Chen Wu

Government of Canada

This paper introduces a 2D angle-of-arrival (AoA) estimator, which has a 6–18 GHz 7-element nonuniformly spaced array (NSA) and a Direct Data Domain- (D3-) based AoA algorithm for a 2D isotropic-element planar array (IEPA). A 2D calibration and data-transformation method is developed to convert the NSA data to the output of the IEPA, so that the NS...

This paper introduces a multi-emitter 2D angle-of-arrival (AoA) estimation scheme. It consists of an AoA estimation algorithm based on impinging signal spatial sparsity, Dantzig Selector (an ${l_{1}}$ -norm minimization solution), and a 6-element non-uniformly random-spaced 2D array. The new scheme can identify more signals than the number of sen...

In this paper, a high-fidelity RF modeling and simulation framework is demonstrated to model an airborne multi-channel receiver system that is used to estimate the angle of arrival (AoA) of received signals from a stationary emitter. The framework is based on System Tool Kit (STK®), Matlab and SystemVue®. The SystemVue-based multi-channel receiver...

In the original publication [...]

The discrete Fourier transform (DFT) is the most commonly used signal processing method in modern digital sensor design for signal study and analysis. It is often implemented in hardware, such as a field programmable gate array (FPGA), using the fast Fourier transform (FFT) algorithm. The frequency resolution (i.e., frequency bin size) is determine...

The hardware-accelerated time–frequency distribution calculation is one of the commonly used methods to analyze and present the information from intercepted radio frequency signals in modern ultra-wideband digital receiver (DRX) designs. In this paper, we introduce the piecewise constant window blocking FFT (PCW-BFFT) method. The purpose of this wo...

It is always an interesting research topic for digital receiver (DRX) designers to develop a DRX with (1) ultrawide instantaneous bandwidth (IBW), (2) high sensitivity, (3) fine time-of-arrival-measurement resolution (TMR), and (4) fine frequency-measurement resolution (FMR) for weak signal detection. This is because designers always want their rec...

This article presents the hardware implementation and a behavioral model-based RF system modeling and simulation (M&S) study of compressive sensing (CS) based 2D angle-of-arrival (AoA) measurement system for 2–18 GHz radar electronic support measures (RESM). A 6-channel ultra-wideband RF digital receiver was first developed using a PXIe-based multi...

In this paper, a novel signal processing algorithm for mitigating the radar blind speed problem of moving target indication (MTI) for frequency modulated continuous wave (FMCW) multi-target tracking radars is proposed. A two-phase staggered pulse repetition interval (PRI) solution is introduced to the FMCW radar system. It is implemented as a time-...

Abstract: Using the finite difference time domain (FD-TD) method, this paper studies radiation structures that can have multiple tunable frequency bands between 0.4 GHz and 4 GHz, a fixed band in [3.97, 5.36] GHz and an extremely wideband from 6.14 GHz to 68.27 GHz, where a frequency band is defined by the voltage standing wave ratio (VSWR) less th...

In this paper, a high-performance antenna array system model is presented to analyze moving-object-skin-returns and track them in the presence of stationary objects using frequency modulated continuous wave (FMCW). The main features of the paper are bonding the aspects of antenna array and electromagnetic (EM) wave multi-skin-return modeling and si...

In this paper, a high-performance antenna array system model is presented to analyze moving-object-skin-returns and track them in the presence of stationary objects using frequency modulated continuous wave (FMCW). The main features of the paper are bonding the aspects of antenna array and electromagnetic (EM) wave multi-skin-return modeling and si...

Research experience has shown that it is expensive to design, build and test a RF/microwave system that is comprised of various RF/microwave components. In order to mitigate the problem, High-Fidelity Modeling and Simulation (HFM&S) is a practical approach that includes high-fidelity behavioural model (HFBM) of the receiving system and scenarios em...

The fast Fourier sampling (FFS) method is related to the new sampling paradigm, compressive sampling (CS). This paper explores the application of the FFS method in an ultra-wide band digital receiver. The aim of the study is to quickly detect sparsely distributed carrier frequencies in an ultra-wide frequency band using fewer digital sampled data w...

Using the data from a signal-element receiver on a moving Unmanned Aerial Vehicle (UAV), this paper introduces a VRA method to obtain the data that can be used in the Direct Data Domain (D3) method for the signal DOA estimation.

UAV emitter geolocation systems force the development of small RF receivers with real-time direction of arrival (DOA) estimation capabilities. This paper introduces the Virtual Receiving Array method. A single element receiver samples an RF signal in time, while the UAV flies with a constant velocity. The data is manipulated and a Direct Data Domai...

An unmanned aerial vehicle (UAV) electronic support payload (ESP) has been developed for the purpose of detecting and analyzing radar signals. The airborne payload control system (PCS) must be controlled from a ground control station (GCS) remotely through a wireless link. For the purpose, a control program, called Radar Signal Acquisition System (...

A linear-tapered slot antenna (LTSA) element fed by a novel suspended microstripline (SML) feed structure is presented in this article. The element is designed using the finite-difference time-domain (FDTD) method. It shows that the element has a wide impedance bandwidth in K-band. Using the new element, a 4 × 4 SML parallel-feed array has been des...

Symmetrical directional couplers have been used as part of the feed network for various wideband antennas. In many cases they are used in conjunction with baluns to allow for polarization diversity. The design and optimization of a nonuniform tapered ultra wideband 90deg coupler is presented as well as a novel approach to the integration of the cou...

The waveform in the far field of an antenna array can be obtained using the convolution of the input signal and the antenna far-field impulse response. Since it is very difficult to measure an antenna far-field impulse response, a numerical approach, i.e., the finite-difference time-domain (FDTD) method, is used in this paper to calculate an antenn...

The waveform in the radiation field of a radar antenna can be obtained by using the convolution of the transmitted signal and the antenna far-field impulse response (AFFIR). In this paper, the finite-difference time-domain (FDTD) method is applied to calculate the AFFIR of an X-band 54-element waveguide slot array at different radiation angles usin...

Not Available

Three different baluns have been designed using FDTD and verified by HFSS. It has demonstrated that all baluns have good return loss at the UBLP from 2 to 18 GHz when their BLP are connected with matched loads. Although balun-1 has the longest UBM to BM converting section, it has the lowest insertion loss when the wave transforms from UBM to BM. Th...

An inverted microstripline-fed linear tapered slot antenna element and a design of its 16-element E-plane array are presented in this paper. The element is designed using the finite-difference time-domain (FDTD) method. The calculated results show that it has a wide-impedance bandwidth in the K-band. To investigate the E-plane array, the return los...

A suspended microstripline-fed linear tapered slot antenna element and its E-plane linear arrays are presented in this paper. The element is studied and designed using the finite-difference time-domain (FDTD) method. The simulated results show that the element has a good antenna performance from 17 to 24 GHz. To build the E-plane arrays, a unique f...

The Vivaldi antenna is a very popular antenna element for those applications requiring a high-gain and a wideband traveling wave antenna element. The antenna usually has very long length L (≥3λ₀). Following basic traveling-wave antenna principles, the longer L, the higher the gain and narrower the beamwidth. Very few references appear in...

Thesis (Ph. D.)--McMaster University, 2000. Includes bibliographical references (p. 171-182).

The finite impulse response (FIR) neural network technique is applied as a nonlinear predictor to extrapolate a time-series signal from FDTD simulations. The FIR neural networks are trained by the temporal backpropagation learning algorithm. The model is applied to predict time-domain evolution in the FDTD simulation of a waveguide filter. ©1999 Jo...

The endfire linearly tapered slot antenna (LTSA) is of considerable interest as a wide band antenna element and has many potential applications such as the feed used with reflector antennas. We present the experimental investigation of the LTSA in an array environment. The study includes 1×2, 1×4, 1×8, 1×16 and 1×32 element arrays operating in the...

A 4-element multibeam microstrip smart antenna system at 1.96 GHz is presented. It can be used in communications system such as the base station antenna of land mobile radio system. Test results showed that this microstrip smart antenna system is capable of automatically adjusting its radiation pattern direction, tracking the stronger receiving sig...

There is considerable interest within the wireless community in the statistics of joint angle-of-arrival and time delay for signals arriving at a smart antenna for both indoor and outdoor propagation environments. These data are required for engineering smart antennas. In this letter we present the FDTD technique combined with adaptive array signal...

The finite-difference-time-domain (FDTD) method is applied to model some discontinuities that are present in C-band beam-forming networks. In particular, a branch line coupler, a phase shifter, and a slope equalizer are modeled. A FDTD algorithm, which makes use of nonuniform grids and a synthetic excitation, gives good results and saves computer r...

Since the mid-1970s, microstrip antennas have received a lot of attention, and significant achievement has been made to improve what is called the `inherent' narrow bandwidth and low gain. However, research in this field is still quite active. In contrast with traditional antenna technology, microstrip antennas provide the potential to form arrays,...

The finite difference time domain method (FDTD) is a very powerful numerical method to solve electromagnetic (EM) problems. It is very flexible to simulate the problems which have very complex boundaries. It is well known that FDTD method requires long computation time for solving the resonant or high-Q passive structures. The reason for this is be...

A method of using different diameters of conducting plates to tune the resonant frequency of cylindrical or ring dielectric resonator (DR) antenna, is presented. This technique has the following two advantages for the DR antenna design. The first is that it provides a very easy way of tuning a DR antenna to operate at the design frequency without c...

An accurate and efficient technique is presented for the analysis of large microstrip antenna arrays. The technique consists of an amalgamation of a spatially discrete scheme, consisting of the CG-FFT method and the complex discrete image (CDI) technique. The unique feature of this approach is the use of the spatially discrete CG-FFT for analyzing...

In recent years, the finite-difference time-domain (FDTD) method has emerged as one of the most popular full-wave numerical techniques for electromagnetic (EM) simulation due to its high level of accuracy, its usefulness for a broad range of structures, and its suitability for computer solution.1 Two examples illustrate the use of the FDTD method t...

The behaviour of the printed monopole when used with a finite ground plane differs considerably from the expected behaviour in an infinite ground plane. When the ground plane is small, this influences the resonant frequency, acting like a reflecting plane. The polarisation is not linear, and the dependence of the operating frequency with the dimens...

Experiments were conducted using a CT2 (operating in the 864-868 MHz frequency range) indoor wireless communications system to measure the received signal strengths in two indoor environments: a cafeteria, and a building corridor including pedestrians. For the cafeteria, a 2D ray launching model is used to predict the radio wave propagation. The mo...

Beam forming networks (BFN) are an important component of a complex satellite antenna system because they are used to provide accurate amplitude and phase excitation to the elements of the feed network. The need for handling high power and the need for a high degree of integrability, often leads one to choose square coaxial metal lines for construc...

There has been tremendous worldwide activity aimed at developing wireless personal communications systems (PCS). With these developments, antennas must meet tougher requirements such as smaller size, attractive appearance, and good gain. Since the frequency for the PCS is in the lower end of the microwave spectrum, the size requirements forces one...

In this letter, we combine the nonorthogonal FDTD method with a perfectly matched layer (PML) absorbing boundary condition to analyze waveguide structures. This combination provides a very useful numerical tool for modeling complex waveguide structures. The PML absorbing boundary condition is tested by simulation of propagation in a WR-75 rectangul...

The nonorthogonal finite-difference-time-domain method is applied to the analysis of structures in a square coaxial waveguide to demonstrate the influence of the mesh on the results. The analysis presented provides insight on how best to discretize the computational domain when modeling discontinuities with this method. Three structures, described...

Some considerations about the stability criterion and the dispersion of the finite difference time domain method in general curvilinear coordinates are presented. An expression for the stability criterion and for the dispersion relation is found to be possible only for a mesh without curvature, and for this particular case, a dispersion relation is...

It is well known that the Finite-Difference Time-Domain (FD-TD) method requires long computation times for solving electromagnetic problems, especially for high-Q structures. The reason for this is because the algorithm is based on the leap-frog formula. In this paper, both linear and nonlinear predictors, which are widely used in signal processing...

The finite-difference time-domain (FD-TD) method is combined with an appropriate time-frequency discrete conversion technique to analyze packaging and time domain transition effects of microwave and high speed digital circuits. The output response of a given input pulse is obtained by linear convolution of the input signal with time domain system f...

The perfectly matched layer (PML) superabsorbing boundary condition is adapted and applied to the non-orthogonal finite difference time domain method. The PML consists of a nonphysically realisable material with properties that are highly effective in absorbing electromagnetic waves. The PML gives excellent results when used with a curvilinear mesh

In this short article we present a new fast finite-difference timedomain (FDTD) method. Producing exactly the same solution to Maxwell's equations as Yee's classic FDTD method, the fast FDTD method offers up to a 50% reduction in the number of multiplications, which is a very important indicator of the computational complexity of an algorithm. Math...

The authors describe the incorporation of the autoregressive method (AR model) and Litva's dispersive boundary condition (DBC) into the finite-difference time-domain method (FD-TD). It is found that the performance of the FD-TD technique is greatly enhanced when used to simulate microwave passive circuits. The results of this study show that for th...

A novel scheme is proposed for rigorous analysis of waveguide circuits which are composed of a number of discontinuities. The scheme combines numerical techniques with analytical techniques, such as the mode-matching method. For a general complicated segment of the waveguide circuit, a numerical technique is used to generate the multimode general s...

The full-wave analysis of finite large printed dipole arrays is performed by the conjugate gradient-FFT method with full-wave discrete image technique. The CG-FFT method has the merits of saving computer memory and computing time. So it is very suitable for the efficient analysis of large printed dipole arrays by combining with the discrete image t...

The authors describe a novel active radiating module in which an FET source is integrated with a multilayer slot coupled patch antenna. A design procedure is given and the performance of an X -band prototype circuit is described. Prototype circuits showed 4.81-mW power output and 50-MHz tuning range at 4.893 GHz. The initial results suggest that th...

The CPW (coplanar waveguide) antenna element is shown to be an effective antenna element, whether used singly, as a two-element array, or as an eight-element array. It is also demonstrated that the finite-difference time-domain technique is a very effective diagnostic tool for designing array antennas. A very inexpensive technique for building phas...

A general approach to the analysis of microwave planar structures, specifically intended to treat complicated geometries and dielectric load, is presented. The proposed approach is based upon the coupling of the finite element and boundary element methods. Using the method, only the complex media subdomains, which may consist of lossy or anisotropi...

The finite-difference transmission line matrix (FD-TLM) method is applied to loss analysis for microstrip and coplanar waveguides (CPWs). A feature of FD-TLM with a variable mesh size is adopted in this loss analysis. The analysis is validated through a comparison with a frequency domain method. The numerical results provide a clear picture of freq...

A full-wave spectral domain model of a series-fed, traveling-wave aperture-coupled patch array antenna is presented. This configuration allows for performance optimization by adjustment of the aperture size, aperture location, and patch size. The theory successfully predicts the input impedance and far-field patterns of various C-band configuration...

An accurate analysis of an arbitrarily shaped microstrip antenna, electromagnetically coupled to a covered microstripline in a substrate superstrate configuration, is presented. The solution is based on the full-wave spectral-domain Green's functions for multilayer dielectric substrates and extended by incorporating the triangular finite element me...

A rigorous analysis of an aperture-coupled stacked microstrip antenna is described. Developed from a coupled integral equation set employing spectral-domain Green's functions, the analysis includes all coupling, radiation, and surface-wave effects. Proper choice of the path dimensions yielded VSWR bandwidths of greater than 20%. Theoretical and mea...