Super-resolution algorithms used in radar imaging, e.g., MUltiple SIgnal Classification (MUSIC), can help us to get much higher resolution image beyond what is limited by the signal's bandwidth. We focus on MUSIC imaging algorithm in the paper and investigate the uniqueness and effectiveness conditions of the MUSIC algorithm when used in 1-D radar range imaging. Unlike conventional radar resolution analysis, we introduced the concept of resolution threshold from Direction of Arrival (DOA) into the MUSIC radar range imaging, we derive an approximate expression of theoretical resolution threshold for 1-D MUSIC imaging algorithm through the approach of asymptotic and statistical analysis to the null spectrum based on the perturbation theory of algebra and matrix theories. Monte Carlo simulations are presented to verify the work.

The plasmonic effects of a gold prolate nanospheroid on the spontaneous emission of an adjacent emitter, regarded as an oscillating electric dipole, at the excitation and emission stages are studied respectively by using the multiple multipole method. The numerical results show that when an irradiating light is at the longitudinal surface plasmon resonance frequency of the nanospheroid and with a polarization parallel to the long axis, the strongest excitation rate occurs at the proximity of the long-axis vertex. In addition, if the emitter is at this region, and its orientation is also parallel to the long axis, the apparent quantum yield of the emission is the maximum, compared to the other locations and orientations. Therefore, for this case the overall enhancement factor of a nanospheroid on an emitter's spontaneous emission is the maximum. In contrast, the emitter's emission could be quenched, if it is near the short-axis vertex.

The paper presents an approach to locate and concentrate electromagnetic energy on targets based on time delays. An array of antennas is used in the approach, in which one antenna sends ultra-wide-band signals, and all antennas receive the signals backscattered by the targets. The time delays can be obtained by the interrelation of the transmitted and received signals. By controlling the timing of the pulses radiated from the individual antennas, high concentration of electromagnetic energy on the targets' locations can be achieved. The performance of this approach is demonstrated by several numerical simulations.

The paper deals with the case of a three-layer liquid crystal tapered optical fiber (LCTOF) for which the dispersion relations are deduced corresponding to the TE and the TM modes. For the LCTOF under consideration, the outermost clad section is made of liquid crystal material with radial anisotropy whereas the core and the inner clad are homogeneous, non-magnetic and isotropic dielectric regions. Rigorous field expressions corresponding to different LCTOF sections are deduced, and the eigenvalue equations are reported followed by the modal behaviour of the guide in respect of the propagation constants and cutoff situations. Apart from that, a glimpse of the power confinement through the TE and the TM excitations in different fiber sections is also touched upon.

This paper is a deep analysis of oscillator plane reference design methods. It defines applicable conditions and the expected accuracy that can be archived with these methods. Some examples will be shown to illustrate wrong solutions that the use of linear reference plane methods can produce. The wrong solutions will be justified by necessary conditions for proper use of these methods. The strengths and weaknesses of the, widely used, plane reference methods are described in this paper. Several classic topologies of microwave oscillators, as Grounded Collector Tuned Bases (GCTB) and Grounded Bases Tuned Oscillator (GBTO), are used to illustrate these results and the additional required conditions.

Dynamic temperature distributions in GaAs HBT are numerically analyzed in frequency domain as a function of power dissipation, frequency and space. Complete thermal characteristics, including frequency-dependent thermal impedance and phase lag behavior, are presented. The analysis is also extended for arbitrary periodic or aperiodic pulse heating operation to predict junction temperature of a Power Amplifier (PA) with non-constant envelope input signal. Dynamic junction temperatures of a single finger 2 μm x 20 μm GaAs HBT are predicted for square pulse envelope signal input with power levels varying with up to 10 dB above a nominal average level of 40 mW and with pulse widths ranging from 10 ns to 100 μs. With the input envelope signal amplitude of 10 dB above the average, the analytical results show that junction temperature rises from room temperature of 27^oC to 39^oC when heated by 10 ns pulse, increase to 36^oC by 100ns pulse, 105^oC by 1μs pulse and to 198^oC by 100 μs pulse. A novel setup is developed for nano-second pulsed measurements, and the analysis is validated through time domain on wafer pulsed measurements at three different power levels: 0 dB, 3 dB, and 6 dB above the average level. Results show that analytical results track well with measured junction temperature within the accuracy of ±5^oC over the entire measurement set.

A detailed analysis and design of thin planar absorbing structure using Jerusalem cross slot (JCS) is presented in this paper. Based on uniplanar compact high-impedance surface characteristics, the resistance loss material layer can be directly attached to the surface of JCS structure, thus absorbing electromagnetic waves effectively. The improved design is characterized by its wider bandwidth and adjustable range. The absorption frequency band can be flexibly adjusted by the slot parameters. The influences of various structure parameters of JCS, including incident wave polarization and variation of incident angles on the absorption properties, are analyzed to provide guidance on theoretical design for practical application. The loaded resistance can be adjusted to obtain the optimum absorbing performance. The validation and effectiveness of the proposed design are conducted by using X-band waveguide simulation and measurement.

This paper introduces an imaging algorithm with application of fractional Fourier transform (FrFT) for ground moving train imaging by Ku-band ground-based radar. In view of the fact that the train speed is varying when acrossing the radar beam, the multiple Doppler parameters are estimated corresponding to different range positions, i.e., they are estimated from different sections of data in FrFT domain, then the train is imaged section by section, and finally these sectional images are combined to get the full image of the train. Because traditional parameter estimation method by two-dimensionally searching the peaks in FrFT domain is inefficient, we transfer the parameter searching problem into an one-dimensional optimization problem, which can be solved with high efficiency by using the golden section searching method.

In this work, a millimeter wave microstrip frequency-mixer design based on graphene is presented. The desired frequency mixing behavior is obtained using a nonlinear component consisting in a microstrip line gap covered by a graphene layer. The circuit includes microstrip filters that have been designed to obtain a high isolation between the input and output ports. The nonlinear behavior of the frequency mixer has been experimentally evaluated in the 38.6-40 GHz input signal frequency range, for different values of the input power and local oscillator power.

The biosensor design for sensing of biological signals is highly complex for accurate detection. Optimal detection of biological signals is necessary for distinguishing different tissues. This paper proposes a threshold-based detection technique which provides significant improvement in FinFET optical biosensor performance using wavelet coefficients. It uses a simple maximum likelihood (ML) function for detecting the threshold values. In this method, we have considered the different layers of body tissue as a turbid medium. To the best of our knowledge, this method is the first of its kind for classifying different tissues using threshold value of optical signals obtained from the surface potential variations of nanoscale FinFET illuminated by laser source of different wavelengths. By using this method, the point to point variations in tissue composition and structural variations in healthy and diseased tissues could be identified. The results obtained are used to examine the performance of the device for its suitable use as a nanoscale sensor.

This paper considers a periodic circular cylinder array with additional cylinders and formulates the electromagnetic scattering problem of this imperfectly periodic structure. Generally, the fields in imperfectly periodic structures have continuous spectra, and the spectral-domain approaches require appropriate discretization schemes in many cases. The present formulation is based on the pseudo-periodic Fourier transform and the discretization scheme can be considered only inside the Brillouin zone.

This study develops a compact 28 GHz bandpass filter on a low-temperature co-fired ceramic substrate for applications in LMDS (Local Multipoint Distribution Service) bands. The filter comprises two pairs of verticallystacked cross-coupled open loops with vertical interconnection structures, achieving compactness, high integration, and superior frequency selectivity. Attaining selective response with two transmission zeros requires adjusting the couplings of adjacent resonators and external quality factor. The open loops are fed by using the three-via vertical interconnections to prevent any electrical effect on the filter. Measurements correlate closely with the simulation results: this study achieved a bandwidth of 2.1 GHz (27.6-29.7 GHz) with two zeros located at 25.8 GHz and 31.1 GHz, and a compact size of 2.69 x 2.66 x 0.4 mm³.

In this paper, we introduce a dispersion equation for 3D photonic crystals made of parallel layers of non-overlapping spheres, valid when both wavelength and separation between layers are much larger than the distance between neighbouring spheres. This equation is based on the Korringa-Kohn-Rostoker (KKR) wave calculation method developed by Stefanou et al.~and can be used to predict the spectral positions of bandgaps in structures made of dispersive spheres. Perfect agreement between the spectral positions of bandgaps predicted with our simplified equation and those obtained with the numerical code MULTEM2 was observed. We find that this simplified relation allows us to identify two types of bandgaps: those related to the constitutive parameters of the spheres and those related to the three dimensional periodicity (distance between layers). Bandgaps of the first type are independent of the frequency and the distance between layers, while those of the second type depend only on these two quantities. We then analyze the influence of the constitutive parameters of the spheres on the spectral position of bandgaps for spheres immersed in dielectric or magnetic homogeneous media. The number and positions of the bandgaps are affected by the permitivity (permeability) of the host medium if the spheres have dispersive permitivity (permeability).

In order to ensure that SAR scene matching aided navigation system can acquire the position errors and yawing errors simultaneously, we propose an image matching algorithm based on Scale Invariant Feature Transform (SIFT). However, the SIFT is proposed for optical image, and its performance degrades when used in SAR image. To enhance the adaptability of SIFT, two ways are employed. One is the application of a preprocessing on image pairs before matching. The other is the establishment of a scale and rotation restriction criteria on tie-points after SIFT matching. Compared with other matching methods, experiment results show that the proposed method is much more suitable for SAR image and successes in matching performance improvement. Furthermore, the method can meet the real-time requirement.

According to the scaling-down theory, the ALD-FET (Atomic Layer Doping-Field Effect Transistor) structure has attracted a lot of attention in view of its uses for developing devices with very short channels and for achieving very-high-speed operation. Therefore, there is a strong need to obtain an accurate understanding of carrier transport (mobility and conductivity) in such devices. In this work, we report the carrier transport based on the electronic structure of devices. Our results include analytical expressions of both mobility and conductivity. Our analytical expressions for the mobility and conductivity allow us to analyze transport in ALD-FET. We report regions where this device operates in digital and analogue mode. These regions are delimited in terms of intrinsic and extrinsic parameters of the system. The width of the Ohmic region as well as the NDR (Negative Differential Resistance) properties of the system are also characterized.

This paper presents a novel structure for compact dual-band balun design. The proposed structure is based on modified Marchand (with the fourth port shorted). To achieve the desired dual-band operation, two additional open-ended stubs are added to the two balanced ports of the modified Marchand balun. Explicit design equations are then derived using even-odd mode analysis. Finally, to verify the design concept, a microstrip balun operating at 0.9/2 GHz are fabricated on Duroid RO3210 printed circuit board. Measurement results are in good agreement with the theoretical predictions.

A new uni-planar structure branch-line coupler with broad bandpass response is proposed. Single section branch line couplers (SSBC) are popular due to their simplicity and ease of use but suffer from narrow return loss bandwidth and poor out of band rejection characteristics. The work presented here overcomes these limitations with the use of coupled port feeding. Through the study of input impedance of feeding network and single section branch line coupler, the bandwidth of the new coupler increased by almost 6-times. In addition, the coupler exhibited band-pass filtering characteristics. Measured results exhibited low insertion loss (≤4-dB), small magnitude difference (≤1-dB), good return loss and isolation (≥10-dB) and small phase variation (90°±5) within the passband. A measured bandwidth of 58% was achieved with this single section coupled port fed branch line coupler at a centre frequency of 1-GHz. Its two output ports achieved rejection levels better than 25 dB in the stopband.

In this paper, we propose a novel fuzzy-control-based particle filter (FCPF) for maneuvering target tracking, which combines the advantages of standard particle filter (SPF) and multiple model particle filter (MMPF). That is, the SPF is adopted during non-maneuvering movement while the MMPF is adopted during maneuvering movement. The key point of the FCPF is to use a fuzzy controller, which could imitate the thoughts of human beings in some degree, to detect the target's maneuver and use a backward correction sub-algorithm to alleviate the performance degradation of MMPF caused by detection delay. Simulation results indicate that the proposed algorithm has a much better tracking accuracy than the SPF while keeps approximately equal computational complexity. Compared with MMPF, both algorithms have no tracking lost, but the tracking accuracy of the proposed FCPF is a little better than the MMPF, and the FCPF consumes about 66% computation time of the MMPF. Thus, the proposed algorithm offers a more effective way for maneuvering target tracking.

Nowadays, millimeter-wave systems are being a key factor to develop wide band applications. In this paper, a directional coupler in millimeter-wave band using dielectric overlay is presented. This leads us to technology aspects, in directional coupler design, are key points to achieve the proper response of the circuit. The coupler proposed in this paper covers the 15-45 GHz band and its response has 15-dB coupling-level, 1-dB coupling-ripple and a reflection coefficient better than 10 dB.

Nonlinear optical processes have been used for sensitive detection of chemicals, optical imaging and spectral analysis of small particles. We have developed an exact theoretical framework to study the angular dependence of coherent anti-Stokes Raman scattering (CARS) intensity in the near field and far field for nanoparticle and microparticle. We obtain exact analytical solution for the CARS signal valid for arbitrary detection distance. Interesting angular dependence is found for nanoparticle, especially with near field detection. The study includes the effects of focused lasers and particle size on the CARS intensity distribution. We find that the detection distance and particle size do not affect the spectroscopic peaks of CARS. However, interference of reflected waves in nanoparticle can produce a dip in the backscattered spectrum.