Uncertainty Analysis Methodology for Measurements of Dynamic Millimeter-Wave Channels

Quantification of uncertainties in the results of channel sounding measurements is important for their interpretation and further usage. In this paper, a novel uncertainty analysis methodology to quantify uncertainties of condensed parameters in measurements of dynamic millimeter-wave channels is presented. The bandwidth limitation and multipath threshold are identified as important impairments. Therefore, the methodology provides three uncertainty metrics for condensed parameters, namely a standard uncertainty to quantify the impact of random variations; a bias due to the multipath threshold; and a total bias including the impact of the bandwidth limitation. These uncertainty metrics are highly channel dependent. Therefore, the proposed methodology creates reference channels, which are representative of corresponding measured channels. Hardware and processing impairments are included in the analysis via a Monte Carlo simulation. This results in a general methodology that can quantify uncertainties in both static and dynamic channel measurements of any wideband channel sounder. The methodology is implemented, verified and demonstrated for the TU/e channel sounder, which exemplifies how it can be used. The proposed methodology can improve the analysis, interpretation and reporting of channel measurement results.</p

Advances and Challenges in Handset Antenna Efficiency for 5G and Beyond

Increasing system requirements for 5G and beyond wireless systems translate into an increasing importance of antenna efficiency. In this paper we show that frequency-reconfigurable antennas are a very promising solution to increase the efficiency, exhibiting an upper bound on the radiation efficiency that is significantly increased compared to traditional designs. We then compare several efficiency measurement techniques, from which we can conclude that reverberation chamber measurements are an ideal solution for 5G and beyond

Contactless Method to Estimate Antenna Efficiency in a Reverberation Chamber

Measuring the efficiency of electrically small antennas (ESAs) and integrated antennas (IAs) is challenging, since for ESAs, the probe may significantly affect the results and for IAs, establishing a connection with the IA is in many cases not possible. Therefore, a contactless method to estimate the efficiency of ESAs and IAs is necessary. This article proposes a novel method to estimate antenna efficiency contactlessly using a reverberation chamber (RC): the contactless efficiency method (CEM). In the CEM, we combine the two-antenna method (TAM) with the contactless characterization method (CCM), to estimate the ${S}$ -parameters contactlessly. To validate the results, the CEM measurements are compared to the measurements of the widely used TAM and for both methods, an uncertainty analysis is performed. Results show a good agreement in the 95% confidence interval between the CEM and the existing connectorized method for both the total antenna efficiency and the radiation antenna efficiency. The uncertainty of the CEM with a 95% confidence level is below 6% for the whole 0.55-1.05-GHz frequency band

Wireless receiver architectures towards 5G: where are we?

With 5G posing different requirements to the mobile (handset) receiver than earlier generations, the receiver architecture needs to be carefully reconsidered. However, an up-to-date and complete overview is not yet available in literature. In this paper such a review of the currently available receiver architectures is provided, as well as an overview of current trends. For the first time, a framework is introduced that allows a systematic classification of architectures. An identification of unexplored possibilities and system-level trade-offs follows. A more flexible, low-power and high-performance receiver architecture than currently applied is needed for 5G, for which this framework becomes a useful tool

Assessment of the Antenna-Equivalence Approach to Common-Mode Input Impedance Modeling

Analytical modeling of the common-mode input impedance of a motor along with its cable for various installation characteristics would allow designers to assess EMI levels and to evaluate in an early stage if adaptations are needed in their cable installation. Earlier work has shown that the input impedance over frequency of such a system is mostly dominated by the cable. A common assumption is that a cable can be approximated as a monopole antenna above a ground plane, which has an input impedance equivalent to that of a dipole with a correction factor. We compare the Hallén and King & Middleton dipole models to a measurement setup which is designed to reproduce parastic effects from the installation, to assess the validity of the analytical model. We analyze these results for various distances between the cable and the groundplane. We show that large discrepancies occur due to paristics of the installation and the presence of the groundplane, but that for some applications such closed-form analytical models may suffice in assessing frequencies at which radiated emissions occur

Simulations Predict Increased Brain Antenna Performance Robustness by Adding Biocompatiblility Layer

The goal of this paper is to study the effects of the simulated reflection coefficient of a cortical UWB antenna in a planar multilayered head model. This study shows that the reflection in these deeply implanted antennas can be heavily influenced by the presence of cerebrospinal fluid. However, when coating the antenna with a thin biocompatible layer of alumina having a thickness of 0.1mm, the reflection coefficient shows much more robustness to interpersonal differences in head geometry and to small variations in antenna placement. This stable behavior to these uncontrollable parameters suggest that direct high-speed brain communication using untethered implants could be feasible. This topology could more elegant than a conventional tethered, subcutaneous approach, as this wire-free option eases surgical implantation and can prevent tissue damage created by the mechanical interaction between the body and the tether cables

Chasing the wave in a reverberation chamber

The power-delay profile is a critical characteristic of a reverberation chamber. In this paper the power-delay profile is used for the first time to study in high detail how a wave interacts with its environment in a reverberation chamber. This is done by tracking the wave, starting from its creation at the antenna reference plane with the antenna in multiple positions. Starting at the antenna port, three regimes are recognized: very-early-time, early - time and late-time. In the very -early - time the response is dictated by the antenna's behavior and placement affects only the duration of this regime. In the early-time period the wave starts interacting with the environment. Antenna positioning makes a clear difference during this period, and the moving-wall stirrer can easily be distinguished from non-moving parts. During late-time the expected exponential decay is observed. The transition point from early to late behavior is dependent on antenna placement in the room that was used. After chasing the wave traveling at light speed for a kilometer, it is finally caught when the chamber losses cause the power delay profile to decay into noise floor

On free-space antenna reflection phase measurements in a reverberation chamber

A reverberation chamber is a very useful tool to obtain the radiation efficiency of an antenna. While it has been shown that the magnitude of the reflection coefficient can be obtained from these measurements as well, this has not yet been shown for the phase of the reflection coefficient. This would allow for a full characterization of the antenna’s behavior as seen from its input port. In this paper it is shown that the phase of the freespace reflection coefficient can be obtained from measurements in a reverberation chamber by taking the angle of the ensemble average of the individual reflection coefficients. This has been empirically verified by comparing several sets of measurement data from the reverberation chamber to their anechoic chamber equivalents for several antennas