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Magnetoelectric (ME) thin film composites consisting of sputtered piezoelectric (PE) and magnetostrictive (MS) layers enable for measurements of magnetic fields passively, i.e. an AC magnetic field directly generates an ME voltage by mechanical coupling of the MS deformation to the PE phase. In order to achieve high field sensitivities a magnetic bias field is necessary to operate at the maximum piezomagnetic coefficient of the MS phase, harnessing mechanical resonances further enhances this direct ME effect size. Despite being able to detect very small AC field amplitudes, exploiting mechanical resonances directly, implies a limitation to available signal bandwidth along with the inherent inability to detect DC or very low frequency magnetic fields. The presented work demonstrates converse ME modulation of thin film Si cantilever composites of mesoscopic dimensions (25 mm × 2.45 mm × 0.35 mm), employing piezoelectric AlN and magnetostrictive FeCoSiB films of 2 µm thickness each. A high frequency mechanical resonance at about 515 kHz leads to strong induced voltages in a surrounding pickup coil with matched self-resonance, leading to field sensitivities up to 64 kV/T. A DC limit of detection of 210 pT/Hz1/2 as well as about 70 pT/Hz1/2 at 10 Hz, without the need for a magnetic bias field, pave the way towards biomagnetic applications.

The method shows that by means of an hybrid-mode field an exact equivalent network for a class of waveguide T-junctions can be derived directly. Unlike mode matching, moment and other field related techniques, this model combines simplicity of form with accuracy and guarantees quick convergence suitable for computer optimization of complex multiple junctions.

A long and well known subfield of the ultra-wideband technology is the time-domain-reflectometry (TDR), which found its ways in a wide field of applications. This paper describes different aspects regarding the way from the first concept of a TDR prototype instrument towards a fully engineered device, suitable for food quality management in an industrial scale. The concept of the described TDR widely depends on the frequency range of the task to be solved, thus is one of the most important aspects in the chain of development. Furthermore industrial requirements with respect to handling of the device and the integration in existing systems have to be kept in mind.

We present a fully integrated microelectromechanical magnetic field sensor based on the ΔE effect. The vacuum encapsulated sensor extends our previous approach [B. Gojdka et al., Appl. Phys. Lett. 99, 223502 (2011); Nature 480, 155 (2011)] and now involves an intermediate piezoelectric AlN layer between a SiO2 cantilever and a magnetostrictive FeCoBSi top layer. The AlN layer serves two functions: It drives the resonator, and it is used for electrical read out. The limit of detection was strongly enhanced to 12 nT/ Hz at 10 Hz.