Filters
total: 3331
filtered: 1567
-
Catalog
- Publications 1567 available results
- Journals 1 available results
- People 87 available results
- Projects 4 available results
- Laboratories 3 available results
- Research Equipment 7 available results
- e-Learning Courses 254 available results
- Events 58 available results
- Open Research Data 1350 available results
Chosen catalog filters
displaying 1000 best results Help
Search results for: 915 mhz
-
Fish gelatin-nanoclay films. Part I: Effect of a kind of nanoclays and glycerol concentration on mechanical and water barrier properties of nanocomposites
PublicationThe aim of work was the improvement of the mechanical and water barrier properties of nanocomposites prepared from fish gelatin and nanoclays (5–15%), plasticized with glycerol at different concentrations. The effect of hydrophilic Cloisite Na1 and Nanomer®PGV was compared with that exerted by organically modified more hydrophobic Nanofil®2 and NanoBent ZR-1. Antimicrobial activity of nanocomposites containing hydrophobic nanoclays...
-
TIME- AND FREQUENCY-DOMAIN QUASI-2D SMALL-SIGNAL MOSFET MODELS
PublicationA novel approach to small-signal MOSFET modeling is presented in this book. As a result, time- and frequency-domain physics-based quasi-2D NQS four-terminal small-signal MOSFET models are proposed. The time-domain model provides the background to a novel DIBL-included quasi‑2D NQS four-terminal frequency-domain small-signal MOSFET model. Parameters and electrical quantities of the frequency-domain model are described by explicit...
-
Wideband Channel Measurements for Polarised Indoor Off-Body Communications
PublicationThis paper presents the initial results of wideband channel measurements for polarised off-body communication at 5.8 GHz, in an indoor environment. Channel Impulse Response measurements were performed simultaneously for two orthogonal polarisations of the wearable antenna, and repeated for vertical and horizontal orientations of the off-body one. Four types of measurement scenarios were considered in order to investigate the influence...
-
Fading Characteristics for Dynamic Body-to-Body Channels in Indoor and Outdoor Environments
PublicationThis paper presents an analysis of the fading characteristics in dynamic body-to-body channels, based on measurements performed at 2.45 GHz in indoor and outdoor environments. The statistical analysis of the small- and large-scale fading shows that the Nakagami Distribution is the best model for the former and the Log-Normal one for the latter. An important influence of body shadowing...
-
An Empirical System Loss Model for Body Area Networks in a Passenger Ferry Environment
PublicationThis paper presents a general empirical system loss model for estimating propagation loss in Body Area Networks in off-body communications at 2.45 GHz in a passenger ferry environment. The model is based on measurements, which were carried out in dynamic scenarios in the discotheque passenger ferry environment. The model consists of three components: mean system loss, attenuation resulting from the variable antenna position on...
-
An Empirical System Loss Model for Body Area Networks in a Passenger Ferry Environment
PublicationThis paper presents a general empirical system loss model for estimating propagation loss in Body Area Networks in off-body communications at 2.45 GHz in a passenger ferry environment. The model is based on measurements, which were carried out in dynamic scenarios in the discotheque passenger ferry environment. The model consists of three components: mean system loss, attenuation resulting from the variable antenna position on...
-
Expedited design of microstrip antenna subarrays using surrogate-based optimization
PublicationComputationally efficient simulation-driven design of microstrip antenna subarrays is presented. The proposed design approach aims at simultaneous adjustment of all relevant geometry parameters of the subarray, which allows us to take into account the effect of the feeding network on the subarray radiation pattern (in particular, the side lobe level, SLL). In order to handle a large number of variables involved in the design process,...
-
Diagnostics of pillars in St. Mary’s Church (Gdańsk, Poland) using the GPR method
PublicationThe main goal of this study was non-destructive evaluation of pillars in the St. Mary’s Church (Gdańsk, Poland) using the ground penetrating radar (GPR) technique. The GPR inspection was conducted on four brick masonry pillars and five pillars strengthened by reinforced concrete jacketing. Data were acquired with a 2 GHz antenna along longitudinal and transverse profiles. The study involved the estimation of the electromagnetic...
-
High Q-factor Microwave Fabry-Perot Resonator With Distributed Bragg Reflectors
PublicationZrealizowany został rezonator Fabry-Perot pracujący na częstotliwości 39 GHz i wykorzystujący dwie pary ćwierćfalowych kwarcowych reflektorów Bragga. Dla fali o długości 98.26 mm otrzymano dobroć ok. 560,000, co oznacza 4.3-krotny wzrost w porównaniu z identycznym rezonatorem bez reflektorów Bragga. Analizę problemu wykonano przy pomocy metody różnic skończonych w dziedzinie częstotliwości (FDFD) i porównano z uproszczonym rozwiązaniem...
-
Measurement microsystem for high impedance spectroscopy of anticorrosion coatings
PublicationW artykule przedstawiono mikrosystem do pomiarów bardzo dużych impedancji ukierunkowany na identyfikację parametrów powłok antykorozyjnych metodą spektroskopii impedancyjnej. Do wyznaczania składowych ortogonalnych sygnałów pomiarowych zastosowano w nim technikę cyfrowego przetwarzania sygnałów. Pozwoliła ona na uzyskanie szerokiego zakresu częstotliwości pomiarowych, zwłaszcza bardzo niskich, od ćHz, przy zachowaniu prostej konstrukcji...
-
System Loss Model for Body Area Networks in Room Scenarios
PublicationThis paper presents an analysis of system loss in Body Area Networks for room scenarios, based on a wideband measurement campaign at 5.8 GHz. The measurements were performed with a fixed antenna transmitting vertically and horizontally polarised signals, while the user wears dualpolarised antennas. The average system losses in co- and crosspolarised channels are 41.4 and 42.6 dB for vertically polarised transmitted signals and...
-
Szerokopasmowy szyk antenowy wykorzystujący radiatory o brzegu fraktalnym
PublicationW pracy przedstawiono koncepcje szyku antenowego zbudowanego w technologii mikropaskowej, w oparciu o promienniki szczelinowe ze zmodyfikowanym kształtem brzegu. Modyfikacje brzegów szczeliny przeprowadzono wykorzystując krzywe fraktalne. Omówiono metodykę projektowania czteroelementowego szyku antenowego, którego radiatory posiadają krawędzie o kształcie fragmentu krzywej von Kocha (druga iteracja). Zaproponowano obwód zasilający...
-
Wysokoczęstotliwościowy falownik napięcia z tranzystorami SiC JFET do zasilania silnika wysokoobrotowego
PublicationW referacie przedstawiono konstrukcję oraz wyniki badań trójfazowego falownika napięcia zbudowanego z wykorzystaniem diod Schottky oraz tranzystorów JFET z węglika krzemu (SiC). Znacznie krótsze czasy przełączeń tych elementów w porównaniu z tranzystorami IGBT i diodami na bazie krzemu (Si) umożliwiają pracę układu z częstotliwością 100 kHz i wyższą. Duża stromość narastania napięcia rzędu dziesiątek kV/µs powoduje problemy EMC...
-
Analysis of thoracic regional impedance changes using PCA approach
PublicationA multichannel impedance and one lead electrocardiographic recording system has been developed. The impedance measurement unit is built using a four-electrode technique. It consists of a sinusoidal, 40 kHz, current source and five measurement channels. Circumferential current electrodes have been located at a neck and an abdomen. Voltagemeasurement disk electrodes formed five two-electrode measurement ports. The impedance change...
-
Wysokoczęstotliwościowy przekształtnik z tranzystorami SiC JFET
PublicationW referacie przedstawiono konstrukcję oraz wyniki badań trójfazowego falownika napięcia zbudowanego z wykorzystaniem diod Schottky oraz tranzystorów JFET z węglika krzemu (SiC). Znacznie krótsze czasy przełączeń tych elementów w porównaniu z tranzystorami IGBT i diodami na bazie krzemu (Si) umożliwiają pracę układu z częstotliwością 100 kHz i wyższą. Duża stromość narastania napięcia rzędu dziesiątek kV/µs powoduje problemy EMC...
-
Multi-Beam Antenna for Ka-Band CubeSat Connectivity Using 3-D Printed Lens and Antenna Array
PublicationIn this paper, the design of a passive multi-beam lens antenna is proposed for the CubeSat space communication system as an alternative application of a 2-D microstrip antenna array that has originally been designed for a 39 GHz 5 G MU-MIMO system. The half-ellipsoid lens is 3-D printed using stereolithography (SLA) technology. The antenna prototype is capable of selecting the main beam between 16 different directions with a gain...
-
Inline Microstrip Bandpass Filter With Two Transmission Zeros and Increased Order Using Spurious Resonance of Frequency-Dependent Inverter
PublicationA design method for a class of fourth-order inline microstrip bandpass filter with two transmission zeros and 20% fractional bandwidth is presented. The filter consists of two quarter-wavelength transmission-line resonators coupled by a frequency-dependent inverter. The inverter is composed of two open-ended stubs that are connected by an interdigital capacitor and introduces two poles and two transmission zeros in the filter response....
-
Fading Modelling in Dynamic Off-Body Channels
PublicationThis paper presents an off-body fading channel model for Body Area Networks. The proposed model, based on both simulations and measurements at 2.45 GHz in a realistic indoor environment, consists of three components: mean path loss, body shadowing, and multipath fading. The first is modelled as a log function of distance, the path loss exponent being in between 0.4 and 1.6. A statistical perspective is taken for the other two components,...
-
Rapid surrogate-assisted statistical analysis of compact microstrip couplers
PublicationIn this paper, a technique for low-cost statistical analysis and yield estimation of compact microwave couplers has been presented. The analysis is executed at the level of a fast surrogate model representing selected characteristic points of the coupler response that are critical to determine satisfaction/violation of the prescribed design specifications. Because of less nonlinear dependence of the characteristic points on geometry...
-
Spectroscopic and magnetic studies of highly dispersible superparamagnetic silica coated magnetite nanoparticles
PublicationSuperparamagnetic behavior in aqueously well dispersible magnetite core-shell Fe3O4@SiO2 nanoparticles is presented. The magnetic properties of core-shell nanoparticles were measured with use of the DC, AC magnetometry and EPR spectroscopy. Particles were characterized by HR-TEM and Raman spectroscopy, showing a crystalline magnetic core of 11.5 ± 0.12 nm and an amorphous silica shell of 22 ± 1.5 nm in thickness. The DC, AC magnetic...
-
Inline Microwave Filters With N+1 Transmission Zeros Generated by Frequency-Variant Couplings: Coupling-Matrix-Based Synthesis and Design
PublicationA general coupling-matrix-based synthesis methodology for inline Nth-order microwave bandpass filters (BPFs) with frequency-variant reactive-type couplings that generate N+1 transmission zeros (TZs) is presented in this brief. The proposed approach exploits the formulation of the synthesis problem as three inverse nonlinear eigenvalue problems (INEVPs) so that the coupling matrix is built from their sets of eigenvalues. For this...
-
STORMWATER AS AN ALTERNATIVE WATER SOURCE: QUALITY CHANGES WITH RAINFALL DURATION AND IMPLICATIONS FOR TREATMENT APPROACHES
PublicationThe pressure on the world’s water resources is rapidly increasing due to population growth and climatic changes. Valorisation of stormwater as a water resource for non-potable reuse can reduce high-quality water demands and save it for potable uses. In this context, not only roof runoff but also drained stormwater outflow, representing considerably higher pollution levels, should be considered as a potential resource. We analysed...
-
Enhanced Visible Light Active WO3 Thin Films Toward Air Purification: Effect of the Synthesis Conditions
PublicationTaking into consideration, our current environmental situation in the world people should face with growing problem of air and water pollution. Heterogeneous photocatalysis is highly promising tool to improve both, air and water quality through decomposition/mineralization of contaminations directly into harmless CO2 and H2O under ambient conditions. In this contribution we focused on the synthesis of self-assembly WO3 thin films...
-
Uczelnie kształcące polskich inżynierów elektryków do II wojny światowej
PublicationNa podstawie notek biograficznych ponad 1000 osób przedstawiono uczelnie, w których wykształcenie w latach 1891-1935 zdobywali polscy inżynierowie elektrycy. Do I wojny światowej były to uczelnie zagraniczne: niemieckie, rosyjskie, francuskie, belgijskie. Później Polacy kształcili się w polskich uczelniach: Politechnice Lwowskiej oraz w utworzonej w 1915 roku i szybko rozwijającej się Politechnice Warszawskiej.
-
Ocena własności mechanicznych lekkich pian poliuretanowych w świetle ich zastosowania do budowy barek rzecznych w niskim zanurzeniu. Część II: Badania.
PublicationBadano pianę poliuretanową o gęstości około 53 ÷ 62 kg/m3. Wykonano niskocyklowe badania zmęczeniowe przy częstotliwości 0,1 Hz, które wykazały szybki wzrost deformacji piany poliuretanowej przy cyklicznych naprężeniach ściskających i ścinających przekraczających około 60% wytrzymałości doraźnej.
-
High frequency oscillations are associated with cognitive processing in human recognition memory
PublicationHigh frequency oscillations are associated with normal brain function, but also increasingly recognized as potential biomarkers of the epileptogenic brain. Their role in human cognition has been predominantly studied in classical gamma frequencies (30-100 Hz), which reflect neuronal network coordination involved in attention, learning and memory. Invasive brain recordings in animals and humans demonstrate that physiological oscillations...
-
Control of the bridge span vibration with high coefficient passive damper. Theoretical consideration and application
PublicationThe research was carried out due to the problem of vibration on the lively pedestrian drawbridge across the Motlawa River in the city of Gdansk. In the design stage, the main span of the footbridge showed unfavorable dynamic properties, which may create a comfort problem for pedestrians. The first vertical bending eigenfrequency was recognized as 1.64 Hz. The original design of the footbridge was equipped with a driving cylinder...
-
Anticancer and antimicrobial properties of novel η6-p-cymene ruthenium(ii) complexes containing a N,S-type ligand, their structural and theoretical characterization
PublicationRuthenium(II) complexes are lately of great scientific interest due to their chemotherapeutic potential asanticancer and antimicrobial agents. Here we present the synthesis of new pyrazole carbothioamidederivatives and their four arene–ruthenium complexes. The title compounds were characterized with theapplication of IR, NMR, mass spectrometry, elemental analysis and X-ray diffraction. Additionally, for newcomplexes DFT calculations...
-
Opinia dotycząca stanu mieszadeł komór fermentacyjnych oczyszczalni ścieków Gdańsk-Wschod
PublicationDokonano oględzin i oceny stanu mieszadła zbiornika 15/3.
-
A Comprehensive Survey on Antennas On-Chip Based on Metamaterial, Metasurface, and Substrate Integrated Waveguide Principles for Millimeter-Waves and Terahertz Integrated Circuits and Systems
PublicationAntennas on-chip are a particular type of radiating elements valued for their small footprint. They are most commonly integrated in circuit boards to electromagnetically interface free space, which is necessary for wireless communications. Antennas on-chip radiate and receive electromagnetic (EM) energy as any conventional antennas, but what distinguishes them is their miniaturized size. This means they can be integrated inside...
-
Generalized temperature dependence model for anammox process kinetics
PublicationTemperature is a key operational factor influencing the anammox process kinetics. In particular, at temperatures below 15 °C, the specific anammox activity (SAA) considerably decreases. This study aimed to describe the temperature dependence of the anammox process kinetics in the temperature range from 10 to 55 °C, including the specific characteristics of“cold anammox”. The commonly used Arrhenius and extended and modifiedRatkowsky...
-
Pułapkowanie i relaksacja ładunku w folii polietylenowej. VI Ogólnopolskie Sympozjum Inżynieria Wysokich Napięć - IW 2002.
PublicationOmówiono wyniki pomiarów prądu depolaryzacji w folii polietylenowej będące odpowiedzią dielektryka na oddziaływanie narażeń napięciowych. Określono rodzaj i ilość wprowadzonego ładunku w płytkie pułapki dielektryka oraz tempo jego narastania i relaksacji dla impulsów prostokątnych oraz napięcia przemiennego 50 Hz.
-
Liquid-solid interaction during formation of nanocomposite systems
PublicationW pracy zaprezentowano wyniki badań nad zmianami strukturalnymi w układach ciekłego Bi i małych cząsteczek Ni lub Cu w zakresie temperatur od 615 do 1145K. Zaobserwowano (SEM) mikrostruktury kompozytowe i przeanalizowano dla różnych temperaturach i różnych czasów mieszania. Strukturę układów Bi-Ni oraz Bi-Cu, zarówno w stanie stałym i ciekłym, zbadano za pomocą dyfrakcji rentgenowskich.
-
Multi-objective optimization of compact UWB impedance matching transformers using Pareto front exploration and adjoint sensitivities
PublicationIn this paper, a technique for fast multi-objective optimization of impedance matching transformers has been presented. In our approach, a set of alternative designs that represent the best possible trade-offs between conflicting objectives (here, the maximum reflection level within a frequency band of interest and the circuit size) is identified by directly exploring the Pareto front. More specifically, the subsequent Pareto-optimal...
-
STANOWISKO DO BADAŃ CHARAKTERYSTYK PROMIENIOWANIA ANTEN W POLITECHNICE GDAŃSKIEJ
PublicationW pracy zaprezentowano budowę oraz wyposażenie stanowiska do pomiaru charakterystyk promieniowania anten, będącego częścią laboratorium antenowego w Wydziale Elektroniki, Telekomunikacji i Informatyki Politechniki Gdańskiej. Opisywane stanowisko zostało stworzone w latach dziewięćdziesiątych ubiegłego stulecia, jednak od samego początku jest modernizowane celem, zwiększenia jego potencjału pomiarowego. Praca opisuje ostatnie modyfikacje...
-
SiC-based T-type modules for multi-pulse inverter with coupled inductors
PublicationThe paper presents SiC-based three-level T-type modules designed for a high-performance 30kVA DC/AC inverter operating at high frequency 85 kHz with low THD of the output voltage. This inverter system consists of two integrated parts. The first part is active and contains three parallelconnected three-phase T-type modules built with fast-switching SiC power transistors. The second, passive part of the system is a set of inductors...
-
Modelowanie tłumienia propagacyjnego w mieście
PublicationOmówiono i porównano z wynikami pomiarów modele propagacyjne: ''wolnej przestrzeni'' oraz zalecane przez ITU-R w dokumencie P.1411. Analizę porównawczą przeprowadzono na podstawie około 20 tysięcy pomiarów wykonanych w różnych miastach Polski, przy wykorzystaniu infrastruktury radiowego systemu dostępu abonenckiego, pracującego w paśmie 2,4 GHz. Badane radiowe łącza dostępowe obejmowały przypadki zarówno spełnienia jak i niespełnienia...
-
Bezstykowe zasilanie pojazdów trakcyjnych.
PublicationOpracowanie dotyczy wybranych aspektów związanych z bezstykowym przekazywaniem energii i zastosowaniem tego rodzaju systemu do zasilania elektrycznych pojazdów trakcyjnych. Wstępna analiza wykazała, że możliwe jest przesyłanie energii wystarczającej do zasilenia pojedynczego pojazdu poprzez układ cewek powietrznych o słabym sprzężeniu magnetycznym. Zapewnienie odpowiedniej wydajności energetycznej układu przy najlepszej sprawności...
-
Solvent residue determination in Uncaria Tomentosa Bark by HS-GC technique
PublicationPrzedstawiono wyniki oznaczeń pozostałości rozpuszczalników organicznych w preparacie uzyskanym z kory liany U. Tomentosa, wykorzystywanej do produkcji farmaceutyków i dodatków do żywności. 1,1,2-trichloroeten oraz dichlorometan są powszechnie stosowane do usunięcia z kory kilku grup alkaloidów o znanych właściwościach biologicznych, co umożliwia zbadanie pozostałych jej związków. Ilościowe oznaczanie tych rozpuszcalników jest...
-
Nowe wymagania jakości energii wytwarzanej przez elektrownie wiatrowe
PublicationZapewnienie odpowiedniego poziomu jakości energii w systemie elektroenergetycznym dla wszystkich odbiorców jest jednym z ważniejszych współczesnych problemów technicznych. Elektrownie wiatrowe coraz częściej instalowane w wielu miejscach wpływają w istotnym stopniu na stan jakości energii w rozległych obszarach sieci elektroenergetycznej w rejonie ich zainstalowania. W artykule przedstawiono najważniejsze negatywne oddziaływania...
-
Sterowanie mocą bierną maszyny dwustronnie zasilanej w elektrowni wiatrowej
PublicationWartość mocy biernej produkowanej/pobieranej przez park wiatrowy jest wielkością podlegającą sterowaniu a na jej wartość wpływ ma wiele czynników: warunki wiatrowe, struktura parku, długość linii kablowych, rodzaj elektrowni a także algorytm sterowania. Są dwie metody sterowania mocą bierną farmy wiatrowej: pasywna (przez kondensatory i dławiki) i aktywna (przez generator i/lub filtr aktywny). W artykule przedstawiono problemy...
-
Water-mediated long-range interactions between the internal vibrations of remote proteins
PublicationIt is generally acknowledged that the mobility of protein atoms and the mobility of water molecules in the solvation layer are connected. In this article, we answer the question whether a similar interdependence exists between the motions of atoms of proteins separated by the hydration layers of variable thickness. The system consisted of a kinesin catalytic domain and a tubulin dimer. It was studied using molecular dynamics simulations....
-
Discrete element method modelling of elastic wave propagation in a meso-scale model of concrete
PublicationThis paper deals with the accurate modelling of ultrasonic wave propagation in concrete at the mesoscopic level. This was achieved through the development of a discrete element method (DEM) model capable of simulating elastic wave signals comparable to those measured experimentally. The main objective of the work was to propose a novel methodology for constructing a meso-scale model of concrete dedicated to the analysis of elastic...
-
Low cost microwave X-band generator
PublicationA low cost microwave X-band generator for educational purposes was designed and built. Its simple construction and user's interface makes it suitable for a student laboratory.The generator is based on a single frequency conversion concept. It uses a digitally tunable PLL chip for intermediate frequency generation and an active frequency multiplier for frequency conversion. The generator covers 9,7 - 11 GHz part of the X frequency...
-
Simulation-Based Design of Microstrip Linear Antenna Arrays Using Fast Radiation Response Surrogates
PublicationFast yet accurate technique for simulation-based design of linear arrays of microstrip patch antennas is presented. Our technique includes: (i) optimization of the corrected array factor of the antenna array under design for a phase excitation taper resulting in reduced side lobes; (ii) simulation-driven optimization of the array element for element dimensions resulting in matching at and about operational frequency, and (iii)...
-
Detection of Objects Buried in the Sea Bottom with the Use of Parametric Echosounder
PublicationThe paper contains results of a in situ research main task of which was to detect objects buried, partially or completely, in the sea bottom. Object detecting technologies employing acoustic wave sources based on nonlinear interaction of elastic waves require application of parametric sound sources. Detection of objects buried in the sea bottom with the use of classic hydroacoustic devices such as the sidescan sonar or multibeam...
-
SPEKTROSKOPOWE BADANIA WYŁADOWANIA MIKROFALOWEGO W ŹRÓDLE PLAZMY TYPU KOMORA REZONANSOWA ZASILANA FALOWODOWO
PublicationW pracy przedstawiono wyniki spektroskopowych badań wyładowania mikrofalowego (2,45 GHz) pod ciśnieniem atmosferycznym, generowanego w źródle plazmy typu komora rezonansowa. Gazami roboczymi były: argon, azot oraz metan, a także mieszaniny argon/metan oraz azot/metan. Natężenie przepływu gazu roboczego zmieniano w zakresie od 50 do 100 l/min, natomiast moc mikrofal absorbowanych przez wyładowanie wynosiła od 300 do 4000 W. Zmierzone...
-
Performance Comparison of a 650 V GaN SSFET and CoolMOS
PublicationThe new technology of wide band gap semiconductors is said to outperform up-to-date silicon devices. High voltage Gallium Nitride (GaN) transistors, now emerging in the market, have even three times shorter switching times and even four times smaller energy losses compared to the best in-class Si devices. In this paper the performance of a 650 V GaN SSFET is evaluated and compared with the newest silicon family of CoolMOS™ technology....
-
Molecular mobility of water protons under interaction with chemically modified starches. DSC and HMR-relaxation investigations
PublicationThe change of water protons mobility in the system chemically modified starches – water were investigated by DSC and NMR-relaxation methods. The amount of unfrozen water at subzero temperature as well as additional unfrozen water which appears after gelatinization have lower values for chemically modified starches in comparison with the native starch. The proton spin-spin relaxation time Т2 for chemically modified starch samples,...
-
Performance Evaluation of GAM in Off-Body Path Loss Modelling for Body Area Networks
PublicationThis paper addresses the performance evaluation of an off-body path loss model, based on measurements at 2.45 GHz, which has been developed with the use of the Generalised Additive Model, allowing to model a non-linear dependence on different predictor variables. The model formulates path loss as a function of distance, antennas’ heights, antenna orientation angle and polarisation, results showing that performance is very sensitive...