Roman Kubacki

The increasing complexity of the electromagnetic environment poses an increasing risk to unmanned aerial vehicles (UAVs) operating in airspaces subject to adverse electromagnetic effects. This paper investigates the potential electromagnetic interference that UAVs may encounter during flight through the lens of electromagnetic compatibility (EMC), which defines the requirements for the proper operation of UAV electronics. According to existing EMC standards, the immunity threshold for typical commercial drones is 10 V/m. However, European standards for public exposure permit electromagnetic fields and suggest that it is possible for an electromagnetic field of a mobile base station antenna to be as strong as 61 V/m. To assess drone vulnerability to its electromagnetic environment, investigation was conducted in an anechoic chamber, which determined that commercially available drones typically experience uncontrolled descent when subjected to an electric field strength of 30 V/m or higher. The primary coupling path for this interference is through the UAV’s internal cables, as induced parasitic currents perturb the motor control signals. This disruption leads to flight instability as the propellers can no longer be reliably controlled, resulting in flight instabilities. Based on a maximum effective radiated power (ERP) of 40 dBW per sector for a base station antenna, a minimum safe operating distance of 20 m was calculated. Adherence to this safe distance is therefore strongly recommended for any commercial drone operator to avoid EMI-induced flight failure.

With the escalating of electromagnetic environment in space, there has been growing attention on the electromagnetic negative effects on unmanned aerial vehicles (UAVs). In the paper the investigation of the potential electromagnetic interference that UAVs may encounter during flight has been presented. Electromagnetic compatibility (EMC) defines requirements necessary to the correct work of UAVs electronics. The immunity threshold of electric field strength according to existing EMC standard for typical commercial drones was established as 10 V/m. On the other hand, European standards for people protection suggest that electromagnetic field emitted by mobile base station antennas can reach level up to 61 V/m. Investigation of drone vulnerability in electromagnetic environment was carried out in the anechoic chamber and it was determined that when electric field strength is 30 V/m or higher the generally available drones have unchecked fall. The UAV’s cables are the main energy coupling path from electromagnetic field. Induced, additional current perturbs the current in drone arms and consequently propellers cannot guarantee the stable flight. Considering the maximum possible base station antenna effective radiated power of 40 dBW per sector the safe distance of R = 20 m from the antenna was specified. The safe distance for UAVs around base station antennas, as a recommendation, should be respected by popular drone users.

In the paper, a new design of a quasi-isotropic antenna for high-power electromagnetic (EM) field measurement is presented, along with its investigation into suitability. The measuring probe is intended for assessing pulsed microwaves, which cannot be measured by available meters due to the high value of electric field strength and short pulse duration. The measurement of such a strong field is required according to guidelines for protecting people against microwave fields, especially those emitted by radars. The proposed probe is based on the concept of dipole–diode detection. To enable high-power measurement, the receiving antenna is electrically “small,” allowing diode detection within the diode square-law characteristics range. Additionally, the shortened dipole length minimizes the spatial integration error, which can be significant in the case of microwave measurement. To obtain the desired antenna polarization, a new dipole geometry was proposed. Fulfilling the requirement of measuring all incident EM field polarizations, the receiving antenna was based on three dipoles arranged within a specific “magic” angular arrangement, ensuring a suitable quasi-isotropic radiation pattern. The proposed probe can operate in a frequency range from 1 GHz to 12 GHz.

W pracy przedstawiono badania przenikalności elektrycznej i magnetycznej zredukowanego tlenku grafenu w zakresie częstotliwości od 100 MHz do 10 GHz. Badania przeprowadzono dla litego materiału uzyskanego z postaci proszkowej poprzez sprasowanie pod naciskiem 2 kN. Na tej podstawie określono współczynnik pochłaniania warstwy materiałów o grubościach 2.5 oraz 5 mm. Badany materiał może być zastosowany jako absorber mikrofalowy, charakteryzujący się wysoką skutecznością ekranowania, do zabezpieczania elektroniki bezzałogowych statków powietrznych, narażonych na promieniowanie emitowane między innymi przez anteny nadawcze stacji bazowych telefonii komórkowej.

Within this study, we explored the augmented security measures for the electronics of unmanned aerial vehicles (UAVs) within an RF environment. UAVs are commonly utilised across various sectors, and their use as auxiliary platforms for cellular networks, as parallel networks working in tandem with ground-based base stations, holds considerable promise. In this context, ensuring the uninterrupted operation of UAVs is a paramount objective. However, the considerable external electromagnetic interference emitted by existing base stations may jeopardise the functionality of UAV electronics. This could potentially lead to an unintended flight path and a sudden cessation of communication with the operator. To mitigate the detrimental impact of the RF field, we advocate covering the UAV casing with reduced graphene oxide (RGO). The efficacy of RGO’s shielding effectiveness (SE) was investigated over a frequency spectrum from 100 MHz to 10 GHz. Our scrutiny of this property was centred around the measurement of scattering matrix coefficients of the unadulterated material—without additives of any kind. Our findings show that this material is a favourable candidate for UAV absorbers due to its low reflection coefficient coupled with its high absorption capacity. The studied absorber ensures an SE value of 25 dB and 30 dB for a 3 mm layer at frequencies of 3.6 GHz (pertaining to the 5G system) and 5.8 GHz (pertaining to LTE), respectively.

In the work the enhanced security of unmanned aerial vehicles (UAVs) electronics in RF environment was investigated. UAVs are commonly used in many areas and the cellular networks as the parallel helping networks for systems: LTE, 5G or especially for future 6G are very perspective and needed. For effective communications in channels: “air-to-ground” as well as “drone-to-drone” the important task is undisturbed work of transportation platforms, ie. UAV. However, high level of outside electromagnetic radiation can affect the correct electronics work. The problem is due to non-conformity of RF environment regulations. The electromagnetic compatibility (EMC) standards guarantee correct electronics work when the radiation level is not higher than established EMC levels. In case of commercially available devices, like UAVs, this level is 3 V/m. On the other hand, permissive exposure level, treated as RF environment emitted by cellular base stations, can reach the level of 61 V/m. Such level of electromagnetic wave pollution, can damage unprotected electronics with fatal consequences. This can cause the unchecked drone flight or unchecked fall down. As a result, due to unchecked flight, the UAV can cause the sudden communication interruption with operator or other drones. To reduce the level of damaging RF field we propose to cover the UAV housing with microwave absorber. In this case absorber must ensure good electromagnetic protection as well as lightweight and resistant on weather conditions. The shielding property of reduced graphene oxide (RGO) as an absorber was investigated. For proposed material the shielding effectiveness (SE) was investigated in the frequency range from 100 MHz to 10 GHz. It has been proved that such material can be a good candidate as an absorber for UAV having low reflection coefficient and high absorption ability. In this work the shielding effectiveness of RGO was analyzed for two layers of 3 and 5 mm at typical frequencies as RF environment, ie. 3.6 GHz (5G system) and 5.8 GHz (LTE). Investigated absorber guarantees the value of SE of 25 dB and 30 dB for 3 mm layer at 3.6 GHz and 5.8 GHz respectively and of 29 dB and 39.5 dB for 5 mm layer at these frequencies respectively.

W pracy przedstawiono układ antenowy umożliwiający kształtowanie wielowiązkowej charakterystyki promieniowania. Układ antenowy został zaprojektowany na bazie anten mikropaskowych, w których łata promieniująca zbudowana została w geometrii fraktalnej. Wykorzystano fraktal o nazwie „wyspa Minkowskiego” (Minkowski Island). Otrzymana antena pracuje na częstotliwości 3.6 GHz co odpowiada zakresowi pasma gigahercowego systemu 5G telefonii komórkowej. Dzięki zastosowanej geometrii fraktalnej uzyskano symetryczną charakterystykę promieniowania w płaszczyźnie E oraz H. Dodatkowo zastosowano reflektor płaski co skutecznie zminimalizowało listki tylne w charakterystyce promieniowania. Na bazie tych anten zbudowano układ antenowy składający się z 4 anten. Charakterystyki promieniowania otrzymanego układu antenowego mają charakter wielowiązkowy co może być wykorzystane w systemie 5G w antenach inteligentnych oraz adaptacyjnych.

Krytycznym elementem urządzeń pomiarowych do badania parametrów pola elektromagnetycznego pochodzącego od impulsowych nadajników jest sonda sygnałów mikrofalowych. W artykule przedstawiono koncepcję budowy oraz wstępne wyniki badań izotropowej sondy 3D. Przedstawiona koncepcja jest podstawą wykonania kilku wersji sondy zapewniających pomiary w szerokim paśmie częstotliwości i dużym zakresie dynamicznym natężeń pola EM.

This work presents the investigation of graphite and reduced graphene oxide (RGO) reflectance as an important parameter for electronic devices’ protection. These materials should protect electronic circuits against external as well as internal reflected radiation. The investigation was focused on comparing the reflectance of both materials on the metal layers. The measurements of constant electromagnetic parameters, such as permittivity and permeability, were carried out on pure materials without any additives, such as polystyrene foam, resin, wax, etc. The measurements were implemented in a coaxial line within the microwave frequency range from 100 MHz to 10 GHz. The measurements show a high value of reflected power, over 90% for graphite while RGO reflects only 80% of incident power. In addition, due to the half-wavelength effect in reduced graphene oxide, the reflection coefficient is reduced to 70%.

Wprowadzenie standardu 5G telefonii bezprzewodowej wymusza poszukiwanie nowych anten lub układów antenowych aby sprostać wymogom transmisyjnym tego standardu. W pracy przedstawiona została dwuzakresowa antena mikropaskowa przeznaczona dla systemu 5G. Antena może pracować jednocześnie w dwóch pasmach częstotliwości 3,5 i 26 GHz przewidzianych dla tego systemu. W zaproponowanej geometrii uzyskano antenę, która może pracować nie tylko w zadanych dwóch pasmach ale również w wielu innych pasmach częstotliwości. Zaproponowana konstrukcja anteny może być zaadoptowana do tworzenia anten w dowolnych pasmach częstotliwości