An unmanned aerial vehicle, or UAV, refer to a vehicle that is able to fly remotely, either with some sort of controller or autonomously. An unmanned aircraft system, or UAS, includes not only the UAV, itself but also the person on the ground controlling the flight, as well as the system in place that connects the two of them.
Today, unmanned aerial vehicles (UAVs) have begun to be seen in our life more often than before. UAVs prevent pilot loss of life. Unmanned aerial vehicles (UAVs), or unmanned aircraft systems (UASs), have been developed and purposed for civilian, military, and recreational activities. The UAVs enable the construction enterprises to quantify engineering progress in real time, allow road network data collection in all directions, help forest fire fighting, enable fast courier service, allow farmers to continuously monitor crop growth and allow mining owners to obtain accurate individual digging information.
Energy and infrastructure companies can thoroughly inspect pipelines, roads and cables by using the UAVs. Humanitarian organizations can use the UAVs to quickly assess the affected zone, adapt to refugee and provide effective relief based on the collected data. A transport UAV with a load capacity can take off and land near a building or a human settlement, enabling developing countries to achieve rapid logistics even without adequate road infrastructure, release the convenience of e-commerce and development of the national economy quickly. In developed countries, transport UAVs can help to achieve better quality of service in crowded or remote areas
They carry out a variety of military and civilian missions such as surveillance and reconnaissance, target recognition, battle damage assessment, EW, search and rescue, and traffic monitoring. An important use of the UAVs is troop support, carrying out reconnaissance and surveillance missions, which requires maintaining a data-link with troops in order to send any data collected, such as video images, or audio.
UAVs vary in weight and size, ranging from vehicles measurable by a few inches to aircraft with wingspans of up to 400 feet. Among numerous other factors, UAVs also vary in altitude and general operating characteristics.
While there is no widely used classification system for UAVs, there are six major classifications for their functionality: target and decoy, reconnaissance, combat, logistics, research and development (R&D), civil, and commercial. Target and decoy UAVs are typically used for military training purposes. Reconnaissance and combat UAVs are used in the battlefield for intelligence attack capability in high-risk missions. As the name suggests, logistics UAVs are used for cargo and logistics operations. Likewise, R&D UAVs are used to further develop UAV technologies.
The UAV Manufacturing industry is in the growth stage of its life cycle. The defense sector currently is, and will likely continue to be, the primary market for UAVs. While most systems will be used for fighter combat, stealth missions, aircraft carrier operations, surveillance, and military communications, industry trends suggest that there will also be a steady expansion in the civil, as well as commercial uses for UAVs. Manufacturers are becoming increasingly focused on developing aircraft for the uses of border enforcement, humanitarian relief, search and rescue, scientific research, meteorology, firefighting, precision agriculture, infrastructure surveying, police surveillance, freight delivery and communication signals relaying.
Although the industry is heavily regulated, more business have been able to operate commercial drones since 2016, following the Federal Aviation Administration’s (FAA) issuance of new and less restrictive regulations. Researches, such as those at IBIS World, suggest that the finalization of FAA regulations over the next few years will create more demand for UAV industry products.
The technology is interdisciplinary with the incorporation of aerospace structures, electronics, telemetry, etc. UAV development and application require the integration of systems to satisfy performance and mission requirements.
UAV Antenna Requirements
Unmanned vehicles, such as UAVs (unmanned aerial vehicles) transmit and receive a variety of signals. These signals may include GPS/GNSS signals, telemetry and sensor data, as well as cellular and wifi communication signals that allow the vehicle to form part of a network or connect to the Internet of Things (IoT). GNSS antennas receive signals transmitted by satellites in GNSS constellations such as GPS, Galileo, GLONASS and BeiDou. These signals contain data that can be used by UAVs and unmanned systems to determine position, velocity and timing.
The unmanned vehicle may communicate with a ground station, satellite or another vehicle and will require an antenna – a transducer that converts electrical energy into electromagnetic waves and/or vice versa – to transmit and receive signals. Antennas are among the most important electronic components of any UAV or UAS, for they allow the vehicle to transmit information to and receive information from other systems, as well as the people on the ground.
UAV-qualified aerodynamic antennas are required in various form factors and frequency ranges for ground‐to-ground, ground‐to‐air, and air‐to‐ground communications systems. Antennas also depend on Applications that include signal intelligence (SIGINT); intelligence, surveillance, and reconnaissance (ISR); and sensor systems. With advances in modern materials, UAV antennas can be constructed with a smaller size and embedded into the aircraft with a low profile, resulting in less weight and less aerodynamic drag on the aircraft.
Reliable and ubiquitous command and control (C2) connectivity everywhere in the air is required to support beyond visual line of sight
flights. The C2 link itself may however not be sufficient to satisfy some demanding use cases as surveillance or realtime video broadcasting UAVs. In such scenarios, a minimum guaranteed uplink bit rate of 10 Mbps is required to satisfy the demands of transmitting video frames in high definition to the cloud servers
A small UAV for non-commercial purposes is defined as weighing between 55 lbs. and 0.55 lbs. These UAVs include fixed wing, helicopter, and multi-rotor designs. The UAV platform introduces constraints for the size, weight, and power needs of extra components and electronics. The UAV usage determines the required payload, e.g. a camera, which further constrains what can be added. Small UAVs have limited load capacity.
The antenna choices must be compatible with this application area. The transmitting antenna must be installed in or on the UAV without adversely affecting its operation. For a fixed-wing UAV, the antenna could be mounted on the wing or in the fuselage. For a quadcopter UAV, the antenna could be mounted along the vehicle arms.
Consequently, the size of the UAV imposes limits on the antenna size, which in turn constrains the choice of operational frequency. Regardless of the specific type of transmitting antenna, its efficient radiation typically requires its size to be on the order of one-fourth to onehalf wavelength, which is inversely proportional to frequency. The receiving antenna must be sized so that an operator can easily transport it to the search area and orientation it to determine the direction from which the signal is emitting.
In addition to size constraints, antenna polarization can also influence the design choices. The receiving antenna’s orientation can be
manipulated by the operator, in order to match the polarization and position of the transmitting antenna. However, the transmitting antenna’s polarization will tend to be randomly oriented, depending on the nature of the crash. Therefore, the designer will need to consider antenna designs that tend to be robust to the transmitters orientation, ranging from simple monopoles to loop antennas, or perhaps a transmitting turnstile antenna, made from orthogonal dipoles fed ninety-degrees out of phase.
UAV Antennas types
The UAV antennas existed in various form factors and frequency ranges. The antennas can be used in ground-to-ground, ground-to-air, and air-to-ground communications systems. Increase the loitering capability and persistence of unmanned aerial vehicles (UAVs) with a lightweight, aerodynamic antenna that can go wherever needed.
Through careful design and extensive testing and evaluation, reliable UAV antennas that conform to the non-planar surfaces of a drone’s fuselage has been realized. The unique wideband blade antennas support VHF through C-band frequencies, reducing the number of required
apertures on an airframe, and aiding in minimizing aerodynamic drag. Octane Wireless’ drone antennas offer greater flight range and increased link performance over traditional airborne antennas, enabling tactical teams to maximize their operational footprint during mission-critical aerial operations .
Unmanned Aerial Vehicles (UAV) currently uses separate antennas for Wireless Local Area Network (WLAN) 802.11b/g and Global Positioning System (GPS) as they are operating in different frequencies and using different polarization . Frequency of 2.45 GHz with linear polarization will be used for Wireless Local Area Network while the frequency of 1.575 GHz with circular polarization will be used for Global Positioning System. Industrial Scientific and medical (ISM)/ Wireless Local Area Network will be facing down towards ground for connection while antenna for Global Positioning System will facing up towards the sky for connection with satellites.
Linear and Circular Polarised
Antennas are tuned to specific frequencies or frequency ranges, and can be either linearly or circularly polarized. There are four types of drone antennas: Linear Polarized Directional Antenna, Linear Polarized Omni Directional Antenna, Circular Polarized Directional Antenna and Circular Polarized Omni Directional Antenna.
Linearly polarized antennas can be simpler to construct and may provide greater range. However, due to the need to keep transmitting and receiving, antennas are aligned to ensure maximum signal overlap, which can make them unsuitable for fast-moving unmanned aircraft, which might change direction frequently and thus bring the antennas out of alignment. Circularly polarised antennas are more suitable for fast-moving vehicles as the radiation pattern ensures that there is some overlap no matter the angle of antenna alignment.
Directional & Omni-Directional Antennas for UAVs
Antennas can also be classified as directional or omni-directional. Directional antennas can achieve greater range at the cost of coverage, whereas omni-directional antennas provide coverage 360 degrees horizontally from the antenna, but are limited in range. Some unmanned vehicle control stations may incorporate directional or omni-directional antenna, monitoring the signal reception and switching antennas as needed.
Microwave Antennas & Communications
Most unmanned vehicle communications signals will occur in the radio frequency range, however due to increasingly crowded airwaves, microwave communications are becoming more common. Microwave signals provide greater bandwidth than radio signals but cannot be refracted in the way that radio frequency signals can, thus limiting microwave antennas to line of sight (LOS) applications.
UAV Tracking Antenna
Unmanned Aerial System (UAS) also requires antennas in ground station. During operations it is necessary to continuously maintain a data and control link with the operator. This requires the ground station antenna to track the UAV so the antenna beam is pointed properly. Ground-based antennas can be used to communicate with UAVs as part of a ground control station or command centre, or to track them as part of a counter-drone system or UTM (unmanned traffic management) platform. A ground based tracking antenna is used to follow the UAV as it flies on its route. The antenna has to keep its main beam pointing at the in-flight UAV in order to maintain a strong video link from the UAV to the ground station.
Chinese Researchers build New Antenna that Will Boost UAV Communication with Satellites in 2020
A group of Chinese researchers has developed a compact, sabre-like antenna for unmanned aerial vehicles (UAVs) that can switch between two radiation patterns for better communication coverage. They describe their work in a study published 26 February in IEEE Transactions on Antennas and Propagation.
For UAVs cruising at high speeds, it’s desirable to have small, aerodynamic antennas that limit drag but can still yield sufficient bandwidth and coverage. Zhijun Zhang, a researcher at Tsinghua University, notes that sabre-shaped antennas are beneficial in the sense that they are very aerodynamic—but there is a major limitation that comes with this design. “Conventional sabre-like antennas generate a donut-shape radiation pattern, which provides an omnidirectional coverage and is ideal for air-to-ground communication. However, a donut-shape pattern has a null at its zenith,” Zhang explains.
While this donut-shaped radiation pattern may be sufficient to help the UAV exchange signals with ground communication systems, the “blind spot” of coverage directly above the UAV is problematic when trying to establish communication with satellites (aka “hemisphere coverage”). Therefore Zhang and his team created a novel sabre-like antenna design that can provide a signal directly above the antenna as well.
To accomplish this, the researchers incorporated two metal radiators into the design. The first is a monopole, which is perpendicular to the ground with an omnidirectional pattern. The second is a dipole, which is parallel to the ground with broadside pattern – creating a signal that fills the blind spot of conventional antennas. “The two radiators not only generate two working modes and desired radiation patterns, but also provide a bonus capacitor loading effect, which shrinks the antenna size,” says Zhang. “The antenna can switch between two modes on the fly, and thus provides top hemisphere coverage.”
Simulations and tests suggest that the design can achieve roughly 20 percent bandwidth, which surprised even the researchers behind the design. Zhang says this efficiency happens because both radiators are used in both modes. “As far as we know, it’s the first effort to realize such a compact aircraft antenna with upper hemispherical coverage and acceptable gain for onboard satellite communication. Next, we intend to design a simpler aircraft antenna with only one mode,” says Zhang, noting that this may involve sacrificing some bandwidth.
Drones carry 5G antennas into the stratosphere
Using Unmanned Aerial Vehicles (UAVs) equipped with wireless transceivers acting as drone base-stations (BSs) is proposed to enhance the ground users’ connectivity in 4G & 5G systems, and beyond. Adopting directional antennas at the UAVs enables direct communication with the intended ground UEs while limiting interferences to other users. Assuming an ideal directional antenna with a given beam-width and no or extremely small side-lobes, each UAV transmitter forms its own exclusive coverage zone. In this exclusive zone, the ground users are
not interfered with by the UAVs whose coverage zones do not overlap. In practice, however UAVs’ antennas are not ideal. In fact, by increasing the UAVs’ altitude, the ground receiver is likely to receive many interfering signals transmitted through the antenna side-lobe of other UAVs
Engineering firm Cambridge Consultants and telecommunications company Stratospheric Platforms Limited (SPL) have unveiled a new proof-of-concept, which could see 5G beams broadcast from the skies thanks to antennas fitted onto drones flying some 20,000 meters above the ground. The prototype that has been tested so far is only one eighth of the intended full size, but the companies hope that the final product will come in the form of a three square-meter antenna capable of beaming 5G directly onto areas up to 140 kilometers in diameter. The antennas will be integrated into zero-emission aircraft powered by hydrogen, and capable of carrying the equipment for up to nine days in a row.
According to Cambridge Consultants, a fleet of 60 aircrafts equipped with antennas would be enough to blanket the whole of the UK with 5G connectivity, delivering mobile speeds evenly across the country in excess of 100 Gbps. SPL has been quietly working since 2014 on high-altitude platforms as a means of delivering communication services back on Earth. To do so, the company is developing hydrogen-powered aircrafts that can be fitted with telecommunications equipment, and essentially act as a telecoms mast in the stratosphere.
Weighing 3.5 tonnes, which is 150 times less than a Boeing 747, the aircrafts can only support a maximum payload of 140 kilograms, meaning that it was necessary to slim down the 5G antennas as much as possible. That’s where Cambridge Consultants’ engineers stepped in, designing ultra-thin antennas weighing 120 kilograms, which the company calls “a breakthrough” in radio design.
SPL’s CEP Richard Deakin said: “It was essential that we overcame significant technical challenges in the design of the antenna to enable us to deliver massive data rates in a unique environment where power was limited, where weight was critical and where cooling in the thin, stratospheric air was difficult. “The development and testing of the antenna has met or exceeded the design criteria and working with such a talented team at Cambridge Consultants has been one of the highlights of the program to date.”
Each full-scale antenna is expected to create 480 individual beams targeting different locations on the surface of the Earth. The beams are steerable and can be shaped into patterns, to “paint” certain areas with 5G, such as a specific road or shipping lane. This could be particularly useful in bringing better connectivity to remote, isolated areas that are harder to reach for terrestrial operators.
By reconfiguring the beams, it will also be possible to target and track specific users, for example drivers in an autonomous car, and to provide coverage exactly where required, stopping if necessary at national borders. A single antenna with beams shaped appropriately, for instance, would be enough to provide coverage for the UK’s 188 kilometer-long M25 motorway. So far, SPL has tested one version of the technology as part of a partnership with Deutsche Telekom, but the trial was carried out at a lower altitude (14 kilometers), and with antennas designed to deliver LTE/4G data.
Although the remote aircraft successfully integrated into Deutsche Telekom’s terrestrial network, delivering download speeds of 70Mbps and upload speeds of 23Mbps, the 5G product is therefore still a prototype. SPL nevertheless confirmed that the next step will be stratospheric 5G, with rollouts of the first commercial service expected to begin in Germany in 2024. “Our role, to design and build this ‘mega cell tower in the stratosphere’, has seen us make breakthrough after breakthrough and we’re excited to build on these innovations with SPL, on the path to commercial deployment,” said Tim Fowler, chief sales officer at Cambridge Consultants.
Once the system is produced at scale, SPL and Cambridge Consultants estimate that the technology could connect over 500 million people, at only a fraction of the cost of maintaining the hundreds of Earth-bound masts that would be necessary to do the work of a single stratospheric antenna. Some challenges remain, particularly when it comes to regulation. Although Cambridge Consultants confirmed that the aircrafts are certified for safe flight in civil airspace, different countries have their own specific rules to manage airborne transportation, and getting the appropriate authorizations might be one of the biggest hurdles going forward.
European Defense Drone Antenna market
European defense drone antenna market is expected to reach US$ 223.33 million by 2027 from US$ 125.99 million in 2019. The market is estimated to grow at a CAGR of 7.9 % from 2020 to 2027. Increasing interest in circular omni directional antennas and rise in drone procurement by military forces due to higher defense budgets are the major factor driving the growth of the Europe defense drone antenna market.
However, problem of signal overlapping with linear antennas hinder the growth of Europe defense drone antenna market. In case of COVID-19, Europe is highly affected specially the UK. The European defense contractors enjoy a significant number of contracts year on year from customer (military forces/governments) across the globe. The UK, Germany, and France have the highest density of defense contractors in the region.
The COVID-19 outbreak has interrupted the manufacturing process and supply chain in these countries. Due to the massive outbreak and governmental regulations, the manufacturers are forced to operate with very limited personnel, which resulted in limited production of drones and its related components like antennas. Several European defense contractors are heavily dependent on the US, China, and Indian defense forces. The international supply chain disruptions coupled with lower military spending has been adversely affecting these European defense contractors’ businesses. The drone antenna manufacturers are also among the European defense equipment manufacturers to witness shock created by the COVID-19 crises.
The Europe market for defense drone antenna is segmented into technology, type, frequency, application, and country. Based on technology, the market is segmented into linear polarized directional antenna, linear polarized omni directional antenna, circular polarized directional antenna, and circular polarized omni directional antenna. In 2019, the linear polarized omni directional antenna segment held the largest share of market. Based on type, the market is divided into lightweight antenna, FPV antenna, telemetry antenna, NLOS antenna, and others. The lightweight antenna segment held the largest share of market in 2019. FPV antenna segment is expected to be the fastest growing segment over the forecast period. Based on frequency, market is segment into high frequency, very high frequency, and ultra-high frequency. The ultra-high frequency segment dominated the market in 2019. On the basis of application, the market is segmented into surveillance, navigation, communication, telemetry, and others. The communication segment contributed a substantial share in 2019 and surveillance segment is projected to be the fastest growing segment.
Alaris Holdings Limited; Antenna Research Associates, Inc.; Cobham Limited; PPM Systems; TE Connectivity; Trimble Inc. are among the leading companies in the Europe defense drone antenna market. The companies are focused on adopting organic growth strategies such as product launches and expansions to sustain their position in the dynamic market. For instance, in 2020, PPM announced the opening of 40 new offices in the UK to expand its engineering and design, sales and marketing, customer service, and accounts work.