A novel wafer level integrated low-insertion-loss filter working at 1.8 GHz (DCS LPF) with suspended inductors and patterned ground shields on the lossy silicon substrate is fabricated. Thick BCB interlayer is used as the supporting dielectric, and the backside cavity on Si wafer is formed by using a two-step back-etching process. The influence of patterned ground shields on the Q factor of the suspended inductors and the influence of low-resistivity silicon on the insertion loss of filters are analyzed by EM simulation. The fabricated 2.7 nH inductor has a maximum Q factor of 49 at 8.2 GHz and high Q factors more than 22 in the broadband frequency range from 1 GHz to 10 GHz. And the realized LPF in DCS band has the insertion loss of 0.35 dB and return loss of more than 15.5 dB at the pass band, with the second harmonic rejection being 23 dB and the third harmonic rejection being 38 dB respectively.

In this paper, an ultra-wideband (UWB) conformal monopole antenna integrated with a narrow-band (NB) rectangular slot antenna is designed and fabricated. The proposed structure consists of a circular disc monopole antenna printed on a cylindrical surface, and fed by a coplanar waveguide line (CPW). A rectangular slot antenna that is excited by a microstrip line, is integrated in the front of the UWB antenna. The simulations are performed using the CST Microwave Studio software. To validate the proposed antenna concept, an experimental prototype is fabricated and measured. The measured results show that the monopole antenna covers an ultra wideband from 2 GHz to 12 GHz with S₁₁ < -10 dB and provides a very good isolation with a transmission coefficient below -20 dB across the operating band. Compared to planar integrated antennas, the proposed conformed structure possesses an important wideband, which can be used in many wearable electronic applications and communication systems.

In this paper, a planar microstrip branch-line coupler is designed to have dual-band operation. A Pi-typed structure is used in place of the conventional quarter wavelength transmission line for dual-band application. This structure consists of a pair of coupled line in which one has two ends while the other has open stubs attached to its two ends, and its circuit parameters are determined by the transmission line theory. Explicit design equations are derived using ABCD-matrix. For verification, a 3-dB branch line coupler with operating frequencies of 900 MHz and 3.5 GHz is fabricated and measured on an FR-4 printed circuit board (PCB). The simulated and measured results are in good agreement with each other.

A modified 1D finite-difference time-domain method is analyzed by using the surface boundary condition (SBC-FDTD) for oblique incidence. The SBC-FDTD iterative formulas are deduced in oblique incidence by TE_z and TM_z wave. The reflection and transmission coefficients of electromagnetic wave in the 1D photonic crystal (PC) including a graphene sheet are calculated by the SBC-FDTD method. The method is also validated by comparison with the existed analytic methods. Finally, this modified method is applied to simulate 1D graphene photonic crystal (GPC). By changing the position of grapheme sheet in GPC, the electromagnetic gap characterizations of 1D GPC by an oblique incidence plane wave in THz spectral range are studied. The computational results show that the graphene sheet can enhance the absorption in THz because of the localization of light and the surface defect formed by graphene.

In this paper we developed the method of broadband Green's function with low wavenumber extraction (BBGFL) for arbitrary shaped waveguide. The case of Neumann boundary condition is treated. The BBGFL has the advantage that when using it to solve boundary value problems in a waveguide, the boundary conditions have been satisfied already. The broadband Green's function is expressed in modal expansion of modes that are frequency independent. To accelerate the convergence of the Green's function, a low wavenumber extraction is performed. The singularity of the Green's function is also extracted by such low wavenumber extraction. Numerical results show that BBGLF and direct MoM are in good agreement. We next illustrate the application of BBGFL for broadband simulations of vias in printed circuit boards (PCB) by combining with the method of Foldy-Lax multiple scattering equation. The results show that BBGFL are in good agreement with MoM and HFSS. It is also shown that BBGFL is many times faster than direct MoM and HFSS. The computational efficiency in broadband simulations makes this technique useful for fast computer-aided design (CAD).

In this paper, a pattern diversity antenna, capable of radiating broad side as well as conical radiation patterns using quarter mode substrate integrated waveguide sub-array, has been presented. The pattern diversity is achieved by in-phase and out-of-phase excitation of the sub-array using a rat-race coupler feed network. The overall profile height of the proposed antenna is 3.17 mm. The measured performance of the antenna, in terms of return loss, isolation, gain and diversity performance in the -10 dB impedance bandwidth, is in agreement with the simulated results. The proposed sub-array occupies 25% less area than the conventional microstrip antenna.

In this paper, a novel dual-band antenna with coupled line and different impedance extension lines is presented and analyzed. This simple antenna is composed of three antenna radiations with symmetric coupled lines, and it occupies a compact space of 80 × 30 × 1 mm³. The achieved 10-dB bandwidths of the dual-band operation in free-space condition are 200 MHz and 100 MHz, respectively, which support the 1.8/2.6 GHz Long Term Evolution (LTE) operating bands. Furthermore, various parameters are investigated to examine the effects of the antenna parameters on return loss as well as the gain of the proposed antenna.

A new balanced bandpass filter (BPF) with tunable bandwidth using tri-mode stub-loaded resonators is proposed. To tune the differential-mode bandwidth, the two even-mode resonance frequencies and two transmission zeros (TZs) are tuned while the odd-mode resonance frequency keeps unchanged. To realize high selectivity for differential mode, another two TZs are created by the source-load coupling and coupling sections. Furthermore, wideband common-mode (CM) suppression is achieved. The fabricated filter has 3-dB fractional bandwidth ranging from 20.0% to 26.0% centered at 1.71 GHz and wideband suppression (17 dB from 2 to 4.4 GHz) for the differential mode, as well as common-mode suppression better than 20 dB from 0 to 4.5 GHz.

A compact 4-port asymmetric coplanar strip (ACS)-fed MIMO antenna working in the ultra-wideband (UWB) frequency band with two shared radiators is presented in this paper. The proposed antenna is composed of two radiators, and each radiator is shared by two antenna elements in order to achieve a very compact size of 36×36 mm². By etching two I-shaped slots in the radiators and attaching a rectangular patch on the back, the operating band width is broadened, and the isolation between any two antenna elements is enhanced. The stub of the ground also has great effect on the return loss and isolation. The working frequency band of the MIMO antenna covers 3.1-10.6 GHz with isolation over 15 dB between any two antenna elements. Furthermore, the proposed antenna with a simple feeding structure and compact size makes it possible to be used in portable devices.

A tri-band multiple-input-multiple-output (MIMO) antenna that covers all frequency bands required for WLAN and WiMAX applications is presented. Three resonant bands are achieved by a folded monopole with a compact size of 11.5×15.6 mm². The MIMO system consists of two symmetrically placed monopoles. A stepped slot ended with an ellipse on the ground plane is etched to reduce the mutual coupling between the two monopoles. The overall dimension of this MIMO system is 50×50 mm². The prototype of the antenna is fabricated and measured. Measured results show that the antenna's impedance bandwidth is 450 (18%), 350 (10%), 1200 (21.8%) MHz at the three resonant frequency points (2.5 GHz, 3.5 GHz, 5.5 GHz) with mutual coupling between the antenna elements less than -18 dB in whole frequency band, making this antenna a good candidate for portable application.

In this paper, we propose an enhancement of the Equivalent Circuit Method (ECM) for analysis of frequency selective surface (FSS) with square loop geometry of the unit cell. For this, genetic algorithms and rational algebraic models are used to obtain a more accurate value of the effective electrical permittivity (ε_eff). We use simulated data obtained with a commercial software to adjust some parameters. So, genetic algorithm is used to obtain a better value of an exponent that calculates ε_eff minimizing the rational algebraic models. In this paper, this is done for the square loop geometry, but the methodology can be extended to any geometry. Finally, prototypes are built and the technique is validated.

This paper introduces a new volumetric conical notch-band antenna. Structure of this antenna is in contrast with planar and printed band rejection antennas currently existing in almost all of the literatures. The radiation pattern of the proposed antenna is symmetrical and stable against frequency variation, while planar and printed antenna types suffer from high variation of their radiation pattern with frequency, and consequently asymmetric and unstable omnidirectional behavior. The frequency band of the antenna is notched with two slots implemented on the antenna structure. Uniform various frequency band rejections are achieved by changing the slots dimensions and position. Both measured and simulation results of manufactured antenna show the frequency bandwidth of the antenna is from 3 to 4.9 GHz and from 6.2 to 11 GHz with reflection coefficient less than -10 dB. Moreover, the antenna notches the frequency band from 4.9 to 6.2 GHz with nearly uniform reflection coefficient level of approximately -3 dB. Stable radiation pattern and proper range of frequency band rejection make the designed antenna an appropriate candidate for the use in UWB and indoor communication systems.

A novel polarization independent RFID tag employing multiple resonators is proposed. The prototype of the tag is fabricated on a low-cost substrate of dielectric constant 4.4 and loss tangent 0.02. Designing a reader for chipless RFID is a hard task since both the polarization and operating frequency agility have to be implemented. The new tag design proposed in this paper is polarization independent, making the design of the reader easier. A prototype of a 3 bit data encoded tag is demonstrated using single structure which can be extended to any order by cascading. This new design is experimentally validated in the frequency domain using monostatic measurement with magnitude response to decode the information.

A three-step molding softlithographic process has been developed for the construction of a sharp Y-junction structure formation in a 1x2 Y-branch plastic optical fiber (POF) coupler design. The 1x2 Y-branch POF coupler is based on a Y-junction splitter which requires that the splitting part is constructed with sharp infinitesimal junction. The softlithographic process enables a PDMS mold to be constructed which then allows mass replication of the polymer-based POF coupler. A standard master mold based on PMMA material is fabricated using CNC milling. A secondary or auxiliary-mold process step is then introduced in order to produce a sharp Y-junction structure which is then transferred to the final PDMS stamp prior to device replication. This step utilizes a free flowing, low viscosity casting-based resin, which after curing and hardening provide the auxiliary mold for PDMS mold fabrication. The result shows that a very fine and sharp Y-junction structure can be produced easily which cannot be produced via standard two step molding softlithographic process. Models for the Y-branch POF coupler produced with and without an auxiliary mold process are constructed which show that a 16% increased in optical performance with the device replicated with the auxiliary mold process.

A planar ultra-wideband (UWB) antenna with triple-notched bands using triple-mode stepped impedance resonator (SIR) is presented in this paper. By coupling the novel triple-mode SIR beside the microstrip feedline, band-rejected filtering properties around the C-band satellite communication band, the 5.8 GHz WLAN band, and the X-band satellite communication band are generated. The notched frequencies can be adjusted according to specification by altering the triple-mode SIR. The results indicate that the proposed planar antenna not only retains an ultra wide bandwidth but also owns triple band-rejections capability. The UWB antenna demonstrates omnidirectional radiation patterns across nearly whole operating bandwidth, which is suitable for UWB communications.

Numerical solution is presented for light scattering from two kinds of free-standing periodic arrays, that is, disks made of noble-metal and circular apertures perforated in a thin noble-metal sheet. The shapes of them are complementary to each other, and the circular areas are allocated along two orthogonal coordinates with the same periodicity. Using the generalized boundary conditions of the surface impedance type, we formulate the boundary value problem into a set of integral equations for unknown electric and magnetic current densities defined over the circular area. Employment of the method of moments allows us to solve the integral equations and give the expansion coefficients of the current densities, from which we can find reflected, transmitted, and absorbed powers. Dependence of the powers on the array parameters and wavelength is discussed in detail from the viewpoint of grating resonance. Special attention is paid to the extraordinary transmission which occurs in the arrays of apertures of sub-wavelength size by analytical derivation of the quasi-static solutions.

This paper proposes a fast Minimum-Variance-Distortionless-Response (MVDR) beamforming algorithm for an antenna array for cancellation of multiple interference signals. The proposed algorithm uses Sample-Average Estimate (SAE) of the data covariance matrix and reduces its computational effort by applying the Matrix-Inversion-Lemma (MIL) to its covariance Matrix Inversion (MI) operation. The proposed algorithm is compared to two SAE-based algorithms: the Sample Matrix Inversion (SMI) algorithm that requires an MI operation and the Auxiliary Vector (AV) algorithm that does not need an MI operation. A non-SAE based algorithm using the Least Mean Square (LMS) method is also included for comparison. Simulation results show that the proposed algorithm converges slower than the SMI scheme but outperforms the AV and LMS schemes during the transient phase. Once convergence is achieved, the proposed algorithm converges to a better Mean Square Error than the rest of the algorithms evaluated.

In this paper, a cylindrical permanent magnet linear motor (PMLM), which has a high performance, was designed and developed, because the motor has a zero normal force and a higher thrust density. The structure of the motor plays a vital role at the stage of design. During the design stage, several models of the PMLM that had different structural parameters were simulated using FEM software, and the model that produced the high-performance was identified. The structural parameters involved include the radius and height of the permanent magnet, r_pm, and h_pm, the height of coil, h_c, and the shaft radius, r_s, within a fixed total radius, r_total. Each model of the PMLM was simulated using FEM software and the model that produced the highest thrust was identified. To prove its high-performance characteristics, the performance of the PMLM was then compared to the commercialized PMLM using four performance indexes which are thrust F, thrust constant k_f, motor constant k_m and motor constant square density G. About 200 commercialized PMLMs with three different types have been chosen which are the slot type PMLM, slotless type PMLM and shaft motor. Based on the comparisons, the designed PMLM had a better performance than the commercialized PMLM. In order to validate the simulation result, the PMLM was manufactured. The simulation and measurement static thrust characteristics were then compared, and it was found that the simulated thrust had a good agreement with the measured one.

In this paper, three omnidirectional microstrip array antennas are optimized, fabricated and measured. The proposed planar antennas are composed from series of microstrip line sections with inverted top and bottom conductors at each section. The antenna design parameters are optimized to design three different antennas: wide bandwidth, high-gain and dual-band antennas. In the wideband antenna, a good impedance matching is obtained for relative bandwidth of 31% that covers the frequency range of WLAN. The dualband omnidirectional antenna operates at 2.45 GHz and 5.25 GHz with gain of 6.69 dBi and 7.71 dBi, respectively. Also, the optimized high-gain antenna achieves 9.3 dBi gain. The three optimized antennas are fabricated and tested. The measurement results show a very good agreement with the simulation ones. The optimization results verify the ability and capability of the antenna to achieve the desired specifications.

This paper presents two dual-band bandpass filters with controllable passband frequencies and bandwidths. The filters are realized utilizing a novel quad-mode stub-loaded ring resonator. All the four mode equivalent circuits of the resonator are quarter-wavelength resonators, and their fundamental resonance frequencies are used to form the passbands. So the designed filters have a compact circuit size and relatively wide upper stopband. For validation, two experimental filters operating at 1.5/2.4 GHz and 1.5/3.5 GHz are designed. In the design of the second filter, hook-shape feed-lines and source-load coupling are applied to generate more transmission zeros, which greatly improve the selectivity of the filter. Finally, the filters are fabricated, and measured. The measured results have good agreement with the simulated ones.