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A new CPW fed elliptical antenna for ultra-wideband (UWB) is proposed. The novelty of this antenna are very small size and uniplanar structure, which results in easy and low cost fabrication. This antenna has elliptical slot configuration which is fed by the CPW. This elliptical slot UWB antenna is enclosed in the extended surface of ground for decreasing the chip surface area. This antenna is designed with the optimal design parameters for the UWB spectrum. The designed antenna is printed on FR4 substrate and Vector Network Analyser is used for measuring return loss. The results of measurement results are similar to simulation results. The complete chip volume of antenna is 18.3 × 23 × 1.6 mm3.

In this study, flaky Fe95Si1B2P0.5Cu1.5 powders with a particle size of 48–75 μm were compounded with graphene (GR) by high-energy ball milling to prepare GR/Fe95Si1B2P0.5Cu1.5 composite powders. The electromagnetic parameters of GR/Fe95Si1B2P0.5Cu1.5 composite powders in the frequency band of 0.3–8.5 GHz were determined by a vector network analyser. The influence of milling time and graphene content on the electromagnetic parameters of GR/Fe95Si1B2P0.5Cu1.5 composite powders was studied. The results showed that with the increase of graphene content, magnetic permeability and dielectric constant increase simultaneously. The 1.0 wt% GR/Fe95Si1B2P0.5Cu1.5 composite powders prepared by milling for 24 h exhibited the best absorbing property. In the frequency band of 0.3–8.5 GHz, for 1.0 wt% GR/Fe95Si1B2P0.5Cu1.5 composite, the dielectric constant was 182.4–18.2, and the magnetic permeability was 7.3–1.0. The dielectric loss tangent was 3.40–6.60, the magnetic loss tangent was 0.48–3.46, and their sum was 5.28–8.60; therefore, 1.0 wt% GR/Fe95Si1B2P0.5Cu1.5 composite exhibited excellent absorbing properties.

To solve the complexity of the conventional time-domain reflectometry method for locating minor cable ageing degradation, a frequency domain-based method for locating cable ageing degradation based on propagation coefficient spectrum is proposed in this study. First, the change pattern of cable input impedance spectrum in frequency-domain reflectometry is analysed to reveal the relationship between input impedance spectrum and propagation coefficient, and thus finds out the working mechanism of ageing degradation on propagation coefficient spectrum. Then, in the experiment, a vector network analyser is used to measure propagation coefficient spectrum and the inverse discrete Fourier transform is applied to locate cable ageing degradation. Finally, kurtosis analysis is performed on locating curves of different bandwidth and the upper limit of frequency of the testing signal is decided. Within a certain limit, the method proposed in this study can locate degradation with higher accuracy and resolution than several time/frequency-domain based methods currently adopted.

This study quantitatively examines the validity of mixture formulae as models to describe the microwave-range dielectric properties of biological tissue of varying water content. Mixture formulae, specifically the Maxwell Garnett and Bruggeman models, are used to predict the dielectric properties of ex-vivo bovine muscle and liver tissue samples varying in water content. The tissues are modelled as comprising of cell and macromolecule inclusions in a water matrix. The model predictions are compared to dielectric measurements performed with a network analyser and dielectric probe in the 0.5 8.5 GHz band. There was a poor match between the properties predicted by the models and the measured results at most frequency points, for both tissue types. However, the overall predicted and measured trends over the measured band correlated well. The Maxwell Garnett and Bruggeman models may prove a valuable tool aiding in the characterisation of the dielectric properties of materials with different water contents, however, currently, direct application of the model with the assumption of solid inclusions in a water matrix is not feasible without substantial improvement to the models. The dielectric properties of biological tissue are of fundamental importance for many medical technologies ranging from diagnostic to therapeutic. There is a need for continuous improvements to be made to the techniques used to measure and characterise the dielectric properties of tissues. Mixture models are investigated in this study as potentially a valuable candidate modelling technique for the dielectric profiling of tissues based on water content. The research leading to these results has received funding from the European Research Council under the European Union's Horizon 2020 Programme/ERC Grant Agreement BioElecPro n.637780, Science Foundation Ireland (SFI) grant number 15/ERCS/3276, the Hardiman Research Scholarship from NUIG, the charity RESPECT and the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA Grant Agreement no. PCOFUND-GA-2013-608728. peer-reviewed

The detection of different types of chipless Radio Frequency Identification (RFID) tags using a single antenna reader is presented in this paper. The performance is evaluated through experiment and measured using Chipless RFID reader system with single antenna and compared with results from vector network analyser. It explains the operation of the reader and how the pic-microcontroller is programmed with the detection algorithm. Two types of tags have been tested, a printed tag which is flexible and will be in high demand for commercialisation and a copper tag which has more durability. The post processing of the measured results to obtain the tag ID is performed using MATLAB. Adaptive Wavelet based detection algorithm is used for the decoding of the tag ID. After the tag ID has been decoded it is sent to a display screen on the DSP unit and/ or via RS-232 to the host computer application. There is no need of human interaction for the reader to interrogate the tag as the user is able to save the tag data received by the reader in a specified database/server.

Nail varnish and its drying properties are explored in detail using a terahertz vector network analyser in a quasioptical transmission configuration. Assessing the ‘dryness' of nail varnish through the measurement of transmitted terahertz radiation, as opposed to qualitative, and typically touch-based techniques, takes into account the non-uniform drying of the nail varnish as a function of its depth. This method can be used to assess the actual dryness of the layer overall and offer measurable parameters to quantify the drying properties of each mixture.

A genetic algorithm, coupled to a finite difference time domain simulator, is presented for the optimisation of passive THz devices. A broadband THz micropatch antenna has been designed using this system and tested using a vector network analyser in the frequency range 0.75 THz to 1.10 THz.

A low profile tri-band microstrip patch antenna is designed and fabricated for GPS and IRNSS application. The design involves Inset feeding technique and substrate FR_4 which is dielectric in nature. The slotted patch is designed using Keysight Technologies, Advanced Design System© where considerable antenna parameters were obtained for the simulated design and for the prototype when measured using Keysight N9917A Vector Network Analyser. Simulated results show that the patch resonates in L1 Band (1.575 GHz), L5 Band (1.176 GHz) and S-Band (2.49 GHz) with reasonable antenna parameter values.

This paper addresses the question of temporal decorrelation at C and L-band in the case of olive tree plantations, considering the very recent tower-based experiments in Morocco, as well as the preliminary results conducted in preparation phases. Based on the expertise gained from the TropiScat-1&2 campaigns, the presented experiments also consist in the acquisition of dense time series using a Vector Network Analyser (VNA) connected to several antennas, herein dedicated to L and C-band data. Likewise, this experiment benefit from auxiliary measurements (meteorological and in-situ data) in order to better understand the processes behind temporal decorrelation, which remains a key issue for future repeat-pass, tandem or geostationary missions. Our first results highlight the importance of the acquisition time during the day, and also rise the challenge on how to disentangle the combined effects of water content variations and wind induced displacements driven by solar convection.

In this article, a novel compact hexagonal slot antenna for wearable devices is proposed. The proposed antenna is designed using textile substrates such as Polyester, Jeans and Cotton. The design and simulation is performed using Ansys High Frequency Structural Simulator. The simulated prototype is fabricated and tested for verification using Vector Network analyser. Results reveal that the proposed prototype provides a return loss of about − 34 dB and bandwidth from 3.9 to 6.5 GHz for cotton substrate. Human hand phantom has been modeled to measure Specific absorption rate using CST-MWS. The average SAR values for Polyester, Jeans and Cotton are 0.02036 W/kg, 0.04839 W/kg and 0.01035 W/kg respectively.

Dielectric properties of sliced Agaricus bisporus samples, with 0.16–0.89 [g/g, wet basis (w.b.)] moisture content, were determined using a network analyser and an open-ended coaxial-line probe, over a frequency range of 915 MHz to 2450 MHz and a temperature range of 25°C to 60°C. The results showed that the permittivity of A. bisporus was a function of frequency, moisture content, and temperature. The dielectric constant and loss factor were directly proportional to moisture content and temperature, respectively, and both decreased with increasing frequency. However, the influence of temperature on the dielectric constant showed a different trend, as this was affected by the moisture content of the sample. The dielectric loss factor initially increased and then decreased with the decrease in moisture content. Both inflection points appeared at the moisture content value of 0.69 (g/g, w.b.), which represents the “semi-bound water transfer” point. Third-degree polynomial models could be used to describe dielectric constant and loss factor values as functions of moisture content and temperature. The penetration depth decreased with increasing frequency and temperature; however, this first decreased with decreasing moisture content and then increased. Notably, the penetration depth was at a low ebb when the moisture content ranged from 0.69 to 0.52 (g/g, w.b.), indicating easier uneven drying. Low frequency (915 MHz) with large penetration depth represents a highly effective method for large-scale industrial dielectric microwave drying of A. bisporus slices from the angle of uniformity.

Dielectric constant (e′) and loss factor (e″) of skim milk samples at different total solids‐not‐fat contents were measured over the frequency range of 20–4500 MHz at 25 °C using a vector network analyser. The results showed that e′ of skim milk decreased as frequency increased, and e″ changed from decreasing to increasing and had minimums at about 2000 MHz. There was a linear relationship between e′ and solids‐not‐fat content with correlation coefficient higher than 0.940 below 50 MHz and keeping at −0.990 above 150 MHz. e″ had positive linear relationship with solids‐not‐fat content, and their correlation coefficient was higher than 0.970 at all investigated frequencies. Penetration depth of electromagnetic wave in milk decreased as increased frequency or solids‐not‐fat content. The study is helpful to know the relationship between solids‐not‐fat content and dielectric properties, and it provides information for developing solids‐not‐fat detector could be used in on‐line detection for skim milk production.

We report on THz metamaterials for chemical sensing fabricated on low-loss, plastic, flexible substrates. The metamaterial is bonded to a paper sheet, which is saturated with the liquid to be analysed. Liquids in contact with the metamaterial surface with different refractive indices result in a shift of the metamaterial resonant frequency. This shift in frequency can be detected by measuring its complex transmission using a THz vector network analyser, in the frequency range 0.75–1.1 THz. The sensitivity of the metamaterial is 0.0015 refractive index units for a spectral resolution of 1 GHz which is well achievable with the VNA system.

Antenna theory lectures provide students to learn theoretical background of antennas whereas antenna laboratory lectures give a practical study of antenna parameters. Anten'it antenna training kit adds a new feature to the content of antenna laboratory lectures. The new feature is the antenna design ability directly in front of a network analyser. The brick type antenna cells make students to feel the electromagnetic design as a game. This paper includes a normal mode antenna (NMHA) design and its S-parameters change with two different ground plane dimensions.

In this paper, we attempt to re-construct the soil shrinkage curve through electromagnetic measurements and modelling. In order to achieve this objective, broadband dielectric measurements based on vector network analyser (VNA) and open ended (OE) coaxial probe have been performed to measure the relative effective complex permittivity of soil during shrinkage over the 50 MHz – 3 GHz frequency range. A novel approach (Augmented Broadband Complex dielectric Mixture model – ABCM) has been used as kernel to model the spectrum in an inversion scheme. Water saturation and porosity have been estimated directly from the measured spectrum in order to retrieve the Soil Shrinkage Characteristic Curve (SSCC). Upon comparison of the reconstructed SSCC with the SSCC obtained from direct measurements of weights and volumes of soil, a reasonable degree of agreement has been observed in the initial portions of the curve (structural and normal shrinkage) prior to zero and residual shrinkage.

This paper outlines the development of an RF Vector Network Analyser (VNA) laboratory for undergraduate electronic engineering students. Because of the expense of high-quality high-frequency vector network analyser systems, these are usually only encountered by a small number of students who undertake a senior-year project in the RF/microwave area. This paper describes a VNA-based laboratory which is intended to be used by all undergraduate Electrical and Electronic Engineering students in the 4th year of the programme, thus giving all students an insight into this sometimes “mysterious” area of the undergraduate curriculum. The paper moves from the initial “wish list” for what the laboratory might incorporate to the final roll-out to a cohort of 23 students. Feedback from the students indicate that the laboratory session was well received while also indicating that there is potential for improvement in some areas.

An important challenge for our society is the transformation of traditional power systems to a decentralized model based on renewable energy sources. In this new scenario, advanced devices are needed for real-time monitoring and control of the energy flow and power quality (PQ). Ideally, the data collected by Internet of Thing (IoT) sensors should be shared to central cloud systems for online and off-line analysis. In this paper openZmeter (oZm) is presented as an advanced low-cost and open-source hardware device for high-precision energy and power quality measurement in low-voltage power systems. An analog front end (AFE) stage is designed and developed for the acquisition, conditioning, and processing of power signals. This AFE can be stacked on available quadcore embedded ARM boards. The proposed hardware is capable of adapting voltage signals up to 800 V AC/DC and currents up to thousands of amperes using different probes. The oZm device is described as a fully autonomous open-source system for the computation and visualization of PQ events and consumed/generated energy, along with full details of its hardware implementation. It also has the ability to send data to central cloud management systems. Given the small size of the hardware design and considering that it allows measurements under a wide range of operating conditions, oZm can be used both as bulk metering or as metering/submetering device for individual appliances. The design is released as open hardware and therefore is presented to the community as a powerful tool for general usage.

Water seepage through cracked concrete structures often causes reinforcement corrosion as well as degradation of the strength of the primary material. Although there have been major tests of humidity sensors in concrete, based on radio-frequency identification, most such approaches rely on a vector network analyser to measure electromagnetic wave parameters as a proxy for the presence of water or moisture, and this is only suitable at laboratory scale. Therefore, the present researchers conducted an experimental study of sensor code-based smart sensor tags’ performance for long-term detection of seepage through cracks in concrete. Similar sensor code-based tags have been applied in many fields, but never previously for this purpose, i.e., as part of a concrete building’s structural health monitoring (SHM) system. The researchers also propose 3D-printed cases made of polylactic acid to protect the sensor tags. Their experiments compared the performance of sensor tags encapsulated in two sizes of 3D-printed cases – one with an overall depth of 8 mm, and the other, of 3 mm – and embedded in concrete cylinders. This established that, while received signal strength and frequency both varied with soaking time, neither was satisfactory as a measurement of seepage. However, change in sensor code as soaking time increased following damage to the concrete specimens was effective as a seepage measurement. The sensor code-based damage index of those smart sensor tags protected by 3 mm-deep 3D-printed cases indicated better overall results than their 8 mm-deep counterparts, and the 3 mm-deep cases were also more cost-effective. In a subsequent experiment, the researchers embedded 24 of 3 mm-deep 3D-printed cases, each containing one smart sensor tag, in a reinforced-concrete beam. This established that only those smart sensor tags with one or more cracks touching them reached the damage-index threshold, confirming the viability of the sensor code-based damage index. A subsequent experiment’s results also showed that, if one of the 24 smart sensor tags experienced an error, the remaining 23 were still able to verify seepage. In short, the proposed system using 3D-printed cases is expected to be a highly useful addition to SHM.

High frequency RFID sensors are attractive in diverse applications where sensor performance is required at a low cost and dimension restriction. An approach adapting commercial passive 13.56 MHz RFID tags has been developed for sensing corrosion stage. This investigation includes balance of sensing and positioning of RFID sensors for corrosion detection by analysing real and imaginary parts of the complex impedance. With passive HF RFID sensors, real part and imaginary part of complex impedance have been extracted from the reader coil with VNA (vector network analyser) and delivering a unique capability for corrosion sensing with different atmospheric exposure time steel samples (1 month, 6 months, 10 months and 12 months). With different positioning (5–25 mm), features extraction based on the complex impedance with PCA (principal component analysis) has been designed for position-independent corrosion evaluation.

A comparison of nonlinear vector network analyser (NVNA) measurements has been carried out involving four organisations (National Physical Laboratory, UK, University of Surrey, UK, Chalmers University of Technology, Sweden and Keysight Technologies, Denmark). Three nonlinear devices consisting of two amplifiers and a nonlinear verification device (NLVD) were measured by each of the organisations. Results are presented which show generally good agreement between the measurements and give some indication of the typical amount of variability to be expected in measurements of this type., Comment: 2018 International Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits (INMMIC)

For the 7-term LRL and TRL calibration of a four-sampler vector network analyser (VNA), expressions for the deviations of the measured S-parameters of two-port test objects from their actual values are presented as functions of the deviations of the S-parameters of the LRL/TRL calibration elements from their ideal values. The obtained sensitivity coefficients are suitable for establishing the Type-B uncertainty budget for S-parameter measurements. They show how the measurements are affected by imperfect calibration elements and nonideal connections.

Conductive needle punched nonwoven fabrics are developed from staple polypropylene (PP) and varying weight fractions (10, 20 and 30 wt.%) of staple carbon fibres. A fibrous webs of staple PP and carbon fibres were formed at a wool-type carding machine, and these webs subsequently bonded on needle punching machine with 132 punches/cm2 and 13.5 mm needle penetration depth. The electromagnetic shielding effectiveness (EMSE), absorption and reflection characteristics of as-produced needle punched nonwoven fabrics were determined using a network analyser as specified in ASTM D4935-10 in the frequency range 15–3000 MHz. The surface resistivity measurements were carried out in accordance with ASTM D 257-07 standard. These results indicate that the EMSE values increase incrementally with frequency in the 15–3000 MHz range. The nonwoven sample with 30 wt.% carbon fibre showed the lowest surface resistivity of 3.348 kΩ and corresponding highest EMSE of ~42.1 dB in the 3000 MHz frequency range. In comparison, the hi...

In this Letter, a method for the broadband measurement of complex permittivity using a quasi‐optical technique is presented. After calibration of the quasi‐optical system, the material under test is inserted into the system and S‐parameters are measured from 220 to 330 GHz using a vector network analyser. An extraction method is then applied to calculate the complex permittivity. The permittivity measurements are validated by comparing with a well‐established extraction method and the comparison shows good agreement.

The developed network analyser with four ports allows very fast measurements of S-parameters in comparison with a conventional network analyser. This is possible because highly linear analogue frequency ramps are used. Thus the settling times of stepped frequency sweeps of conventional analysers are eliminated. The required high linearity and high stability of the frequency ramps is achieved by using fractional divider phase locked loop circuits. For a practical realization it is necessary to accept small nonlinearities for the linear analogue frequency ramps. For this reason investigations were performed to clarify effects of small nonlinearities on the measurement precision. Nonlinearities are willingly implemented by programming the fractional frequency ramps accordingly. The gained expertise allows for a further improvement of measurement accuracy and dynamic range.

Loop antennas are widely used in various military and civil test applications in order to measure the magnetic fields especially below 30 MHz. They are commonly calibrated as per the standards IEEE 291 and SAE-ARP 958. Although there are a good number of researches in literature about the comparisons of loop antenna calibration methods, we brought the comparison measurements one more step further in this paper and investigated the existing 3 antenna loop calibration method that requires a Vector Network Analyzer (VNA) and included it into our loop antenna calibration comparison. Ultimately, we present the determined advantages and disadvantages of the three antenna method with respect to the other standard methods.

In this paper, a novel technique is presented for measuring permittivity and permeability of honeycomb structured absorbing materials by multiple incident free-space method. The measurement system consists of transmit and receive horn antennas mounted on an arch frame, a network analyser and a flat test bench. The reflection coefficients S 21 of metal-backed specimen is obtained with different incident angle. The complex permittivity and permeability can be extracted from three S 21 by genetic algorithm. Very good agreement is observed between simulated and measured S-parameter of honeycomb structured absorbing materials. The convenience of this approach is the simple calibration procedure besides free-space measurement advantage.

Film bulk acoustic resonators (FBAR) are promising candidates to replace surface acoustic wave devices as filters or delay lines, but also offer exciting opportunities as biological or gas sensors. In this work, solidly mounted FBARs were manufactured by substituting commonly used pure aluminium nitride (AlN) by scandium doped aluminium nitride (ScAlN) thin films as the piezoelectric layer. The ScAlN-based resonators feature a significant improvement of the electromechanical coupling factor from ~3% to ~12% compared to the pure AlN, while the decreased stiffness of ScAlN results in a decrease of the quality factor from ~300 to ~100 due to increased damping losses in the piezoelectric material.

LTE-A has likely been seen as an overwhelming framework utilized by administrators in coming years because of its promising answers for accomplishing high limit, information rate but packet arranging and circulating packets among clients is as yet the principle challenge anticipated of injustice and low execution which arise while allotting packets to clients. In this paper, all these previously mentioned difficulties are examined and broken down, concentrating on two schedulers; they are Proportional Fair (PF) and Maximum Throughput (MT). These techniques do not give QoS to clients that that use different kinds of application streams. NetSim network analyser is utilized to look at between the specified schedulers as far as throughput, hold off period. The suggested algorithim in this paper is to alter the PF scheduler keeping in mind the end goal to satisfy the QoS criteria increasing throughput and reducing the hold off period for continuous streaming for real time application. Voice and video have been preferred as real time traffic and CBR, HTTP, Custom as non-genuine time constrain traffic.

The progression characterisation of exposed atmospheric corrosion on metal substrates is a major problem in the field of corrosion science and Non-destructive Evaluation (NDE). High frequency radio frequency identification (HF RFID) sensors are attractive in diverse applications where sensor performance is needed at a low cost and dimension restriction. An approach adapting commercial passive 13.56MHz RFID tags for sensing corrosion stage has been developed. The investigation includes balance of sensing and positioning of RFID sensors for corrosion detection by analysing real part and imaginary part of the complex impedance. With passive RFID sensors, real part and imaginary part of complex impedance are extracted from the reader coil with Vector network analyser (VNA) and delivering a unique capability for corrosion sensing with different atmospheric exposure time steel samples (1 month, 6 months, 10 months and 12 months). The relationship between these features and corrosion exposed time has been derived which is useful for corrosion progression measurement, early stage corrosion monitoring and prediction in industrial fields such as the marine industry.

This paper presents our work for the measurement of the complex permittivity of liquids, carried out in the framework of a European Metrology research project entitled “Traceable measurement of field strength and SAR for the Physical Agents Directive”. One of the aims of this project was to establish the traceability of the specific absorption rate measurements to the SI up to 10 GHz. We use a vector network analyser to measure the S 21 parameter of coaxial cells containing the liquid under test (a reference liquid or an equivalent tissue liquid). The method does not require the network analyser to be calibrated in terms of impedance. In fact, only the length of the coaxial cell and the working frequency need to be known.

Summary This experimental study investigated the trend of structure and dielectric properties during microwave freeze-drying process banana chips. The mass of banana samples was 160 g, the microwave power set as 2 W g−1 and the highest drying temperature set as 55 °C. The whole drying process can be finished within 6 h. A network analyser and light microscope were used to determine the dielectric properties and structure. The dielectric properties, e′ (from 20.80 to 1.20) and e′′ (from 7.74 to 0.15), and the size of cell get smaller as the drying process continues, especially during the 3–4 h drying, which is the end of primary drying stage and the beginning of secondary drying stage. The trend of dielectric properties and microstructure of samples during drying can be an exact indication of drying stage of MFD.

The dielectric properties of kenaf filled epoxy composites was investigated. Composites was fabricated using kenaf fibres and epoxy resin. The composites was manufactured using a cold press method; the volume fraction of the natural fibres were 7 and 14%. The dielectric test were conducted using Agilent/Keysight E8363B PNA Network Analyser. Result shows that the 14% Kenaf filled epoxy composites successfully decrease the dielectric constant between 12.4 GHz and 16.66 GHz. It shows that the dielectric constant increased with decreased on the fibre loading. Besides that, 14% Kenaf has a higher dissipation loss factor compared to 7% Kenaf filled epoxy composites and reached its peak at 17.89 GHz. In summary, the 14% Kenaf shows a lowest dielectric constant and permeability compared to 7% Kenaf filled epoxy composites.

The resonant frequencies of five different ring resonators are measured with the aid of a network analyser within the frequency range of about 1.5 to 2.8 GHz. The resonant frequencies for those configurations are also determined from numerical calculations using the commercially available MICRO-STRIPES package. The experimental and numerical results are shown to be very close to each other. Analytical results from various authors, available for three of the configurations, are also compared with the experimental results; one of them leads to a large discrepancy, but the other analytical approximations are shown to be not too far off. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 473–476, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21021

U radu je dan pregled radijskih tehnologija koje se koriste u bežičnim senzorskim mrežama. Opisane su aktivne i pasivne metode praćenja mrežnog prometa te mrežni analizatori Wireshark i Perytons. Implementirana je jednostavna bežična senzorska mreža korištenjem ZigBee protokola radijske komunikacije. Na ovoj mreži korištena je aplikacija razvijena u radu kao prototip za studiju izvedljivosti sustava za aktivno praćenje mrežnog prometa. Sustav za praćenje mrežnog prometa korišten je za utvrđivanje skalabilnosti mreže u odnosu na varijacije u mrežnom prometu. In this thesis an overview of radio technologies used in wireless sensor networks is presented. Active and passive network traffic monitoring methods are described, as well as network analyzer softwares Wireshark and Perytons. A simple wireless sensor network was implemented using ZigBee radio communication protocol. On this network an application that was developed as a proof of concept of active network traffic monitoring system was used. Network traffic monitoring system was used to determine scalability of network in relation to variations in network traffic.

Current electromagnetic immunity tests mainly rely on single-frequency sources. However, the evolution of electronic systems leads to miniaturisation and low-cost solutions, in which filters are omitted in front of active non-linear components, also for efficiency reasons. As a result, intermodulation products may leak into the band of operation. The authors propose a comprehensive strategy consisting of design and test methodologies to evaluate in-the-band leakage of out-of-band undesired components, using multiple-tone excitation and relying on an anechoic chamber as test facility. The aim of this study is to demonstrate that an anechoic chamber together with a dual-source network analyser represents an optimal facility to investigate signal integrity issues owing to leakage of intermodulation products.

This paper presents comparison of two measurement techniques for ultra wideband (UWB) off-body radio channel characterization. A measurement campaign was performed in indoor environment using UWB wireless active tags and reader installed with the tag antenna and same set of measurement was repeated in the frequency domain using Vector Network Analyser (VNA) and cable connecting two standalone tag antennas for comparison/with a view to finding out the cable effects. Nine different off-body radio channels were experimentally investigated. Comparison of path loss parameters and path loss model for nine different off-body radio channels for the propagation in indoor environment both measurement cases are shown and analyzed. Results show that measurement taken by VNA connecting two standalone antennas through cables experiences lower path loss value for all nine different off-body channels. Least square fit technique is obtained to extract the path loss exponent. Increase of 12.96% path loss exponent is noticed when measurements are made using UWB tags and reader, i.e., without cable measurement scenario.