Benoit Derat

Connectivity is at the core of the automotive technology revolution, which will enable not only self-driving cars but also new services and features. However, antennas interact with adjacent components and the performance of integrated car transceivers must be evaluated in situ. As a consequence, full-vehicle over-the-air (OTA) testing has become a subject of growing interest in the automotive industry. This article discusses the most recognized measurement methodologies, their implementation… Mehr anzeigen

Connectivity is at the core of the automotive technology revolution, which will enable not only self-driving cars but also new services and features. However, antennas interact with adjacent components and the performance of integrated car transceivers must be evaluated in situ. As a consequence, full-vehicle over-the-air (OTA) testing has become a subject of growing interest in the automotive industry. This article discusses the most recognized measurement methodologies, their implementation and the rationale behind the metrics of interest. Weniger anzeigen

This paper proposes a novel approach for fast human exposure absorbed power density assessment, based on a combination of over-the-air radiative field measurements and full-wave electromagnetic simulations. This so-called augmented OTA technique relies on the computation of an equivalent source or digital twin, which reproduces the radiation properties of the device under test. At short separation distances, the interaction between the human model and the device is however not negligible. A… Mehr anzeigen

This paper proposes a novel approach for fast human exposure absorbed power density assessment, based on a combination of over-the-air radiative field measurements and full-wave electromagnetic simulations. This so-called augmented OTA technique relies on the computation of an equivalent source or digital twin, which reproduces the radiation properties of the device under test. At short separation distances, the interaction between the human model and the device is however not negligible. A novel solution to model the influence of multiple reflections is introduced, where the inside of the equivalent source box is partially filled with a perfect electric conductor, thereby creating a reflective digital twin model. Simulation and measurement results demonstrate the relevance of this technique for enabling accurate absorbed power density evaluations. A discussion on aspects influencing the measurement time and uncertainty is also provided, where a new demonstration is delivered how spatial-averaging contributes positively to the accuracy of the method. Weniger anzeigen

5G communications have supported the deployment of mmWave antenna array beam steering technologies at an unprecedented commercial scale. As per 3GPP1 and CTIA2 test specifications, 5G mmWave capable mobile phones must undergo a large number of tests to guarantee adequate performance. The defined measurement methodology relies on far-field over-the-air (OTA) assessments in compact antenna test ranges (CATR). As temperature influences the active electronics in the wireless devices and, hence, the… Mehr anzeigen

5G communications have supported the deployment of mmWave antenna array beam steering technologies at an unprecedented commercial scale. As per 3GPP1 and CTIA2 test specifications, 5G mmWave capable mobile phones must undergo a large number of tests to guarantee adequate performance. The defined measurement methodology relies on far-field over-the-air (OTA) assessments in compact antenna test ranges (CATR). As temperature influences the active electronics in the wireless devices and, hence, the beamforming characteristics, OTA measurements are also required in temperature conditions ranging from -10°C to +55°C, per 3GPP test specifications. For such tests, an innovative realization of a CATR with an embedded thermal compartment meeting conformance and compliance testing needs is required. Weniger anzeigen

This paper presents results for active and passive measurements using a novel method based on multiple compact antenna test range (CATR) reflectors to perform simultaneous multiple angle measurements in order to characterize the beam-forming characteristics in a real environment of the 5G devices operating in the millimeter wave frequency band: 24–44 GHz. The over-the-air (OTA) system generates four planar wavefronts with different incidence angles, realizing up to five pairs of angular spreads… Mehr anzeigen

This paper presents results for active and passive measurements using a novel method based on multiple compact antenna test range (CATR) reflectors to perform simultaneous multiple angle measurements in order to characterize the beam-forming characteristics in a real environment of the 5G devices operating in the millimeter wave frequency band: 24–44 GHz. The over-the-air (OTA) system generates four planar wavefronts with different incidence angles, realizing up to five pairs of angular spreads or four switched/simultaneous angles of arrival. The initial target application is radio resource management (RRM) testing, where the execution of mobility procedures and radio link monitoring of a 5G millimeter wave device are evaluated. The applicability of the multi-reflector approach to RRM testing is measured with commercial 5G handsets, through three test scenarios. The paper demonstrates that baseband (non OTA) testing is not sufficient for RRM FR2, as the results are influenced by the direction of arrival of the signal. It is further shown that OTA testing in a multi-reflector CATR system and a careful selection of a representative set of test directions is critical for full characterization of the performance of a wireless device operating in the millimeter wave bands. Weniger anzeigen

5G is all about data, speed and reliability in high frequency mmWave bands. The lack of conventional external RF connectors makes 5G device characterization challenging enough. However, for beamforming scenarios where multiple angles of arrival need to be considered, the test setup reaches a new level of complexity. With a novel multiple compact antenna test range (CATR), the required footprint for radio resource management (RRM) measurement, for example, can be reduced significantly, while… Mehr anzeigen

5G is all about data, speed and reliability in high frequency mmWave bands. The lack of conventional external RF connectors makes 5G device characterization challenging enough. However, for beamforming scenarios where multiple angles of arrival need to be considered, the test setup reaches a new level of complexity. With a novel multiple compact antenna test range (CATR), the required footprint for radio resource management (RRM) measurement, for example, can be reduced significantly, while maintaining low measurement uncertainty inside a defined quiet zone encompassing the entire wireless device.

In the 5G FR2 mmWave frequency bands, several measurement applications require multiple angles of arrival for device characterization: MIMO, a technique with two or more spatial layers to increase data speeds, used in both 4G and 5G; RF fading with multiple impinging waves; simultaneous in-band and spurious emissions monitoring; and RRM.1 One common example of an RRM scenario is when a 5G wireless device monitors the power levels from several base stations and performs a handover to a different base station when the signal from the first one drops below a given threshold. Weniger anzeigen

Evaluating the realistic performance of antennas integrated into complex setups has been a long-term challenge, currently relevant to automotive connectivity, for example. Numerical electromagnetic (EM) modeling offers a cost-effective alternative to device testing but is often limited by an incomplete or inaccurate knowledge of the device under test (DUT). While this shortcoming does not apply to test approaches, the implementation of adequate measurement systems, such as full-vehicle… Mehr anzeigen

Evaluating the realistic performance of antennas integrated into complex setups has been a long-term challenge, currently relevant to automotive connectivity, for example. Numerical electromagnetic (EM) modeling offers a cost-effective alternative to device testing but is often limited by an incomplete or inaccurate knowledge of the device under test (DUT). While this shortcoming does not apply to test approaches, the implementation of adequate measurement systems, such as full-vehicle over-the-air (OTA) test setups, requires large investments and, possibly, a significant amount of space. We present a way to converge both worlds in an optimal cost-benefit technique by combining antenna measurements with full-wave simulation. Weniger anzeigen

This paper presents a novel method using multiple compact antenna test range (CATR) reflectors to perform simultaneous multiple angle measurements for 5G devices that are capable of beam-forming in the millimeter wave frequency range. Four CATR reflectors and their respective feed antennas are arranged on a planar semi-circle arc with the device under test placed on a positioner at the center of the arc. This arrangement is designed to generate four planar wavefronts with different incidences… Mehr anzeigen

This paper presents a novel method using multiple compact antenna test range (CATR) reflectors to perform simultaneous multiple angle measurements for 5G devices that are capable of beam-forming in the millimeter wave frequency range. Four CATR reflectors and their respective feed antennas are arranged on a planar semi-circle arc with the device under test placed on a positioner at the center of the arc. This arrangement is designed to generate four planar wavefronts with different incidences, realizing up to five pairs of angular spreads or four switched/simultaneous angles of arrival. The objective of this setup is to reproduce configurations involving multiple base-stations radiating from different directions. The initial target application is radio resource management (RRM) testing, where the execution of mobility procedures and radio link monitoring of a 5G millimeter wave device are evaluated. The reflectors create far-field conditions at the device under test for quiet zones up to 30 cm in diameter inside a portable system with a footprint of 3.25 x 1.4 meters. The applicability of the approach to RRM testing is demonstrated through measurements, performed with both sinusoidal and modulated signals, using horn antennas and commercial 5G devices. Weniger anzeigen

Over-the-air (OTA) performance evaluation for wireless devices require electromagnetic field measurements in the far-field (FF). This is typically achieved by using one or multiple test probes to scan a sphere encompassing the device under test (DUT), which can be either set to transmit (Tx) or receive (Rx). Measurement data are usually collected in magnitude-only and near-field to far-field transformations cannot be straightforwardly applied in a majority of test cases. In the case of large… Mehr anzeigen

Over-the-air (OTA) performance evaluation for wireless devices require electromagnetic field measurements in the far-field (FF). This is typically achieved by using one or multiple test probes to scan a sphere encompassing the device under test (DUT), which can be either set to transmit (Tx) or receive (Rx). Measurement data are usually collected in magnitude-only and near-field to far-field transformations cannot be straightforwardly applied in a majority of test cases. In the case of large DUT, the active antenna in the device may not be located at the center of the measurement coordinate system, due to mechanical positioner or anechoic chamber constraints. Such an offset is known to introduce significant errors on assessed radiated quantities, which are mostly due to variations in the path length and the angular position of the apparent phase center of the Tx/Rx structure, with respect to the probe boresight direction. This article proposes a novel solution to this problem and introduces an algorithm to compensate errors from known antenna displacements within the coordinate system. This compensation applies to both OTA Tx and Rx cases. The accuracy of the identified solution is demonstrated through simulated and experimental results, using setups operating at 5G NR millimeter-wave frequencies. Weniger anzeigen

The influence of the user's hand holding a mobile phone to the ear on the peak spatial-average Specific Absorption Rate (psSAR) averaged over any 1 g and 10 g of tissue in the head is investigated. This study is motivated by recent reports that found substantial increases in psSAR by the presence of the hand in some cases. Current measurement standards prescribe the measurement of SAR in a head phantom without a hand present. The mechanisms of interaction between the hand and mobile phone… Mehr anzeigen

The influence of the user's hand holding a mobile phone to the ear on the peak spatial-average Specific Absorption Rate (psSAR) averaged over any 1 g and 10 g of tissue in the head is investigated. This study is motivated by recent reports that found substantial increases in psSAR by the presence of the hand in some cases. Current measurement standards prescribe the measurement of SAR in a head phantom without a hand present. The mechanisms of interaction between the hand and mobile phone models are studied. Simulations and measurements at 900 and 1800 MHz have been conducted to complement the understanding of the hand grip parameters leading to higher SAR in the head. Numerical simulations were conducted on four mobile phone models, and parameters such as the palm-phone distance and hand position were varied. Measurements of 46 commercial mobile phones were made, and the maximum psSAR with different hand positions and palm-phone distances was recorded. Both simulations and measurements have found increases in the psSAR in the head of at least 2.5 dB due to the presence of the hand. Furthermore, the psSAR is sensitive to the hand grip, i.e., the variations can exceed 3 dB. Weniger anzeigen

An international interlaboratory comparison for numerical calculations of head phantom SAR involving three mobile phones with computer-aided design-based models has been conducted in order to evaluate the repeatability of such calculations and for providing input in the development of standardized procedures. SAR in the standardized specific anthropomorphic mannequin (SAM) head phantom was calculated by ten laboratories in a blind study manner. The agreement in calculated SAR between the… Mehr anzeigen

An international interlaboratory comparison for numerical calculations of head phantom SAR involving three mobile phones with computer-aided design-based models has been conducted in order to evaluate the repeatability of such calculations and for providing input in the development of standardized procedures. SAR in the standardized specific anthropomorphic mannequin (SAM) head phantom was calculated by ten laboratories in a blind study manner. The agreement in calculated SAR between the participating laboratories is very similar to the agreement obtained in interlaboratory comparisons involving SAR measurements. The results support the opinion that standardized procedures for numerical calculations of SAR can be developed. The agreement between calculated SAR results and corresponding measurement results ranges from good to poor for the three phone models. Most probably, a significant reason for the observed deviations is the simplifications made to the models, which implies that device modeling specifications are of utmost importance in standards. Weniger anzeigen

We study how the power dissipated into a lossy medium excited by a nearby antenna is affected by drifts in the electrical parameters of the lossy medium. The statistical distribution of the sensitivity of the dissipated power is determined by means of a spectral analysis of the transmission of electromagnetic energy from air into the lossy half-space. A clear link is drawn between the reactive content of the field excited by the source and the dispersiveness of the sensitivity. The case of a… Mehr anzeigen

We study how the power dissipated into a lossy medium excited by a nearby antenna is affected by drifts in the electrical parameters of the lossy medium. The statistical distribution of the sensitivity of the dissipated power is determined by means of a spectral analysis of the transmission of electromagnetic energy from air into the lossy half-space. A clear link is drawn between the reactive content of the field excited by the source and the dispersiveness of the sensitivity. The case of a stratified structure is also addressed, by defining a modification factor representing the alteration of the transmissivity and of its sensitivity when a buffer layer is introduced. All of the results provided point out that, in general, the sensitivity of the total amount of power dissipated into the half-space cannot be predicted independently from a precise knowledge of the source characteristics, unless under a paraxial propagation approximation or in a far-field configuration. Weniger anzeigen

What is the minimal/maximal power that can be absorbed in a lossy object located in the reactive field region of an antenna? The aim of this paper is to propose a general and analytical solution to this question, applicable to any source-scatterer system. To this purpose, a method, allowing to describe power deposition mechanisms in near-field regions, is introduced. This approach is based on an equivalent junction/circuit model which is shown here to result from an appropriate modal expansion… Mehr anzeigen

What is the minimal/maximal power that can be absorbed in a lossy object located in the reactive field region of an antenna? The aim of this paper is to propose a general and analytical solution to this question, applicable to any source-scatterer system. To this purpose, a method, allowing to describe power deposition mechanisms in near-field regions, is introduced. This approach is based on an equivalent junction/circuit model which is shown here to result from an appropriate modal expansion of the radiated field. The dual interpretation of this model in terms of localized circuit and lumped junction is used to demonstrate how trends and bounds in power absorption phenomena can be derived. Firstly, the analogy with the microwave circuit theory provides the concepts of available power and load factor for electromagnetic fields, which allow to highlight the parameters influencing power dissipation and to analyze consequent trends. Secondly, the junction matrix formalism is used to obtain analytical lower and upper bounds of the power absorbed in a lossy object, located in the near field region of any radiating source. Those bounds give a clearer insight of the relationship between the total radiated power due to the antenna and the minimal or maximal power potentially dissipated in any scatterer exposed to such a radiated field. An example of bounds in a simple source-load configuration is finally provided, showing the link, to be further investigated, between the near-zone electric-field pattern of the antenna and the total dissipated power. This example also suggests that the power dissipated in a given object can be rapidly increased or reduced as the modal complexity of the source increases. Weniger anzeigen

Over the last decade, problems related to electromagnetic power absorption by human bodies or phantoms have been motivating a large scientific and technical effort. In many situations, the ultimate goal is to characterize and get as close as possible to the minimum or maximum value of a fraction of the total dissipated power (TDP) in a given volume. As is well known in mathematics, to find an optimum of a function can be a very tough question, whose complexity strongly depends on the… Mehr anzeigen

Over the last decade, problems related to electromagnetic power absorption by human bodies or phantoms have been motivating a large scientific and technical effort. In many situations, the ultimate goal is to characterize and get as close as possible to the minimum or maximum value of a fraction of the total dissipated power (TDP) in a given volume. As is well known in mathematics, to find an optimum of a function can be a very tough question, whose complexity strongly depends on the constraints imposed, and the number of variables. Considering this point, the following paper gives a brief review of some optimization problems involving radiating sources and phantoms, and tries to highlight their complexity. The particular situation of a two-dimensional (2-D) source, radiating close to homogeneous or two-layer cylindrical phantoms, is analyzed. Thanks to an equivalent junction model derived from a modal-based approach, the sources minimizing and maximizing the TDP in these phantoms are obtained, as well as the sources giving the maximal or minimal difference between the TDP in two chosen phantoms. Finally, the obtained results are discussed, and shortly extrapolated to the problem of specific absorption rate (SAR) due to wireless devices Weniger anzeigen