In this letter, a novel compact UWB bandpass filter (BPF) with sharp rejection skirt is realized using quintuple-mode stub-loaded resonator. The resonator can generate three odd-modes and two even-modes in the desired band. By simply adjusting the lengths of open stubs in shunt and shortcircuited stubs, the first five resonant modes of the resonator can be roughly allocated within the 3.1-10.6 GHz UWB band meanwhile the sixth resonant mode in the upper-stopband can be suppressed. The pair of short stubs can generate two transmission zeros near the lower and upper cut-off frequencies, leading to a sharp rejection skirt. A quintuple-mode UWB BPF is designed and fabricated and the measured results demonstrate the feasibility of the design process.
This paper presents a novel bulk acoustic wave stacked crystal filter (SCF) configuration that improves the inherent narrow bandwidth of this kind of devices and increases their selectivity by means of the allocating of transmission zeros. A set of parallel connected SCFs with their resonant frequencies split along the passband achieves the bandwidth improvement. The SCF detuning is carried out by the thickness of its middle metallic electrode. The filter response covers the 60 MHz bandwidth of a W-CDMA RF application working at 2.14 GHz. The use of SCFs considerably simplifies the layer stack configuration in contrast to other acoustically coupled structures as coupled resonator filters.
A novel compact planar antenna with a frequency band-filter characteristic for UWB applications is proposed and investigated. Having a dual-Y-shaped slot on the patch, a frequency-notched characteristic at 5.2 GHz is obtained. The band-notched mechanism of the designed antenna is implemented and experimentally studied.The designed antenna satisfies the voltage standing wave ratio (VSWR) requirement of less than 2.0 in the frequency band between 2.8 and 18.6 GHz while showing the band rejection performance in the frequency band from 5.0 to 5.6 GHz. This technique is suitable for creating ultra-wideband (UWB) antenna with narrow frequency-notched characteristics.
Aiming at the bandwidth enhancement for patch antennas, a new impedance matching scheme is presented. In this design, open-ended microstrip-lines are used as the matching resonators; the gaps between the lines are used as the J inverters. Numerical and experimental studies are executed to demonstrate this new structure. The measured and predicted results are in good agreement. The measured data show that the bandwidth of a sample antenna is increased by a factor of 3.3 after adding two matching resonators. The proposed matching structure is good in performance, and smaller in size than traditional matching structures.
A microstrip dual-mode dual-band bandpass filter using stepped impedance resonators (SIRs) is designed for dual-band wireless local area network (WLAN) applications at 2.4 and 5.2 GHz. By appropriately selecting the impedance ratio (Rz) and length ratio (α) of the SIRs, the harmonic frequencies can be tuned for generating the dual-bandpass response. Based on SIRs, a dual-mode dual-band bandpass filter is designed with one transmission zero. To improve the selectivity, another three transmission zeros in stopbands be created by introducing two stubs in input/output (I/O) lines. Two experimental filters are fabricated. Both simulated resulted and measured resulted are presented.
This paper presents a fast and effective electromagnetic reconstruction algorithm with phaseless data under weak scattering conditions. The proposed algorithm is based on the phaseless data multiplicative regularized contrast sources inversion method (PD-MRCSI). We recast the weak scattering problem as an optimization problem in terms of the undetermined contrast and contrast sources. Using the conjugate gradient iterative method, the problem is solved by alternately updating the contrast sources and the contrast. Additionally, this method can combine with the PD-MRCSI method. Taking advantage of the properties of fast convergence of this algorithm and stable convergence of PD-MRCSI method, the combined technique makes image reconstructions more fast and effective. Although the method is derived from weak scattering situation, it is also useful for the case which weak scattering approximation is not satisfied. The synthetic numerical reconstruction results, as well as experimental reconstruction results, presented that the proposed method is a very fast and effective reconstruction algorithm.
Novel complementary split ring resonator (CSRR) is introduced to increase the stop bandwidth. Despite of their exotic behavior due to negative permittivity, their performance is limited by their stop bandwidth. The orientation of CSRR etched on the ground has strong coupling that can be altered for the increased stop bandwidth. The proposed design has measured stop band from 4~7.25 GHz whereas conventional CSRR of same dimension has stop band from 4.1~5.0 GHz.
A compact dual-mode open stub-loaded resonator and bandpass filter (BPF) is proposed in this paper. The resonator, which is formed by attaching a disc-shaped open stub and circular open stubs in pairs to a high impedance microstrip line, generates two operating modes in the desired band, and the even-mode resonance frequency can be flexibly controlled by the disc-shaped open stub at central plane, whereas the odd-mode one is fixed. The four transmission zeros are created to sharpen the rejection skirt, suppress two high harmonic resonant modes and deepen upper-stopband, respectively. Experimental results of the dual-mode filter which incorporates this resonator with parallel-coupled feed line with tuning stub at 5.8 GHz show good agreement with the simulated ones. The size for the resonator is only 4.7 × 3.4 mm (0.29λg×0.21λg in which λg is the guided wavelength of 50 Ω microstrip at 5.8 GHz).
In this paper, a novel compact quintuple-mode UWB bandpass filter (BPF) with sharp rejection skirt and wide upper-stopband performances is realized using stub-loaded multiple-mode resonator (MMR). The proposed resonator is formed by attaching two pairs of circular impedance-stepped open stubs in shunt and a pair of short-circuited stubs to high impedance microstrip line. By simply adjusting the radius of circular impedance-stepped open stubs and the lengths of short-circuited stubs, the first five resonant modes of the resonator can be roughly allocated within the 3.1--10.6 GHz UWB band meanwhile the high resonant modes in the upper-stopband can be suppressed. The short stubs in pairs can generate two transmission zeros near the lower and upper cut-off frequencies, leading to sharper rejection skirt outside the desired passband. Finally, a quintuple-mode UWB BPF is designed and fabricated, and the measured results demonstrate the feasibility of the design process.
This paper proposes a novel multi-band monopole antenna for PDA phone. A simple inverted-U-shaped driven element operates frequency bands centered at 1710 and 2350 MHz, which achieve a bandwidth based on 6-dB return loss from 1550 to 2490 MHz sufficient for DCS, PCS, UMTS, and WLAN applications. A low frequency meander path and an impedance matching stub with a truncated slit located at ground plane operates frequency band centered at 910 MHz. The bandwidth from 868 to 995 MHz covers the GSM 900 application band. The design procedures and both simulated and measured results are presented and discussed in this paper.
Consider a TEM plane wave incident on a spherical multilayer structure, then the following theorem is valid. This theorem reveals a duality between permeability and permittivity of media in a spherical multilayer structure. Theorem: Consider a sphere with arbitrary radius and parameters s (ε2,μ2) surrounded by a homogenous medium with parameters (ε1,μ1). Then consider the case that each medium is filled by its dual medium according to the interchange εi↔μi. Then, the forward and backward radar cross sections of the structure are the same for the two dual cases. However, in half planes φ=((2k+1)π)/4;(k=0,1,2,3), the interchange εi↔μi has no similar effect on the value of the radar cross section.
HF radar in ocean remote sensing makes use of electromagnetic waves of 10m to 100m wavelength from the rough sea surface to measure surface current and ocean wave parameter. Recently, a new time division multiple frequency HF radar system called OSMAR2009 has been developed by the Wuhan University. One main advantage of the system is that it is of great help in extracting current parameters and significant wave height. A further advantage is the ability to avoid interference. In addition, this technique offers the opportunity to measure the current shear. These advantages are gained by transmitting time division multiple frequency chirp instead of one frequency chirp. This paper introduces the technical design and the advantage of OSMAR2009 and describes the remote sensing experiment implemented in East China sea during 2009, followed by the field results and the brief analysis of such results.
A novel compact microstrip bandpass filter using folded open loop resonator is presented. The resonator elements are placed in close proximity to parallel coupled microstrip lines. The presence of undesired harmonics is eliminated here by properly modifying the configuration of the folded resonator. The measured and simulated results are in good agreement.
A low profile dual-band mobile phone antenna with a very small volume of 0.768 cm3 (40 × 4 × 4.8 mm3) is presented. The antenna is formed by a monopole and an open-end slot embedded therein. The impedance bandwidths for the lower and upper bands with a definition of 3:1 VSWR (6 dB return loss) reach 215 MHz (815-1030 MHz) and 515 MHz (1660-2175 MHz) respectively. Furthermore, small excited surface current distributions on the ground plane of the antenna are achieved, and the ground plane length has smaller effect on the achievable bandwidths of the antenna compared with the conventional internal patch antennas for mobile phones, which make the antenna very attractive to be applied to the mobile phones with various possible ground plane lengths. Good radiation characteristics over the operating bands are obtained.
Unlike ellipsometry using light, ellipsometry using microwaves can be subject to significant standing wave effects resulting from reflection of the received wave back to the source. This paper examines these effects on the apparent homogeneity of circular polarization. These effects are examined experimentally using an ellipsometer with no sample and compared with calculated results for a single order of reflection. Good agreement is obtained. That the peak-to-peak variations in the observed irradiance are on the order of four times the amplitude reflectance is observed. The angular dependencies of these effects are path length dependent.
The spectral switch phenomenon of light induced by scattering from a collection of particles is, to the best of our knowledge, reported for the first time. It is shown that when a spatially coherent light wave with a spectrum of Gaussian distribution is scattered from a collection of particles, the rapidly transition of the spectrum of the scattered field from red shift to blue shift (i.e., spectral switch) can be observed. It is also found that the spectrum of the scattered field will experience several spectral switches with the increase of the scattering angle.
A modified microstrip combline array antenna (MMCA) is designed to obtain wide beamwidth (≈90°) in E-Plane radiation pattern and therefore the better coverage for using in the radio controller systems for avionic application. Beside wide beamwidth, wide bandwidth can be obtained by designing of MMCA in travelling wave mode. Moreover, as will be seen in the paper, to achieve a better performance we need the low sidelobe level and tilted radiation pattern, which can be obtained by suitable tapering the amplitudes of array elements and adjustment the phase difference between them, respectively.
A method to diagnose on-off faults in a planar antenna arrays using far field radiation pattern is presented. A systematic approach is suggested for detecting location of faulty elements using Artificial Neural Networks (ANN). Radial Basis Function neural network (RBF) and Probabilistic neural network (PNN) are considered for performance comparison.
A double-side radiating leaky-wave antenna based on composite right/left-handed (CRLH) coplanar-waveguide (CPW) is proposed. Dispersion diagram of the unit cell is investigated, and balanced property is confirmed. Thus, the CRLH leaky-wave antenna can have backfire radiation due to the left-handed property of the CRLH structure and broadside radiation at the balancing frequency point. The measured results show that the proposed antenna can offer a scanning angle covering almost backfire-to-endfire directions.
Understanding the propagation of light in continuous inhomogeneous materials is important to design optical structures and devices. To have accurately numerical calculations Berreman's 4×4 propagation matrix method is generally used, and layer approximation, i.e., the whole one-dimensional continuous inhomogeneous material is divided into many small homogeneous layers, is assumed. However, this layer approximation is only correct up to the second-order of the layer thickness. To efficiently solve Berreman's first-order differential equation, a simple fourth-order symplectic integrator is presented. The efficiency of the fourth-order symplectic integrator was studied for a cholesteric liquid crystal. Numerical results of reflectance spectra show that the fourth-order symplectic integrator is highly efficient in contrast to the extensively used fast 4×4 propagation matrix.
Submit
