A wide band, integrated linear printed antenna array with low sidelobe cosecant square-shaped beam pattern is presented. Array synthesis mainly about the wide shaped coverage, low ripple and sidelobe level (SLL) has been done using the modified least square method by matrix inversion. A printed dipole integrated with wideband balun has been chosen as the array element for wide bandwidth and good integration with the feeding network. Simulated results have shown good agreement with the measured asured results of the antenna array, which has a VSWR≤1.3 bandwidth 15% and good pattern with cosecant square-shaped region beyond 30°and SLL≤−27 dB in L-band.
A new quasi-lumped suspended-substrate stripline structure admitting implementation of miniature highly selective narrowband filters is studied. Appreciable improvement of the device selectivity is achieved with supplementary strip conductors introduced between the resonators, which induce attenuation poles near both passband edges. Furthermore, these supplementary conductors reducing the coupling between the resona-tors allow diminishing the inter-resonator spacing and the total size. A four-resonator filter is synthesized using the intelligence optimization method. Experimental results of the manufactured filter are presented.
This paper suggests a new solution for enhancing the immunity against the influence of size variation in ground on a boardintegrated GPS antenna. The original GPS antenna considered has the advantages of a simple design, low cost, and being directly integrated with the associated circuit board. Nevertheless, its performance depends on the ground of the circuit board. Without any special solution, the original antenna can withstand a ground size enlarged up to 122%, with respect to the minimal size required, for meeting the GPS specification. By using the suggested solution, the antenna can allow a ground size enlarged up to 269%. Thus, the improved antenna is more suitable for practical employment. In this investigation, various prototype antennas, with the suggested solution, were created and examined. Both simulated and measured results obtained demonstrate its promising performance stated above.
In this paper, a novel nine elements array dielectric resonator antenna (DRA) is presented. The DRA was excited by a microstrip feeder with a rectangular aperture coupled slots. The slot positions were determined based on the characteristic of standing wave ratio over a short ended microstrip. The measured gain of the array DRA operating at 5.84 GHz was about 10 dBi having impedance bandwidth of 60 MHz. The proposed DRA exhibits an enhancement of the gain in comparison with a single pellet DRA. The size of the whole antenna structure is about 60 mm × 40 mm and potentially can be used in wireless systems.
This research uses innovative approaches for characterizing spring probes, a final-test bottleneck applied to microwave packaging. The modeling method depends on conventional microwave on-wafer measurement. This paper compares the novel microwave 3D direct calibration and measurement to observe the issues of spring probe reliability. We makes the key component of a novel approach to 3D calibration and measurement, the double-sided thru calibration element with delay time delivers from 3D EM simulation. The current study compares the modeling method and 3D direct measurement to prove the capability of the latter and presents the reliability about compressing distance of spring probes.
A novel complex structure of Printed Dielectric Resonator Monopole Antenna (PDRMA) with multi-bands operation is presented and investigated. In the proposed structure, a printed fork-like stepped monopole antenna is used for exciting two new modified hemi-cylindrical dielectric resonators with a great relative permittivity of 80. A narrow medium substrate with a low permittivity is also applied between two mentioned dielectric resonators and the monopole antenna, to improve the matching, especially at the lower frequencies. By using this novel designed antenna applying two dielectric resonators with very high permittivity, many frequency wide bands for VSWR < 2 are practically measured and supported which are as follows: 1.54--3.25 GHz (GPS, GSM, PCS, UMTS 2000, 2.4 GHz-Bluetooth, WLAN, WiMax), 3.3--3.6 GHz (WiMax), 3.8--4.4 GHz (C-band), 4.8--6.2 GHz (5.2, 5.5 & 5.8 GHz-WLAN & WiMax). Experimental and numerical results are carried out and discussed, showing good agreement.
A bidirectional directly modulated cable passive optical network (PON) based on a reflective semiconductor optical amplifier (RSOA) as a colorless modulator in the optical network unit (ONU) is proposed and demonstrated. Good performances of downstream carrier-to-noise ratio (CNR)/composite second-order (CSO)/composite triple beat (CTB) and upstream bit error rate (BER) were achieved over a 40-km single-mode fiber (SMF) transmission. This proposed directly modulated cable PON is simpler and cost lower than the externally modulated one.
A novel of wideband monopole antenna with UTM-Logo shape is proposed to create specific wide band frequencies which can be applied in the cognitive radio. The antenna is designed to be operated between 1.98 to 6.46 GHz frequency bands (106.16%). It has been fabricated on 30×51 mm2 FR4 board with thickness of 1.6 mm and the dielectric permittivity and tangent loss of 4.7 and 0.019, respectively. Two slots also been attached on the ground plane for the purpose of increasing the bandwidth of antenna. Simulation and measurement results show good agreement.
This paper investigates the application of frequency-selective surface (FSS) in reflectarray antennas for the purpose of reducing radar cross section (RCS) level. Different from previous reports, the presented band-stop FSS structure is also characterized by the suppression of surface waves, which makes a contribution to better radiation performance. Two 14 x 14 reflectarray antennas backed on the FSS ground and a solid ground are designed and fabricated. Simulated and measured results show that the FSS ground can improve the `in- band' gain by 1.1 dB, decrease the sidelobe level by 6.4 dB, and reduce the `out-of-band' RCS effectively when compared with the antenna with a solid ground plane of the same size.
In this paper, a novel printed monopole antenna for ultra wideband applications with variable frequency band-notch characteristic is presented. The proposed antenna consists of a stepped square radiating patch with modified W-shaped slot and a ground plane with rectangular sleeve and pair of L-shaped resonator which provides a wide usable fractional bandwidth of more than 130% (3.05-14.7 GHz). By cutting a modified W-shaped slot with variable dimensions on the radiating patch frequency band-stop performance is generated and we can control its characteristics such as band-notch frequency and its bandwidth. The designed antenna has a small size of 12×18 mm2 while showing the band rejection performance in the frequency band of 5.08 to 5.91 GHz.
Vibrations and noise in electrical machines are directly related to the characteristics of the radial forces on one hand, and mechanical behavior on the other. The characteristics of these forces depend on the air gap flux density, and they are influenced by other factors such as stator slots and poles, saturation level, winding type and certain faults. The aim of this work is to investigate the effect of eccentricity faults on electromagnetic noise generated by the external surface of PM synchronous machine (PMSM). For this purpose an analytical electromagnetic vibroacoustic model is developed. The results confirm the effect of eccentricity fault in generating some low modes radial forces. An experimental device is installed to validate the results of the analytical model.
In this paper, a new ultra wideband circular antenna array (UCAA) combining particle swarm optimizer (PSO) to minimize the bit error rate (BER) is proposed. The ultra wideband (UWB) impulse responses of the indoor channel for any transmitter-receiver location are computed by applying shooting and bouncing ray/image (SBR/Image) techniques, inverse fast Fourier transform and Hermitian processing. By using the impulse response of multipath channel, the BER performance of the binary pulse amplitude modulation (B-PAM) impulse radio (IR) UWB system can be calculated. Based on the topography of the circular antenna array, and the BER formula, the array pattern synthesis problem can be reformulated into an optimization problem and solved by the PSO. The novelties of our approach is not only choosing BER as the object function instead of sidelobe level of the antenna pattern, but also consider the antenna feed length effect of each array element. The strong point of the PSO is that it can find out the solution even if the performance index cannot be formulated by simple equations. Simulation results show that the synthesized antenna array pattern is effective to focus maximum gain to the LOS path which scales as the number of array elements. In other words, the receiver can increase the received signal energy to noise ratio. The synthesized array pattern also can mitigate severe multipath fading in complex propagation environment. As a result, the BER can be reduced substantially in indoor UWB communication system.
A large bandwidth wide-slot antenna, fed by coplanar waveguide (CPW), is proposed. Experimental investigations and detailed simulations are conducted to understand its behavior and to optimize for broadband operation. The impedance bandwidth, determined by 10-dB return loss of the proposed slot antenna using both measurement and simulation, is about 131% (2.8 to 14 GHz). In addition to be small in size, the antenna has low cross polarization, relatively high gain, and it exhibits stable far-field radiation characteristics in the entire operating bandwidth. The design with very wide operating bandwidth and improved radiation pattern is obtained by properly choosing the suitable slot shape, selecting similar feed patch shape, and tuning their dimensions. Numerical sensitivity analysis has been used to understand the effects of changes of various antenna dimensions and to optimize the performance of the designed antenna. Based on our computer simulations it is shown that the antenna dimensions parameters have uncorrelated effects on the upper edge of the bandwidth. Simulation results show that the impedance matching of this kind of antenna is sensitive to the feed-slot combination and feed gap width. The simulated and measured results for return loss, far-field E-plane and H-plane radiation patterns, and gain of the designed antenna are presented and discussed.
In this paper, a stacked ring-patch two layer planar artificial substrate is analyzed numerically and is shown to possess the properties of a high impedance surfaces (HIS). Its properties are evaluated by investigating the surface wave propagation and plane wave reflection characteristics. Its application to reduce the mutual coupling of microstrip antennas and to improve the radiation pattern are investigated by simulation tool CST microwave studio. Experimental measurements using a pair of monopoles are used to confirm the surface waves suppression band. One of the main advantages of the proposed geometry is that it is simple and planar in nature, without the need for any via connections across dielectric layers and thus can be realized by planar technologies. Another advantage is that it exhibits over lapped surface wave suppression and in-phase reflection bands. Also it can be scalable to operate in different frequency range.
A novel compact Epsilon Near Zero (ENZ) tunneling circuit with microstrip coupling for high integrability applications is presented. Full design procedure, simulation and experimental results are shown, and a methodology to extract the effective permittivity and propagation constants in the tunnel is described. Detailed analysis of the dependence on external quality factor and tunnel to feed height ratio is investigated. Simulation and measurement results of the ENZ tunnel structure are in good agreement.
In this paper, a novel circular slot UWB antenna with dual notched frequency band is presented and investigated. A C-shaped slot is inserted into the fed element, and a parasitic strip is printed in the circular slot, so that the proposed antenna achieves dual band-notched characteristics, respectively. The measured and simulated results show that the proposed antenna meets the requirement of wide working bandwidth of 3.1-10.6 GHz with VSWR < 2, while avoiding the interference with the 3.5 GHz WiMAX and 5.5 GHz WLAN band. Study of transfer function (amplitude of S21/group delay) and time domain characteristic (radiated pulses/power spectrum density (PSD)) correspond well with the VSWR, which indicate the dual band notched characteristic of the antenna.
In this paper a new method is proposed to achieve a temperature insensitive, broad and flat gain C-band erbium-doped fiber amplifier (EDFA) with aid of macro-bending. This gain flattened C-band EDFA is demonstrated by utilizing 2.5 m macro-bent Erbium-doped fiber (EDF) at room temperature of 25℃. Further to this, it is shown that gain fluctuation at different temperatures is compensated in the proposed design. The EDFA performance at different temperatures is investigated for various macro-bending diameter and EDF length. The gain saturation and energy transfer from shorter wavelengths to longer wavelengths can be controlled by varying the bending radius and the length of the doped fiber, consequently, a flattened and broadened gain profile in the C-band region can be achieved. The amplifier uses a 2.5 m long EDF with 2000 ppm concentration and bending radius of 6.5 mm as a gain medium. The gain variation of the EDFA is obtained within ±0.5 dB over 35 nm bandwidth of C-band region.
The impedance matching problem in the presence of signal and noise coupling in compact MIMO arrays is addressed. By maximizing an upper bound of the ergodic capacity for an N×N MIMO system with signal and noise coupling at the receiver in high signal-to-noise ratio (SNR) scheme, a set of equations is formulated to find the optimal matching circuit. A closed-form result for the optimum matching circuit is given. For two-element arrays, we show numerically that significant performance improvement can be achieved by introducing the optimal matching.
A new detection algorithm based on constant false alarm rate (CFAR) algorithm, which is applicable to radar image with homogeneous background, is proposed in this paper. This algorithm firstly estimates the parameters of the probability model of background accurately. Then a conventional global CFAR is done using the results of estimation. In estimating the parameters of background, a novel iterative algorithm, which is self-adaptive, is given. The simulation results demonstrate that the performance of the proposed detection algorithm is very close to the theoretical optimum value, and better than CA-CFAR, GO-CFAR and SO-CFAR.
A compact and simple interdigital capacitor inverted-F antenna (IFA) operated at its quarter-wavelength (λ/4) mode as the fundamental resonant mode for achieving multiband operation in the mobile phone is designed. The proposed antenna consists of a monopole antenna and an IFA. The proposed interdigital capacitor IFA has a simple structure of comprising two meandered radiating strips of length about λ/4 and is fed using an interdigital capacitor coupling feed. The two meandered radiating strips also generate two λ/4 resonance modes at about 900 MHz and 2100 MHz to cover the GSM850/900/1800/1900/DCS/PCS/UMTS bands and the 2.4 GHz WLAN (IEEE 802.11b) band operations. Further, the proposed antenna has a simple planar structure and occupies only a small area of 10×40 mm2 on the system circuit board of the mobile phone. This proposed antenna with multiband, broadband matched impedance, stable radiation patterns, constant antenna gains, good radiation efficiency and compact size can be suitable for mobile phone applications.