This article reports on the principles of evaluation and the experimental results obtained by a mm-wave FMCW MIMO radar system with a sparse aperture con- figuration and an additional receive antenna for the application of the phase monopulse principle. While ranging information is obtained by standard FMCW techniques the 2D system capability stems from the generated virtual array. The azimuth information is evaluated by exploiting the characteristics of the signal covariance matrix. Supplementary information about elevation can be obtained from the originating monopulse virtual array. A new evaluation method which can handle the occurring phase ambiguities and allows to correct for the system-inherent coupling between elevation and azimuth, is presented. Laboratory experiments confirm suitability and accuracy of the approach.

For a multiple input multiple output (MIMO) radar system that uses a frequency modulated continuous wave (FMCW) signal and time domain multiplexing (TDM), different effects occur in the presence of relative motion between radar system and target. These effects have an influence on the correct position detection of the targets. Therefore, two different modulation schemes are analyzed that have the ability to overcome the issues of movement and estimate the correct target location and velocity.

This paper covers coherent MIMO radar with colocated antennas distributed according to minimum redundancy principles. The fundament of the first are virtual arrays which can be considered as a discrete convolution of local transmitter and receiver distributions. Now this technique shall be combined with sparse array principles considering minimum redundancy (MR) aspects. Optimal results for so-called restricted MR arrays, found by brute-force search algorithms had already been presented. However, those are usually not suited for aperture antennas since the smallest element spacing is around half or quarter of the wavelength. This paper shall not only present an analysis of the effects relevant for design of general MR arrays, but also shows results for braced and nested arrays. This leads to MR-MIMO arrays with a smallest element spacing which is larger than a wavelength, giving a higher degree of freedom in choice of antenna type. Measurement results for a radar sensor operating in lower W-band and equipped with the afore-mentioned array type, demonstrate high angular resolution with suppression of grating lobes at the same time.

In general, coherent multiple-input multiple-output (MIMO) radar systems with co-located antennas, form monostatic virtual arrays by discrete convolution of bistatic setups of transmitters and receivers. Thereby, a trade-off between maximum array dimension, element spacing and hardware efforts exists. Compressed sensing techniques can help to improve resolution or to suppress angular ambiguities for a given hardware expense. This paper demonstrates the application of a compressed sensing technique on an existing MIMO radar operating in lower W-band. Theoretical results improving the azimuth resolution and the suppression of azimuth ambiguities are presented.

A coherent multiple input multiple output (MIMO) radar system that uses the principles of a frequency modulated continuous wave (FMCW) radar and a time domain multiplexing technique can use a special modulation scheme to enable the unambiguous location estimation as well as a velocity estimation and compensation in a short measurement time [1]. To use this modulation scheme a special calibration procedure is needed. This strategy shall be displayed here.

Coherent multiple-input multiple-output (MIMO) radar systems with co-located antennas, form monostatic virtual arrays by discrete convolution of a bistatic setup of transmitters and receivers. Thereby, a trade-off between maximum array dimension, element spacing and hardware efforts exists. In terms of estimating the direction of arrival, the covariance matrix of the array element signals plays an important role. Here, minimum redundancy arrays aim at a hardware reduction with signal reconstruction by exploiting the Toeplitz characteristics of the covariance matrix. However, the discrete spatial convolution complicates the finding of an optimal antenna setup with minimum redundancy. Combinatorial effort is the consequence. This paper presents a possible simplified algorithm in order to find MIMO array setups of maximum dimension with minimum redundancy.

The presence of motion has several influences on the azimuth focusing and the correct range estimation of a target in a frequency-modulated continuous wave (FMCW) multiple-input multiple-output (MIMO) radar system, when time domain multiplexing is used. The influences are discussed in the following. A modulation scheme which can compensate these issues is presented. The method is verified by several measurements.

In a frequency-modulated continuous wave (FMCW) multiple input multiple output (MIMO) radar system, where a time domain multiplexing (TDM) is used, a relative motion between system and target has several influences. In this paper a modulation scheme is examined according to its capability to compensate these effects.

The European Defence Agency (EDA) engages countermeasures against Improvised Explosive Devices (IEDs) by funding several scientific programs on threat awareness, countermeasures IEDs or land-mine detection, in which this work is only one of numerous projects. The program, denoted as Surveillance in an urban environment using mobile sensors (SUM), covers the idea of equipping one or more vehicles of a patrol or a convoy with a set of sensors exploiting different physical principles in order to gain detailed insights of the road situation ahead. In order to give an added value to a conventional visual camera system, measurement data from an infra-red (IR) camera, a radiometer and a millimetre-wave radar are fused with data from an optical image and are displayed on a human-machine-interface (HMI) which shall assist the vehicle's co-driver to identify suspect objects or persons on or next to the road without forcing the vehicle to stop its cruise.This paper shall especially cover the role of the millimetre-wave radar sensor and its different operational modes. Measurement results are discussed. It is possible to alter the antenna mechanically which gives two choices for a field of view and angular resolution trade-off. Furthermore a synthetic aperture radar mode is possible and has been tested successfully. MIMO radar principles like orthogonal signal design were exploited to from a virtual array by 4 transmitters and 4 receivers.In joint evaluation, it was possible to detect e.g. grenade shells under cardboard boxes or covered metal barrels which were invisible for optical or infra-red detection.

Coherent multiple-input multiple-output (MIMO) radar systems with co-located antennas, form monostatic virtual arrays by discrete convolution of a bistatic setup of transmitters and receivers. Thereby, a trade-off between maximum array dimension, element spacing and hardware efforts exists. In terms of estimating the direction of arrival, the covariance matrix of the array element signals plays an important role. Here, minimum redundancy arrays aim at a hardware reduction with signal reconstruction by exploiting the Toeplitz characteristics of the covariance matrix. However, the discrete spatial convolution complicates the finding of an optimal antenna setup with minimum redundancy. Combinatorial effort is the consequence. This paper presents a possible simplified algorithm in order to find MIMO array setups of maximum dimension with minimum redundancy.

For MIMO radar systems orthogonal waveforms are required to distinguish between the different transmitted signals at the different receivers. A hardware cost efficient way is the use of time-multiplexing, where the transmitters are active sequentially after each other. In the presence of platform or target movement, the sampling theorem in the spatial domain (along track) might not be fulfilled anymore which causes problems in the azimuth focusing. In this paper an interlaced switching scheme for a FMCW MIMO radar is proposed to overcome this issue. To verify the proposed method measurements were performed.

This paper covers the role of a millimetre-wave (mmw) radar sensor within a European scientific program with the aim of preventing security or supply patrols from harms caused by improvised explosive devices (IEDs), land-mines etc. in hostile conflict zones. In order to give an added value to a conventional visual camera system, measurement data from an infra-red (IR) camera, a visual camera, a radiometer and a millimetre-wave radar are fused and displayed on a human-machine-interface (HMI) which shall assist the vehicle's co-driver to identify suspect objects or persons on or next to the road without forcing the vehicle to stop its cruise. Within an international consortium, a complete demonstration system with the afore mentioned sensors, as well as a data fusion engine were designed, constructed, mounted on a military patrol truck and successfully tested for different objects in different scenarios. Furthermore, this paper introduces the applied radar modes in more detail and gives measurement results. (6 pages)

This paper covers the implementation of a near-range FMCW radar within a joint European scientific program for force protection from IEDs or landmines. The radar is one of four sensors whose data are fused and evaluated to provide a threat classification of suspicious objects or persons on or nearby the road ahead of a patrol or transport vehicle. A fully functionally low-cost demonstrator system has been implemented and successfully tested. Results are given.

Traditionally well-known from communication applications, the multiple-input multiple-output principle (MIMO) has found its way into radar system theory in the last years. Different arrangements of transceivers equipped with orthogonal signals, lead to arrangements of virtual elements which is denoted as virtual array in the context of coherent MIMO approaches. In order to proof practical feasibility of ongoing theoretical considerations, experiments have been started and evaluated.

The input power dynamic range (IPDR) of a semiconductor optical amplifier (SOA) gives the input power range within which an SOA can be operated error free. It is among the most important parameters describing the usability range of an SOA in an access network. In this paper, we give design guidelines to maximize the IPDR at a given gain. Our IPDR description indicates that a large IPDR can be obtained if SOAs are designed properly. A particular large IPDR is predicted to be found for well-designed quantum-dot (QD)-SOAs. We apply both theory and experiment to a 1.3- μm QD-SOA and investigate the IPDR as a function of bitrate, wavelength, and bias current. Large IPDRs of 41 and 36 dB are found for single-channel experiments with a signal quality of Q2 = 12.6 dB at 2.5 and 40 Gbit/s, respectively.

Experimentally we find a 10 dB input power dynamic range advantage for amplification of phase encoded signals with quantum dot SOA as compared to low-confinement bulk SOA. An analysis of amplitude and phase effects shows that this improvement can be attributed to the lower alpha-factor found in QD SOA.

All-optical wavelength conversion of 56 Gbit/s NRZ-DQPSK based on four-wave mixing is demonstrated in a silicon-organic hybrid strip waveguide operated in TM mode.

We fabricated organic light-emitting diodes with one-dimensional Bragg gratings as light extraction elements for substrate and waveguide modes. A Ta2O5 layer was introduced to obtain a high refractive index contrast to the subsequent anode layer. As anode we employed a highly conductive polymer. Laser interference lithography and physical plasma etching were used to pattern gratings into the Ta2O5 layer with a lattice constant of 370 nm and various grating depths. Mainly attributed to the outcoupling of the substrate modes, the structured devices exhibit a luminous flux which is up to four times higher compared to the unstructured reference devices.

Design guidelines for SOA with largest possible input power dynamic range as needed in extended GPON networks are given. Indications are that long QD SOA with few layers may provide input power dynamics >35 dB