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Transient interference cancellation is necessary for high-frequency sky-wave radar and usually requires accurate interference detection and localisation which is complicated due to the non-uniform noise level caused by sea-clutter mitigation in Doppler domain. A novel approach is proposed by converting the detection of interference into a problem of straight line extraction in the constructed fast- and slow-time images. The line edges are detected by an edge detector, such as Canny method, followed by Hough transform. Then, each edge is classified as a rising, falling or false-alarm edge based on multi-threshold segmentation of image sub-blocks. Experimental results demonstrate the effectiveness of the proposed approach.

The Inmarsat Broadband Global Area Network (BGAN) L-band downlink signal from a radar viewpoint is studied. The signal is modelled and its ambiguity function (AF) is analysed and the AF is compared with that of the real recorded signal. It is shown that the AF of a single Inmarsat channel has an interference floor of −40 dB for 80 ms integration time. The AF of the Inmarsat BGAN signal is improved by combining multiple frequency channels with channel overlap.

A 30 bit high-density circular chipless RF identification tag based on C-shaped open end polarisation independent slots is presented. The encoding capacity of this design is enhanced in a compact size. Patch diameter of the tag is 24 mm. Circularly polarised incident plane waves are used for excitation. Data capacity of 30 bits is achieved in the frequency band of 3.1–11.7 GHz. Spectral signature-based radar cross-section results are also measured for flexible and temperature sensor integrated design. The prototype is inkjet printed on Kapton® HN heat resistant conformal sheet.

Orthogonal frequency division multiplexing multiple-input multiple-output (OFDM-MIMO) radar has different frequencies for different array elements’ transmitting signal. To a same moving target, different array elements obtain different Doppler frequencies. Hence, coherent integration gain of all array elements cannot be obtained if using traditional fast Fourier transform to process radar echo. Proposed is the scale-transform discrete Fourier transform algorithm for achieving Doppler frequencies focus, thus coherent integration of different array elements and a higher processing gain for moving target detection can be achieved.

A design consideration for super-Nyquist frequency modulated continuous-wave (FMCW) radar systems relating to transmitter to receiver noise leakage is introduced. Phase noise curves comparing the fundamental direct digital synthesisers frequency and its second super-Nyquist image show a significant increase in relative noise level at all offsets from the carrier. This results in a reduced transmitter signal-to-noise ratio. It is shown with a simple example that this can lead to a significant degradation in receiver sensitivity if not managed properly. A design rule-of-thumb that can be used by radar designers to avoid or mitigate this problem is provided.

A subspace-based auto-paired range and direction-of-arrival (DOA) estimation algorithm without joint diagonalisation for multi-target detection of dual-channel frequency modulated continuous-wave (FMCW) radar are proposed. The proposed method, which is based on signal subspace, exploits the shift invariant structure of the stacked Hankel matrix for the paired range and DOA estimation of multiple targets. To verify the effectiveness of the proposed method, the dual-channel FMCW radar is implemented and its effectiveness verified in an anechoic chamber environment.

A novel passive wireless temperature sensor is presented, which aims at operating in harsh environments. For this purpose, the tag is designed quasi-chipless and it uses a harmonic radar sensing principle: it combines the backscattering on the first harmonic of the transmitted frequency with frequency-position encoding of the measured value. The harmonic radar approach brings significant advantages for the wireless readout, since it isolates the undesired radar clutter from the useful tag signal. The tag signal carries the desired temperature information encoded in the position of a resonance transmission peak. The tag is built up planar and consists of two patch antennas, a temperature-dependent bandpass filter and a diode-based harmonic generator. It works at 1.59 GHz and backscatters at 3.18 GHz. Wireless indoor measurements have proven the concept. The sensor has shown a temperature sensitivity of 1.2 MHz/K in the range of 22–109 °C.

An experimental bistatic X-band continuous-wave life-detection radar is proposed. The system operates with two directive high gain antennas and a programmable transmitter and receiver. A method based on the independent component analysis, and accurate breath and heartbeat movements models are applied to suppress the interference and to better identify the respiratory and heart movements. The obtained experimental results show that this system can effectively detect the heartbeat and the respiratory activity with a good accuracy and demonstrated the capabilities and the potentialities of such system.

A report is presented on results achieved with an FM band commensal radar system in which the surveillance and reference antennas are widely separated, making use of common view, Global Positioning System disciplined oscillators to maintain timing synchronicity. The proposed configuration allows greater DPI suppression by means of terrain shielding and independent selection of the surveillance receiver position to enhance target visibility.

A waveform generator for a 77 GHz automotive radar that uses multiple frequency shift keying (MFSK) modulation is presented. The use of this modulation can improve the detection ability of radar applications in multi-target situations. The proposed generator consists of a conventional 77 GHz Σ-Δ fractional-N synthesiser and MFSK modulation control logic (MMCL). The key innovation is the introduction of the MMCL, which has the ability to track the linear frequency increase while generating the frequency shift keying in each time step. Prior to realising the hardware implementation, a behavioural simulation was evaluated. In addition, a 77 GHz generator module was designed using 130 nm CMOS technology. In a chirp time of 6 ms, there were a total of 128 modulation steps. The bandwidth and frequency step of the chirp were 100 MHz and 300 kHz, respectively.

A novel efficient detection method is proposed for radar transmitting direct sequences spread spectrum (DSSS) signals with high dynamics in the low signal-to-noise ratio (SNR) scenario. The core idea of the proposed method is first to eliminate the linear code phase drift via keystone transform (KT), then the derived modified Radon-Fourier transform (MRFT) is employed to accumulate the energy of the target effectively to achieve target detection and parameter estimation. Compared with the generalised RFT (GRFT) method, the proposed method has a similar detection performance, but requires much lower computational burden. Simulation results verify the validity of the proposed method.

A novel weighted l2,1 minimisation algorithm for a high range resolution profile with stepped frequency radar is proposed. The raw stepped frequency pulse train is converted into jointly sparse multiple measurement vectors by using the sliding window technique. Then, by using the Capon cepstrum a support-related weighting matrix is designed to control the priority class of bases in the reconstruction process so that the bases whose indices are inside the support are likely selected. Simulations and experiments on real radar data show that targets can be well separated and spurious peaks can be expelled from the range profile.

The test and evaluation of modern radars using hardware in the loop simulators requires the use of wideband high-fidelity, digital radio frequency memories (DRFM) in order to generate realistic target returns. Important aspects of wideband DRFM design on a printed circuit board are highighted and the architecture of the DRFM that was implemented using commercial-off-the-shelf components is presented. The spurious free dynamic range of the DRFM was characterised as -47 dBc worst case over an instantaneous bandwidth of 800-MHz. An experimental pulse-Doppler radar was used to compare the fidelity of the returns from the DRFM and an optical delay line.

To select a better kind of feature for radar specific emitter identification, the unintentional frequency and phase modulation features are compared through theoretic analysis and experimental verification with 104 real radar instances. Results show that the unintentional phase modulation feature outperforms the unintentional frequency modulation feature.

The microwave Doppler radar sensor enables a non-contact approach for measuring movement in various applications. One of the most challenging issues is radar signal demodulation because it requires accurate DC offset compensation. Existing works either require a complicated setup procedure or are sensitive to environmental changes. In this reported work, a compressed sensing based approach to effectively demodulate a radar signal is discussed. Through l 1 minimisation, the proposed method can reliably demodulate noisy signals with large measurement residuals. To validate the algorithm, three sets of experiments were run to evaluate the demodulation performance. Experimental results show that the proposed method is promising in both simulation and real-case studies.

Wireless microwave signals can be more efficiently converted to lightwave signals in a new design of electro-optic (EO) microwave-lightwave converter. A team at Osaka University have found that they can increase sensitivity by 10 dB by employing an optical waveguide with a quasi-phase matching (QPM) array of rectangular patch antennas, each containing a narrow gap.Although not yet widely used, these devices are particularly promising for optical modulation in radio-over-fibre systems, and they can also be applied in other areas such as electromagnetic compatibility (EMC) tests, remote sensing and radar.

A novel super-broadband planar monopulse comparator is presented, and demonstrated experimentally. This comparator is based on a recently discovered 180° hybrid coupler derived from the conventional Wilkinson divider. Because of its symmetric configuration, the proposed comparator exhibits frequency-independent nulls at its three difference output ports and therefore features a quasi unlimited bandwidth. This property substantially enhances the overall broadband resolution performance of monopulse comparators with direct benefits in tracking radar applications.

A compact low-noise quadrature receiver for 24 GHz ISM applications in 0.13 µm CMOS technology is presented. The chip offers a conversion gain of 18 dB and a noise figure of 5 dB. The differential circuit consumes only 24 mW from a single 1.5 V supply. The low-noise amplifier, two mixers and on-chip quadrature generation are integrated on a minimal chip area of 0.48 mm2 including pads.

A quasi-circulator, composed of two branch-line couplers and an asymmetric power combiner, is proposed to effectively cancel the transmitter leakage signals in a monostatic six-port radar. The effective isolation is improved by 12.2 dB at 24 GHz. With the proposed quasi-circulator, the maximum detectable range of the six-port radar is improved by 167 , compared with that of the six-port radar with a conventional branch-line coupler.

A simple microwave sensor for the detection of the dynamic characteristics of large structure vibration is proposed. It consists of a continuous-wave radar capable of detecting the structure movement by measuring the phase of the back-reflected wave. The system performances have been demonstrated in a case study monitoring a pedestrian bridge.

The design and measured results of the developed radar sensor for automotive applications are presented. The radar sensor is highly integrated with the transceiver module, antenna and baseband circuits. The proposed antenna is composed of a novel microstrip-line-fed horn antenna and a quasi-optic lens antenna.

A new behavioural model of a power amplifier (PA) at system level is presented, dedicated to radar applications. This model, which is able to take into account output loading impedance mismatch, is based on a similar topology to the PA's circuit. The model, implemented in Agilent Advanced Design System (ADS), is validated for different loading impedances, until VSWR=2 (voltage standing wave ratio), on the PA's bandwidth. This approach permits an extraction, resulting from simple CW measurements or simulations, and easy model implementation. This work has been supported by DGA (French Defense and Security Agency).

Proposed is a self-multiplier mixer circuit that has an independent multiplication capability to improve the sensitivity of upper bands, a problem not only with radar detectors but also with similar multi-broadband receivers (i.e. receiver systems that have several reception bands with wide distribution). The circuit's superiority was verified by designing and producing the front-end for a multi-broadband receiver to be implemented in radar detectors, and its simulation performance was measured.

A 35 GHz, magnetron-based, compact pulse radar is presented. It contains some novel solutions of four electrically switched slot array antennas having fan beam patterns, solid-state modulator adaptive for the miniature magnetron and digital receiver techniques with advanced processing. It is designed for obstacle and rain detection for collision warning in helicopter applications.

The differential radar cross-section (RCS) of an RFID tag is an important parameter which determines the power of the modulated backscattered tag signal. The vector differential RCS of an RFID tag as seen by the reader is analysed and, for the first time, compared with experimental results in UHF band.

The impulse response of the human body can provide useful information of the body for medical purposes. An ultra-wideband (UWB) radar method is used to determine this impulse response. To this end, the study probed into human phantoms and the human body using discrete electromagnetic pulses. The received signal is processed primarily to extract the impulse response. The measurement result shows that impulse responses can provide information on the shape and electrical properties of the human body.

A high-speed coherent radar for dynamic testing of civil engineering structures is proposed. The radar operates a continuous-wave (CW) step-frequency in Ku-band, and the base-band signal is generated by direct digital synthesis. Vibration measurements carried out on a 200 m-long bridge forced by vehicular traffic are reported.

A microelectronic 20-stage tapped delay line consisting of cascaded lowpass filter amplifier stages has been demonstrated. The delay per tap is ~2.7 ns, and different versions have been optimised for pulsed and narrowband operation in the 30 – 70 MHz frequency range. Potential applications are in radar and adaptive antenna systems.

Signal space projection techniques are introduced to filter the direct-path signal component from the passive coherent location (PCL) receiver target channel. Filter performance is characterised using ambiguity function analysis of the digital audio broadcast (DAB) waveform, considered here as a PCL waveform of opportunity. For ideal DAB phase reference synchronisation, the direct-path component is perfectly eliminated. For non-ideal phase synchronisation, the direct-path component is sufficiently attenuated to permit target detection; approximately 22 dB of direct-path signal attenuation is demonstrated.

It is shown that the modulation components present in the backscattered signal from an aircraft to an ATC radar system have a significant energetic content. Furthermore it is reported how these components can be mathematically modelled and how they present a good degree of matching with actual data both in the time and the frequency domains.

A technique is presented for the adaptive tuning of a Jaumann radar absorber by the incorporation of controllable resistance or impedance layers. The discussion considers several candidate absorber geometries and outlines criteria for achieving the maximum practical tuning range.

The authors describe a technique for the design of a radar waveform with ultralow range sidelobes (

A scheme is presented for reducing the RCS of patch antennas outside their operational band without compromising gain performance. This is achieved by placing a narrow resistive strip (distributed loading) around the periphery of the patch which has minimal effect at the operational frequency of the patch. Results are presented using a finite element-boundary integral code demonstrating the effectiveness of this scheme over the traditional method of using lumped loads.

Radar cross-section measurements in the time domain are performed for the very first time, over a compact range. Apart from the hardware configuration and calibration used, extended analysis capabilities are discussed and illustrated with measurements. An enormous potential is envisaged in industrial and military applications, e.g. reverse engineering, radome optimisation and stealth design.

A method for designing multilevel sequence, based on chirp and frequency hopping (FH) waveforms is presented. The main feature of the synthesised transmitter-receiver pair of sequences is the very low sidelobe level. The receiver sequences are considered as mismatched compression filter coefficients. The DIRLS (Doppler optimised iterative reweighted least square) algorithm is applied to the iterative optimisation of the receiver mismatched coefficients, as well as to the multilevel transmitter sequence.

Recent advances in conducting polymer materials have enabled the realisation of radar absorbers with very wide dynamic tuning ranges. The author examines possible techniques for internally monitoring the frequency response of such absorbers so that they may be integrated effectively into an elecfronic warfare system.

A new suboptimal method for time-space signal processing in airborne phased array radar is proposed which can significantly reduce the necessary computation compared with other optimal or suboptimal methods. The numerical results obtained from simulation illustrate that this method possesses ideal performance and is a realisable scheme for real-time processing

Rapidly manoeuvring targets moving in and out of the range gate of a split gate tracker can result in loss of track. By using an adaptive switch on a multiple-split gate to cater for the rapidly changing target dynamics, the tracking performance is improved.

Combining the attributes of charge-coupled-device analogue signal processors with those of surface-acoustic-wave devices promises a compact and inexpensive way of extracting Doppler frequency information from coherent pulse-radar signals. Experimental tests confirm the feasibility of the technique and point the way to a fairly simple processing module which should be applicable to a range of radar parameters.

A simple circuit is described in which SAW and conventional electrical components are combined to form an agile-frequency source. The principle is illustrated by a prototype version developed for use in an experimental radar and providing 20 clean outputs at 10 MHz intervals.

The implementation of a c.c.d. signal integrator to improve the signal/clutter ratio of radar returns is described. A parallel-transfer scheme is employed, in which the effects of transfer inefficiency on performance are minimised. Preliminary investigations with a test device are reported.

The letter describes the application of non-Fourier methods of moving between the time and frequency domains in the signal processing associated with an FMCW radar used for detecting hidden objects. It is shown that, compared with earlier techniques, the target returns are sharper and that there is less of a problem resulting from spectral sidelobes.

The finite-element method is applied to compute the skin current and radar cross-sections of perfectly conducting square surfaces. The predictions are compared with those given other methods. The efficiency, economy, accuracy and applications

The sensitivity of radar receivers is checked with a pulsed radio frequency signal which is adjusted until the observed magnitude is distinguishable from the background noise level as displayed on an oscilloscope. Because of the noisy nature of the display the results are highly subjective, but by eliminating the idiosyncratic element, a calibration instrument has been designed to give a rapid and accurate presentation to the operator.

The temporary modification of electrical networks on a sub-nanosecond time scale via photoconductive gating of circuit components is reported. Frequency agility and amplitude-shifting of VHF signals, as well as enhanced tunability of transient wave shapes, have been demonstrated. The signals generated are applicable to fusion, communications and radar studies, perhaps up to the millimetre- and submillimetre-wave regimes.

A prototype clutter-rejection filter for radar is described. It uses analogue shift registers of the bucket-brigade type, which, in common with charge-coupled devices, can combine the flexibility of digital processing with the simplicity of analogue operation. Certain imperfections in the devices are shown to be particularly important for moving-target-indicator filtering.

High-voltage pulses from a radar modulator have been used to determine the electric strength of two fluorocarbon insulating liquids. The effects of electrode spacing and pulse duration have been investigated.