Localizing micro unmanned aerial vehicles (MUAV) using passive radar systems makes it possible to counter the threat they pose to critical infrastructure. In this paper, we discuss an efficient signal processing chain for their localization and demonstrate the detection and localization of cooperative MUAVs using a five-element array and Digital Audio Broadcast (DAB) signals. The MUAVs were detected up to their maximum flight distance from the receiver of 2.6 kilometers. By estimating the direction of arrival of the target echoes in addition to the bistatic range and Doppler frequency shift, the MUAVs could be localized with a mean position error below 90 meters.

This contribution presents a reference setup to measure the power of the cell-specific resource elements present in downlink long term evolution (LTE) signals in a way that the measurements are traceable to the international system of units. This setup can be used to calibrate the LTE code-selective field probes that are used to measure the radiation of base stations for mobile telephony. It can also be used to calibrate LTE signal generators and receivers. The method is based on traceable scope measurements performed directly at the output of a measuring antenna. It implements offline digital signal processing demodulation algorithms that consider the digital down-conversion, timing synchronization, frequency synchronization, phase synchronization and robust LTE cell identification to produce the downlink time-frequency LTE grid. Experimental results on conducted test scenarios, both single-input–single-output and multiple-input–multiple-output antenna configuration, show promising results confirming measurement uncertainties of the order of 0.05 dB with a coverage factor of 2.

Constellation modulation (CM) is introduced as a new degree of freedom to increase the spectral efficiency and to further approach the Shannon limit. Constellation modulation is the art of encoding information not only in the symbols within a constellation but also by encoding information by selecting a constellation from a set of constellations that are switched from time to time. The set of constellations is not limited to sets of partitions from a given constellation but can e.g., be obtained from an existing constellation by applying geometrical transformations such as rotations, translations, scaling, or even more abstract transformations. The architecture of the transmitter and the receiver allows for constellation modulation to be used on top of existing modulations with little penalties on the bit-error ratio (BER) or on the required signal-to-noise ratio (SNR). The spectral bandwidth used by this modulation scheme is identical to the original modulation. Simulations demonstrate a particular advantage of the scheme for low SNR situations. So, for instance, it is demonstrated by simulation that a spectral efficiency increases by up to 33% and 20% can be obtained at a BER of 10-3 and 2×10-2 for a regular BPSK modulation format, respectively. Applying constellation modulation, we derive a most power efficient 4D-CM-BPSK modulation format that provides a spectral efficiency of 0.7 bit/s/Hz for an SNR of 0.2 dB at a BER of 2 × 10-2.

An advanced receiver algorithm is proposed for constellation modulation. A SE increase of 33.3% and 8.3% is shown in simulation at a negligible SNR penalty for a BER=1×10-3.

In this paper, we demonstrate ultra-fast millimeter wave beam steering with settling times below 50 ps. A phased array antenna with two elements is employed to realize beam steering. The phased array feeder is implemented with a recently introduced time delay line that provides, at the same time, an ultra-fast tunability, broadband operation, and continuous tuning. Our implementation is used to perform symbol-by-symbol steering. In our demonstration, the beam direction is switched between two sequentially transmitted symbols toward two receivers placed 30° apart. We show the successful symbol-by-symbol steering for data streams as fast as 10 GBd. The suggested scheme shows that the ultra-fast beam steering is becoming practical and might ultimately enable novel high bit-rate multiple access schemes.

We show a spectral efficiency increase by combining constellation modulation and symbol mapping. The SE increases by 12.5% in theory and 6% in experiments for QPSK at a negligible SNR penalty for a BER=1×10-3.

Complementing plasmonic slot waveguides with highly nonlinear organic materials has rendered a new generation of ultracompact active nanophotonic components that are redefining the state of the art. In this paper, we review the fundamentals of this so-called plasmonic- organic-hybrid (POH) platform. Starting from simple phase shifters to the most compact IQ modulators, we introduce key devices of high-speed data communications. For instance, all-plasmonic Mach-Zehnder modulators (MZMs) are reviewed and long-term prospects are discussed. This kind of modulator already features unique properties such as a small footprint (<; 20 μm 2 ), a large electro-optic bandwidth (> 110 GHz), a small energy consumption (~25 fJ/b), a large extinction ratio (> 25 dB) in combination with a record small voltage-length product of 40 Vμm. Finally, as an example for seamless integration we introduce novel plasmonic IQ modulators. With such modulators we show the generation of advanced modulation formats (QPSK, 16-QAM) on footprints as small as 10 μm × 75 μm. This demonstration ultimately shows how plasmonics can be used to control both phase and amplitude of an optical carrier on the microscale with reasonably low losses.

In this paper we compare different integratable ultra-fast tunable true-time delay concepts with respect to their performances in a phased array system. The performances of the schemes are assessed with respect to the supported range, i.e. the range within which beam steering for a given fractional bandwidth can be achieved with a gain flatness better than 3dB. We also compare the array gain as of function of steering angle and fractional bandwidth.

We demonstrate a microwave photonic phased array antenna concept capable of symbol-by-symbol steering at symbol rates of 10 GBd. Such a system may increase mobile network capacity and reach by spatially addressing individual users.

Cette contribution montre comment effectuer des mesures tracables de l’intensite du rayonnement LTE (Long Term Evolution, ou telephonie mobile de quatrieme generation). Pour pourvoir controler que les valeurs limites sont respectees,, il est important de pouvoir mesurer le champ produit par des antennes de telephonie mobiles. Comme le champ varie suivant le nombre d’utilisateurs connectes, il est important de pouvoir mesurer le “canal de controle” dont la puissance est constante. Si pour GSM cela etait relativement aise, pour LTE qui utilise une modulation plus complexe (OFDMA), il faut d’abord demoduler le signal avant de pouvoir le quantifier. Cette contribution presente une methode qui permet de mesurer de facon tracable les signaux des cellules de reference specifiques (CSR) d’un signal LTE. Les premieres evaluations experimentales de cette methode sont egalement presentees.

A scheme for the direct conversion of millimeter and THz waves to optical signals is introduced. The compact device consists of a plasmonic phase modulator that is seamlessly cointegrated with an antenna. Neither high-speed electronics nor electronic amplification is required to drive the modulator. A built-in enhancement of the electric field by a factor of 35 000 enables the direct conversion of millimeter-wave signals to the optical domain. This high enhancement is obtained via a resonant antenna that is directly coupled to an optical field by means of a plasmonic modulator. The suggested concept provides a simple and cost-efficient alternative solution to conventional schemes where millimeter-wave signals are first converted to the electrical domain before being up-converted to the optical domain.

The optical properties of plasmonic nanoparticles along with the plasmon resonance wavelengths are tunable by varying their size, shape and material composition. In this work we report a new efficient numerical calculation algorithm to study the light scattering properties of plasmonic nanoparticles over a wide range of wavelengths which is based on the spectral Boundary Integral Equation method. Its performances are compared with those of the Multiple Multipole Program. Plasmon resonances of gold nanostars and their wavelength dependence on the nanoparticle shape are investigated. For isolated core/shell nanostructure the dependence of plasmon resonances on the material composition is studied. Our numerical results demonstrate that the plasmon resonance of a 100 nm gold nanostar near 555 nm may be red-shifted to 593-693 nm by embedding a silica core and blue-shifted to 527-534 nm by embedding a silver core. For bimetal nanoparticles with variable core size the difference in optical response is significant only for the excitation wavelengths shorter than 580 nm, namely when the imaginary parts of the dielectric functions for both metals are significantly different. The numerical analysis demonstrates that such core shell structures are promising for biological sensing and imaging and for molecular diagnostics via plasmon resonance scattering from core/shell nanorods.

This paper describes the accurate calculation of the propagation constant of a precision coaxial transmission line with rough plated conductors. The results are compared with previous publications and with traceable measurements of 2.4- and 1.85-mm air lines. In contrast to all tested existing procedures the present algorithm's results agree simultaneously with the real and imaginary part of the measured propagation constant. In the new algorithm, the effects of roughness and plating are represented by perturbed material parameters of a smooth coaxial line problem. A highly accurate multiple multipole field solver is used for the computation of the perturbed material parameters. The differences between the predicted and the measured propagation constant of 1.85-mm air lines are less than 0.01% at 67 GHz. Such high-precision computations are needed for the specification of offset short standards for vector network analyzer calibration.

A new overdetermined vector network analyzer (VNA) calibration algorithm is presented. The new algorithm shows significant advantages in the measurement of very high-impedance devices such as carbon nanotube transistors and can be applied to all types of VNA calibration. It was found that, for high-impedance devices, the new algorithm yields up to four times more accurate results. The focus of this study is on the accuracy and robustness of the algorithm. A statistical error model of calibration, which includes errors in the calibration standards and errors in the VNA, is converted into a formula for calibration by Bayes' theorem. The numerical implementation of this formula makes use of nonlinear optimization techniques and Monte Carlo integration. The resulting new algorithm is compared against various other algorithms. Benchmarking shows that the presented calibration algorithm is robust and more accurate than all other tested algorithms in all tested calibration scenarios.

Electromagnetic modeling of coaxial 1.85mm and 1.0mm standards for Vector Network Analyzer (VNA) calibration shows only limited accuracy. The approach presented in this paper can overcome this accuracy limitation. Instead of handing over the standards' S-parameters to the calibration algorithm, parameterized models of the standards are used as input into the calibration algorithm. The technique is demonstrated with an offset short calibration where the unknown phase constant of the short's parameterized model is estimated with the calibration algorithm. No assumptions on the frequency dependency of the phase constant are needed. Further on we describe the best constellation of the offset shorts' reflection coefficients in the Smith chart when calibrating a one-port.

The uncertainty of a Vector Network Analyzer (VNA) measurement is a consequence of the uncertainties both of calibration standards and the VNA. How the latter uncertainties move forward to the final measurement uncertainties is a complicated multistage process. The first stage (calibration of the VNA) essentially results in the error box terms. The nonlinear relationship between the parameters of the standards and the error box terms poses in this stage a problem. In the second stage (measurement of Device Under Test (DUT)) the uncertain error box terms are used to calculate the S-parameters of the DUT and again mix up with uncertainties of the VNA and the connectors. In this stage the correlation of error box terms amongst each other poses a second problem. It is important to note that only uncertainty distribution functions (with assumed parameters such as shape and variance) of the VNA and the standards are used to obtain predictions about the final measurement uncertainties. One common simplification of conventional approaches in VNA uncertainty computations is that stage one formulas (which express error box terms as a function of the standards' S-parameters) are replaced by their respective Taylor expansions. Another commonly applied approximation is that computed distributions of error terms are subsequently applied to the DUT without accounting for correlation of error terms among themselves. The goal of a good approach must be that the effects of different types of input uncertainties (e.g., transmission phase or reflection coefficient of standards) can be studied separately. Unfortunately, as a consequence of the above approximations and in contradiction to more rigorous approaches nearly the same measurement uncertainty is calculated for different types of uncertainties in the standards. Unlike traditional approaches the method presented in this paper is (1) based on Monte Carlo Simulation (MCS) and (2) does not use any simplifying assumptions to compute- - the measurement uncertainty. Essentially the whole calibration and subsequent measurement process is simulated a couple of ten thousand times by starting with random input values for the standards. The resulting distribution of the S-parameters of a given DUT is then analyzed using a statistics software. This approach was particularly useful for studying different calibration techniques in conjunction with snap on connectors which show large phase and small reflection coefficient variances. The MCS makes it possible to clearly distinguish between effects of transmission phase deviations and reflection coefficient deviations. We found that MCS is a well suited method for the computation of uncertainties in VNA calibration. In particular we make comparisons between different calibration strategies in conjunction with snap on connectors. The main outcome of the study is that it is favorable to use a calibration for 1.85 mm connectors and de-embed the used 1.85 mm to snap on connector adapters, rather than making a calibration using snap on standards. Experienced measurement engineers mostly would have proposed this kind of calibration for a snap on connector. Our results do not only confirm these heuristic approaches but give additional hard facts and quantify the differences between selected calibration strategies.

This paper presents a detailed investigation of the influence of pin gap size on the S-parameters of the 1.85 mm connector. In contrast to earlier publications connector geometry is simulated with all chamfers, gaps and contact fingers. Simulation results are verified by cross-checking between finite element frequency domain and finite difference time domain methods. Based on reliable simulation results, a very fast tool was developed to calculate S-parameters for a given connector geometry. This was done using database and interpolation techniques. The most important result is that very small pin gaps in conjunction with large chamfers have a drastic impact on connector S-parameters for frequencies above 50 GHz.

This paper demonstrates the suitability of the finite-volume time-domain (FVTD) method to analyse electromagnetic ‘real-world’ problems. As a challenging example, a 1–18 GHz broadband double-ridged horn antenna is chosen. The horn antenna consists of non-orthogonal and curved parts and a small coaxial feeding that is modelled in detail. The simulation results of the far-field patterns, the return loss and the gain are successfully compared to measurements. They show that the FVTD method—using an inhomogeneous tetrahedral mesh—is very well suited for simulating complex structures. Copyright © 2004 John Wiley & Sons, Ltd.

A correction method for the measurement of complex reflection coefficients using vector network analyzers is presented. The method is based on the invariance property of the cross ratio of the bilinear transformation and is traceable to calculable air line impedance standards. The application of an accurate diameter measurement system (laser micrometer and air gauge system) allows the treatment of air lines as inhomogeneous transmission lines consisting of a cascade connection of a number of equally spaced line sections. Each line section is assumed to be homogeneous and characterized by the characteristic impedance and the propagation constant, which are traceable to the measured diameter values. The presented procedure is an extension and improvement of prior work using the same principle of correction, whereas the air lines were specified by nominal diameter and length values. The aim of this work is to enhance the accuracy of the correction or to reduce the requirements of the manufacturing tolerances of air lines. The derived theory is accompanied by a brief uncertainty consideration and by measurement results obtained by PC-7 air lines at frequencies up to 18 GHz and by numerical simulation results for a hypothetical air line.