Military suitability of COTS UAV due to the level of radiated emissions

The article presents the assessment of the levels of radiated electromagnetic interference by commercial UAVs in the context of their popular use for various military tasks. The test was conducted in the frequency range from 30 MHz to 6 GHz, in an electromagnetically anechoic chamber, in accordance with the procedures provided for this type of checks. Apart from the control frequencies (which of course exceed the standards), it can be said that most of the tested UAVs using brushless motors do not exceed the emission levels specified by the military standard MIL-STD-461G. This opens the way to the use of COTS UAV as a carrier of electronic systems for the tasks of recognizing sources of radio signals in the investigated band

Crescent Microstrip Antenna for LTE-U and 5G Systems

The field of wireless cellular network technology has seen a significant development in recent years, allowing the emergence of many new applications in addition to the traditional mobile phone calls. We are currently implementing the 5G system, which is replacing the previous cellular technologies on the market. Parallel to the development of cellular technologies, wireless local networks based on the IEEE 802.11× standards are rapidly spreading. The desire to use the advantages of both mobile telephony and wireless local networks has led to the idea of integrating the currently used communication systems in one device and requires a well-designed antenna, which should be given a lot of attention when designing the radio system. This article presents the proposed model of a two-band microstrip antenna for which the main assumption is its operating frequencies in the LTE-U (LTE-Unlicensed) band and one of the 5G system bands. The antenna dimensions and parameters have been calculated, simulated, and optimized using CST Microwave Studio software. The developed antenna has a compact structure with dimensions of (60 × 40 × 1.57) mm. The dielectric material RT Duroid 5880 with a dielectric constant εr = 2.2 and thickness h = 1.57 mm was used as a substrate for the antenna construction. The article presents an analysis of the results of simulation and measurements of selected electrical parameters and radiation characteristics of the proposed antenna. The antenna described in the article, working in 5G systems and LTE-U systems, is characterized by two operating bands with center frequencies equal to 3.52 GHz and 5.37 GHz, a low reflection coefficient (for resonances −31.54 dB and −23.16 dB), a gain value of 4.45 dBi, a wide frequency band of 3.0 GHz (68.18%), and a high energy efficiency in the range of 80–96.68%

High Gain WAT Antenna for 38 GHz 5G Systems

The article presents a high gain WAT microstrip antenna designed for 5G communication systems operating in the 38 GHz band. The antenna concerned has a compact structure with dimensions of 5. 16× 5. 05 mm. Rogers RT5880 laminate with a dielectric coefficient of 2. 2 and a thickness of 0. 254 mm was used as its substrate. The antenna works at a center frequency of 38 GHz and is characterized by a low reflection coefficient of – 29 .11 dB, a high energy gain of 7. 61 dB and a wide operating band of 1 .21 GHz (3. 18%). The paper presents an analysis of the simulation results and measurements of the device’s electrical parameters and radiation patterns

Shielding Effectiveness of Unmanned Aerial Vehicle Electronics with Graphene-Based Absorber

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

Specifying Power Filter Insertion Loss Values in Terms of Electromagnetic Safety of IT Equipment

At present, one of the main methods of minimizing risk resulting from electromagnetic information leakage is to attenuate the undesired levels of radiated and conducted disturbances generated by IT equipment, as these disturbances can carry information processed by said equipment. Attenuation of conducted compromising emissions is most commonly handled with filters with a sufficiently high insertion loss. This article defines an original analytical relation specifying insertion loss value requirements for mains filters and estimates values of parameters included in the defined relation. Furthermore, this defined relation was used to define requirements for insertion loss provided by the mains filters, above which the ratio value of potentially compromising conducted emission levels to the environmental noise level at the infiltrating system input S/N < 0 dB. As a consequence, electromagnetic infiltration is significantly impeded

Właściwości materiałów kompozytowych na bazie kopolimeru styren-butadien-styren napełnionego EMCCO-201 absorbujących fale elektromagnetyczne

In this paper, a manufacturing method for composite materials that absorb electromagnetic waves in the form of blends of EMCCO-201 with SBS (styrene-butadiene-styrene copolymer, trade name Kraton) is shown and the absorption characteristics of the prepared samples are discussed. The materials were manufactured on the basis of extrusion technology. The absorption characteristics of the tested materials were measured as a function of the testing signal angles of incidence. The samples were 300 × 300 mm, made of aluminum alloy sheet and covered with either absorption elements that were spheroids of diameters 1–2 mm and 3–4 mm made of 50 vol. % of EMCCO-201 with SBS (styrenebutadienestyrene) copolymer or pyramids with a 25 × 25 mm base and height of 50 mm made of epoxy resin covered by spraying with a layer of EMCCO-201 material without SBS copolymer. Absorption measurements were carried out in the frequency range from 3.0 to 11.0 GHz. The largest absorption of 5.5–6.0 dB at the frequency range of 7.0–10.0 GHz was obtained for samples with the epoxy resin pyramids of a square base 25 × 25 mm and height of 50 mm covered with a layer of EMCCO-201 material. The samples with the spheroids showed smaller absorption between 1–3 dB at the same frequency range.Przedstawiono metodę wytwarzania kompozytów absorbujących fale elektromagnetyczne w postaci mieszanek materiału absorbującego typu EMCCO-201 z kopolimerem SBS (styren-butadien-syren, nazwa handlowa Kraton). Materiały kompozytowe otrzymywano metodą wytłaczania. Charakterystykę absorpcji badanych materiałów wyznaczano przy użyciu próbek blachy o wymiarach 300 × 300 mm ze stopu aluminium, pokrytej elementami absorbującymi w postaci sferoidów wykonanych z kompozytu kopolimeru SBS zawierającego 50% obj. EMCCO-201, o średnicach 1–2 mm oraz 3–4mm, a także w postaci ostrosłupów charakteryzujących się podstawą o wymiarach 25 × 25 mm i wysokością 50 mm wykonanych z żywicy epoksydowej, pokrytych warstwą materiału EMCCO-201 bez kopolimeru SBS. Pomiary absorpcji fal elektromagnetycznych przeprowadzono w zakresie częstotliwości od 3.0 do 11.0 GHz. Największą absorbcją 5–6 dB w zakresie 7.0–10.0 GHz charakteryzowały się próbki z elementami tłumiącymi w kształcie ostrosłupów o podstawie kwadratowej 25 × 25 mm i wysokości 50 mm wykonanymi z żywicy epoksydowej i pokrytymi materiałem EMCCO-201. Próbki z elementami tłumiącymi w formie sferoidów charakteryzowały się małą absorbcją o wielkości 1–3 dB w analogicznym zakresie częstotliwości