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Abstract. In this paper, a stripline split-ring resonator microwave-induced plasma source, aimed for integration in complex systems, is presented and compared with a traditional microstrip design. Devices based on the two designs are evaluated using a plasma breakdown test setup for measuring the power required to ignite plasmas at different pressures. Moreover, the radiation efficiency of the devices is investigated with a Wheeler cap, and their electromagnetic compatibility is investigated in a variable electrical environment emulating an application. Finally, the basic properties of the plasma in the two designs are investigated in terms of electron temperature, plasma potential, and ion density. The study shows that, with a minor increase in plasma ignition power, the stripline design provides a more isolated and easy-to-integrate alternative to the conventional microstrip design. Moreover, the stripline devices showed a decreased antenna efficiency as compared to their microstrip counterparts, which is beneficial for plasma sources. Furthermore, the investigated stripline devices exhibited virtually no frequency shift in a varying electromagnetic environment, whereas the resonance frequency of their microstrip counterparts shifted up to 17.5%. With regards to the plasma parameters, the different designs showed only minor differences in electron temperature, whereas the ion density was higher with the stripline design.Keywords: Split-ring resonator, Microwave plasma, Microstrip, Stripline, Plasma, Wheeler cap, Langmuir probe

In this letter, measurements and simulations of wave propagation inside a jet engine fan have been performed. The investigation was done using both EM simulations of different cases of propagation inside the engine and by measuring the corresponding cases inside a half-scale model of a jet engine fan. The average path loss was calculated, and the shapes of the fading distributions were extracted. The time between two consecutive fading dips was measured in the empirical part. Measurements were performed with engine speeds of both 30 and 60 rpm and were shown to be linearly scalable from 60 rpm to full speed of 10 000 rpm. The results showed an average path loss of about 55 dB. When scaling the measurements from 60 rpm to full-speed rotation of about 10 000 rpm, the fading was so severe that the time slot between consecutive fading dips was limited to 290 s.

Abstract-Mode-stirred chambers (MSCs) consist of one or more resonant cavities coupled in some way in order to allow the measurement of different antenna parameters such as antenna efficiency, correlation, diversity gain, or multiple-input-multiple-output (MIMO) capacity, among others. In a single-cavity MSC, also known as a reverberation chamber (RC), the environment is isotropic and the amplitude of the signal is Rayleigh distributed. Real environments, however, rarely follow an isotropic Rayleigh-fading scenario. Previous results have shown that a Rician-fading emulation can be obtained via hardware modification using an RC. The different methods lack from an accurate emulation performance and are strongly dependent upon chamber size and antenna configurations. With the innate complexity of more-than-one-cavity MSC, the coupling structure generates sample sets that are complex enough so as to contain different clusters with diverse fading characteristics. This letter presents a novel method to accurately emulate a more realistic Rician-fading distribution from a Rayleigh-fading distribution by selecting parts of the sample set that forms different statistical ensembles using a complex two-cavity multi-iris-coupled MSC. Sample selection is performed using a genetic algorithm. Results demonstrate the potential of MSCs for versatile MIMO fading emulation and over-the-air (OTA) testing. The method is patent protected by EMITE Ing., Murcia, Spain.Index Terms-Diversity gain, mode-stirred chamber (MSC), multiple-input-multiple-output (MIMO) capacity.

Today, the majority of wagon failures on railroad systems are because of the poor maintenance of ball bearings, which causes emergent stops and delays. The existing stationary detectors, lack in predicting failures which cause troubles in scheduling maintenance. During the fall of 2011, a trial was performed by applying a wireless sensor network (WSN) aboard a train wagon with the objective to demonstrate a proof of concept for monitoring the temperature of ball bearings aboard the train wagon. This trial investigates several key aspects when applying sensor networks such as radio wave propagation, energy scavenging and performance of the WSN aboard the wagon. Two wireless links were used in the WSN. The aboard network communicates at 2.45 GHz, and the external communication is an 868 MHz radio frequency identification radio link. Since the energy in the WSN node is limited, appropriate energy scavenging devices are also presented and evaluated in a lab environment. Effort has been made to overcome these problems. The energy consumption in the network is still a problem; the most promising energy scavenging technique is piezoelectric harvesting by vibrations, which in the experiments scavenged 2.32 mW.