Advances in Radio Science

Syndicate content
Recent articles of the journal Advances in Radio Science
Updated: 1 day 4 hours ago

Verification and first test measurement of a microwave-based vital sign monitor

Mon, 10/14/2019 - 13:06
Verification and first test measurement of a microwave-based vital sign monitor
Daniel Schmiech, Aly Marnach, and Andreas R. Diewald
Adv. Radio Sci., 17, 249–256, https://doi.org/10.5194/ars-17-249-2019, 2019
One of the most important signs of a living body demonstrating its life-sustaining functions is the respiration rate. State of the art for measuring this vital sign is using a monitoring system cable connected to electrodes which are attached to the patients' skin. Especially in the case of newborn infants this method is not always suitable and causing several problems, like skin injuries, high stress levels and random loosening of the sensor. To avoid these a non-contact system is developed.

Realization and opto-electronic Characterization of linear Self-Reset Pixel Cells for a high dynamic CMOS Image Sensor

Fri, 09/20/2019 - 13:06
Realization and opto-electronic Characterization of linear Self-Reset Pixel Cells for a high dynamic CMOS Image Sensor
Stefan Hirsch, Markus Strobel, Wolfram Klingler, Jan Dirk Schulze Spüntrup, Zili Yu, and Joachim N. Burghartz
Adv. Radio Sci., 17, 239–247, https://doi.org/10.5194/ars-17-239-2019, 2019
Applications in the fields of e.g. industrial image processing, image based robotic control systems and autonomous driving require high dynamic range image sensors. Conventional linear CMOS image sensors only have a limited dynamic range. To extend the dynamic range the concept of a linear self-reset pixel is implemented with several pixel variants being realized and characterized on a CMOS chip. A second topic is the design with digital readout of a cluster structure composed of a pixel matrix.

D region observations by VHF and HF radars during a rocket campaign at Andøya dedicated to investigations of PMWE

Thu, 09/19/2019 - 13:06
D region observations by VHF and HF radars during a rocket campaign at Andøya dedicated to investigations of PMWE
Ralph Latteck, Toralf Renkwitz, and Boris Strelnikov
Adv. Radio Sci., 17, 225–237, https://doi.org/10.5194/ars-17-225-2019, 2019
In April 2018 the PMWE1 sounding rocket campaign was conducted at the Andøya Space Center involving coordinated measurements with rockets and ground instruments to measure parameters relevant for testing of the existing theories of PMWE formation. The Middle Atmosphere Alomar Radar System (MAARSY) was operated to detect PMWE with multiple beam directions. The Saura MF radar was operated with a multiple beam experiment to derive horizontal winds and electron density profiles.

Tidal wind shear observed by meteor radar and comparison with sporadic E occurrence rates based on GPS radio occultation observations

Thu, 09/19/2019 - 13:06
Tidal wind shear observed by meteor radar and comparison with sporadic E occurrence rates based on GPS radio occultation observations
Christoph Jacobi and Christina Arras
Adv. Radio Sci., 17, 213–224, https://doi.org/10.5194/ars-17-213-2019, 2019
We analyze tidal phases and related wind shear in the mesosphere and lower thermosphere as observed by a meteor radar. The wind shear phases are compared with those of sporadic E occurrence rates, which were derived from GPS radio occultation observations. We find good correspondence between radar derived wind shear and sporadic E phases for the semidiurnal, terdiurnal, and quarterdiurnal tidal components, but not for the diurnal tide.

Estimation of ionospheric reflection height using long wave propagation

Thu, 09/19/2019 - 13:06
Estimation of ionospheric reflection height using long wave propagation
Dieter Keuer
Adv. Radio Sci., 17, 205–212, https://doi.org/10.5194/ars-17-205-2019, 2019
Phase height measurements of low frequency radio waves are used to study the long-term variability of the mesosphere over Europe. But a refinement of this measurements suggest that it must be considered as one that only reflects integral properties of the hole region from the mesosphere over the stratosphere down to the troposphere. The sole coupling of these measurements to the mesosphere must be dropped.

Dielectric corner reflectors for mmWave applications

Thu, 09/19/2019 - 13:06
Dielectric corner reflectors for mmWave applications
Christian Buchberger, Florian Pfeiffer, and Erwin Biebl
Adv. Radio Sci., 17, 197–203, https://doi.org/10.5194/ars-17-197-2019, 2019
This article investigates the properties of dielectric corner reflectors for use in a number of millimeter wave applications, such as road safety for autonomous driving. Material characterizations of different typical plastics using transmission measurements are presented, as well as an analysis of their respective radar cross section (RCS) when used as corner reflectors. They exhibit similar behavior as conventional metallic reflectors, while intrinsic dielectric losses reduce the overall RCS.

Extending the vehicular network simulator Artery in order to generate synthetic data for collective perception

Thu, 09/19/2019 - 13:06
Extending the vehicular network simulator Artery in order to generate synthetic data for collective perception
Christoph Allig and Gerd Wanielik
Adv. Radio Sci., 17, 189–196, https://doi.org/10.5194/ars-17-189-2019, 2019
A fundamental for an automated driving car is the awareness of its surrounding road participants. Current approach to gather this awareness is to sense the environment by on-board sensors. In the future, Vehicle-to-X (V2X) might be able to improve the awareness. We propose to create synthetic data for investigating cooperative perception by a simulation tool. Therefore, Artery and its counterpart SUMO is extended by modelling realistic vehicle dynamics and probabilistic sensor models.

Singularity Expansion Method for thin wires and the Method of Modal Parameters

Thu, 09/19/2019 - 13:06
Singularity Expansion Method for thin wires and the Method of Modal Parameters
Sergey V. Tkachenko, Juergen B. Nitsch, Felix Middelstaedt, Ronald Rambousky, Martin Schaarschmidt, and Ralf Vick
Adv. Radio Sci., 17, 177–187, https://doi.org/10.5194/ars-17-177-2019, 2019
Using the method of modal parameters, developed earlier, equations for the Singularity Expansion Method (SEM) poles were obtained. Numerical investigation of solutions for the poles of the fist layer have shown good agreement with analytical and numerical results obtained earlier.

Analysis of an Iterative Approach to Determine the Current on the Straight Infinite Wire Above Ground

Thu, 09/19/2019 - 13:06
Analysis of an Iterative Approach to Determine the Current on the Straight Infinite Wire Above Ground
Felix Middelstaedt, Sergey V. Tkachenko, and Ralf Vick
Adv. Radio Sci., 17, 169–176, https://doi.org/10.5194/ars-17-169-2019, 2019

An iterative approach which was recently applied to approximate the reflection and scattering coefficients of transmission line ports is analyzed. The iterative solution for the current on an infinite wire above ground is compared to the exact solution. The example is chosen since it is one of the few problems where an exact solution exists. The wire is excited by a lumped voltage source or a plane wave. The convergence of the iterative approach is shown. It can be concluded that the zeroth iteration, which is the classical transmission line solution, coincides with the general transverse electromagnetic mode. Furthermore, it is shown that the first iteration is a very good approximation of the radiation and leaky modes, that occur in the close neighborhood around the lumped source.

10-bit tracking ADC with a multi-bit quantizer, variable step size and segmented current-steering DAC

Thu, 09/19/2019 - 13:06
10-bit tracking ADC with a multi-bit quantizer, variable step size and segmented current-steering DAC
Stefan Bramburger and Dirk Killat
Adv. Radio Sci., 17, 161–167, https://doi.org/10.5194/ars-17-161-2019, 2019

This paper presents a 10-bit tracking ADC using a multi-bit quantiser and a segmented current-steering DAC. The quantiser allows a dynamical adjustment of the step size dependent on the input signal waveform. This mitigates the limited slew rate of delta encoded ADCs. Energy consumption induced by 1 LSB ripple is removed by the quantiser. The segmented current-steering DAC allows simple control, good monotonicity and improved transient response when compared to previous design as well as potential power reduction.

Optimization of loosely coupled inductive data transfer systems by non-Foster impedance matching

Thu, 09/19/2019 - 13:06
Optimization of loosely coupled inductive data transfer systems by non-Foster impedance matching
Christian Schmidt, Martin Buchholz, and Madhukar Chandra
Adv. Radio Sci., 17, 151–160, https://doi.org/10.5194/ars-17-151-2019, 2019

Wireless energy transfer is often used in industrial applications to power actors or sensors, for example in rotating applications as replacement for mechanical slip rings. In addition to the energy transfer, we have developed inductively coupled data transfer systems to expand the range of possible applications. The data transfer is accomplished by using loosely coupled coils on both sides of the power transfer system. In pure energy transfer systems, resonant coupling is used, meaning that the power transfer coils are both tuned to a common frequency to compensate the relatively small coupling factor between power transmitter and receiver and to achieve an impedance matching between both sides by compensating the inductive component of the transfer coils. In this case, capacitors can be connected in series or in parallel to the coils, leading to a sharp, narrow band resonance peak in the transfer function. In inductively coupled data transfer systems, this approach is often not useful because not just a pure sine wave has to be transferred but more likely a signal of a certain bandwidth. In one of our applications, a 100 Mbit s−1 Ethernet stream is transferred with an occupied bandwidth of 62.5 MHz. The coil structures used so far in our data transfer applications were intrinsically unmatched to the data transfer systems. Additionally, due to the small coupling factor between the data transfer coils, transfer losses in the range of up to 15 dB or worth had to be accepted. This is especially critical regarding the high noise level in vicinity of the energy transfer system and the cross coupling between the two transfer channels.

For passive, lossless circuits, Foster's theorem states that the reactance increases monotonically with frequency. Subsequently, the inductive part of a circuit can just be exactly compensated with a capacitance for one single frequency. In contrast, active circuits like a negative impedance converter (NIC) can be used to achieve a non-Foster behaviour, for example a negative inductance can be realized. In theory, an inductance in series or parallel to a negative inductance of the same magnitude would be cancelled out for every frequency applied. For low power level applications like active receiving antennas, this approach has already been successfully used in the past to achieve improved matching of simple antenna structures over a comparably large bandwidth.

We make use of non-Foster circuits, namely negative impedance converters, to compensate the inductive part of two loosely coupled inductors to achieve smaller transfer losses and better impedance matching, which should lead to a decreased transfer signal loss and higher signal to noise ratio. The results of this paper serve as a basis for this development. So far, we achieved almost complete cancellation of the reactive part introduced by the loosely coupled data transfer inductors. Unfortunately, the circuits active device used to form the negative impedance converter introduced a highly resistive element, greatly increasing the signal transfer losses. Nevertheless, the theory of loosely coupled inductors is shown in a compact form and a strategy to cancel the reactive part is presented. Simulations and measurements of a transfer system are carried out, both showing good agreement regarding the reactance cancellation. Based on this, optimised implementations will be developed in the future.

A low complexity digital frequency calibration with high jitter immunity for ultra-low-power oscillators

Thu, 09/19/2019 - 13:06
A low complexity digital frequency calibration with high jitter immunity for ultra-low-power oscillators
Markus Scholl, Ralf Wunderlich, and Stefan Heinen
Adv. Radio Sci., 17, 145–150, https://doi.org/10.5194/ars-17-145-2019, 2019
Today's wireless transceivers are demanding for lowest power consumption to support long battery lifetime. These architectures utilize dutycycle schemes based on ultra-low-power (ULP) oscillators to reduce power consumption. These ULP oscillators are either using external components increasing the cost or they need calibration techniques to achieve absolute accuracy. This work presents an improved ULP calibration technique overcoming typical limitations of settling time and calibration accuracy.

Fast post-Doppler STAP with road map for traffic monitoring: overview and first results

Thu, 09/19/2019 - 13:06
Fast post-Doppler STAP with road map for traffic monitoring: overview and first results
André B. C. da Silva, Stefan V. Baumgartner, and Alberto Moreira
Adv. Radio Sci., 17, 137–143, https://doi.org/10.5194/ars-17-137-2019, 2019
Synthetic Aperture Radar is an efficient solution for traffic monitoring due to its high spatial resolution and independence from daylight and weather conditions. This paper presents a fast processor based on the powerful post-Doppler space-time adaptive processing technique. The algorithm has great potential for real-time processing, decreased hardware complexity and low costs compared to state-of-the-art systems. It is tested using real 4-channel data acquired with the DLR’s airborne F-SAR.

A machine learning joint lidar and radar classification system in urban automotive scenarios

Thu, 09/19/2019 - 13:06
A machine learning joint lidar and radar classification system in urban automotive scenarios
Rodrigo Pérez, Falk Schubert, Ralph Rasshofer, and Erwin Biebl
Adv. Radio Sci., 17, 129–136, https://doi.org/10.5194/ars-17-129-2019, 2019
This work presents a deep learning approach to classify road users as pedestrians, cyclists or cars using a lidar sensor for detection and a radar sensor for classification. A dataset was gathered on urban roads to train and test the deep learning algorithms. The results show that the system reliably classifies cars, but has trouble with pedestrians and cyclists. The results are improved after aggregating decisions with a Bayes filter. Overlapping targets remain a challenge for the system.

Inkjet printing of metal nanoparticles for green UHF RFID tags

Thu, 09/19/2019 - 13:06
Inkjet printing of metal nanoparticles for green UHF RFID tags
Bruna Cruz, Andreas Albrecht, Philipp Eschlwech, and Erwin Biebl
Adv. Radio Sci., 17, 119–127, https://doi.org/10.5194/ars-17-119-2019, 2019
In this work, silver and gold nanoparticle inks were printed by a consumer inkjet printer on eco-friendly substrates like paper and PET in order to make the RFID tag manufacturing process less harmful to the ecosystem. A dipole antenna was designed and based on this design, simulations of the greener tags are presented and compared as a proof of concept for the different materials. First measurements are conducted and simulations with the optimized antenna designs are shown.

Target simulation for UHF RFID DoA estimation systems

Thu, 09/19/2019 - 13:06
Target simulation for UHF RFID DoA estimation systems
Philipp Eschlwech and Erwin Biebl
Adv. Radio Sci., 17, 109–118, https://doi.org/10.5194/ars-17-109-2019, 2019
A target simulator for RFID direction of arrival estimation systems is proposed. This simulator can be used in the evaluation of such systems and offers a method for fast, economical and, above all, reproducible and transferable analysis of their performance. Signal models and descriptions of two typical detrimental propagation effects are derived. The developed system structure and hardware modules are presented and exemplary evaluation results are given, showing the application of this method.

Analysis of the frequency conversion of spurious tones in frequency dividers and development of an event-driven model for system simulations

Thu, 09/19/2019 - 13:06
Analysis of the frequency conversion of spurious tones in frequency dividers and development of an event-driven model for system simulations
Christoph Beyerstedt, Jonas Meier, Fabian Speicher, Ralf Wunderlich, and Stefan Heinen
Adv. Radio Sci., 17, 101–107, https://doi.org/10.5194/ars-17-101-2019, 2019
Modern integrated circuits for wireless communication include several receive and transmit path as well as large digital blocks for signal processing. Due to the complexity of these system only event-driven simulation are fast enough for system simulation. This work describes the development of a fast and accurate event-driven frequency divider model with special focus on its transfer characteristic of harmful spurious tones. A simulation example of a receiver is given.

Signal degradation through sediments on safety-critical radar sensors

Thu, 09/19/2019 - 13:06
Signal degradation through sediments on safety-critical radar sensors
Matthias G. Ehrnsperger, Uwe Siart, Michael Moosbühler, Emil Daporta, and Thomas F. Eibert
Adv. Radio Sci., 17, 91–100, https://doi.org/10.5194/ars-17-91-2019, 2019
Radar is well known for its utilization in the aeronautical and the automotive sector. Affordable systems have started conquering safety relevant applications as permanent monitoring units. New applications also entail new challenges. The paper investigates the effects of signal degrading sediments and assesses them. It is pointed out that liquid water has a particularly negative influence. In order to limit this disturbance factor, a methodology is presented to weaken its impact by up to 75 %.

Near-field measurement of continuously modulated fields employing the time-harmonic near- to far-field transformation

Thu, 09/19/2019 - 13:06
Near-field measurement of continuously modulated fields employing the time-harmonic near- to far-field transformation
Fabian T. Faul, Jonas Kornprobst, Torsten Fritzel, Hans-Jürgen Steiner, Rüdiger Strauß, Alexander Weiß, Robert Geise, and Thomas F. Eibert
Adv. Radio Sci., 17, 83–89, https://doi.org/10.5194/ars-17-83-2019, 2019
Near-field far-field transformations are commonly performed for time-harmonic fields. Considering in-situ measurement scenarios with given transmission signals, time-varying aspects of modulated signals have to be taken into consideration. Two methods for the measurement of modulated fields are investigated and characterized, which work with a time-domain representation of the radiated fields and, at the same time, allow to employ the standard time-harmonic near-field far-field transformation.

Multilayered Transmission Lines on Quasi-planar Substrates With Anisotropic Medium

Thu, 09/19/2019 - 13:06
Multilayered Transmission Lines on Quasi-planar Substrates With Anisotropic Medium
Veenu Kamra and Achim Dreher
Adv. Radio Sci., 17, 77–82, https://doi.org/10.5194/ars-17-77-2019, 2019

This paper exhibits the extension of the discrete mode matching (DMM) method to analyze conformal structures with anisotropy. It represents a simple formalism as a basis to analyze multilayered structures with quasi-planar anisotropic dielectric layers. The dyadic Green's function is then calculated using a full-wave equivalent circuit (FWEC) of the structure, where each layer is represented with the hybrid block consisting of the tangential field components. The application is demonstrated by computing propagation constants for partially filled quasi-planar waveguides and microstrip lines with isotropic, uniaxial and biaxial anisotropic dielectrics.

Theme by Danetsoft and Danang Probo Sayekti inspired by Maksimer