Drone-Based Measurement System for Radiofrequency Exposure Assessment: Introduction
From hobby photography to medical research, drones are changing the world. Drones or unmanned aerial vehicle (UAV) technology has the potential to revolutionize research, business, and leisure. Robotic aerial vehicles have been adopted in a wide variety of fields, including radiofrequency exposure assessment, and their global use continues to increase. In fact, the Federal Aviation Administration (FAA) reveals there’ll be more than 30,000 drones in use over US airspace by 2020. Micro aerial vehicles (MAV) with a size of less than 15 centimeters and weight of less than 100 grams are also increasing in popularity, specifically in military observation, surveillance, and environment observation.
Drone-based measurement systems are highly beneficial in radiofrequency (RF) exposure assessment. Note that radio frequency is defined as any frequency within the electromagnetic radiation spectrum with radio wave propagation, usually in the range of 3 kHz to 300 GHz. As radio frequency energy is essential in telecommunication services, non-communication use (e.g., microwave ovens), radar bands, industrial heaters, and medical applications, drone-based measurement systems for radiofrequency exposure assessment have become a major topic in research. Evidence shows that drones can be employed in radiofrequency exposure assessment, as well as evaluation of electromagnetic disturbances, emissions, and immunity.
Drone-Based Measurement System for Radiofrequency Exposure Assessment: Technical Specifications
Drone-based measurement systems for radiofrequency exposure assessment can facilitate true isotropic evaluations at different heights and hard-to-reach areas. Moreover, novel systems allow experts to sample and visualize data in real time in order to improve safety and health outcomes. Joseph and colleagues (2016) proposed a drone-based measurement system for isotropic evaluation of 3D radiofrequency electromagnetic exposure. This system consists of a drone, three identical nodes, and either three orthogonal lightweight monopoles or linearly polarized planar patch antennas:
- The drone is a hexacopter of six motor arms and a printed circuit board with wireless drone control and lithium polymer batteries. In addition, the drone has a GPS, a barometric pressure altimeter, and a compass.
- The three compact nodes form the radiofrequency exposure acquisition system, with a minimal impact on battery consumption. Interestingly, there’s a log detector output which allows collected data to be transferred to a personal device and analyzed in real time.
- The three antennas calculate total electric-field strength. As the antennas are placed on plastic material below the drone, the drone influence is limited.
We should note that the research team (Joseph et al., 2016) calculated the uncertainty of the system (2.3 dB) regarding factors, such as received power, small scale fading, and out-of-band signals. Uncertainty analysis showed low combined uncertainty compared to other methods. To set an example, as the system operates in free space, antenna anisotropy caused by an operator or a carrier is eliminated. Interestingly, this novel drone-based system revealed radiofrequency exposure pattern as a function of height up to 60 meters (for GSM 900 MHz base station exposure), with highest exposure (0.52 V/m) at 24 meters.
Drone-Based Measurement System for Radiofrequency Exposure Assessment: Benefits over Conventional Methods
Drone-based measurement systems for radiofrequency exposure assessment reveal numerous benefits over traditional methods, such as spectrum analyzers, exposimeters, and car-based measurement systems. Although exposimeters, defined as portable monitoring systems, allow measurement with various spatial samples, such devices are worn on the body, which can lead to measurement uncertainty. Car-mounted systems, on the other hand, allow a broad frequency band (30 MHz-3 GHz) over large areas but suffer from antenna anisotropies due to vehicle reflection or shielding (Joseph et al., 2016).
In contrast, drone-based systems allow true isotropic radiofrequency exposure assessment at a wide range of locations without carrying expensive equipment or wired technology. Note that unmanned aircraft systems consist of a drone, a ground-based controller, and a communication system. Novel drone-based measurement systems can be controlled via a remote or a smartphone app, which eliminates offsets in measurement. Measurements can occur in real time and at a variety of environments. Data can be obtained simultaneously to support compliance testing, fast sampling, epidemiological studies, and 3D exposure heat maps. Although weather conditions may limit measurement accuracy, drone-based systems are highly beneficial and cost-effective in the evaluation of radiofrequency assessment. The triaxial isotropic measurement system for radiofrequency exposure assessment developed by Joseph and colleagues (2016), for instance, does not suffer from antenna anisotropies or shielding effects and provides high-quality data.
Drone-Based Measurement System for Radiofrequency Exposure Assessment: Applications and Health Outcomes
Given the fact radio frequency technology has immense applications, radiofrequency exposure assessment is vital. By evaluating electromagnetic disturbances, emissions, exposure, and immunity, drone-based measurement systems for radiofrequency exposure assessment can benefit telecommunication services, non-communication use, and industrial applications. Perhaps one of the most curious applications of unmanned aerial vehicles is within medical settings, with a focus on radiofrequency fields and human health (Ahlbom et al., 2004).
Due to high residential and occupational exposure from radios, television transmitters, and cellular phones, researchers aim to explore the effects of radio frequency on health effects and illnesses, such as cancer, cardiovascular diseases, brain tumors, and cataract. Moreover, the heating of cells and mass from radio frequency may result in heat imbalance and physiological strain to remove the heat, especially in children and vulnerable people. In particular, the central nervous system and the eye are highly sensitive to thermal damage and whole-body heating imbalance. We should note that radio frequency can also interfere with implanted medical devices (Ahlbom et al., 2004). To measure possible associations between radiofrequency exposure and human health, the quality of radiofrequency exposure assessments is paramount. Drone-based systems for radiofrequency exposure assessment can benefit the evaluation of population exposure, analyses of different sources, and prognoses of long-term adverse effects.
Radiofrequency Exposure Assessment and Drones in Indoor Settings
With the rapid implementation of wireless communication devices, radiofrequency exposure assessment in indoor settings (e.g., public places, transportation) is also an important research topic. Chiaramello and colleagues (2019) conducted a systematic review and found that the highest maximum mean levels of radiofrequency exposure were found in offices (1.14 V/m) and in public transports (0.97 V/m), while the lowest levels of exposure were observed in private homes (0.13–0.43 V/m).
Note that common sources to measure indoor exposure include personal exposure meters, which however are prone to body shielding, residual uncertainties due to calibrations, and measurement artifacts. Although indoor assessment often includes spot measurements in selected locations via narrowband and broadband methods, drone-based measurement systems for radiofrequency exposure assessment can surpass traditional methods. Note that indoor exposure depends on both outdoor (e.g., antennas) and indoor (e.g., smartphones) sources. Interestingly, data shows there are more than 8.98 billion mobile connections worldwide. When it comes to indoor environments, more and more researchers are considering the option of sending mini-drones in enclosed and hazardous areas to perform remote evaluations, damage assessment, and air quality evaluation. Some of the advantages of this aerial technology involve a 360° evaluation angle of objects in a 3D space and additional equipment, such as motion capture system, laser range finder, and wireless technologies.
Radiofrequency Levels in 5G Technology, Drone-based Measurement Systems, and International Regulations
With the recent rise in 5G technology development and cloud architecture, radiofrequency electromagnetic fields and exposure limits are becoming more and more relevant worldwide. We should note that 5G technology is complex and constitutes of macrocells (under 1GHz), small cells (between 1GHz and 6GHz), and picocells (above 6GHz) (Pawlak et al., 2019). Picocells are defined as small cellular base stations used to apply wireless services to hard-to-reach areas and managed by a network provider. All these transmitters, in combination with multi-radio access technology (RAT) networks, will contribute to radiofrequency exposure and result in stricter guidelines on exposure limits. Interestingly, one of the main global regulations is the guidelines proposed by the International Commission on Non-Ionizing Radiation Protection (ICNIRP), with several national and local modifications.
There’s no doubt that drone-based measurement systems for radiofrequency exposure assessment can benefit regulatory and research initiatives, as well as the safe implementation of 5G technology. In addition, drones can facilitate the actual implementation of 5G technology and boost mobile connectivity from the air. In fact, some companies are already planning to launch solar-powered drones to achieve ultra-connectivity and low levels of end-to-end latency.
Drone-Based Measurement System for Radiofrequency Exposure Assessment: Conclusion
Drone or unmanned aerial vehicle technology has the potential to transform telecommunication services, industrial settings, and medical research, especially in remote and hazardous areas. Drone-based measurement systems can improve radiofrequency exposure assessment and surpass technologies, such as spectrum analyzers, exposimeters, and car-based measurement systems (Joseph et al., 2016). Drone-based measurement systems for radiofrequency exposure assessment allow true isotropic evaluation at a variety of locations and eliminate the need for costly and wired technology. Novel technologies also decrease the risk of antenna anisotropies and shielding and provide accurate data in real time. Note that such data can benefit compliance testing, 3D exposure heat maps, and epidemiological studies. As radiofrequency energy is essential, drone-based evaluations of exposure, electromagnetic disturbances, and immunity become vital. Drone-based systems can also benefit regulatory radiofrequency regulation worldwide and improve the safe implementation of stellar and 5G technologies.
In the end, drones are an evolving technology which is defined as the future of human augmentation. From solar-powered drones to micro aerial vehicles, drone-based systems can be employed in business, military settings, indoor environments, research, and leisure. While many people still associate drones with aerial photography, the truth is that robotic aerial vehicles can benefit research and improve safety and health outcomes across the globe.
- Ahlbom, A., Green, A., Kheifets, L., Savitz, D., & Swerdlow, A. (2004). Epidemiology of Health Effects of Radiofrequency Exposure. Environmental Health Perspectives, 112 (17), p. 1741-1754.
- Chiaramello, E., Bonato, M., Fiocchi, S., Tognola, G., Parazzini, M., Ravazzano, P., & Wiart, J. (2019). Radio Frequency Electromagnetic Fields Exposure Assessment in Indoor Environments: A Review. International Journal of Environmental Research and Public Health, 16 (6).
- Joseph, W., Aerts, S., Vandenbossche, M., Thielens, A., & Martens, L. (2016). Drone based measurement system for radiofrequency exposure assessment. Bioelectromagnetics, 37 (3), p. 195-199.
- Pawlak, R., Krawiec, P., & Zurek, J. (2019). On Measuring Electromagnetic Fields in 5G Technology. IEEE Access.