Chuangming Tong

Bio: Chuangming Tong is an academic researcher from Southeast University. The author has contributed to research in topics: Scattering & Physical optics. The author has an hindex of 11, co-authored 88 publications receiving 396 citations.

Y-junction power divider based on substrate integrated waveguide

Abstract: The substrate integrated waveguide (SIW) plays a very important role in millimetre-wave and microwave integrated circuits and systems with low return loss and high Q-factor. Also, the half-mode substrate integrated waveguide (HMSIW) has been developed in recent years. A new Y-junction four-way power divider is proposed by integrating the 90° Y-junction SIW power divider and HMSIW power divider. Simulated and measured results show that the return loss of the input port is below -15 dB over 8.6 to 12.2 GHz and transmissions are about -7.6 dB ± 0.2 dB in the passband. So, it makes the 6 dB power divider used preferably in a broad bandwidth. The new power divider can be produced in batches and can be widely used in millimetre-wave and microwave circuits owing to its simple and novel structure.

SIW-Fed Yagi Antenna and Its Application on Monopulse Antenna

Abstract: Planar Yagi antennas are commonly hard to possess simple structure, high gain, and broad bandwidth at the same time. In this letter, a new substrate integrated waveguide (SIW)-fed Yagi antenna is proposed with nonplanar director element, and it achieves bandwidth of 25.7% and gain of 9.46 dBi at 10.0 GHz. Integrated of an SIW hybrid ring coupler, a Yagi monopulse antenna is designed. Measured gain of the sum pattern is higher than 13 dBi, whereas the maximum null depth of the difference pattern is lower than ${-}$ 20 dB in 9.4–10.05 GHz. This type of monopulse antenna presents an excellent candidate in directional-finding system.

Extraction of Vibrating Features With Dual-Channel Fixed-Receiver Bistatic SAR

Abstract: Strong ground clutter may submerge the signals of vibrating targets and bring great difficulties to extract their micro-Doppler (m-D) signatures. Furthermore, if the vibrating direction is perpendicular to the radar line of sight, its m-D would be very weak in the monostatic synthetic aperture radar (SAR). In this letter, a configuration of bistatic SAR with a dual-channel fixed receiver is presented to handle the two problems. The displaced phase center antenna technique is adopted to suppress the clutter and to reserve the signals of vibrating targets in the range-compressed data domain. Then, the fractional Fourier transform is utilized to compensate for the radar Doppler shift. Finally, the m-D feature of vibration can be extracted effectively by using time-frequency transform. The validity of the proposed method is evaluated with simulated data.

Wideband Hybrid Ring Coupler Based on Half-Mode Substrate Integrated Waveguide

Abstract: A substrate integrated waveguide ring coupler and a half-mode substrate integrated waveguide ring coupler in X-band are designed from the principle of traditional 180 ° hybrid ring coupler. The HMSIW hybrid ring coupler, adopted closed side to closed side designing for connections of HMSIW branches, is proposed for the first time. It has 24.6% bandwidth for the amplitude imbalance of coupling coefficient less than ±0.5 dB and phase differences between outputs are 15.0 ° ~ -5.8 ° and 175.5 ° ~ 189.7 ° for the in-phase and the out-of-phase operations, respectively, which shows much better performance than SIW coupler.

Bistatic Scattering from Two-Dimensional Dielectric Ocean Rough Surface with a PEC Object Partially Embedded by Using the g-Smcg Method

Abstract: An e-cient approach called general sparse matrix canonical grid (G-SMCG) method is proposed to analyze the electromagnetic scattering from 2-D dielectric rough surface with a conducting object partially buried. In this paper, the scattering of 3-D arbitrarily shaped object is computed by using the traditional method of moments (MoM) with RWG basis function, and the scattering of rough surface is analyzed by using the SMCG method. The coupling interactions between an object and rough surface are calculated by iterative method. Combing the ocean rough surface with Pierson Moskowitz (PM) spectrum, the bistatic scattering coe-cients of typical objects buried in the ocean surface have been computed by using the proposed method. Then the accuracy and e-ciency of this method are discussed. Finally, the bistatic scattering coe-cients of a ship located on ocean surface are calculated, and the in∞uence of sea state and wind direction on the scattering coe-cients is indicated.

Table Of Integrals Series And Products

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A novel acceleration algorithm for the computation of scattering from rough surfaces with the forward-backward method

Abstract: The forward-backward method has been shown to be an effective iterative technique for the computation of scattering from one-dimensional rough surfaces, often converging rapidly even for very large surface heights. However, previous studies with this method have computed interactions between widely separated points on the surface exactly, resulting in anO(N2) computational algorithm that becomes intractable for large rough surface sizes, as are required when low grazing incidence angles are approached. An acceleration algorithm for more rapidly computing interactions between widely separated points in the forward-backward method is proposed in this paper and results in an O(N) algorithm with increasing surface size. The approach is based on a spectral domain representation of source currents and the Green's function and is developed for both perfectly conducting and impedance boundary surfaces. The method is applied in a Monte Carlo study of low grazing incidence backscattering from very rough (up to 10 m/s wind speed) ocean-like surfaces at 14 GHz and is found to require only a small fraction of the CPU time required by other competing methods; such as the banded matrix iterative approach/canonical grid and fast multipole methods.

Frequency Selective Surfaces: A Review

Abstract: The intent of this paper is to provide an overview of basic concepts, types, techniques, and experimental studies of the current state-of-the-art Frequency Selective Surfaces (FSSs). FSS is a periodic surface with identical two-dimensional arrays of elements arranged on a dielectric substrate. An incoming plane wave will either be transmitted (passband) or reflected back (stopband), completely or partially, depending on the nature of array element. This occurs when the frequency of electromagnetic (EM) wave matches with the resonant frequency of the FSS elements. Therefore, an FSS is capable of passing or blocking the EM waves of certain range of frequencies in the free space; consequently, identified as spatial filters. Nowadays, FSSs have been studied comprehensively and huge growth is perceived in the field of its designing and implementation for different practical applications at frequency ranges of microwave to optical. In this review article, we illustrate the recent researches on different categories of FSSs based on structure design, array element used, and applications. We also focus on theoretical breakthroughs with fabrication techniques, experimental verifications of design examples as well as prospects and challenges, especially in the microwave regime. We emphasize their significant performance parameters, particularly focusing on how advancement in this field could facilitate innovation in advanced electromagnetics.

Capacitive Circuit Method for Fast and Efficient Design of Wideband Radar Absorbers

Abstract: A simple, fast and efficient method for designing wideband radar absorbers is proposed. The idea is to modify the circuit analog absorber method without perturbing the bandwidth. This is done by utilizing the asymptotic behavior of such an absorber at low frequency and replacing the band-stop resonating frequency selective surfaces with low-pass capacitive ones, which can be synthesized by square patches. It is shown that higher frequencies are not influenced by these modifications. A thin wideband capacitive circuit absorber (CCA) is presented with 28% reduction of thickness and 57% increase of bandwidth in comparison to the Salisbury screen. It is also explained why some optimized metamaterial designs fail to compete with the CCA method. For high permittivity layers, it is shown that the CCA is a better solution than the Jaumann absorber and improvements both in thickness and bandwidth are possible. A three layered ultra wideband (4-24 GHz) CCA is presented with total thickness of 15.1 mm. Finally, a design capable of handling oblique angles of incidence for both polarizations and fulfilling different mechanical, thermal and fabrication constraints is given. The absorption band covers the entire C, X and Ku radar bands (4-18 GHz), showing significant improvement compared to the published circuit analog absorbers. (Less)

Review of micro-Doppler signatures

Abstract: Micro-Doppler signals refer to Doppler scattering returns produced by the motions of the target other than gross translation. The small micro-motions of a subject, and even just parts of a subject, can be observed through the micro-Doppler signature it creates in response to an active emitter such as a radar, laser, and even acoustic emitters. These micro-Doppler signatures are produced by the kinematic properties of the subject's motion and can be used to extract the salient features of the subject's motion, and often, identify the subject. The rapidly declining cost of micro-Doppler-capable active sensors like radar with their dramatically improving capabilities, provide significant motivation in developing micro-Doppler techniques that can improve the exploitation of these sensors. Micro-Doppler techniques aim at extracting the micro-motion of the subject that may be unique to a particular subject class or activity in order to distinguish probable false alarms from real detections, as well as to increase the value of the information extracted from the sensor. The source of micro-motion depends on the subject and can be a rotating propeller on a fixed-wing aircraft, the multiple spinning rotor blades of a helicopter, or an unmanned aerial vehicle (UAV); the vibrations of an engine shaking a vehicle; an antenna rotating on a ship; the flapping wings of birds; the swinging arms and legs of a walking person; and many other sources. Confuser detections, such as birds for UAVs or animals for humans, can be interpreted as false alarms for a sensor system, so using the available micro-Doppler returns for classification can significantly reduce the sensor false alarm rate, thereby improving the utility of the sensor system. This study reviews the current research in micro-Doppler based on subject type, sensor capabilities, as well as environmental effects, and then proposes future research areas for micro-Doppler.