Focus on Low-Altitude Communications Trends in Drone Video Transmission, Navigation And Countermeasure Antenna Technologies

Against the backdrop of the low-altitude economy taking off in full swing, unmanned aerial vehicles (UAVs) are no longer merely isolated flying hardware, but have evolved into intelligent aerial mobile nodes integrating advanced communication, navigation and remote control (CNR) functions. With the widespread application of eVTOLs (electric vertical take-off and landing aircraft) and industrial-grade UAVs in scenarios such as urban logistics, power line inspection and emergency rescue, the low-altitude electromagnetic environment is becoming increasingly complex.

As the critical interface between electromagnetic waves and the radio frequency front-end, the quality of antenna design directly determines the communication range, positioning accuracy and security capabilities of the entire system. This article will provide an in-depth analysis of current technical challenges, mainstream solutions and future trends across three core areas—video transmission, navigation and countermeasures—from the perspective of a professional antenna engineer.

1. UAV video transmission antenna technology: high bandwidth, multi-frequency conformal design and channel adaptation

High-definition, low-latency image transmission is central to the operation of unmanned aerial vehicles (UAVs). Currently, the demand for transmitting 4K/8K ultra-high-definition video streams and multiple channels of digital and intelligent networked data places extreme demands on video transmission antennas, requiring them to be ‘high-gain, wide-bandwidth and compact’.

1.1 Multi-band and Ultra-wideband (UWB) Technology

Traditional UAVs typically employ separate antennas for different operational frequency bands (such as the 1.4 GHz government dedicated network and the 2.4 GHz/5.8 GHz industrial and civil bands). This ‘one frequency, one antenna’ design not only consumes a significant amount of airframe surface area but also leads to severe intermodulation interference (PIM) and electromagnetic compatibility (EMC) issues due to the antennas being positioned too close to one another.

The prevailing trend in modern antenna engineering is the adoption of Ultra-Wideband (UWB) fractal designs or multi-mode, multi-frequency shared antenna technologies.

Fractal Antenna: By utilising the self-similarity of geometric fractals, the antenna resonates simultaneously across multiple discrete frequency bands, thereby replacing the three antenna units previously required with a single unit.

Multi-layer Low-Temperature Co-fired Ceramic (LTCC) Integration: By integrating the multiplexer and antenna within the RF front-end, filtering, impedance matching and the radiating element are combined into a single unit, significantly reducing the on-board load.

1.2 Conformal Antennas and Omnidirectional High-Gain Radiation

To avoid compromising the aerodynamic configuration of unmanned aerial vehicles (UAVs) and to reduce aerodynamic drag, conformal antenna technology is rapidly replacing external whip antennas.

By directly and discreetly integrating microstrip patch arrays and flexible printed circuit (FPC) antennas into the leading edge of the drone’s wings, the landing gear or the interior of the composite fuselage, a ‘seamless’ installation is achieved. However, conformal designs are often constrained by the curvature of the airframe, which can easily lead to distortion of the radiation pattern. Engineers are introducing metamaterials to manipulate surface waves, ensuring that the antenna maintains excellent omnidirectional circularity and circular polarisation characteristics even during drastic changes in the airframe’s attitude (such as dives or high-angle turns), thereby effectively suppressing image tearing or flickering in video transmission caused by multipath effects.

2. UAV Navigation Antenna Technology: System-wide High Precision and RF Front-end Interference Resistance

Navigation systems serve as the ‘eyes’ of a UAV. Whether it is an industrial UAV performing centimetre-level autonomous inspections or specialised equipment used for public safety, both rely heavily on stable and reliable satellite navigation systems (GNSS).

2.1 System-Wide Multi-Frequency High-Precision Positioning

To meet the technical requirements of RTK (Real-Time Kinematic) and PPP (Precision Point Positioning), modern UAV navigation antennas must be capable of simultaneously covering all frequency bands of the world’s major navigation systems, including China’s BeiDou (B1/B2/B3), the US GPS (L1/L2/L5), Russia’s GLONASS and Europe’s Galileo.

In engineering design, the core metric for evaluating high-precision navigation antennas is Phase Centre Variation (PCV).

Engineers employ a multi-feed network design to ensure that the antenna’s electrical phase centre and physical centre coincide spatially to within the millimetre.

By optimising the antenna’s gain performance at low elevation angles, the drone can still lock onto a sufficient number of ‘low-altitude satellites’ in challenging electromagnetic environments, such as urban canyons and forested areas, thereby preventing loss of position.

2.2 Evolution and Miniaturisation of the Quadrifilar Helix Antenna

In small and consumer-grade drones, the quadrifilar helix antenna (QHA) is the preferred choice due to its unique structural advantages. The QHA is capable of delivering excellent circular polarisation purity (i.e. an extremely low axial ratio) and a near-perfect hemispherical radiation pattern without the need for a large metal ground plane.

The current direction of technological advancement involves the use of high-dielectric-constant microwave ceramics as the dielectric substrate. By increasing the dielectric constant, the physical dimensions of the antenna can be reduced by more than 60%. Furthermore, when combined with an integrated high-linearity low-noise amplifier (LNA) and high-Q surface acoustic wave (SAW)/bulk acoustic wave (BAW) filters, strong harmonic interference from ground-based base stations (such as 5G/6G signals) can be filtered out at source.

3. Drone Countermeasure Antenna Technology: The Transition from Electromagnetic Jamming to Integrated Communications, Sensing and Computing

The boom in the low-altitude economy inevitably necessitates upgrades to defence technologies against illegal ‘black flight’ drones. Traditional countermeasure antennas predominantly employ omnidirectional, high-power jamming; this ‘scorched earth’ approach is highly likely to interfere with surrounding civilian communication networks. New-generation countermeasure antenna technology is evolving towards intelligence, directionality and the integration of communications, sensing and computing.

3.1 5G-A Integrated Sensing and Communication and Metasurface Phased Arrays

With the coverage of low-altitude airspace by 5G-A (5G-Advanced) and future 6G networks, Integrated Sensing and Communication (ISAC) antennas have become a cutting-edge research topic in the RF field.

Countermeasure systems are no longer merely single “jammers”, but have evolved into intelligent terminals that integrate radar detection and electromagnetic suppression.

Active Electronically Scanned Array (AESA) Antennas: Combined with Digital Beamforming (DBF) algorithms, countermeasure arrays can synthesise high-gain narrow beams in an extremely short time (millisecond scale) to direct electromagnetic interference at intruding UAVs at long range.

Reconfigurable Intelligent Metasurfaces (RIS): By dynamically altering the phase of metasurface elements in real time, these systems can flexibly manipulate reflected or transmitted beams, enabling the construction of low-power, omnidirectional, and cost-effective electromagnetic fences.

3.2 Ultra-wideband Directional Suppression and Adaptive Beam Notching

Modern illicit UAVs frequently employ frequency-hopping spread spectrum (FHSS) technology and non-standard frequency bands for remote control and video transmission, which requires countermeasure antennas to possess an extremely wide dynamic operating range.

Logarithmic-periodic dipole (LPDA) and high-gain horn antenna arrays are widely used in portable ‘jamming guns’ and fixed defence stations due to their ultra-wideband characteristics. To address the issue of collateral damage to friendly legitimate aircraft during jamming operations, modern countermeasure antenna systems have introduced adaptive beam nulling technology. On the digital signal processing side, whilst the antenna is directed at unauthorised drones, it can automatically create electromagnetic notches (i.e. blind spots where the radiation gain is close to zero) in the direction of friendly police and rescue drones or nearby civilian base stations, thereby achieving an advanced defence configuration characterised by ‘precise, directional strikes with no impact on friendly communications’.

4. Summary and Future Outlook for Antenna Engineering Technology

In the future, low-altitude communication, navigation and countermeasure antenna technologies will no longer follow isolated development paths, but will instead exhibit characteristics of deep integration, miniaturisation and intelligence:

For antenna engineers, the challenges of the future will lie not only in the design of the RF hardware itself, but also in how to seamlessly integrate advanced physical electromagnetics, cutting-edge materials science and artificial intelligence algorithms. Continuously pushing the boundaries of electromagnetics in complex low-altitude channels is the cornerstone of building a secure, efficient and seamless low-altitude Internet of Things.