Due to its ability to meet requirements such as e.g. telemetry, millimeter-wave transceiver technology has gained research interest for various sensor applications, including the automotive and consumer sector. This work presents a resonant metamaterial for millimeter-waves that enables telemetric position sensing. The concept is based on a resonant unit cell that can be tuned to enable position encoding. A 2D metamaterial design was developed to parametrize the resonance frequency via a geometric parameter of the structure. The tuneable range of the metamaterial was estimated using a finite element method (FEM) simulation. This allowed for a unique mapping of resonance frequency and the geometric parameter, where a linear range for the sensor effect was selected. The resonance frequency shift encodes the absolute position via the geometry parameter of the metamaterial. A linear position encoded bar was fabricated using well-known PCB manufacturing techniques for position determination. The position encoded metamaterial was successfully tested with a vector network analyser under lab conditions. This telemetric position sensor concept offers a compact and contactless read-out without mechanical interference with the moving object. The metamaterial is completely passive, resulting in low maintenance and failure issues. The overall sensor concept includes a state-of-the-art radar chip as millimeter-wave transceiver which is currently under development.

We present a fully telemetric sensor concept for angle and position measurement. It is based on single-layer millimeter-wave metamaterials that exhibit an anisotropic resonant behavior in interaction with incident electromagnetic waves. The angle of rotation is determined from the reflected millimeter waves of the metamaterial target using a millimeter wave chip transceiver. We use a metamaterial geometry exhibiting anisotropic Fano-type resonant behavior. The Fano-type resonance shows a distinct minimum in the reflection spectrum, even with a single layer of metamaterial. The metamaterial target is manufactured on a printed circuit board (PCB) laminate with low-cost standard manufacturing methods. We present an analytical model estimating the resonance frequency of the metamaterial used. The model allows us to assess whether with the Fano-type metamaterial unit cell structure resonance frequencies in the millimeter wave regime are achievable and compliant with standard PCB manufacturing design rules. We performed proof-of-principle experiments with the metamaterial targets and a vector network analyzer, assisted by a detailed analysis of the sensor effect by means of finite-element method calculations. Finally, we implemented a demonstrator setup containing a state-of-the-art frequency-modulated continuous-wave (FMCW) radar chip and a metamaterial target manufactured with standard PCB manufacturing processes.

Enhancing fields is an important task in millimeter-wave applications, such as nondestructive microwave inspection, metamaterial sensing applications, or millimeter-wave imaging. This demand for compact yet high-performance devices for field enhancement operating in the millimeter-wave regime has led to innovative approaches regarding lens design. State-of-the-art lens designs in this wavelength regime tend to be bulky and operate in the far field, making them unsuitable for small form factor applications. In this context, formulating the required functionality and algorithmically looking for the desired material topology is an inversion of the standard approach. This paper presents an inverse-designed field-amplifying metalens operating in the near field of a 60GHz patch antenna. With a size of about three times the wave length, the given structure promises good performance while maintaining a smaller form factor than conventional solutions. It yields an enhancement of the power amplitude by over 7dB.

We present a fully telemetric strain sensor concept based on a novel millimeter wave metamaterial and show the experimental proof of concept. The metamaterial consists of a single layer of copper structures that are embedded between two sheets of thermoplastic polyurethane (TPU). Our metamaterial design specifically exploits the significant difference in elastic modulus between copper and TPU, so that the sensor effect does not require deformation of the copper structures. This prevents degradation due to delamination or cracking of the copper layer. The metamaterial is manufacturable with low-cost state-of-the-art manufacturing methods of conformable electronics. The geometrical parameters of the unit cell structures are determined from finite element simulations. We present a semi-analytical model of the sensor effect that allows for a low computational cost calculation of the sensitivity and provides a detailed analysis of the metamaterial unit cell components in terms of their contribution to the sensitivity. Our model shows that the change in relative permittivity due to strain, an effect analogous to inverse electrostriction, contributes significantly to the sensitivity. We recorded reflection spectra of a sample using millimeter wave laboratory equipment and determined the sensitivity from the strain-induced shift of the characteristic minima in the reflection spectra. The experiment gives a sensitivity of (13 117 ± 465) Hz/microstrain. The distinguishing features of our proposed sensor concept are the minimal strain-induced delamination due to negligible deformation of the metallic structures and that read-out is implemented in reflection which allows for measurement on metal components.

We propose a millimeter wave metamaterial for high-order OAM generation. The concept uses a reflecting metasurface irradiated by a small antenna (e.g., on-chip antenna) that emits linearly polarized millimeter waves at an operating frequency of 61 GHz. We present the numerical proof of principle using finite element simulations. Results show that OAM generation of the order of ten is feasible by varying one geometrical parameter of the metamaterial unit cell. Subsequent work is to further optimize the OAM generation by combining variations of multiple parameters to minimize the amplitude response variation and experimentally analyze the concept.

Torque is a key parameter in any type of drive system. Real-time torque sensing allows to monitor true power transfer, which is crucial for drive control systems, especially in terms of efficiency and safety improvement. However, up to now, there is a lack of available torque sensor technology meeting the high demands within powertrains or robotics, such as robustness against electromagnetic interferences, vibrations and limited installation space. In this work we present a new concept for torque measurement using tunable millimetre-wave metamaterials together with a continuous wave radar chip as read out. The concept is to mechanically translate torque signals into a shift of the metamaterial resonance frequency which in turn leads to a tuning of phase and amplitude of its reflection spectra. Determining the amplitude tuning with in-phase and quadrature demodulation then allows to calculate the torque. We show the feasibility of this concept with finite element simulations. Further, we build a demonstrator providing the proof-of-concept, using a modified millimetre-wave Doppler radar chip for read out. The demonstrator gives a sensitivity for torque measurement of (15.7 ± 0.4) mV/Nm. We believe that our proposed torques sensor concept paves the way towards future torque sensor technology that is suitable for applications in powertrains and robotics.