This paper examines the feasibility of LTE-based passive radar for detecting ground moving targets. Specifically, the focus of this paper is to describe the proposed LTE-based passive radar system and to conduct an experiment using a real LTE eNB transmitter as an illumination source. Seven scenarios were carried out to investigate the detection performance of the proposed system on ground moving targets with different speeds, trajectories and range. In addition, multi-target detection was also tested. The experimental results showed that the LTE-based passive radar system has the capability to detect typical ground targets/objects like cars, motorbikes and humans moving at different trajectories. The positive results opened up a new frontier for passive radar systems to be used in many potential applications, including security, border protection, microwave fences, monitor of buildings and others.

Fractional slots concentrated windings (FSCWs) are characterized with high magnetic motive force (MMF) harmonics which results in undesirable effects on permanent-magnet (PM) machines. A new design technique is reported in this paper in order to simultaneously reduce the sub- and high MMF harmonics. By using multiple layer windings and different turns per coil, a new 18-teeth/10-poles FSCWs PM machine is designed. Then, this machine is evaluated as compared with a conventional 12-teeth/10-poles FSCWs PM machine. Both machines are designed under the same electrical and geometrical constrains. The obtained results verify the high performances of the newly designed machine. Due to the adopted new winding type, the proposed design can effectively reduce eddy current loss in PMs as compared with the conventional design.

A compact omnidirectional vertical-polarized broadband slot antenna for indoor distributed antenna systems is presented. The proposed antenna consists of a deformed printed monopole on one side of the substrate and a polygon slot in the circular ground plane on the other side. Due to the utilization of the wideband slot structure, the antenna achieves small electrical dimension of 0.327λ×0.327λ×0.0046λ at the lowest operating frequency, and an impedance bandwidth of about 129% (0.66-3.07 GHz) for VSWR≤1.5 is achieved, covering all frequency bands for 2G, 3G, 4G and some Wi-Fi communications. The proposed antenna has stable radiation patterns over the operating bands. The measured gains of the antenna range from 1.5 dBi (lower band) to 5.5 dBi (higher band). Compact planar structure makes the proposed antenna a perfect candidate for ceiling or surface mounted indoor distributed antenna applications.

In this study, a dumbbell-shaped metamaterial (MTM) antenna has been proposed for dual-band applications using finite difference time domain (FDTD) technique. Such a composite MTM antenna consists of dumbbell-shaped patch, microstrip and partial ground plane. The proposed antenna shows dual-band behavior having impedance bandwidths (|S₁₁| < -10 dB) of 28.5% and 8.7% at 1.72 GHz and 3 GHz respectively. It has been designed to operate at various cellular standards such as GPS, GSM1800 and WCDMA. Design and analysis have been carried out using FDTD code based on uniform meshing and convolutional perfectly matched layer (CPML) absorbing boundary conditions. Further, simulation results have been verified using HFSS, and a prototype has been fabricated to validate the results experimentally. The overall electrical size of the proposed antenna is 0.287λ_o × 0.346λ_o × 0.009λ_o. The proposed dual-band antenna offers excellent radiation characteristics with a gain of 1.2 dBi and 1.5 dBi at 1.72 GHz and 3 GHz respectively with omnidirectional radiation patterns in xz-plane.

A compact multiband bow-tie dipole slot antenna fed by coplanar waveguide (CPW) is proposed in this paper. Multiple resonant mode technique and notch-band technique have been combined in this design to form triple-band operation just by adding single elements. Based on this, a pair of hairpin-shaped branches is implemented on each arm of the bow-tie slot antenna. A notch-band property is achieved compared with the original wideband bow-tie antenna (without branches). Meanwhile, a new lower resonant frequency is obtained by using this kind of structure, which means the size is compact in nature and the triple-band operation is achieved. The notch-band and lower resonant frequency can be tuned by changing the length of the branch. The parameters of the antenna, including reflection coefficients, current distributions, radiation patterns and gain, are achieved by numerical simulations and measurements. The results indicate that the slot size of the proposed antenna is 52.4 mm×22.3 mm, and the proposed antenna can offer triple-band operation at 2.39-2.50 GHz (4.5%), 3.38-3.79 GHz (11.4%) and 4.87-6.23 GHz (24.5%), which is suitable for WLAN in the 2.4/5.2/5.8-GHz bands and WiMAX in the 3.5/5.5-GHz bands.

Novel compact dual-band branch-line couplers are presented. By using ahalf elliptical-ring impedance stub as a basic unit, dual-band branch-line couplers are obtained. Sincea couple of half elliptical-ring impedance stubs can be folded inward to its enclosed areawithout overlap, the branch-line couplercan be miniaturized. In order to verify the effectiveness of the half elliptical-ring impedance stub, two different branch-line couplers operating at 2.4/5.8 GHz are designed, fabricated and tested. Measured results agree well with simulated ones. Compared with the stepped-impedance-stub branch-line couplers, sizes of the proposed couplers are reduced by 43% and 30%, respectively.

Two novel microstrip bandpass filters with improved selectivity based on dual-mode ring resonators are proposed. Tow and four transmission zeros close to the passband are realized to improve the selectivity for the passband. Sixth-order passband is realized with two open/shorted stubs and a dual-mode ring resonator. The transmission zeros near the passband can be adjusted conveniently by changing the characteristic impedances of the coupled lines. For demonstration, two planar bandpass filters (3-dB bandwidths 20.9%, 20.2%) are designed and fabricated.

A simple end-fire high-gain antenna with side-lobe level suppression is proposed for 60 GHz technology in this paper. The antenna has a tapered slot radiation patch which is obtained by subtracting a quarter of ellipse from a bigger quarter. Two reflecting circle units (RCU) are located at both sides of radiant patch to suppress side-lobe level of radiation patterns. The antenna has a simple two-layered planar structure with on via and is fabricated on a Rogers 4350 substrate with a compact size of 15 mm × 15 mm. Simulated and measured results match well, and both show makes it fit 60 GHz wireless communication systems.

The radio blackout problem stands as one long obstacle for hypersonic flight and planetary atmosphere reentry. Rather than previous physical mitigation methods aiming to reduce the plasma electron density, this paper proposes a novel method which attempts to communicate at carrier frequency much higher than the plasma cutoff frequency. To overcome the highly dynamic channel characteristics, the reflected wave is used online to estimate the instantaneous channel states and enable adaptive transmission. According to the predicted channel states, the plasma sheath induced phase shift and amplitude attenuation are compensated by baseband modulation and power adaptation, respectively. Numerical simulations are presented and discussed, in order to illustrate the effectiveness of the proposed method.

A capacitively fed rectangular patch antenna for anti-metal RFID tag was studied. It was found that by using capacitively feeding and a thin micro-strip line, the input impedance could be stabilized with respect to ground plane size. As a result, the reading range degradation was avoided, and the presented antennas have almost the same reading range when used on metal or non-metal objects. The mechanism was explained by a basic antenna design and a transmission line model. Then a more practical compact design having much smaller size was presented. Prototypes of both the basic design and the compact design were fabricated and tested. The testing results validated the effectiveness of the designing method.

In this letter, a novel sleeve antenna with wideband characteristic is presented for wireless communication applications. By employing a sleeve structure, impedance bandwidth of the antenna is improved through exciting a new resonant point. To obtain an impedance bandwidth enhancement further, four symmetrical ridges are introduced between the sleeve and the main radiator. An excellent wideband impedance bandwidth for VSWR≤2 of 148.45% is achieved, covering the frequency range from 1.04 to 7.03 GHz, and good monopole-like radiation patterns are obtained where the un-roundness in the H-plane is less than 1.49 dB. It is very suitable for recent wireless communication services such as DCS, PCS1900, UMTS, IMT2000, WLAN, WiMAX2350/3500, WiBro, etc.

In this paper, a novel frequency reconfigurable U-slot microstrip antenna with T- shaped feed line for Software Defined Radio applications is proposed. The proposed antenna, indexed as A-I in this paper, operates at three different frequencies: 1.85 GHz, 1.9 GHz and 2.4 GHz depending on the switching states of PIN diodes. Furthermore, to strengthen the proposed design concept and strategy another improved antenna (A-II) is designed and tested. In comparison to antenna A-I, the improved antenna design (A-II) utilizes four slots/PIN diodes in order to increase the number of reconfigurable frequency states. Depending on the switch states of four PIN diodes, antenna A-II operates on five different reconfigurable frequency bands centered at: 1.5 GHz, 1.6 GHz, 1.8 GHz, 1.9 GHz and 2.24 GHz. The measured results show a return loss better than 22dB, maximum gain of 2.5 dB and maximum efficiency of 78%. Moreover, radiation pattern for the proposed antennas is stable at all operating frequencies.

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.