Within the European Commission Seventh Framework Programme (FP7), CONSORTIS (Concealed Object Stand-Off
Real-Time Imaging for Security) has designed and is fabricating a stand-off system operating at sub-millimetre wave
frequencies for the detection of objects concealed on people. This system scans people as they walk by the sensor.
This paper presents the top level system design which brings together both passive and active sensors to provide good
performance. The passive system operates in two bands between 100 and 600GHz and is based on a cryogen free cooled
focal plane array sensor whilst the active system is a solid-state 340GHz radar.
A modified version of OpenFX was used for modelling the passive system. This model was recently modified to include
realistic location-specific skin temperature and to accept animated characters wearing up to three layers of clothing that
move dynamically, such as those typically found in cinematography. Targets under clothing have been modelled and the
performance simulated. The strengths and weaknesses of this modelling approach are discussed.
This paper focuses on the feasibility of tracking micro-motion with coherent Ultra-Wide Band Pulsed Radar. The proposed micro-motion detection principle consists in measuring the phase difference of the Ultra-Wide Band carrier waveform between the transmitted and the received pulse signals. Those signals are acquired directly on the working frequency band, with equivalent time sampling techniques. An experiment based on a double staged equivalent time sampling is set to emulate real-time acquisition with an oscilloscope. This experiment shows clear high precision ranging capabilities by revealing a millimeter order woofer displacement equal to λ⁄10. This reveals a great potential in phase tracking and confirms the choice to go further on the development of a real time radar. This platform provides refreshing rates of 2 ms, required to developed effective phase detection algorithms for micro-motion detection and tracking of human targets, especially for through-the-wall radar applications when humans remain in static position.
We discuss a correlation function using for developing of new algorithm that allows us to detect a hidden object
without analyzing of image captured by the passive THz camera. Main idea of this approach concludes in correlation
calculating between the image characteristics and corresponding characteristics of standard image. Obviously, a
difference in temperature between a person body and object hidden under clothes takes place always. However, this
difference can be invisible for human eyes. Using the correlation function we can increase a contrast between two
objects and this allows to see an object or to produce alarm by computer.
We discuss a choice of standard image characteristics for an achievement of correlation function for high contrast.
Other feature of our approach arises from a possibility of a person image coming to the THz camera by using a
computer processing of the image only. It means that we can “decrease” a distance between a person and the passive
THz camera. This algorithm is very convenient for using and has a high performance.
Active imaging systems for security screening at the airport or other checkpoints have proven to offer good results. Present
systems require a specific position and posture,13 or a specific movement2 of the passenger in front of the imaging system.
Walk Through Systems (WTS) which screen the passenger while passing the imaging system or a screening hallway would
be more pleasant for the passenger and would result in a great improvement in the throughput. Furthermore the detection
performance could be enhanced since possible threats are visible from different perspectives and could be tracked within
different frames. The combination of all frames is equivalent to a full illumination of the passenger.
This paper presents the concept of a WTS basing on a multistatic imaging system in the mmW range. The benefit is that the
technology of existing portals can we reused and updated to a WTS. First results are demonstrated with an experimental
In this paper, we present a millimeter wave radar system which will enhance the performance of infrared cameras used for fire-fighting applications. The radar module is compact and lightweight such that the system can be combined with inertial sensors and integrated in a hand-held infrared camera. This allows for precise distance measurements in harsh environmental conditions, such as tunnel or industrial fires, where optical sensors are unreliable or fail. We discuss the design of the RF front-end, the antenna and a quasi-optical lens for beam shaping as well as signal processing and demonstrate the performance of the system by in situ measurements in a smoke filled environment.
In this paper we present two system approaches for perimeter surveillance with radar techniques focused on the detection of Micro Aerial Vehicles (MAVs). The main task of such radars is to detect movements of targets such as an individual or a vehicle approaching a facility. The systems typically cover a range of several hundred meters up to several kilometers. In particular, the capability of identifying Remotely Piloted Aircraft Systems (RPAS), which pose a growing threat on critical infrastructure areas, is of great importance nowadays. The low costs, the ease of handling and a considerable payload make them an excellent tool for unwanted surveillance or attacks. Most platforms can be equipped with all kind of sensors or, in the worst case, with destructive devices. A typical MAV is able to take off and land vertically, to hover, and in many cases to fly forward at high speed. Thus, it can reach all kinds of places in short time while the concealed operator of the MAV resides at a remote and riskless place.
In this work we describe and demonstrate a method for up-conversion of millimeter wave (MMW) radiation to the visual band using a very inexpensive miniature Glow Discharge Detector (GDD), and a silicon detector (photodetector). Here we present 100 GHz up-conversion images based on measuring the visual light emitting from the GDD rather than its electrical current. The results showed better response time of 480 ns and better sensitivity compared to the electronic detection that was performed in our previous work. In this work we performed MMW imaging based on this method using a GDD lamp, and a photodetector to measure GDD light emission.
Millimeter-wave and terahertz continuous-wave radar systems have been used to measure physiological signatures for
biometric applications and for a variety of non-destructive evaluation applications, such as the detection of defects in
materials. Sensing strategies for the simplest homodyne systems, such as a Michelson Interferometer, can be enhanced
by using Frequency Modulated Continuous Wave (FMCW) techniques. This allows multiple objects or surfaces to be
range resolved while monitoring the phase of the signal in a particular range bin. We will discuss the latest
developments in several studies aimed at demonstrating how FMCW techniques can enhance mmW/THz sensing
This paper presents the theory and algorithm of how a three-dimensional (3D) image can be generated using crosscorrelations
of radiometric emission from a source measured using antennas in the near field. An example of how the
algorithm is used to create 3D images of emission measured from a noise source is presented, indicating the presence of
Fresnel noise and aliasing in the experimental data when the source is moved away from the phase centre. Simulations
are presented which reproduce the Fresnel noise as generated by a 3x3x3 array of point sources located at the centre of a
2 metre diameter array of antennas representing a security screening portal. Two methods of reducing the Fresnel noise
are presented: 1) a software method which makes successive more accurate estimates of the locations and intensities of
sources; 2) a hardware method which reduces the coherence length of the radiation by increasing the radiation
A system for the detection of spectral signatures of chemical compounds at the Terahertz regime is presented. The system consists on a holey metal film whereby the presence of a given substance provokes the appearance of spectral features in transmission and reflection induced by the molecular specimen. These induced effects can be regarded as an extraordinary optical transmission phenomenon called absorption-induced transparency (AIT). The phenomenon consist precisely in the appearance of peaks in transmission and dips in reflection after sputtering of a chemical compound onto an initially opaque holey metal film. The spectral signatures due to AIT occur unexpectedly close to the absorption energies of the molecules. The presence of a target, a chemical compound, would be thus revealed as a strong drop in reflectivity measurements. We theoretically predict the AIT based system would serve to detect amounts of hydrocyanic acid (HCN) at low rate concentrations.
The shock plasma waves in Si MOS, InGaAs and GaN HEMTs are launched at a relatively small THz power that is
nearly independent of the THz input frequency for short channel (22 nm) devices and increases with frequency for
longer (100 nm to 1 mm devices). Increasing the gate-to-channel separation leads to a gradual transition of the nonlinear
waves from the shock waves to solitons. The mathematics of this transition is described by the Korteweg-de Vries
equation that has the single propagating soliton solution.
The need to detect non-metallic items under clothes to prevent terrorism at transport hubs is becoming vital. Millimetre wave technology is able to penetrate clothing, yet able to interact with objects concealed underneath.
This paper considers active illumination using multiple transmitter and receiver antennas. The positioning of these antennas must achieve full body coverage, whilst minimising the number of antenna elements and the number of required measurements. It sets out a rapid simulation methodology, based on the Kirchhoff equations, to explore different scenarios for scanner architecture optimisation.
The paper assumes that the electromagnetic waves used are at lower frequencies (say, 10-30 GHz) where the body temperature does not need to be considered. This range allows better penetration of clothing than higher frequencies, yet still provides adequate resolution.
Since passengers vary greatly in shape and size, the system needs to be able to work well with a range of body morphologies. Thus we have used two very differently shaped avatars to test the portal simulations. This simulation tool allows many different avatars to be generated quickly.
Findings from these simulations indicated that the dimensions of the avatar did indeed have an effect on the pattern of illumination, and that the data for each antenna pair can easily be combined to compare different antenna geometries for a given portal architecture, resulting in useful insights into antenna placement. The data generated could be analysed both quantitatively and qualitatively, at various levels of scale.
The specially calculated and prepared antiradar surfaces on special ships is very good for detecting them by the
microwave radiometers. It is interesting to evaluate the possibility of using a passive millimeter wave (PMMW)
radiometric discriminator for the remote controlling and finding such objects at real distances and also for
In this paper, an advantage of sapphire shaped crystal use for highly efficient terahertz (THz) waveguiding is discussed. The THz photonic crystal waveguide has been manufactured using the edge-defined film-fed growth (EFG) or Stepanov technique of shaped crystal growth. The effective mode index and extinction coefficient of the waveguide have been experimentally studied using the THz pulsed spectroscopy. The observed results have shown that the multichannel sapphire crystal allows guiding the THz waves with minimal dispersion in frequency range of 1:0 to 1:55 THz and minimal loss of 2 dB/m at 1:45 THz. The waveguides based on sapphire shaped crystals can be employed in wide range of THz technology applications, including non-destructive evaluation of materials, medical diagnostics, and sensing in aggressive environment.
Polarimetric measurements can provide additional information as compared to unpolarized ones. In this paper, linear polarization ratio (LPR) is created to be a feature discriminator. The LPR properties of several materials are investigated using Fresnel theory. The theoretical results show that LPR is sensitive to the material type (metal or dielectric). Then a linear polarization ratio-based (LPR-based) method is presented to distinguish between metal and dielectric materials. In order to apply this method to practical applications, the optimal range of incident angle have been discussed. The typical outdoor experiments including various objects such as aluminum plate, grass, concrete, soil and wood, have been conducted to validate the presented classification method.
In this paper, we present a novel hardware-efficient direction of arrival (DOA) estimation method based on digital channelized receiver. The proposed method splits the wideband array output into multiple frequency sub-channels and estimates the signal parameters using digital channelization receiver. Based on the accurate signal parameters estimation, signals with different bandwidths are isolated reasonably. Different DOA estimation methods are used to signals with different bandwidths. The proposed channelization based method can improve the output signal noise ratio (SNR). It outperforms those conventional DOA estimation methods on estimation accuracy, especially in real environment. Simulations are presented to demonstrate the performance. The results verify the effectiveness of the proposed method.
Electromagnetic model (em-model) provides a concise and physically relevant description of target through representative scatterers. In a forward built em-model, detailed information about each scatterer’s position, scattering amplitude along with its provenance can be predicted. This makes em-model a good candidate for use in synthetic aperture radar (SAR) automatic target recognition (ATR). In this paper, we introduce scatterers’ provenance as attributed information into target recognition, and an attributed em-model based target recognition method is proposed. Firstly, according to the purpose of ATR, each scatterer in em-model is endowed with an importance factor based on its provenance. Secondly, a detection is implemented to decide whether the em-model predicted scatterer has a corresponding scatterer in measured data. If the scatterer exist in measured target, evaluate how similar the scatterer pair resembled with each other. Next, similarities of all the scatterer pairs are synthesized as a whole match score between em-model and SAR data. In the synthesis, the importance factor servers as a weighting factor that scatterer with more attention will be more discriminative for recognition. In the end, target in measured SAR data is recognized as the model type or not based on the match score. The novelty of this method comes from taking into account of the provenance information of scatterers as attributed information and endowing the scatterers with different important factors according to their importance in recognition. This makes the attributed scatterer based recognition method pertinent to the purpose of ATR. Experiments on simulated Tank SAR data that produced by a high frequency electromagnetic simulation software verified the effectiveness of this method.