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A simple measuring method for acquiring the radiation pattern of an ultrawide band Vivaldi antenna is presented. The measuring is performed by combining two identical Vivaldi antennas and some of the intrinsic properties of a stepped-frequency continue wave radar (SFCW radar) in the
range from 1.0 GHz to 6.0 GHz. A stepper-motor provided the azimuthal rotation for one of the antennas from 0 ◦ to 360 ◦. The tests have been performed within the conventional environment (laboratory / office) without using an anechoic chamber or absorbing materials. Special measuring devices have not been used either. This method has been tested with different pairs of Vivaldi antennas and it can be also used for different ones (with little or no change in the system), as long as their operational
bandwidth is within the frequency range of the SFCW radar.
Keywords — SFCW Radar, Antenna Gain Characterization,
Azimuthal Radiation Pattern
Vorrichtung (2) zur Analyse von Urin, umfassend: – eine Zuführ- und Abführeinrichtung (7), welche zur Zuführung einer bestimmten Urinmenge in eine wenigstens einen Analysebereich (8) aufweisende Analysekammer (9) eines Urinteststreifens (10) und zur Abführung einer bestimmten Urinmenge aus einer wenigstens einen Analysebereich (8) aufweisenden Analysekammer (9) eines Urinteststreifens (10) eingerichtet ist, wobei die Zuführ- und Abführeinrichtung (7) wenigstens ein bewegbar gelagertes Zuführ- und/oder Abführelement (28, 29) zum Zuführen einer bestimmten Urinmenge in einen Zuführbereich (33) der Analysekammer (9) des Urinteststreifens (10) und/oder zum Abführen einer bestimmten Urinmenge aus einem Abführbereich (34) der Analysekammer (9) des Urinteststreifens (10) aufweist, und – eine Erfassungseinrichtung (11), welche zur Erfassung einer zumindest abschnittsweisen Änderung wenigstens eines optisch erfassbaren Parameters, welcher sich in Abhängigkeit der Zusammensetzung einer diesen kontaktierenden Urinmenge optisch erfassbar verändert, des oder eines entsprechenden Analysebereichs (8) des oder eines entsprechenden Urinteststreifens (10) sowie zur Erzeugung einer Erfassungsinformation, welche wenigstens einen optisch erfassten Parameter des oder eines entsprechenden Analysebereichs (8) oder eine Änderung eines solchen beschreibt, eingerichtet ist.
Vorrichtung (2) zur Analyse von Urin, umfassend: – eine Zuführ- und Abführeinrichtung (7), welche zur Zuführung einer bestimmten Urinmenge in eine wenigstens einen Analysebereich (8) aufweisende Analysekammer (9) eines Urinteststreifens (10) und zur Abführung einer bestimmten Urinmenge aus einer wenigstens einen Analysebereich (8) aufweisenden Analysekammer (9) eines Urinteststreifens (10) eingerichtet ist, wobei die Zuführ- und Abführeinrichtung (7) wenigstens ein bewegbar gelagertes Zuführ- und/oder Abführelement (28, 29) zum Zuführen einer bestimmten Urinmenge in einen Zuführbereich (33) der Analysekammer (9) des Urinteststreifens (10) und/oder zum Abführen einer bestimmten Urinmenge aus einem Abführbereich (34) der Analysekammer (9) des Urinteststreifens (10) aufweist, und – eine Erfassungseinrichtung (11), welche zur Erfassung einer zumindest abschnittsweisen Änderung wenigstens eines optisch erfassbaren Parameters, welcher sich in Abhängigkeit der Zusammensetzung einer diesen kontaktierenden Urinmenge optisch erfassbar verändert, des oder eines entsprechenden Analysebereichs (8) des oder eines entsprechenden Urinteststreifens (10) sowie zur Erzeugung einer Erfassungsinformation, welche wenigstens einen optisch erfassten Parameter des oder eines entsprechenden Analysebereichs (8) oder eine Änderung eines solchen beschreibt, eingerichtet ist.
Existing ultrasonic stress evaluation methods utilize the acoustoelastic effect for bulk waves propagating in volume, which is unsuitable for a surface treated material, possessing a significant variation in material properties with depth. With knowledge of nonlinear elastic parameters – third-order elastic constants (TOEC) close to the surface of the sample, the acoustoelastic effect might be used with surface acoustic waves. This work is focused on the development of an independent method of TOEC measurement using the effect of nonlinear surface acoustic waves scattering – i.e. the effect of elastic waves interaction in a nonlinear medium.
In this paper, the possible three wave interactions of surface guided waves and bulk waves are described and formulae for the efficiency of harmonic generation and mode mixing are derived. A comparison of the efficiency of surface waves scattering in an isotropic medium for different interaction types is carried out with the help of nonlinear perturbation theory. First results for surface and bulk wave mixing with known second- and third-order elastic constants are shown.
In this paper, we establish a simple model for the exchange of messages in a vehicular network and we consider fundamental limits on the achievable data rate. For a vehicular network, the exchange of data with other nearby vehicles is particularly important for traffic safety, e.g. for collision avoidance, but also for cooperative applications like platooning. These use cases are currently addressed by standards building on IEEE 802.11p, namely ITS-G5 and DSRC (dedicated short range communication), which encounter saturation problems at high vehicle densities. For this reason, we take a step back and ask for the fundamental limits for the common data rate in a vehicular network. After defining a simple single-lane model and the corresponding capacity limits for some basic multiple- access schemes, we present results for a more realistic setting. For both scenarios, non-orthogonal multiple-access (NOMA) yields the best results.
This paper evaluates the implementation of Medium Access Control (MAC) protocols suitable for massive access connectivity in 5G multi-service networks. The access protocol extends multi-packet detection receivers based on Physical Layer Network Coding (PLNC) decoding and Coded Random Access protocols considering practical aspects to implement one-stage MAC protocols for short packet communications in mMTC services. Extensions to enhance data delivery phase in two- stage protocols are also proposed. The assessment of the access protocols is extended under system level simulations where a suitable link to system interface characterization has been taken into account.
Micro-cracks give rise to non-analytic behavior of the stress-strain relation. For the case of a homogeneous spatial distribution of aligned flat micro-cracks, the influence of this property of the stress-strain relation on harmonic generation is analyzed for Rayleigh waves and for acoustic wedge waves with the help of a simple micromechanical model adopted from the literature. For the efficiencies of harmonic generation of these guided waves, explicit expressions are derived in terms of the corresponding linear wave fields. The initial growth rates of the second harmonic, i.e., the acoustic nonlinearity parameter, has been evaluated numerically for steel as matrix material. The growth rate of the second harmonic of Rayleigh waves has also been determined for microcrack distributions with random orientation, using a model expression for the strain energy in terms of strain invariants known in a geophysical context.
Nonlinearity can give rise to intermodulation distortions in surface acoustic wave (SAW) devices operating at high input power levels. To understand such undesired effects, a finite element method (FEM) simulation model in combination with a perturbation theory is applied to find out the role of different materials and higher order nonlinear tensor data for the nonlinearities in such acoustic devices. At high power, the SAW devices containing metal, piezoelectric substrate, and temperature compensating (TC) layers are subject to complicated geometrical, material, and other nonlinearities. In this paper, third-order nonlinearities in TC-SAW devices are investigated. The materials used are LiNbO 3 -rot128YX as the substrate and copper electrodes covered with a SiO 2 film as the TC layer. An effective nonlinearity constant for a given system is determined by comparison of nonlinear P-matrix simulations to third-order intermodulation measurements of test filters in a first step. By employing these constants from different systems, i.e., different metallization ratios, in nonlinear periodic P-matrix simulations, a direct comparison to nonlinear periodic FEM-simulations yields scaling factors for the materials used. Thus, the contribution of the different materials to the nonlinear behavior of TC-SAW devices is obtained and the role of metal electrodes, substrate, and TC film are discussed in detail.