Ilona Rolfes

Bio: Ilona Rolfes is an academic researcher from Ruhr University Bochum. The author has contributed to research in topics: Radar & Antenna (radio). The author has an hindex of 16, co-authored 243 publications receiving 1371 citations. Previous affiliations of Ilona Rolfes include Leibniz University of Hanover.

The multipole resonance probe: characterization of a prototype

Abstract: The multipole resonance probe (MRP) was recently proposed as an economical and industry compatible plasma diagnostic device (Lapke et al 2008 Appl. Phys. Lett. 93 051502). This communication reports the experimental characterization of a first MRP prototype in an inductively coupled argon/nitrogen plasma at 10?Pa. The behavior of the device follows the predictions of both an analytical model and a numerical simulation. The obtained electron densities are in excellent agreement with the results of Langmuir probe measurements.

A highly linear frequency ramp generator based on a fractional divider phase-locked-loop

Abstract: A highly linear analog frequency ramp generator based on a fractional divider concept is presented. The frequency ramp linearity achievable in this fractional phase-locked-loop configuration is better than 10/sup -4/. This value is revealed by numerical simulations as well as by measurements performed. With a prototype synthesizer implemented in a FMCW-radar system suitable for distance and velocity measurements.

Multiport method for the measurement of the scattering parameters of N-ports

Abstract: The multiport method for the precise measurement of the scattering parameters of N-port devices with a two-port vector network analyzer (VNA) is presented. The scattering parameters of an N port cannot be measured directly with a two-port VNA if N>2. Only the scattering parameters of all two-port combinations of the device-under-test (DUT) are measurable. Thereby, the measured two-port scattering parameters strongly depend on the external terminations of the DUTs ports, which are not connected to the VNA during the measurements. In order to eliminate the influences of these external possibly reflective terminations, an error correction has to be performed. In comparison to known correction methods, the multiport method has some advantages. Firstly, the external terminations can be chosen arbitrarily, i.e., short and open circuits are realizable as long as the topology of the DUT allows it. Secondly, the terminations, except for one, can be unknown, leading to a reduction of the inconsistency problem caused by erroneous data of the external terminations, which is also known from the calibration of VNAs with completely known calibration standards. The good performance of the multiport method is shown by measured results.

Millimeter-Wave Characterization of Dielectric Materials Using Calibrated FMCW Transceivers

Abstract: This paper presents a measurement setup, an extraction algorithm, and the results from material characterization measurements in the millimeter-wave (mm-wave) regime using ultrawideband frequency-modulated continuous-wave (FMCW) radar transceivers. The complex permittivity of dielectric and nonmagnetic materials is derived from radar echoes using a high-gain dielectric lens antenna setup and a measurement setup comprising elliptic mirrors. The radar transceivers perform fast and accurate measurements from 200 to 250 GHz within milliseconds. The FMCW transceivers are calibrated using a frequency-domain model that describes the systematic errors in the measurement setup. The characterization is done by a holistic model-based approach. Several well-known dielectric materials, such as polytetrafluorethylene, polyvinylchloride (PVC), or acrylic glass, are characterized among others to validate the setup’s accuracy. The characterization is also done for different samples of polylactide, which is commonly used in additive manufacturing processes and 3-D printing, making it of high interest for the construction of mm-wave components.

Inductorless Low-Voltage and Low-Power Wideband Mixer for Multistandard Receivers

Abstract: This paper presents the design and implementation of a low power wideband mixer for multistandard receivers, covering global system for mobile communications, universal mobile telecommunications system, wireless local area network, Bluetooth, and ultra-wideband. The circuit topology is based on the folded technique with a current reuse shunt feedback RF input stage operating at a low supply voltage of 1 V. The mixer offers a peak gain of 12.8 dB, a 3-dB bandwidth from 1 to 10.5 GHz, and a minimum double-sideband noise figure of 7.6 dB. The input referred compression point is better than -15 dBm with an output referred intercept point of better than 5.75 dBm over the entire bandwidth. The mixer circuit was fabricated in a 65-nm standard CMOS process and draws 5 mA of dc current, leading to a power dissipation of only 5 mW. Gain and noise performance can be further increased when operating at nominal supply voltage of 1.2 V at the expense of an increasing power dissipation.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Electromagnetic Compatibility Engineering

Abstract: Praise for Noise Reduction Techniques IN electronic systems "Henry Ott has literally 'written the book' on the subject of EMC. . . . He not only knows the subject, but has the rare ability to communicate that knowledge to others." EE Times Electromagnetic Compatibility Engineering is a completely revised, expanded, and updated version of Henry Ott's popular book Noise Reduction Techniques in Electronic Systems. It reflects the most recent developments in the field of electromagnetic compatibility (EMC) and noise reductionand their practical applications to the design of analog and digital circuits in computer, home entertainment, medical, telecom, industrial process control, and automotive equipment, as well as military and aerospace systems. While maintaining and updating the core informationsuch as cabling, grounding, filtering, shielding, digital circuit grounding and layout, and ESDthat made the previous book such a wide success, this new book includes additional coverage of: Equipment/systems grounding Switching power supplies and variable-speed motor drives Digital circuit power distribution and decoupling PCB layout and stack-up Mixed-signal PCB layout RF and transient immunity Power line disturbances Precompliance EMC measurements New appendices on dipole antennae, the theory of partial inductance, and the ten most common EMC problems The concepts presented are applicable to analog and digital circuits operating from below audio frequencies to those in the GHz range. Throughout the book, an emphasis is placed on cost-effective EMC designs, with the amount and complexity of mathematics kept to the strictest minimum. Complemented with over 250 problems with answers, Electromagnetic Compatibility Engineering equips readers with the knowledge needed to design electronic equipment that is compatible with the electromagnetic environment and compliant with national and international EMC regulations. It is an essential resource for practicing engineers who face EMC and regulatory compliance issues and an ideal textbook for EE courses at the advanced undergraduate and graduate levels.

Recent advances in electromagnetic interference shielding properties of metal and carbon filler reinforced flexible polymer composites: A review

Abstract: The rapid proliferation and elevated usage of electronic devices have led to a meteoritic rise in electronic pollutions such as electronic noise, electromagnetic interference (EMI) and radiofrequency interference (RFI) which leads to improper functioning of electronic devices. Metals and their alloys can serve as the best EMI shielding materials but their heavy weight, high cost and low corrosion resistance have limited their applications in EMI shielding. The emergence of flexible polymer composites have substituted the metal and metal alloy based EMI shielding materials due to their unique features such as light weight, excellent corrosion resistance, superior electrical, dielectric, thermal, mechanical and magnetic properties that are highly useful for suppressing the electromagnetic noises. In this review article, the EMI shielding effectiveness of flexible polymer composites comprising of metals and various forms of carbon nanofillers such as carbon black, carbon nanofibers, carbon nanotubes, graphite, graphene, graphene oxide, graphene nanosheets, graphene nanoribbons and graphene nanoplatelets have been deeply reviewed.

Vehicular Channel Characterization and Its Implications for Wireless System Design and Performance

Abstract: To make transportation safer, more efficient, and less harmful to the environment, traffic telematics services are currently being intensely investigated and developed. Such services require dependable wireless vehicle-to-infrastructure and vehicle-to-vehicle communications providing robust connectivity at moderate data rates. The development of such dependable vehicular communication systems and standards requires accurate models of the propagation channel in all relevant environments and scenarios. Key characteristics of vehicular channels are shadowing by other vehicles, high Doppler shifts, and inherent nonstationarity. All have major impact on the data packet transmission reliability and latency. This paper provides an overview of the existing vehicular channel measurements in a variety of important environments, and the observed channel characteristics (such as delay spreads and Doppler spreads) therein. We briefly discuss the available vehicular channel models and their respective merits and deficiencies. Finally, we discuss the implications for wireless system design with a strong focus on IEEE 802.11p. On the road towards a dependable vehicular network, room for improvements in coverage, reliability, scalability, and delay are highlighted, calling for evolutionary improvements in the IEEE 802.11p standard. Multiple antennas at the onboard units and roadside units are recommended to exploit spatial diversity for increased diversity and reliability. Evolutionary improvements in the physical (PHY) and medium access control (MAC) layers are required to yield dependable systems. Extensive references are provided.