Hans Georg Krauthauser

Yet another antenna efficiency measurement method in reverberation chambers

Radiation efficiency is one of the most difficult to measure quantities of antennas. Established methods are mostly either based on the Weehler-Cap-Method and limited to small antenna, or require a full 3D scan around he antenna under test. We present an alternative method for the measurement of antenna efficiency in the reverberation chamber. The measurement is based on an emission measurement method presented in [1]. Using this method, antenna efficiencies can be estimated along with the emission measurement of the equipment under test (EUT). This can help to reduce the uncertainty during radiated emission testing in the reverberation chamber. Of course, the method can also be used without an EUT present in the chamber to characterize the antenna only.

Number of Samples Required to Meet a Field Inhomogeneity Limit With Given Confidence in Reverberation Chambers

We derive equations to calculate the number of samples (tuner positions) required to achieve a certain inhomogeneity for the maximum of a rectangular field strength component with given confidence in reverberation chambers. Perfect and limited reverberation are investigated. The results are in good agreement with unreferenced values found in reverberation standards, e.g., IEC 61000-4-21. They can be used to a priori predict the required number of independent samples from the quality factor and the chamber volume only. Evidence is given that current homogeneity limits in standards (3 dB, IEC 61000-4-21) are inconsistent with the minimum number of samples to use (namely 12) at high frequencies.

Increasing electromagnetic compatibility of Contactless Inductive Flow Tomography

In many metallurgical and silicon crystal growth applications the knowledge about the flow field of the respective liquid metals is vital for proper process management. The high temperatures and the opaqueness of those melts set severe restrictions on the applicable flow measurement methods. The Contactless Inductive Flow Tomography (CIFT) is able to reconstruct the mean flow structure of liquid metals by measuring the flow induced perturbation of an applied magnetic field outside the melt. Typically, these perturbations are about 4 orders of magnitude smaller than the applied magnetic field. Therefore, special care has to be taken to ensure a very high dynamic range of the utilized magnetic field sensors and to minimize the effect of electromagnetic interferences. In this paper we give a short overview on CIFT and delineate some methods to increase its electromagnetic compatibility.

Field coupling to nonlinear circuits in resonating structures

We present a novel approach to the study of backdoor-coupling of electromagnetic fields to non-linear electronic circuits in resonating enclosures. We measured voltages coupled to a nonlinear loaded wire placed inside a resonator. The resonator was excited by two independent high frequency signals. Correlation analysis was used to distinguish between the influence of line to resonator mode coupling and other effects at low frequencies. We found that high frequency field to line coupling is dominant over low frequency spectral components. However, low frequency line to resonator mode interaction can not be neglected.

Network analysis of full wave multi-conductor transmission lines

Complex electrical systems usually contain several wires that influence each other. The analysis of such systems can be time consuming. A network approach that includes the majority of the influences and overcomes the limitations of the classical transmission line theory would be desireable for the computation of the complete system. The possibility of such a network analysis including its prerequisites is shown by an example.

Cross-validation of transmission-line super theory radiated power calculations with measurements for open waveguide structures

In this paper we present the methodology and the results of measurements of the radiated power of open waveguide structures using a reverberation chamber. We examine an open planar waveguide and wire based waveguide models like they are common for NEMP simulators. For the wire based models we compare the measurements to the numerically calculated radiated power using the transmission-line super theory method. Furthermore, we analyze the influence of a matched termination on the radiated power for the planar waveguide. For the wire based waveguides we investigate additionally the influence of the wire density (number of wires) on the radiated power.