DAAA, Drone Active Antenna Array
A Portuguese SME and a Portuguese Telecom Institute offer a solution to help create additional drone applications in the civil/commercial field: monitoring maritime areas, real-time image visualization and radio communications in disaster situations. Active antenna arrays are used in the drones to focus on the area of interest, maximizing efficiency, and increasing operating range. Multiple partnership options are sought: commercial/service/license agreements or joint venture.
One of the current trends is for the use of drones, also known as Unmanned Aircraft System (UAS), in a number of civil and commercial scenarios. In particular, railway operators are seriously considering the use of drones for maintenance and inspection purposes.
Drones can be controlled remotely or can fly autonomously based on pre-programmed flight plans or even more complex dynamic automation systems. One of the major issues with drone technology at the moment is the connection to a ground station, which allows a set of functions to be run in real-time, such as real-time video monitoring of areas that are inaccessible to humans. Improving the connection to the ground station (either fixed or mobile) would allow better Radio Frequency (RF) link budgets to the drone, thus allowing higher data bit rates to be exchanged between the two platforms.
One of the major factors in improving radio communications is the antenna (the last item in the RF chain). At the drone side, the use of traditional antennas, such as simple dipoles, is imposed by the physical limitations (must be thin and lightweight), and this limits the robustness of the communication because they are inefficient.
At the ground station, parabolic antennas are commonly used to link to the UAV device for image transmission and control. Although this solution permits a link connection, it is certainly not optimized because this kind of antenna requires mechanical pointing of the radiating beam and thus it is difficult to automatically follow the UAV route. Also, its radiation pattern is quite broad (the beam width is not focused) and thus the link quality can be rather unstable.
To develop efficient, cost-effective antenna solutions to help maximize the range, persistence, data rate and lifetime of this kind of vehicle, a feasible option is the use of electronically scanned antennas. This type of solution has enabled countless RF applications where fixed beam and/or mechanically gimballed apertures are not viable solutions. This is achieved with the use of an active antenna array concept already being applied in the micro/nano satellite space market due to its low mass, mechanical simplicity and allowing the radiated energy (say the signal to be transmitted or received) to be concentrated in a specific spot, which can follow the route electronically in a real-time manner.
For a UAV/drone application this possibly means simplicity and higher efficiency of energy, leading to better autonomous flight duration.
A ground station can follow the planned route of a drone, steering its own beam using an active array or, the drone can maintain a connection to one or various ground stations that are situated in fixed and known positions.
Innovations & Advantages
An active antenna array concept (planar array) allows higher radiated power signals, by employing the concept of spatial power combination of several lower power parallel paths to achieve a very high power link. Also, when it is connected with beam steering capability by adding phase shifting in each of the paths, it is possible to implement automatic control of the beam steering angle, which allows a drone route to be followed in an electronic way. Some of the key advantages of the active antenna arrays are:
- Eliminates the need for multiple independent RF channels and associated phase shifters or time delay units
- Large electronic scan angles (�60�) are possible, unlike traditional leaky wave antennas
- Can be synthesized using conventional printed circuit board (PCB) manufacturing methods
- Additional adaptive degrees-of-freedom can be introduced without introducing more RF channels
- Inherently low physical volume and, especially, low profile (e.g., a few mm thick)
- Inherently low cost due to aforementioned architecture and PCB design compatibility
- The radiation efficiencies are comparable to a parabolic dish
- Enables the potential for delivering a true conformal aperture that performs just as effectively as a planar aperture (projected aperture constraints)
Current and Potential Domains of Application
- Environmental monitoring of maritime areas and coastal areas
- Security surveillance
- Emergency Disaster Recovery
- Civil Protection real time support