Drones have gone from being a simple hobby to becoming key professional tools for precision work: photogrammetryPrecision agriculture, industrial inspection, maritime operations, filmmaking… In all these scenarios, the heart of navigation is always the same: good GNSS integration and, especially, a GNSS antenna optimized for UAVs.
When it comes to centimeter-level navigation, simply mounting "any old GPS" on the drone isn't enough. The quality of the receiver is important, but the GNSS antenna for precision navigation UAV It makes the difference between a stable flight and one riddled with errors, signal loss, deviations upon landing, or data unusable for mapping. Understanding what a GNSS antenna actually does, what types exist, and how they are used in UAVs is fundamental to designing or choosing a reliable flight system.
What is a GNSS antenna and why is it so critical in a UAV?
A GNSS antenna is the element that acts as bridge between the GNSS receiver and the satellite constellation that orbit around the Earth. Their mission is to capture the extremely weak signals emitted by systems such as GPS, Galileo, GLONASS, or BeiDou and deliver them to the receiver with the best possible quality so that it can calculate position, speed, and time.
These GNSS signals are transmitted in the L-band, they reach the surface with powers close to -130 dBm And they are very easily masked by interference or noise. Therefore, high sensitivity, low internal noise, and very precise filtering are fundamental in a GNSS antenna for UAVs. Any degradation at this initial stage results in loss of accuracy, timing errors, and, in extreme cases, the inability to maintain drone guidance.
Another key aspect is compatibility with constellations and frequencies. An antenna can be single-frequency or multi-band (for example, L1/L2 or L1/L5) and support one or more GNSS constellations at the same timeThe more bands and constellations it receives, the more satellites the receiver can track, resulting in better availability, more robust geometry, and less degradation of positioning in challenging environments such as urban canyons or dense forests.
In high-precision applications, the stability of the antenna's so-called "phase center" is crucial. The phase center is, simply put, the point within the antenna from which the signals are considered to originateIf that point shifts slightly with the angle of arrival or the frequency, it introduces systematic errors in the position. In scenarios such as reference stations, geodetic surveying, or demanding mapping missions, a phase-center stable GNSS antenna is essential to achieve consistent results over time.
In a UAV, all of this is complicated because the drone is constantly in motion, subject to vibrations, changes in orientation, and thermal variations. Hence the GNSS antennas specifically designed for unmanned aerial vehicles combine high-quality electrical design with compact, robust, and aerodynamic formats that minimize weight and drag.
Gain, radiation pattern, and interference rejection
An antenna's gain and radiation pattern directly influence navigation quality. For a drone, the ideal setup is a hemispherical, virtually omnidirectional radiation pattern, which allows receiving satellite signals across the entire sky, paying special attention to low elevation angles, where signals suffer more atmospheric attenuation.
A well-designed GNSS antenna offers sufficient gain in that upper hemisphere and usually integrates a Very low noise LNA (Low Noise Amplifier) along with narrowband filters. The goal is to increase the signal-to-noise ratio (SNR) before the signal reaches the receiver, reducing the impact of thermal noise and nearby interference. Without this, the receiver would be forced to work with signals at the limit of what is usable.
In addition to amplification, the antenna must defend itself against two common enemies: multipath propagation and radio frequency interference (RFI). Multipath propagation occurs when GNSS signals bounce off surfaces such as buildings, vehicles, metal structures, or water before reaching the antenna, generating delayed aftershocks that distort the calculation of distances to the satellites. To mitigate this, ground planes, choke rings, and specific geometric designs are used to reduce sensitivity to signals coming from grazing or reflected angles.
RFI, on the other hand, can originate from nearby transmitters, radio links, onboard telecommunications equipment, or even other systems on board the UAV itself. High-performance GNSS antennas often integrate highly selective band filters and optimized LNA stages to reject signals outside the GNSS bands, thus improving its performance against sources of jamming or accidental interference.
In particularly harsh contexts, such as defense, tactical applications, or contested GNSS environments, there are advanced designs like CRPA (Controlled Reception Pattern Antennas) capable of generating nulls in the direction of interference sources, providing anti-jamming and anti-spoofing capabilities that allow navigation to continue even when someone deliberately tries to degrade GNSS signals.
Types of GNSS antennas and common applications
Depending on the type of mission and the sector, different types of antennas are used. In professional surveying and mapping, the following are very common: high-precision geodetic GNSS antennasThese antennas are typically multiband and multiconstellation, often incorporating shock rings and robust housings. Their aim is to maximize centimeter-level accuracy and minimize multipath drift, so they are usually mounted on tripods or fixed stations with careful control of the physical reference.
In the automotive world, consumer electronics, and many light UAVs, ceramic patch or helical antennas, which are much more compact, tend to be used. Despite their small size, these antennas offer a A very reasonable balance between size, weight, consumption, and performanceThis makes them ideal candidates for small and medium-sized drones, where every gram counts.
In maritime and manned aviation environments, antennas must withstand vibrations, humidity, salinity, solar radiation, and large temperature variations. In these cases, sealed designs are used. high levels of sealing, such as IP67 or higherDurable materials and mechanical supports designed to withstand wind and intense accelerations. They are typically mounted on the exterior of ships and aircraft to ensure a clear view of the sky at all times.
For professional UAV platforms, it is common to combine robustness requirements with a lightweight form factor. Antennas such as those specifically designed for drones or high-precision UGVs (for example, models designed to work with RTK receivers like the ZED-F9P) are advertised as solutions for High gain and high accuracy for RTK applications and precision navigation, adjusting weight, size and performance to the UAV ecosystem.
In defense and aerospace, where the environment can be openly hostile, GNSS antennas often integrate advanced interference mitigation technologies, withstand a wider thermal and vibration range, and are combined with GNSS+INS systems, radars, and other sensors to offer robust navigation even with degradation or temporary loss of satellite signals.
Example of a multi-GNSS and multi-frequency antenna for UAVs: Hemisphere HA32
A good example of the type of solutions used in professional drones is the Hemisphere GNSS HA32 antenna. It is an antenna Multi-GNSS and multi-frequency optimized for UAV, GIS, RTK and high-precision navigation tasks, capable of working with GPS, GLONASS, Galileo, BeiDou and the company's own Atlas L-band correction service.
The HA32 uses an antenna architecture called “4-helix” or quadruple helix, which improves filtering and jamming performanceInside, it integrates an LNA with a typical noise figure of 2,0 dB and a gain of up to 30 dB, placing it in the range of high-performance antennas intended for demanding applications.
From a physical point of view, this antenna has a very compact format, with approximate dimensions of 40 x 75 mm and a weight close to 40 gramsThese are key factors when installed on a UAV, as they reduce both payload and aerodynamic drag. Despite its small size, it offers the necessary robustness to withstand vibrations and wind forces during flight.
To ensure its operation in adverse environmental conditions, the HA32 is sealed and features IP67 protection rating against dust and waterIt also incorporates an O-ring to help ensure a watertight seal. Assembly and integration are simple thanks to its widely used SMA RF connector.
An interesting aspect of Hemisphere's offering is the HA32's compatibility with the Atlas global correction service. Atlas provides L-band GNSS corrections with accuracies ranging from less than one meter to less than one decimeterThis system relies on approximately two hundred reference stations distributed around the globe. These corrections are transmitted via L-band satellite, resulting in virtually global coverage.
Atlas can be used not only with Hemisphere's own hardware but also as a complement to third-party GNSS receivers, leveraging integration capabilities such as BaseLink and SmartLink. This allows UAV platforms to be equipped with high-precision positioning solutions without relying exclusively on terrestrial correction networkswhich is very interesting in remote or over-the-sea missions.
GNSS+INS solutions and their role in UAV navigation
In a modern unmanned aerial vehicle, GNSS rarely works alone. It is usually combined with inertial system (INS) and other sensors within the flight control For a more stable, robust, and continuous navigation solution, this GNSS+INS fusion allows accuracy to be maintained even during brief satellite losses or signal degradation.
UAVs are used today for professional aerial photography, inspection of power lines and pipelines, infrastructure review, agricultural monitoring, aerial surveillance, and audiovisual production, among many other tasks. In all these applications, the flight control system is responsible for the stability, safety, and precision with which the mission is executed, and GNSS is a basic sensor for determining position, speed, altitude and orientation.
Manufacturers like Unicore Communications offer compact modules and at a reasonable cost, integrating high-precision positioning capabilities or even simultaneous positioning and headingThese types of products are designed to be integrated directly into the UAV's flight control system, simplifying the avionics design and reducing weight and power consumption.
The key is to have the most reliable information possible about the drone's position and attitude anywhere in the world and in almost any weather condition. To achieve this, it is important to understand the different GNSS architectures available, their advantages and limitations, and choose the most appropriate one based on the mission profile, platform type, and operating environment.
The following section analyzes three common approaches to using GNSS in UAVs: RTK GPS/GNSS, GNSS Compass Moving Base and GNSS Compass Static BaseAll of them focused on improving the accuracy and orientation of the aerial platform without relying exclusively on sensors susceptible to interference, such as magnetometers.
RTK GPS/GNSS positioning in drones
RTK (Real Time Kinematic) mode has become a de facto standard for those seeking Relative accuracy at the centimeter level between drone and base stationIn this scheme, the UAV calculates its position relative to a GNSS base located on the ground (often integrated into the control station or GCS).
The base station measures its own position with high precision and sends differential corrections to the drone's GNSS receiver in real time. This compensates for common errors due to the atmosphere, clock, satellite orbit, and other factors, achieving a very precise relationship between both unitsIf configured correctly, RTK allows working with centimeter-level precision in 3D.
In a UAV, RTK positioning can be used throughout the entire flight or activated only during critical phases, depending on the mission requirements. A common use is to enable RTK in the approach and landing phase, to hit the “touch point” on fixed wings or for precise landings on a specific point in the case of multirotors. It is also very useful for advanced operations such as landings on nets or on moving vehicles.
One of the applications that makes the most of RTK in drones is photogrammetry. In this field, it is necessary to know the exact position of the camera in each shot in order to generate 3D modelsorthomosaics and highly accurate measurementsWith RTK, the camera position is calculated in real time with a margin of error of a few centimeters, both horizontally and vertically, reducing the need to place a large number of ground control points.
To take full advantage of RTK mode on a UAV, it is essential that the onboard GNSS antenna be high-quality, multi-constellation, and preferably multi-band. This combination allows the receiver to resolve phase ambiguities more quickly and robustly, maintaining the "FIX" solution stable even in environments where signals are not ideal.
GNSS Compass Moving Base: orientation without a magnetometer
The GNSS Compass Moving Base approach focuses on obtaining the attitude and heading of a moving vehicle without relying on magnetometers or other sensors susceptible to electromagnetic interference. To achieve this, it employs at least two GNSS antennas located on the same vehicle, with a known distance between them.
The idea is that one of the antennas acts as a "mobile base," while the other (or others) are considered "mobile" relative to it. The system calculates the relative vector between the antennas in real time, thus estimating the heading and, depending on the configuration, also the pitch and roll. The interesting thing is that Both the base and the mobiles can be in motion.and yet a precise vector that defines the orientation of the platform is achieved.
This technique avoids relying on a magnetometer, which is highly sensitive to external magnetic fields. In helicopters and other UAVs operating near large metal structures or high-voltage power lines, magnetic measurements can become unreliable or even useless. In such cases, a GNSS Compass Moving Base is used. It provides redundancy and stability in the heading estimate.reducing the risk of autopilot loss of orientation.
This method requires well-positioned antennas, separated by a known distance and with adequate visibility of the sky. Furthermore, it is highly recommended that the antennas and receiver support multiple constellations and, if possible, RTK (Real-Time Kinematic) to improve the resolution of the antenna spacing and the stability of the solution.
The mobile-based GNSS Compass is not limited to helicopters; it can also be applied to boats, land vehicles, UGVs, or any platform where it is necessary to have a GNSS compass. Precise and robust orientation without relying on the local magnetic field.
GNSS Compass Static Base: orientation from a fixed station
The GNSS Compass Static Base approach shares the previous philosophy but with one key difference: the reference is a fixed ground station. In this scheme, a stationary GNSS station with well-known coordinates It provides the necessary corrections and reference to improve both the drone's absolute position and its orientation.
The UAV's avionics system can be configured to use the previously measured coordinates of the base station antenna as an absolute reference. In this way, knowing both the vector between the base station and each of the drone's antennas and their geometry on the aerial platform, The relative vector between the onboard antennas can be calculated and the orientation derived from it..
One particularly interesting application of this architecture is in landings on mobile platforms, such as ships or special vehicles. In these scenarios, the fixed base station can be located at a known point, and the orientation corrections it transmits are used to achieve a more accurate estimate of the attitude and relative position of the mobile platformfacilitating complex landing maneuvers.
This approach requires good planning of the ground infrastructure, as well as robust communication links between the base and the UAV, since the quality of the guidance depends heavily on the integrity and latency of the corrections sent over the air.
As with Moving Base, the better the GNSS antenna used on the base and the drone—in terms of phase center stability, gain, filtering, and multipath rejection—the more reliable the signal will be. resulting orientation for the flight control system.
Integration into autopilot systems: the case of Veronte Autopilot 1x
For all these GNSS architectures to be truly useful, the autopilot The UAV must be able to manage them without needing to add extra hardware. A representative example is the Veronte Autopilot 1x, which integrates a dual GNSS sensor (GPS, GLONASS and BeiDou) both on land and in the air, allowing the flexible use of RTK, Moving Base and Static Base.
These modes are configured using the Veronte PIPE software, which includes wizards for different operating scenarios. This allows the integrator or operator to... Activate advanced GNSS features in a guided wayreducing the complexity of commissioning and avoiding configuration errors that could compromise accuracy.
Behind these types of solutions are usually engineering teams dedicated to continuously incorporating the latest GNSS and inertial technologies. In the case of Embention, for example, there is a group of around fifty engineers working on the development and improvement of their navigation systems, with the goal of offering Highly accurate position and attitude information in virtually any location and under any weather..
The philosophy is clear: the tighter and more efficient the integration between GNSS antennas, multi-constellation receivers, INS and autopilot, the greater the navigation quality, flight stability and overall safety of UAV operations.
This becomes especially critical in high-value applications, such as critical infrastructure inspection, sensitive goods logistics, BVLOS (beyond visual line of sight) operations, or flights in environments with a high presence of interference, where the resilience of the integrated GNSS+INS system It can make the difference between a successful mission and a serious incident.
Installation, antenna location and practical factors in UAVs
Even the best GNSS antenna on the market can perform poorly if installed incorrectly. To maximize its performance, it's essential that it has an unobstructed view of the sky, with no immediate obstacles that block or reflect signals. Elements such as batteries, metal structures, cameras, or antennas of other radio systems must be positioned with this in mind.
On mobile platforms such as multirotor or fixed-wing drones, vibration isolation, the type of mechanical mounting, and electromagnetic compatibility with the rest of the onboard electronics must also be considered. A poorly isolated antenna can suffer micro-movements or flexes that subtly affect position calculations, and a deficient design of the ground plane or mass can worsen the radiation pattern and the effective gain.
Another point that is sometimes overlooked is the length and quality of the coaxial cable connecting the antenna to the GNSS receiver. Every meter of cable introduces attenuation, and if low-quality materials or connectors are used, additional losses, reflections, and impedance mismatches can occur. Therefore, it is advisable Keep cables as short as possible and use appropriate connectors and coaxial cables. to the frequency and the environment of use.
In small drones, where space is very limited, compact antennas are often integrated directly into the structure or into combined modules. In these cases, a good electromagnetic design of the assembly is even more critical to minimize interference between systems, especially when video transmitters, command and control links, telemetry, Wi-Fi, or 4G/LTE coexist.
Maintenance planning also matters: periodically checking the antenna's physical condition, ensuring the connectors are clean and secure, and confirming there is no damage to the radome or seal that could allow the entry of water or dirt It is a simple practice that avoids many performance and reliability problems in the medium term.
This entire ecosystem of GNSS antennas, multi-constellation receivers, correction services such as RTK or Atlas, advanced usage architectures (Moving Base, Static Base), and proper integration with the autopilot and INS is what allows current UAVs to achieve centimeter-level navigation, landings at very specific points, and complex missions in almost any environment, so that The choice and correct installation of the GNSS antenna has become a decisive factor to get the most out of any precision navigation drone.
