This paper presents a compact and novel coupling structure for diplexers and power dividers based exclusively on coupled resonators. It consists of two cross-coupled structures joined together by two common resonators with a cluster of only four resonators. For a diplexer, it represents one of the most compact topologies that produces two 2nd-order channel filters with two fully controllable transmission zeros. This can be used to increase the rejection and isolations between channels without increasing the number of resonators. The same topology can also be used to realise a 3rd-order filtering power divider (FPD), with its embedded cascade trisection (CT) structure generating an asymmetric transmission zero. The coupling matrices of several diplexers and power dividers have been synthesized. Two microstrip diplexers with different positions of the transmission zeros have been demonstrated to verify the device concept. A 1.8 GHz FPD with a fractional bandwidth of 5% has also been prototyped, showing an improved out-of-band rejection from 15 dB to 25 dB below 1.71 GHz. The isolation performance of the divider has been investigated and improved from 7 dB to 18 dB across the band by adding only one resistor.

In animal production, behavioral selection is becoming increasingly important to improve the docility of livestock. Several behavioral traits, including motion, are experimentally recorded in order to characterize the reactivity of animals and investigate its genetic determinism. Behavioral analyses are often time consuming because large numbers of animals have to be compared. For this reason, automatization is needed to develop high throughput data recording and efficient phenotyping. Here we introduce a new method to monitor the position and motion of an individual sheep using a 24 GHz frequency-modulated continuous-wave radar in a classical experimental paradigm called the arena test. The measurement method is non-invasive, does not require equipping animals with electronic tags, and offers a depth measurement resolution less than 10 cm. Parasitic echoes (or ``clutters'') that could alter the sheep backscattered signal are removed by using the singular value decomposition analysis. In order to enhance the clutters mitigation, the direction-of-arrivals of electromagnetic backscattered signals are derived from applying the MUltiple Signals Classification algorithm. We discuss how the proposed automatized monitoring of individual sheep could be applied to a wider range of species and experimental contexts for animal behavior research.

For slower computation speed and lower classification accuracy of the traditional image classification methods, wavelet transform, multi-strategy, particle swarm optimization (PSO) algorithm and support vector machine (SVM) are introduced into image classification in order to propose a new remote sensing image classification (RIWMPS) method. First of all, wavelet transform method with multi-resolution characteristics is used to extract the features of remote sensing image. Then the steepest descent strategy, corrective decline strategy, random movement, aggregation strategy and diffusion strategy are used to improve the PSO algorithm to obtain an improved PSO (MSPSO) algorithm, which is used to optimize the parameters of the SVM model in order to construct an optimized SVM classifier for realizing remote sensing classification. Finally, the remote sensing image of Chongming Island is select to test the effectiveness of the RIWMPS method. The experiment results show that the RIWMPS method has higher classification efficiency and accuracy, and takes on better superiority and effectiveness. This study provides a new classification method for processing the remote sensing image.

Body worn antennas generally face the problem of isolation when operated in close proximity to human body. Use of magneto-dielectric material as substrate for antenna makes the system compact and reduces the influence of body on performance of antenna. In addition, miniaturization of antenna size also takes place. 7 wt.% of nano-sized Ni_0.5Zn_0.5 Fe₂O₄ is dispersed as magnetic filler in flexible linear low density polyethylene matrix. Beyond 7 wt.%, the sample stiffens and loses flexibility because of percolation limit of the polymer. Verification of the composite as a potential substrate for a body worn antenna is carried out by fabricating a coplanar waveguide fed simple rectangular monopole antenna, using transmission line model at 6 GHz. Antenna performance is studied by wearing the patch on human wrist. S₁₁ of -21.78 dB at 5.32 GHz and -10 dB bandwidth of 49.62% is observed. For comparison, an antenna at the same resonant frequency is developed on linear low density polyethylene with magnetic inclusions. The antenna on magneto-dielectric substrate shows better performance than dielectric substrate. The magnetic and dielectric properties of the Nickel Zinc Ferrite-linear low density polyethylene composite magneto-dielectric substrate reduces the influence of the human body which makes the antenna system compact and robust as additional techniques are not required for shielding of human body influence on antenna performance.

Metallic pipelines have attendant problems of alternating current (AC) assisted corrosion when installed in the utility corridor with high voltage transmission lines. Research studies in the past and recent years have shown that this corrosion is a primary function of the AC density through the pipe coating defect. While several other AC corrosion risk assessment indices have been proposed, the AC density is regarded as a valuable parameter in assessing pipeline corrosion risk due to AC interference. Also, there exists a threshold value which, if exceeded, guarantees the possibility of pipeline corrosion damage. However, for buried pipelines, monitoring these AC corrosion assessment indices is a major challenge. Therefore, to avoid severe corrosion damage to such pipelines, a corrosion assessment for evaluating the corrosion risk of the pipelines due to AC interference is presented in this paper. The assessment was demonstrated on a buried pipeline in one of the Rand Water sites, South Africa where AC interference is frequent. The overall simulation results yield useful information which may be essential for pipeline operators, most especially Rand Water, South Africa and corrosion engineers for AC corrosion assessment of metallic pipelines installed near transmission lines. The analysis presented in this paper may also be used for the evaluation of a safe position for installing new pipelines near existing power lines right-of-way.

Earlier, we considered the use of the apparatus of fractional derivatives to solve the two-dimensional problem of diffraction of a plane wave on an impedance strip. We introduced the concept of a ``fractional strip''. A ``fractional strip'' is understood as a strip on the surface, which is subject to fractional boundary conditions (FBC). The problem under consideration on the basis of various methods has been studied quite well. As a rule, this problem is studied on the basis of numerical methods. The proposed approach, as will be shown below, makes it possible to obtain an analytical solution of the problem for values of fractional order v = 0.5 and for fractional values of the interval v∈[0,1], the general solution needs to be investigated numerically.

A frequency-domain-based electromagnetic model of the lightning protection system of buildings is presented in this paper. Numerical model can accurately take into account all conductors of the lightning protection system, i.e. air-termination system, down-conductor system and earth-termination system. Using the presented electromagnetic model, attenuation effects of a grid-like spatial shield - sometimes used in lightning protection of buildings - will be analyzed for both the electric field and the magnetic field caused by a lightning strike. Three-dimensional distributions of the fields inside the shield are provided in the paper.

In this paper, a planar simplified dual composite right/left-handed (SD-CRLH) transmission line (TL) structure is proposed and applied to the design of branch-line coupler. The SD-CRLH TL is obtained by a microstrip line with an open-ended stub in spiral form. Since this structure has unusual phase shift characteristics with a transmission zero out of the passband, the branch-line coupler with the planar SD-CRLH TL can achieve both size reduction and harmonic suppression. Such a branch-line coupler operating at 0.915 GHz is investigated and fabricated. The equivalent circuit simulation, full-wave simulation and measurement results agree well with each other. From the results, it is shown that the area of the proposed branch line coupler is reduced by 74% compared to the conventional one while maintaining similar performance, and the second harmonic suppression can be lower than -45 dB.

A novel hexagonal ring-based reactive impedance surface (RIS) has been proposed and comprehensively employed as a ground plane of a circular polarized patch antenna (CPPA) for enhancing impedance bandwidth (IBW) and axial ratio bandwidth (ARBW), simultaneously. Furthermore, a simple analytical model analysis has been developed to estimate the resonance frequency and to predict the surface characteristics of the RIS structure. Two slits over the patch render the antenna to radiate circular polarized (CP) wave. The RIS has improved the CP antenna performance in terms of compactness, improved gain and increased efficiency. The proposed loaded structure has been numerically and experimentally studied with a layout of 40×40×3.2 mm³ at 3.7 GHz. The measured results indicate that the prototype antenna has produced a relatively wider IBW and ARBW of 9.32% and 2.1%, respectively with peak gain about 2.98 dBiC. Both gain and efficiency of the loaded structure have been improved owing to the low conductive loss of the ring-shaped RIS. The proposed CP antenna might be suitable for radar application used in S-band.

The article analyzes a nine-channel Wavelength Division Demultiplexer based on a two-dimensional photonic crystal lattice. In the design of the device, defects and air holes are shifted in the resonant cavities: by changing characteristics such as radii of defects, distance between them and position of defects, a compact optical filter circuit is designed with a 1 nm channel spacing. The properties of these devices are investigated using finite-difference time-domain method. The resonant wavelengths of nine channel demultiplexers are 1481.4, 1503.7, 1526.6, 1538.4 ,1550.3, 1562.3, 1574.7, 1587.2 and 1612.9 nm. The value of transmission efficiency for channels was obtained in 79-96% range. In addition, the maximum value of crosstalk and average quality factor for channels were calculated -11.3 dB and 2000, respectively. The overall size of the structure is small (11.3 μm × 15.3 μm) which is suitable for photonic integrated circuits and optical communication network applications.

This paper deals with uncertainty propagation applied to the analysis of crosstalk in printed circuit board microstrip traces. Complex interconnection networks generally are affected by many uncertain parameters and their point-to-point transfer functions are computationally expensive, thus making Monte-Carlo analyses rather inefficient. To overcome this situation, a metamodel is highly desirable. This paper presents a sparse and accelerated polynomial chaos approach, which proves to be well adapted for high-dimensional uncertainty quantification and well suited for the sensitivity analysis of crosstalk effects. We highlight the significant advantage of the advocated approach for the design of microstrip line networks of complex topology. In fact, we demonstrate how a small number of system simulations can help to quantify the statistics of the output variability and identify a reduced set of high-impact parameters.

A compact wideband bandpass filter (BPF) based on half-mode substrate integrated waveguide (HMSIW) is proposed in this paper. The proposed BPF is achieved by etching a couple of S-shaped complementary spiral resonators (S-CSRs) on the top layer of HMSIW cavity to achieve a wide passband as well as generate two transmission zeros in the vicinity of the passband respectively to improve the selectivity. In addition, compared with a conventional CSRs-loaded HMSIW structure, the proposed S-CSRs-loaded HMSIW makes the overall size of the filter largely reduced with the same electrical length. Among the HMSIW structures ever reported, the proposed S-CSRs are the first time to be introduced into HMSIW. To validate its practicability, a compact wideband HMSIW BPF loaded with S-SCRs has been designed and implemented through the PCB process. The measured and simulated S-parameters of the filter are presented to show the proposed filter's predicted performance, and good agreements is obtained between them. This result demonstrates that the newly proposed HMSIW structure loaded with S-CSRs is an excellent candidate for compact filters.

A simplified design of substrate integrated waveguide (SIW) is proposed here. The requirement of side walls using via which is quite cumbersome in the manufacturing process is eliminated in this structure. The design is based on producing an imaginary electric boundary by exciting the SIW using differential feed. It behaves as a pair of half mode substrate integrated waveguides (HMSIWs) sharing a common electric boundary. The new structure gives similar characteristics of the conventional SIW in terms of cutoff frequency, stopband rejection and operating bandwidth.

When a narrow straight slot is etched obliquely in the upper metallic strip of a microstrip line, a bandstop response can be observed from the terminations of the microstrip line. The whole circuit behaves as a single-stage bandstop filter, of which the center operation frequency and the fractional bandwidth can be adjusted by changing the length and the inclined angle of the slot, almost independently. Parametric studies are made to demonstrate the filtering performance, via numerical simulations. An LC equivalent circuit model is given to explain the bandstop behavior, shows its potential use in high order filter design. Samples are designed, fabricated and measured for verification, the experiment results show that the filters have good bandstop performance. It can be used as an alternative or complementary candidate for the traditional spur-line bandstop filter.

In this work, we report a novel phase change material: Hf-doped VO2(M1) with negligible thermal hysteresis width for low-power silicon photonic reconfigurable device applications. As dopant concentration rises from 0% to 3%, the material maintains the metal-insulator transition (MIT) property of VO2(M1) thin films, and the thermal hysteresis width significantly narrows from 7 ºC to <1 ºC, leading to a good control of material electrical and optical constants as a function of temperature. A ring resonator with Hf-doped VO2(M1) material partly deposited on the ring has been fabricated. Temperature dependent transmission spectrum of the device has been tested, which shows resonant peak shift due to the phase transition of Hf doped VO2(M1). Doping Hf makes this material become a promising candidate for a variety of silicon integrated reconfigurable photonic devices.

Traditionally, the direction of arrival (DOA) estimation usually employs homogeneous antenna arrays consisting of many identical antennas. This paper proposes a new technique of DOA estimation by using a heterogeneous array which has many elements with each element pointing to a different direction from others. A general expression of the manifold for planar heterogeneous array is derived. Then, a polarized MUSIC (Pol-MUSIC) method for unknown polarizations is proposed. One advantage of this Pol-MUSIC method is that it can obtain the DOA of signals with any unknown polarizations while no search of the polarizations is required. The proposed method is verified by simulation, and its performance is analyzed. The heterogeneous array is a polarization-sensitive array though it has one channel at each point of spatial sampling. This provides favorable conditions for simplifying the systems.

In order to effectively improve the communication quality in the extremely-low frequency (ELF) communication, an integrated model of the analog circuit combined with the multi-channel array algorithm is constructed, and a highly sensitive magnetic sensor is designed. An array algorithm based on generalized singular value decomposition is proposed to find the optimal filter coefficient, and then to achieve the purpose of suppressing interference in ELF communication. In the manufacture of magnetic antenna, the method of partitioned windings divided by acrylic effectively reduces the distributed capacitance of the magnetic antenna, and the rational design of the amplification filter circuit lays the foundation for the interference suppression in the next step. Specific process of the proposed algorithm is deduced. The corresponding evaluation indices are given, and the correlation among evaluation indice is expounded. The simulated and experimental results are discussed respectively. The experimental setups are designed and presented. The results show that no matter which the simulated signal or the experimental data is, the proposed algorithm can effectively suppress the interference, and the output signal to interference ratio is increased by 30 dB.

A new microstrip ultra-wideband (UWB) bandpass filter (BPF) with quad notched bands using quad-mode stepped impedance resonator (QMSIR) is investigated in this paper. The resonance properties of the QMSIR are studied. Then, quad notched bands inside the UWB passband are implemented by coupling the proposed QMSIR to the main transmission line of a basic microstrip UWB BPF. The quad notched bands can be easily generated and set at any desired frequencies by varying the design parameters of QMSIR. For verification, a new microstrip UWB BPF with quad notched bands respectively centered at frequencies of 5.2 GHz, 5.8 GHz, 6.8 GHz and 8.0 GHz is designed and fabricated. Both simulated and experimental results are provided with good agreement.

In this study, a varactor-loaded slotted ground structure is investigated and utilized to construct a new tunable common-mode (CM) suppression filter for differential signals. A four-port distributed equivalent circuit model is developed for interpreting the working mechanism of CM signal suppression. It is found that the proposed simple structure is capable of tunable CM suppression with a wide frequency tuning range. The parameter selection and design principle are also given. Finally, the design theory is well vindicated by a common-mode filter using three periodic varactorloaded slots. Simulated and measured results, showing good agreement, exhibit a tuning range from 0.80 to 2.10 GHz, corresponding to the fractional tuning range of 89.7% and more than 30 dB CM rejection level.

A wideband circularly polarized antenna with wide half power beamwidth (HPBW) and 3 dB axial-ratio beamwidth (ARBW) is proposed in this paper. The circularly polarized (CP) radiation is realized by feeding two crossed printed dipoles through a wideband feeding network with broadband 90º phase shift. By adding a thick substrate layer and a notched-corner metal cavity around the antenna, the impedance bandwidth (VSWR < 2) is greatly enhanced. The HPBW of the proposed antenna are greater than 110º while the ARBW are greater than 130º in the operating band, simultaneously. The overall dimension of the antenna is only 70×70×36 mm³. The measured results show that the impedance bandwidth of the proposed antenna reaches 54.7% (1.06 GHz-1.86 GHz) while the AR bandwidth (AR<3 dB) is 48.6% (1.08 GHz-1.78 GHz). As such, the proposed antenna can be widely used in various global navigation satellite system (GNSS) applications.