This paper presents a compact diplexer with high selectivity. The proposed diplexer employs two sets of triple-mode bandpass lters. Using this approach, the pair of even-mode resonant frequencies can be flexibly controlled by adjusting the characteristic impedance or electrical lengths of the two open-circuited stubs while the odd-mode resonant frequency remains at the fundamental resonant frequency. For a demonstration, a diplexer with two passbands centred at 1.50 and 1.70 GHz and the transmission zeros are created close to the passband edges which extremely improve the skirt selectivity. As a result, the proposed diplexer occupies an extremely small area, i.e., approximately 0.30λ_g x 0.35λ_g. The measured results are in good agreement with the simulated predictions.

Multiple target situation is a typical situation of nonhomogeneous clutter environment, which can cause excessive target masking in radar signal detection system. In order to reduce target masking caused by multiple target situations, this paper proposes a new detection structure based on positive-denite matrix space and limited training samples. The proposed detection structure uses a positive-denite matrix to estimate the background power level. In addition, with limited training samples, the detection structure is used to resist the multiple target situations. The simulation results show that the proposed detection structure exhibits a better detection performance than that of the well-known CA-CFAR in homogeneous environment. The detector also performs robustly in multiple target situations, even though 10 interfering targets exist in a length of 24 samples of reference window. Furthermore, the measured results validate the performance of the proposed method.

A wideband omnidirectional circularly polarized (CP) patch antenna is proposed in this paper. The proposed antenna is composed of a disk-loaded coaxial probe and four pairs of modified Γ-shaped strips loaded with shorting pins. Each pair of modified Γ-shaped strips consists of an inner Γ-shaped strip and an outer Γ-shaped strip. The approach employed in this design to improve the impedance bandwidth is to add an inner Γ-shaped strip and make it couple to the outer one. By introducing the two coupled Γ-shaped strips, two different monopole modes can be achieved simultaneously and controlled separately by two different corresponding parts of these two Γ-shaped strips, respectively, and they can be merged to realize a wide-band impedance matching. Meanwhile, the dual minimum axial ratio (AR) points around the resonance frequency of the antenna are excited by the coupled Γ-shaped strips, and they can be reallocated closely to each other for wide AR bandwidth. In the design, the monopole mode of the patch antenna is excited by the disk-loaded coaxial probe for generating the θ-polarization and the Γ-shaped strips are utilized for achieving the φ-polarization. Omnidirectional CP radiation pattern is obtained once the two orthogonal components are equal in amplitude but in phase quadrature. is conducted to further verify the proposed design.

The presence of the primary field in the helicopter transient electromagnetic system makes the dynamic range of the response signal so large that it is difficult to observe the secondary field. Therefore, a bucking coil is usually introduced to eliminate the primary field. However, in a traditional design, the size of the bucking coil increases with the size of the system, which makes the bucking coil hard to install, and opposite magnetic moment is large in huge systems. In this paper, a new bucking coil design for a helicopter transient electromagnetic system is proposed. Compared with the traditional design, the bucking coil diameter, total weight and total magnetic moment in two designs are calculated. The results show that the bucking coil we designed is more than 8 times smaller and 5 times lighter than that in the traditional design, which is easier for installation. The bucking moment impact is reduced to 0.03% of the total magnetic moment when the diameter of the transmitting coil increases to 35m, which improves the efficiency of the system. Then we analyze the requirement of manufactory precision and installation accuracy for the bucking coil in our design to get the best bucking result.

In this work, an E-shape Defected Ground Structure (DGS) is achieved to reduce the mutual coupling between two nearby microstrip antennas up to 47%(from 0.064 to 0.03). Both antennas radiate in the same frequency band of 10 GHz. The technique is based on a wall integrating periodic structure permitting the absorption of the electromagnetic field. By using this structure, it was possible to achieve a 20dB reduction in the insertion loss S21 between the two microstrip patch antennas with center-to-center distance of 0.37λ0 (λ0 is the free-space wavelength). The obtained coupling coefficient demonstrates that we have a good isolation between the two antennas. EM solver, simulating and measuring the reflection and transmission coefficients of the designed antenna arrays, achieves the reduction of the mutual coupling. The simulated results are verified by measuring the fabricated prototypes.

In the spatial dimension, the variation of the wind speed along the overhead transmission line makes the conductor temperature and line parameter show a nonuniform distribution characteristic, which has an important influence on the operating status of the system. In order to describe the actual situation more accurately, a line cutting model based on the wind speed variation along the line is proposed. This paper proves the application value of the model by using a typical 4-bus system. From the two aspects of the power flow and the maximum power transmission capacity, we contrast the line cutting model with the traditional models, indicating that the cutting model is closer to the actual situation of the system.

This paper presents a novel binary algorithm named as binary butterfly mating algorithm (BBMO) combined with sub-array strategy for thinning of antenna array. The proposed algorithm has been adapted from a recently developed nature inspired optimization, butterfly mating optimization (BMO). The subarray strategy is dividing the linear array into two parts, one part with a fixed number of element turned on in the middle of array and the rest elements on the edge of array composing another subarray. In order to reduce the complexity of the thinning process, BBMO algorithm is used to optimize the element on the edge of an array. The proposed BBMO with subarray strategy is used to synthesize a linear sparse antenna array in order to reduce maximum sidelobe level and at the same time keeping the percentage of thinning equal to or more than the desired level. To evaluate the performance of the proposed thinning method, a linear array with 100 elements is optimized by BBMO algorithm without and with subarray strategy. And we discuss the impact of number of fixed elements on thinning results. The novel method BBMO with subarray strategy gives reduced SLL as compared to the results available in literature of ant colony algorithm, genetic algorithm, binary differential evolution algorithm, chaotic binary particle swarm optimization, and improved binary invasive weed optimization algorithm. Moreover, the convergence rate of BBMO with subarray strategy is faster than BBMO without subarray strategy and the other methods.

Wideband arrays have recently received considerable attention in 5G applications to cover larger frequency bands. This paper presents a novel design of a high gain and wideband antenna subarray from 23 GHz to 32 GHz, which covers the frequency bands proposed by the Federal Communications Commission (FCC) for 5G communications. The proposed subarray consists of four radiating elements with wideband and high gain characteristics. These elements are composed of two stacked patches, which are fed using the proximity coupling technique. A unit-cell element prototype is first fabricated and tested to validate the gain and bandwidth performances. A 1x4 subarray prototype is then fabricated and tested, while maintaining an element spacing less than half-wavelength at the center frequency, to avoid grating lobes and to keep the small size of the antenna subarray. The measurement results of the prototypes, i.e. unit cell element and subarray prototypes, show good agreements with the simulations. The subarray measurements demonstrate a high gain of 10-12 dBi, an impedance bandwidth of 33.4 %, and a 1-dB gain bandwidth of 10.5 %. The proposed antenna subarray is a good candidate for wideband and high gain antenna arrays suitable for 5G mmW applications.

A parallel frequency-dependent, finite-difference time domain method is used to simulate electromagnetic waves propagating in dispersive media. The method is accomplished by using a single-program-multiple-data mode and tested on up to eight Nvidia Tesla GPUs. The sppedup using different numbers of GPUs is compared and presented in tables and graphics. The results provide recommendations for partitioning data from a 3-D computational model to achieve the best GPU performance.

This study proposes a real-time method to solve the electromagnetic inverse scattering problem. This technique converts this problem into a regression problem using a support vector machine (SVM). The SVM-based solution successfully deals with the nonlinearity and ill-posedness inherent in thisproblem. Simulation results show the feasibility and effectiveness of the proposed method. The method can effectively locate the tumor target of the stomach regardless of the presence of noise. The positioning effect of the method improves as SNR increases. When the SNR is higher than 50 dB, noise minimally affects the results. Finally, the SVM prediction model is utilized to study the effect of the number of sampling locations on the prediction results. The results show that the more sampling locations, the better the prediction results.

A microstrip antenna system operating in the 2.4 GHz WLAN band is presented for in-band full-duplex operation. The design includes a patch antenna fed by a 180° hybrid. Two feeding methods are presented, probe and aperture. The measured bandwidths are 2.5% (60 MHz) and 2.1% (50 MHz) for the probe fed and aperture fed, respectively. The probe fed system reaches measured isolation (S21) < -50 dB and the aperture fed < -45 dB in a reflective environment. The design also has an omnidirectional radiation pattern, reasonable gain values, and a very low envelope correlation coefficient (<0.01).

Comb generator has been an indispensable tool in the electromagnetic compatibility (EMC) testing field. It is used for calibration and self checking of the test systems. This paper presents a rarely explored yet promising radiated comb generator that makes use of a single-ended PECL D Flip-Flop as the pulse forming component. Measurements show that the generated pulses typically possess fall time and rise time of 330 ps and 410 ps, respectively. Its frequency accuracy is offset by +24 ppm, which is common for crystal oscillators. When being connected to a monopole rod antenna, the comb generator is able to generate radiated emissions that have smooth envelope profile up to 1000 MHz frequency range.

A magnetic resonance imaging (MRI) duodenoscope is demonstrated, by combining non-magnetic endoscope components with a thin-film receiver based on a magneto-inductive waveguide. The waveguide elements consist of figure-of-eight shaped inductors formed on either side of a flexible substrate and parallel plate capacitors that use the substrate as a dielectric. Operation is simulated using equivalent circuit models and by computation of two- and three-dimensional sensitivity patterns. Circuits are fabricated for operation at 127.7 MHz by double-sided patterning of copper-clad Kapton and assembled onto non-magnetic flexible endoscope insertion tubes. Operation is verified by bench testing and by 1H MRI at 3T using phantoms. The receiver can form a segmented coaxial image along the length of the endoscope, even when bent, and shows a signal-to-noise-ratio advantage over a surface array coil up to three times the tube diameter at the tip. Initial immersion imaging experiments have been carried out and confirm an encouraging lack of sensitivity to RF heating.

A broadband ultra-high-frequency (UHF) Radio Frequency Identification (RFID) antenna using double-tuned impedance matching theory is proposed. This paper presents a proximity coupled vertical meandered strip feed technique based on double-tuned impedance match which results in a wide bandwidth. This antenna mainly consists of a rectangular ground plane, a U-shaped radiation patch, and a suspended vertical meandered strip (VMS) by mesas of rotated г-shaped strip. The U-shaped radiation patch is fed by the VMS. The simulated and measured results show that the antenna has a very wide impedance matching bandwidth of 150MHz (820-970 MHz) or 16.8% with the voltage standing wave ration (VSWR) less than 1.5 and achieves a high gain level about 8.5 dBi. Therefore, the proposed antenna can cover the entire UHF band of 840-960 MHz and is a good candidate for universal UHF RFID applications.

This paper presents design and analysis of six different configurations of Coplanar Waveguide Band Reject Filters (CPW-BRF) using Rectangular Dumbbell Electromagnetic Band Gap (RDEBG) cell structures. The performance in terms of rejection bandwidth, attenuation, cutoff characteristics of the proposed design are found superior to the earlier reported CPW-BRF. Using cascading of six RDEBG cells, rejection bandwidth has been improved up to 2.8 GHz with attenuation of -38.8 dB and filter selectivity of 26.9 dB/GHz. In addition, the radiation losses have also been analyzed by extracting equivalent R, L and C values from electromagnetic (EM) simulation results. Fabricated CPW-BRF using four RDEBG cells has been analyzed. For the fabricated CPW-BRF simulated and measured results are found in good agreement.

This paper presents an unequal-split Bagley power divider that consists of uniform transmission lines and is terminated at different impedances. This divider should be only adjusted by altering the length of the transmission lines. Such alteration of the transmission lines will result in an arbitrary power ratio between output ports. The Bagley divider consists of uniform transmission lines of same characteristic impedance value despite different impedances for input and output port termination. For analysis, two Bagley dividers are considered, one 3-way and one 5-way divider, both with arbitrary power ratio and arbitrary termination impedances. A good agreement can be observed between the simulated and measured results.

On the basis of equivalent circuit analysis, we investigated the electromagnetic characteristics of artificial dielectric layers (ADLs) having arrays of square metal patches for the normal incidence of plane waves, where the electromagnetic wavelength ranges from p/10 to p/2 (p: period). A good agreement was obtained between measured and calculated S parameters and electromagnetic parameters (permittivity and permeability) for a fabricated ADL except at around 5.2 and 9.2 GHz. A possible cause of the discrepancy between the measured and calculated electromagnetic characteristics is discussed by investigating the electromagnetic wave propagating along the surface of the ADL. Applications of the equivalent circuit analysis to ADLs with other geometries are also discussed.

A simple but efficient method is investigated for predicting electromagnetic interference between antennas on vehicles. By modeling the vehicle body with a conducting wedge, the geometrical optics and uniform theory of diffraction are used to predict the interference power. Comparisons show that the interference power can be accurately predicted with only four dominating rays taken into account. The presented method is validated by measurements in typical environments. A further investigation of various parameters considered in predictions is also presented. Based on the proposed method, the interference power can be easily predicted just in MATLAB instead of the time-consuming full-wave simulation of the entire large-scale structure.

This work presents the design of a magneto-electric dipole (MED) antenna for the base station antenna of FM radio broadcasting implementation. The advantages of MED antenna are high gain, stable and symmetrical radiation patterns in both electric and magnetic planes, and low back lobe radiation pattern. The antenna was designed and studied to achieve the optimal dimensions of configuration parameters. The prototype antenna was fabricated and measured to validate its S11, radiation patterns, and gain. The impedance bandwidth was 33.49%, and the average gain was 7.78 dBi at the entire operating frequency (88-108 MHz). The measured results are in good agreement with the simulated ones.

This paper proposes a two-element LTE MIMO handset antenna with physically different main and diversity antennas. The performance of the design is studied theoretically and experimentally. The investigated design utilizes physically different main and diversity antennas to improve especially the low-band MIMO performance. A Combined Parasitic-coupled, Aperture-Matched (CPAM) antenna is used as the main antenna, and the diversity antenna is a simple Capacitive Coupling Element (CCE) design. The antenna covers the LTE bands from 698-960MHz and 1710-2690MHz with fixed matching circuits suitable for low-band (LB) Carrier Aggregation (CA). Measured total efficiency of the antennas is from -3 to -6 dB and -2 to -5 dB at the low and high bands, respectively. In the MIMO case, envelope correlation (ECC) and multiplexing efficiency are studied also from measurements.