Adding a fused passive sensing layer to IAMD systems

On February 28, 2026, military bases, critical national infrastructure, and civilian infrastructure on the Arabian Peninsula and wider Middle East were attacked. Targets ranged from oil refineries to airports.

Air defenses in the region proved highly effective, with some Gulf states reporting an interception rate of over 90%. Integrated Air and Missile Defense (IAMD) systems proved particularly adept at neutralizing ballistic missiles as part of the F2T2EA kill chain.

However, despite the successes, the attacks revealed several vulnerabilities in air defense. This article will outline problems experienced by air defenders and military forces and detail how adding an RF sensing layer can help alleviate them.

Low flying one-way attack drones

Long-endurance one-way attack drones are designed to operate at low altitude and at relatively low speeds, enabling long-range attack. Their design results in a small radar cross-section, making the drones difficult to detect and track.

These features pose a challenge for many modern surface-to-air missile systems, whose radars are primarily optimized for medium- and high-altitude threats and can be strained when rapidly switching between altitude bands while processing multiple simultaneous tracks.

While speed and heat are the Achilles' heels of ballistic missiles, most one-way attack drones and loitering munitions rely on some form of wireless technology. RF signals emitted by drones support command links, telemetry, or satellite navigation, meaning they rely on the electromagnetic spectrum—even when they are not continuously emitting RF signals.

When drones do emit RF signals, highly sensitive RF sensors and specialist geolocation software can be used to detect and geolocate them.

Counter-targeting of radar

IAMD systems rely on active radar as a core sensing layer. Because active radar functions by transmitting RF energy, it generates electromagnetic signatures that can be detected and geolocated by an adversary, making radar installations vulnerable to one-way attack drones pre-programmed against fixed emitter coordinates and to anti-radiation missiles (ARMs). Radar equipment is a high-value asset that is vulnerable to destructive Suppression of Enemy Air Defense (SEAD).

Any fixed radar installation that emits continuously and predictably is vulnerable to attack. Mobile radar that uses frequency agility and networking is much harder to destroy. Active radar reveals location, enabling adversaries to target the installation, avoid interceptors, or establish methods to degrade, disrupt, or deny a radar sensor feed.

Flexibly-deployed passive RF sensors can contribute to keeping radar installations safe. Under Emission Control (EMCON), passive sensors can continue to monitor the electromagnetic spectrum without emitting RF signals. If a target is detected, other sensors can be tipped and cued, only becoming active in the event of a threat. Passive RF sensors can also be used to ensure that the correct EMCON level is being observed, preventing the installation from being targeted.

Using expensive munitions to neutralize inexpensive drones

As drone development has iterated at speed, conventional air defense systems have struggled to match the pace. Using expensive missiles to counter low-cost threats is one of the most salient vulnerabilities of IAMD systems.

To counter this cost-exchange imbalance, military forces have invested heavily in lower-cost interception methods and in developing operational experience against massed drone attacks. A key requirement is accurate target characterization before engagement. Analyzing a target’s RF footprint can help distinguish drones from other aerial objects—for example, by identifying the data link frequencies associated with unmanned systems.

Once a target has been correctly classified, air defenders can assign the most efficient response, including low-cost interceptor drones. In increasingly transparent and contested battlespaces, where active radar emissions may expose defensive positions, passive RF sensor networks are becoming a principal cueing layer for low-cost drone defeat systems.

Fratricide

Conflict involves the unfortunate risk of fratricide. When defending airspace, there is a high risk of fratricide as many targets may appear similar, engagements happen rapidly, and identification windows are short.

Adding an additional method to discriminate between friend and foe could be advantageous in high-stress environments. Specialist electromagnetic spectrum detection software, functioning in conjunction with distributed RF sensors, can be programmed to detect key signals, such as friendly data links or IFF emitters, allowing air defenders to use multi-sensor data fusion to more easily discriminate between friendly and enemy aircraft.

Image 1: RF emissions from a Su-35 tactical aircraft

Enhancing situational awareness

Understanding the Recognized Air Picture (RAP) allows ground-based air defenders to detect and respond to threats. Using kinematic information such as altitude, heading, speed, and track history, the RAP supports airspace control and engagement decisions. However, solely using a RAP cannot immediately answer questions such as:

• Is the target a drone or a cruise missile?

• Is the object hostile or civilian?

• Is the target emitting radar or datalink RF?

• Is the object maneuvering in a hostile manner?

In a context such as the Middle East, which has congested airspace and electromagnetic spectrum, relying on the RAP alone presents air defenders with a classification gap that can be resolved by understanding the Recognized Electromagnetic Picture (REMP).

Passive RF sensing provides the REMP. RF data gathered, such as emitter identity, signal type, and waveform behavior, can be fused with the RAP to improve and accelerate early warning, classification, and engagement decisions.

While RAP explains movement, REMP reveals behavior. Fusing these pictures and complementing the view with additional sensors such as EO/IR and acoustic provides enhanced situational awareness that can be shared with allies across the region.

Resilience to jamming

Active radar sensors are susceptible to electronic attack (EA), which degrades air defense networks. Critical infrastructure and military installations are then vulnerable to kinetic strikes.

Passive electromagnetic sensors, however, remain unaffected by targeted high-power emissions. Instead of being blinded, these sensors can detect and geolocate the position of any deliberate electromagnetic interference. Using the Time Difference on Arrival (TDoA) method, air defenders could precisely locate the emitter delivering EA and neutralize it.

Conclusion

Even highly capable IAMD architectures remain vulnerable when confronted by low-cost drones. While active radar remains essential for surveillance, tracking, and engagement, relying on it as the sole sensing layer creates vulnerabilities.

Adding a fused passive RF sensing layer does not replace radar; it strengthens it. By contributing early warning, emitter detection, target characterization, and electromagnetic awareness, passive RF sensing helps air defenders maintain resilience when radar performance is degraded.