Bart Boesman

Correlating the High-Frequency Shielding Performance of 'On-Board' Gaskets when Characterized using a Stripline or Reverberation Room Method

This paper compares the shielding performance or shielding effectiveness of gaskets for on-board applications when determined with either a stripline method or a reverberation room method. The shielding performance is considered in the frequency range from 1 up to 40 Ghz. Similar to PCB-level enclosures, gaskets for on-board applications differ significantly from other shielding products, therefore requiring an appropriate definition for their shielding effectiveness. It is shown by full-wave simulations that a 3rd order polynomial fit of the shielding effectiveness obtained with the stripline method correlates well with the shielding effectiveness obtained with a reverberation room method, in which case the shielding effectiveness is defined as the ratio between the radiated/received power with and without gasket.

Towards a stripline setup to characterise the effects of corrosion and ageing on the shielding effectiveness of EMI gaskets

This paper introduces a novel measurement set-up dedicated to the characterization of the evolution of the high-frequency shielding-effectiveness of gaskets due to corrosion and ageing. The measurement set-up is based on the recently introduced stripline set-up which has been validated previously up to 40 GHz. Compared to the original stripline set-up, the adapted set-up has a removable “clamping module” which can be easily mounted and removed from the set-up. The clamping module allows to age the gasket inside e.g. a climate chamber while always keeping the gasket under the same compression rate. As the clamping module can be made out of different materials, it allows to study the influence of shielding-effectiveness of gaskets when applied to different materials. In order to avoid parallel leakage inside the measurement set-up, a high-performant gasket needs to be compressed below the module. Based on full-wave simulations, it is shown that the shielding-effectiveness given by this gasket underneath the clamping module is the main determining factor for the dynamic range of the set-up. In addition, a first set of measurements show the validity of the measurement set-up and approach.

Spherical Wave Based Macromodels for Efficient System-Level EMC Analysis in Circuit Simulators Part I: Optimized Derivation and Truncation Criteria

This work presents a general framework that enables one to compute near- and far-field interactions inside a circuit simulator environment, aimed at efficient system-level electromagnetic compatibility (EMC) analysis. For readability, the paper is subdivided in two parts. Part I focuses on deriving (high-order) spherical wave based macromodels in optimal time and describes two truncation criteria which define the maximum complexity of the models. The latter is generally a compromise between the accuracy of reconstructed near-fields and the computation time for evaluating interactions between these models, and is therefore a crucial parameter when such models are to be applied in fast circuit solvers. Existing guidelines on truncating spherical wave expansions are held against the newly derived criteria. In part II, the framework is extended with optimized routines that enable one to compute efficiently near- and far-field interactions between the macromodels discussed in part I. It will be shown that by extensive understanding of spherical wave expansions, the underlying computations only add negligible computational cost compared to traditional S-parameter simulations, partially contributed to correctly chosen truncations of the applied models.

Spherical Wave Based Macromodels for Efficient System-Level EMC Analysis in Circuit Simulators Part II: Optimized Calculation of DUT–DUT Interactions

In this second part of two papers, the framework presented in Part I is extended with optimized routines that enable one to evaluate interactions between several devices under test (DUTs) through free space inside a circuit simulator environment, aimed at efficient system-level electromagnetic compatibility (EMC) analysis. Using a generalized scattering matrix formulation and an extensive understanding of the underlying theory of spherical wave expansions (SWEs), it is shown that the presented routines only add negligible computational cost to traditional scattering parameter simulations. The latter is obtained on the one hand by optimally truncating SWE based macromodels as described in Part I and on the other hand by observing that both near- and far-field interactions are only determined by a subset of parameters in the models. Therefore, this paper derives guidelines on the number of parameters needed to assure accurate simulations and validates them using two applications: 1) computing the radiated coupling between two DUTs; and 2) extending the first example in order to simulate efficiently a cylindrical scan of a DUT by an arbitrary measurement antenna.

Fast and efficient near-field to near-field and near-field to far-field transformation based on the spherical wave expansion

This paper presents efficient methods to transform, interpolate and filter recorded near- and far-fields on spherical surfaces, based on a spectral decomposition of these fields in spherical harmonics. Combining a Fast Fourier Transform (FFT), Discrete Cosine Transform (DCT) and Discrete Sine Transform (DST) reduces the computation time of existing algorithms to a matter of seconds, even for densely sampled fields. Due to these fast run times, the proposed methods are very well suited for implementation in existing full-wave solvers and allow to only store the spectral decomposition of the fields. The latter heavily decreases necessary disk space, which is now indepedent from the chosen number of interpolation samples. Efficient and fast field visualisation tools have wide-spread applications in amongst others Electromagnetic Compatibility (EMC) diagnosis, education, and noise removal from gridded field data.

Reciprocity-based simulation methodology to estimate the power distribution received by electromagnetic energy harvesters

The capability to efficiently harvest power from ambient energy sources is a crucial element for the development of low-maintenance wireless sensor networks. Available energy levels that can be harvested from ambient electromagnetic (EM) sources are rather low (0.1 µW/cm2). Insufficient information about the available EM energy under different working conditions results in poor design decisions, leading to a sub-optimal system design. In this study, a novel and efficient simulation methodology is developed which predicts the statistical distribution of the power harvested by an antenna when immersed in a given (statistical) EM environment. The methodology is used to quantify the impact of the antennas orientation, location, exact geometry and so on, on the quantity of the harvested energy. The methodology is successfully applied to a realistic energy harvesting antenna in different EM environments (indoor, outdoor etc.)