Low-Observable Antenna Geometries and Radar Cross-Section Reduction
Any protruding antenna element on a combat aircraft creates a specular reflection point detectable by hostile radar — eliminating such protrusions is the foundational requirement of conformal antenna design for stealth performance. Conformable antenna designs address this by integrating radiating elements flush with, or embedded in, the aircraft skin, removing the geometric discontinuities that elevate radar cross-section (RCS). Two patents filed in 2020 — one from Hanwha Systems in South Korea, one from Israel Aerospace Industries — formally codify this requirement at both the component and systems levels.
Hanwha Systems’ VHF Low RCS Conformable Antenna patent (2020) discloses a VHF-band antenna apparatus formed in a conformable type where the radome assembly and antenna assembly are overlapped to achieve a smaller thickness than the antenna area. The design uses a sleeve pin bound to an internal radiation body for wideband matching, and an EMI shielding gasket installed at a short-circuit pin on the external radiation body to increase low-frequency bandwidth coverage. This architecture achieves a reduced profile directly compatible with airframe-flush integration, enabling acceptable VHF-band resonance while keeping the physical footprint within stealth constraints.
Hanwha Systems’ 2020 VHF Low RCS Conformable Antenna patent discloses a VHF-band antenna where the radome assembly and antenna assembly are overlapped to achieve a smaller thickness than the antenna area, enabling airframe-flush integration without protruding elements.
Israel Aerospace Industries’ complementary systems-level patent — Waterborne and Airborne Systems with Reduced Radar Cross-Section Signature (2020) — explicitly describes airborne vehicles configured to lack signal-reflecting protrusions above the upper surface and below the lower surface. Critically, it provides for the installation of one or more hidden communications antennas as part of the initially constructed airframe, not as a retrofit add-on. The patent also allows for imaging systems to be mounted in hidden regions of the vehicle, further minimising detectable electromagnetic and optical signatures.
“IAI has explicitly categorised antennas as ‘hidden communications antennas’ — reflecting the operational philosophy that every aperture must either be recessed, covered by a frequency-selective surface, or embedded in a way that does not perturb the aircraft’s RCS profile.”
Radar cross-section is a measure of how detectable an object is by radar. It is determined by the object’s size, shape, and material composition. In combat aircraft design, reducing RCS — including the contributions of antenna apertures — is the central objective of low-observable (stealth) engineering. Standards and measurement methodologies are documented by bodies including IEEE.
Together, these two patents define the structural requirements for stealth-compatible antennas: near-zero protrusion height, wideband performance that does not require external matching networks or protruding elements, and integration within the radome or skin structure itself. The VHF band is a particularly important frontier because low-frequency radar — operating in the VHF and UHF bands — is specifically effective against stealth aircraft, as conventional shaping techniques offer limited RCS reduction at these wavelengths, a fact well-documented in open literature published by organisations such as NATO.
Plasma-Assisted Low-Observable Communication: Solving the Blackout Problem
Plasma-based low-observable coatings, and the ionized boundary layer generated by high-velocity flight, attenuate electromagnetic signals and can effectively silence a stealth aircraft’s communication antennas — a critical tactical liability that conformal antenna systems must resolve. Addressing this engineering trade-off is the subject of two related patents from Kwangwoon University, filed in 2023 and 2024 respectively.
Kwangwoon University’s 2024 patent discloses a device installed around the communication antenna of an air vehicle that applies a magnetic field — leveraging the gyromagnetic properties of plasma formed around the antenna — to reduce signal attenuation and maintain active communication while the platform remains in a low-observable plasma state.
The 2024 filing, Apparatus and Method for Communication in Low Observable State Using Plasma, describes a device installed around the communication antenna of an air vehicle that mitigates communication radio wave attenuation caused by plasma. The disclosed method applies a magnetic field, leveraging the gyromagnetic properties of the plasma formed around the communication antenna, to reduce signal attenuation and maintain active communication even while the platform remains in a low-observable plasma state. The 2023 predecessor filing confirms the core technique: the magnetic-field-based plasma management system is mounted as a conformal element around the antenna aperture, ensuring the antenna’s physical integration with the vehicle is not compromised while its electrical performance is restored.
Kwangwoon University’s dual patents (2023 and 2024) demonstrate that magnetic-field-based plasma management, mounted conformally around antenna apertures, can preserve datalink, IFF (identification friend-or-foe), and communications functionality simultaneously with plasma-based signature suppression — without introducing any additional aerodynamic protrusion that would compromise the low-RCS profile.
This approach is strategically significant because it enables next-generation stealth aircraft to retain datalink, IFF, and communications functionality simultaneously with plasma-based signature suppression. The conformal mounting of the plasma mitigation system around the antenna means no additional aerodynamic protrusion is introduced, preserving the low-RCS profile established by the airframe geometry. Research into plasma-electromagnetic interactions relevant to hypersonic flight has also been documented in publications indexed by Nature, underscoring the broader scientific context in which these patents operate.
Explore the full patent landscape for stealth antenna and low-observable technology in PatSnap Eureka.
Explore Patent Data in PatSnap Eureka →Conformal Array Beam Pattern Optimization on Curved Airframe Surfaces
Integrating antenna arrays conformally onto curved airframe surfaces — wing leading edges, fuselage flanks, and nose cones — introduces significant beam pattern distortion compared to planar arrays, because the phase and amplitude relationships between elements are altered by the curvature of the mounting surface. LIG Nex1’s 2024 patent and ELTA Systems’ 2023 filing address this problem through two complementary signal processing approaches.
LIG Nex1’s 2024 conformal array optimization patent converts the beam weight optimization problem into a convex optimization problem, allowing the resulting optimal weight vector to be transmitted to the antenna device to produce beam patterns on curved airframe surfaces that closely approximate the performance of a planar AESA array.
LIG Nex1’s Method and Apparatus for Processing Optimization for Optimal Beam Pattern Formation in Conformal Array Antenna (2024) discloses a systematic optimization pipeline. The system acquires reference beam pattern information based on a reference (planar) antenna structure, then acquires initial beam pattern information based on the conformal antenna structure. A model of the optimization problem is constructed using both sets of information, and the optimal weight is calculated by converting the problem into a convex optimization problem using a convex optimization method. The resulting optimal weight vector is transmitted to the antenna device to realize a beam pattern that closely approximates the reference planar performance.
This convex optimization approach is significant because it allows real-time or pre-computed weight sets to be loaded for different flight attitudes and target geometries, making the conformal array functionally equivalent to a planar AESA in terms of beam quality while retaining the airframe-flush physical profile essential to stealth.
ELTA Systems’ Method and Systems for Controlling an Antenna Pattern (2023) advances this further by describing a method in which the trajectory of the electromagnetic antenna field is deliberately curved in the near-field region as a result of amplitude control across array elements. By assigning individual weighting parameters to each antenna unit and constraining the curvature of the near-field propagation trajectory, ELTA Systems enables conformal arrays to produce shaped beams that compensate for the geometric distortions introduced by the curved mounting surface. A companion filing from the same assignee (2018) confirms the cross-jurisdictional protection strategy for this near-field beam curvature technique. Near-field antenna measurement and modeling standards relevant to this approach are maintained by IEEE.
Map the competitive patent positions of Hanwha Systems, LIG Nex1, ELTA Systems, and IAI in stealth antenna technology.
Analyse Competitor Patents in PatSnap Eureka →Key Players, National Strategies, and the Broader Electronic Warfare Context
The patent data reveals a concentrated cluster of assignees driving conformal antenna stealth technology, with the majority of filings originating in South Korea and Israel — reflecting active national investment in stealth-adjacent antenna research for defense aviation platforms. Each assignee occupies a distinct technical niche within the broader innovation ecosystem.
Hanwha Systems
Hanwha Systems emerges as the primary South Korean industrial actor, contributing the VHF low-RCS conformable antenna patent directly targeting airborne stealth platforms. The assignee also holds active patents on active protection systems employing phased-array-adjacent radar, reflecting a vertically integrated approach to aircraft self-protection and antenna management. The 2020 VHF conformable antenna patent specifically addresses the low-frequency detection challenge — an area where conventional stealth shaping is least effective and where conformal design is especially critical.
LIG Nex1
LIG Nex1 maintains the broadest active patent portfolio among Korean defense electronics firms in this dataset, spanning conformal array beam optimization, acousto-optical search devices for interference-wave defense, UAV interception, and anti-drone systems. Their 2024 conformal array optimization patent demonstrates active investment in the signal processing infrastructure needed to make conformal arrays operationally viable on stealth platforms.
Kwangwoon University
Kwangwoon University represents academic-industrial research at the critical plasma-communication intersection, with two active patents (2023 and 2024) addressing antenna performance under plasma low-observable conditions. This is a technically specialized niche with direct implications for hypersonic and next-generation fighter platforms. Academic-defense technology transfer of this type is tracked by institutions including WIPO as part of broader analysis of dual-use technology patenting trends.
Israel Aerospace Industries and ELTA Systems
IAI holds a systems-level patent on reduced-RCS airborne vehicles with hidden antennas, while ELTA Systems protects near-field beam pattern control methods applicable to conformal arrays. IAI’s approach integrates antenna concealment as a native design parameter rather than an afterthought, consistent with Israeli combat aviation experience. ELTA Systems’ cross-jurisdictional protection of its 2018 and 2023 beam curvature patents signals long-term strategic commitment to conformal array signal processing.
Elettronica S.p.A. and the Electronic Warfare Context
Elettronica S.p.A. holds active patents in Japan and Korea on reactive jamming systems — specifically the Zenith Reactive Jammer (2023) and Ceiling Reaction Jammer (2023) — that use multiple receiving antennas covering specific elevation angle ranges. This approach is conceptually related to conformal array angular coverage management and highlights the electronic warfare integration context in which stealth-compatible antenna systems must operate.
The Defense Agency for Technology and Quality’s 2024 patent on a Deception System for Ship Self Defense Using Swarm Aircraft further illustrates the broader strategic context: RCS management through radar cross-section adjustment via coordinated positioning of flight vehicles establishes a conceptual link between conformal antenna RCS control and electronic deception strategies. Defense technology acquisition and standardization frameworks relevant to these systems are maintained by organizations including NATO.
“Convex optimization is the key signal processing enabler for conformal arrays on curved airframes — transforming the array weight problem into a convex form allows beam patterns to match planar AESA performance even on curved fuselage or wing surfaces.”