Gert-Jan Stockman

Design of a Wearable, Low-Cost, Through-Wall Doppler Radar System

A novel, low-cost, low-weight, wearable Doppler radar system composed of textile materials and capable of detecting moving objects behind a barrier is presented. The system operates at 2.35 GHz and is integrable into garments, making it well-suited for usage in difficult to access terrain, such as disaster areas or burning buildings. Wearability is maximized by relying on flexible, low-weight, and breathable materials to manufacture the key parts of the system. The low-complexity Doppler radar system makes use of an array of four textile-transmit antennas to scan the surroundings. The beam emitted by this array is right-hand circularly polarized along all scanning angles and provides a measured gain of 9.2 dBi. At the receiving end, textile materials are used to develop an active wearable receive antenna, with 15.7 dBi gain, 1.1 dB noise figure, left-hand circular polarization, and a 3 dB axial ratio beamwidth larger than 50°. Several measurement setups demonstrate that the onbody system is capable of detecting multiple moving subjects in indoor environments, including through-wall scenarios.

Efficient Modeling of Interactions Between Radiating Devices With Arbitrary Relative Positions and Orientations

A novel method to efficiently compute the interaction between two devices is proposed with the aim of accurately reproducing radiated immunity and emission tests in simulations. The technique allows an arbitrary relative position and orientation between the two devices. It relies on a single simulation (or measurement) of the radiation pattern of each device. To take rotation of the devices into account, a spherical harmonics decomposition is applied together with Wigner-D rotation matrices. The resulting procedure is practical, has a low computational cost, and shows good agreement with measurements and full-wave simulations.

Stochastic Analysis of the Efficiency of a Wireless Power Transfer System Subject to Antenna Variability and Position Uncertainties

The efficiency of a wireless power transfer (WPT) system in the radiative near-field is inevitably affected by the variability in the design parameters of the deployed antennas and by uncertainties in their mutual position. Therefore, we propose a stochastic analysis that combines the generalized polynomial chaos (gPC) theory with an efficient model for the interaction between devices in the radiative near-field. This framework enables us to investigate the impact of random effects on the power transfer efficiency (PTE) of a WPT system. More specifically, the WPT system under study consists of a transmitting horn antenna and a receiving textile antenna operating in the Industrial, Scientific and Medical (ISM) band at 2.45 GHz. First, we model the impact of the textile antenna’s variability on the WPT system. Next, we include the position uncertainties of the antennas in the analysis in order to quantify the overall variations in the PTE. The analysis is carried out by means of polynomial-chaos-based macromodels, whereas a Monte Carlo simulation validates the complete technique. It is shown that the proposed approach is very accurate, more flexible and more efficient than a straightforward Monte Carlo analysis, with demonstrated speedup factors up to 2500.

Full-Wave Modeling of Interacting Multiport Devices With Arbitrary Relative Positions and Orientations for Efficient EMI Assessment

A novel method to accurately and efficiently model the interaction between radiating devices is proposed. Whereas previous work of the authors dealt with singleport devices (antennas), this paper constitutes an important extension to actual multiport devices, as such paving the way for electromagnetic interference assessment of real-life (sub)systems early in their design cycle. The method solely relies on the knowledge of the radiation patterns of the different ports of the devices, which can either be measured or simulated using a solver of choice. These patterns are then used to compute the electromagnetic interaction between the devices that may be positioned in each others radiative near-field (Fresnel region) or far-field (Fraunhofer region). Furthermore, in the model, their relative positions and orientations can be altered at a very low computational cost. The technique is thoroughly validated and illustrated, demonstrating its appositeness to study the electromagnetic compatibility behavior of the multiport devices.

Efficient full-wave modeling of radiative near-field interactions in semi-anechoic conditions

In this paper, a full-wave method to efficiently compute the electromagnetic interaction between two devices placed in semi-anechoic conditions is proposed. The aim of this research is the accurate and efficient reproduction of radiated immunity and emission tests in simulation. The employed technique relies on a single simulation (or measurement) of the radiation pattern of each device and allows an arbitrary relative position between the devices. The resulting procedure is practical, has a low computational cost, and shows good agreement with reference solutions.

Efficient full-wave modeling of electromagnetic interference in the presence of multiple non-collocated noise sources

In this contribution a novel method is discussed that is of practical use for analyzing the electromagnetic compatibility behavior of electronic systems. The aim is to develop an efficient technique that mimics radiated immunity and emission tests in the presence of multiple non-collocated noise sources in simulation. The proposed method is simple in that it only relies on the simulated (or measured) radiation pattern of the devices in the system while allowing arbitrary positions. Rotation of the devices is performed by a spherical harmonics decomposition of the radiation patterns together with the application of Wigner-D rotation matrices. The adopted assumption is that the devices are spaced sufficiently far from each other such that there is no coupling via the reactive near-field. The proposed procedure shows good agreement with measurements and full-wave simulations while at the same time it has a low computational cost.

Efficient modeling of the wireless power transfer efficiency for varying positions and orientations between transmitter and receiver

A method that efficiently calculates the Power Transfer Efficiency (PTE) of a Wireless Power Transfer (WPT) system is described in this paper. It allows for arbitrary relative positions and orientations between devices in the system, both in far-field and radiative near-field configurations. The method uses a single simulation or measurement of the radiation patterns of the antennas employed in the WPT system, from which the interaction between devices at any relative position and orientation can be modeled. A spherical harmonics decomposition, together with Wigner-D rotation matrices, is applied to perform efficient translations and rotations of the devices used in the WPT system.

EMC-aware analysis and design of a low-cost receiver circuit under injection locking and pulling

In low-cost receiver applications, the preselect filter is often omitted in order to reduce the footprint of the total system. However, the immunity of the receiver can be severely compromised by this approach. This paper focuses on the effects of co-located sources on the local oscillator (LO), specifically injection locking and pulling. To this end, a low-cost radio receiver (RF) front-end is designed for operation in the 2:45 GHz industrial, scientific and medical (ISM) radio band. In addition to the effects on the oscillator, the consequences on the receivers performance are evaluated as well. For the first time in literature, this work demonstrates the critical necessity to take the potentially detrimental effects caused by injection locking and pulling into account during Electromagnetic Compatibility (EMC)-aware design.