave (…

The governance challenge therefore becomes one of balancing breadth against discrimination. A beam wide enough to defeat a swarm may also increase the burden of ensuring that unintended systems remain protected.

Rules and Deconfliction Before Field Use

Because of these risks, microwave weapons are most credible when integrated into a larger defensive architecture rather than treated as stand-alone solutions.

Effective deconfliction generally begins before an engagement occurs. Defenders must know which friendly systems are operating nearby, which areas are electronically sensitive, and whether alternative defensive tools are available. In many scenarios, commanders may choose a missile, gun, jammer or laser instead of a microwave system if collateral electronic exposure appears unacceptable. [GAO]gao.govgao 23 106717Science & Tech Spotlight: Directed Energy Weapons25 May 2023 — For example, wider beam DEWs, such as high power microwave or millimete…Published: May 2023

Several practical measures are commonly discussed in the context of HPM employment:

Electromagnetic mapping. Commanders require awareness of nearby friendly and civilian electronic assets before authorising use. [QinetiQ]qinetiq.comThe challenges of Directed Energy30 Mar 2021 — Understanding collateral effects and interoperability with infrastructure is key. –…

Protected zones. Operational plans may establish areas where microwave engagements are restricted because critical systems are present. [Tectonic Defense]tectonicdefense.comexclusive epirus leonidas downs fiber optic drone during testsTectonic DefenseExclusive: Epirus' Leonidas Downs Fiber-Optic Drone…13 Jan 2026 — Leonidas is a vehicle-mounted high-power microwave (…

Equipment hardening. Shielding and protective design can reduce vulnerability among friendly systems expected to operate near HPM weapons. [Electronics For You]electronicsforu.comElectronics For YouDirected Energy Weapons: High Power Microwaves4 Oct 2016 — Proper planning before an HPM attack could prevent unintend…

Layered engagement doctrine. Microwave weapons are often best viewed as one option among several, reserved for situations where swarm density justifies their broader effects. [DroneShield]droneshield.comA Counter to Drone Swarms: High-Power Microwave…Military forces must prioritise a counter to drone swarming tactics with wh…

The broader lesson is that microwave swarm defence is not merely a technical problem. The technology’s usefulness depends on whether operators can generate enough area effect to defeat hostile drone groups while maintaining confidence that friendly electronics, communications and infrastructure remain protected. As drone swarms become a more prominent threat, that balance between mass engagement and electromagnetic restraint is likely to become one of the defining questions in the operational use of high-power microwave weapons. [GAO+2Office of Naval Research]gao.govgao 23 106717Science & Tech Spotlight: Directed Energy Weapons25 May 2023 — For example, wider beam DEWs, such as high power microwave or millimete…Published: May 2023

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Further Reading

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Army of None

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Army of None: Autonomous Weapons and the Future of War

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Endnotes

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   Published: May 2023

2. Source: droneshield.com
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   A Counter to Drone Swarms: High-Power Microwave...Military forces must prioritise a counter to drone swarming tactics with wh...

3. Source: qinetiq.com
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   The challenges of Directed Energy30 Mar 2021 — Understanding collateral effects and interoperability with infrastructure is key. –...

4. Source: arxiv.org
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   Counter-Drone Technologies Could Enhance Safety and...5 Apr 2022 — Counter-drone technology can detect and—when needed—jam, capture...

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8. Source: epirusinc.com
   Title: Tap to unmute.Read more
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9. Source: unmannedairspace.info
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   The demonstration peaked with a 49-drone swarm defeat, using [one burst]({{ 'one-burst/' | relative_url }}) of...

10. Source: twz.com
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12. Source: epirusinc.com
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    EpirusEpirus Leonidas High-Power Microwave: Directed Energy...Leonidas is a solid-state, high-power HPM system, utilizing Gallium Nitrid...

13. Source: tectonicdefense.com
    Title: exclusive epirus leonidas downs [fiber optic]({{ ‘fiber-drones/’ | relative_url }}) drone during tests
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    Tectonic DefenseExclusive: Epirus' Leonidas Downs Fiber-Optic Drone...13 Jan 2026 — Leonidas is a vehicle-mounted high-power microwave (...

14. Source: epirusinc.com
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    Home of Leonidas, the Premier High-Power...Epirus combines the latest in directed energy, long-pulse high-power microwaves (HPM), AI, an...

15. Source: market.us
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    2035 from USD 9.7 Billion in 2025, at a CAGR of 14.3%...

Additional References

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   11 Dec 2025 — The Leonidas system's ability to intercept a large number of drones simultaneously constitutes a breakthrough in the field...

2. Source: realcleardefense.com
   Title: a counter to drone swarms high power microwave weapons 1109557
   Link: https://www.realcleardefense.com/articles/2025/05/12/a_counter_to_drone_swarms_high-power_microwave_weapons_1109557.html
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   A Counter to Drone Swarms: High-Power Microwave...12 May 2025 — Military forces must prioritise a counter to drone swarming tactics with...

   Published: May 2025

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   Link: https://www.researchgate.net/publication/401707891_Cost-Effectiveness_Analysis_of_Counter-Unmanned_Aircraft_Systems_Technologies_A_Comparative_Study_of_Kinetic_Electronic_Warfare_and_Directed_Energy_Countermeasures_2022-2026
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   Cost-Effectiveness Analysis of Counter-Unmanned Aircraft...9 Mar 2026 — This quantitative study conducted a comprehensive cost-effective...

4. Source: tomshardware.com
   Title: Tom’s Hardware High-power microwave system downs 49 drones in [one shot]({{ ‘one-shot/’ | relative_url }})
   Link: https://www.tomshardware.com/tech-industry/high-power-microwave-system-downs-49-drones-in-one-shot-weaponized-electromagnetic-interference-erases-drone-swarms-en-masse
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   electronics warfare company, successfully demonstrated a major advancement in counter-drone technology with its Leonidas high-power micro...

5. Source: calibredefence.co.uk
   Title: epirus zaps fibre optic fpv with leonidas microwave weapon
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   Epirus zaps fibre-optic FPV with Leonidas microwave...28 Jan 2026 — Epirus has developed a microwave weapon called Leonidas that has dem...

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   Directed Energy Weapons in CounterDrone Missile Defense4 May 2026 — The high-energy lasers that are being used to defeat any aerial threa...

   Published: May 2026

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