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A novel broadband circularly polarized (CP) planar antenna based on off-centered coplanar waveguide (CPW) feeding method is proposed. To obtain circular polarization, traditional methods are mainly by employing external polarizer or by introducing perturbation segments into radiator. Different from traditional methods, off-centered CPW feeding provides 90° phase difference between the two orthogonal...
The metamaterial superstrate, composed of periodic unit cells of novel structure which exhibit a narrow band in the microwave regime with simultaneously near-zero values of permeability and permittivity, provide a way to enhance the gain of antenna [1]. The bandwidth of the unit cells is narrow, because it only works when it is resonant. The superstrate, composed of the periodic unit cell with optimized...
We propose the design and simulation of a dual-band reflective polarization converter in the microwave region based on multiple resonances. An ultra-thin broadband polarization conversion composing of arrays of electric-field-coupled (ELC) resonator, a dielectric layer and a continuous metallic layer is further demonstrated numerically. The proposed converter can rotate the linearly polarized (LP)...
In recent years, terminal equipment has been developed more multi-band and integrated. In order to reduce the interference between antennas and realize the feature of simpleness, the design of broadband antenna has become the focus of research. Because of the limited spaces of the mobile terminals, the antenna gain, bandwidth and roundness of pattern are the difficult points of designing the sleeve...
The rapid advancement in wireless communications systems and the narrow bandwidth accessibility is a challenging work in the communication field. One possible suggestion for the bandwidth restriction is to use smart antenna systems. The preferred bandwidth is one of the decisive considerations used to adopt upon an antenna. For example, various antenna types have very narrow bandwidths and this is...
In this paper, a frequency-selective flexible metamaterial absorber is designed in microwave frequency band, which based on single dielectric layer. This frequency-selective absorber is polarization insensitive owing to the high-degree symmetry of structure. With loaded lumped elements, we can achieve a broadband better absorption. Simulation results show that the proposed absorber has high absorption...
A novel broadband metamaterial absorber based on the fractal structure and loaded lumped resisters is proposed in this paper, which consists of three metallic layers separated by two dielectric substrates. Five metallic vias connect three metallic layers. This absorber can achieve 90% absorption from 5 to 12 GHz under the normal incidence and the bandwidth of absorption is 7 GHz, equivalent to a relative...
The loop types such as the three- and four-legged loaded unit cells, the circular loops, and the square loops and the hexagonal loops are widely used to design the frequency selective surface (FSS) for a number of applications. Correlation analysis and evaluation of them are investigated in previous works. In this work, we try to use another loop, namely triangular loop, for designing the FSS. A multi...
Considering that the current information content being exchanged is increasingly multimedia, it is quite natural to the demand for a relatively short time downloading or to a certain extent uploading large information files to the Internet. Mobility is increasingly demanded along with broadband. Certain to locations do not have the necessary infrastructure for broadband. Users that are residing in...
A novel low-profiled broadband multi-frequency double-layer patch antenna is proposed in this paper, which operates in GSM900, DCS1800 and Wifi. Considering the broadband, directivity, and low-profile of the antenna, seven patches with different resonant frequencies are placed together on one plane. These patches are arranged to have line polarization and are perpendicular to each other. By forming...
In this paper, a novel broadband microwave metamaterial absorber is successfully realized by randomly distributed metallic loop-shaped elements. Such amorphous arrangement of single-sized elements can result in a spatially disordered distribution of multi-resonance absorption, thus dramatically improving the absorption bandwidth. On this basis, we further broaden the bandwidth by using three differently...
A linear-to-circular polarization conversion transmitter is proposed using 3 × 3 periodic metallic strips, which are twisted 900 in the upper and bottom layers. The metallic strips are printed on both sides of the dielectric substrate that are subjected to enhance the axial ratio bandwidth at resonance frequencies. The proposed structure is excited by a normal incident of x-linearly polarized wave,...
Using a wavelength division multiplexer, we increase the spectral bandwidth of a multimode-fiber-based spectrometer to 100nm with the spectral resolution of 0.03nm. An effective algorithm is developed to achieve fast, accurate reconstruction of diversified spectra.
A compact dual-broadband antenna is proposed for 2G/3G/LTE (4G) mobile communications. The radiation unit of the proposed antenna consists of a lower-band element and an upper-band element. The lower-band element comprises a rectangular patch fed by an L-shaped probe, the upper-band element comprises a pair of two folded printed dipole fed by an L-shaped probe as well. The upper-band element is stacked...
In this paper, a wideband circularly-polarized patch antenna is presented. The patch is fed by four probes arranged by sequential rotation arrays, the four probes are connected to a feed network comprising of a pair of broadband 90° phase shifter and Wilkinson power divider. The proposed antenna shows a compact low profile, wide axial-ratio (AR) bandwidth, wide reflection coefficient bandwidth, as...
A graphene absorber is proposed using frequency selective surface (FSS) and resistive graphene strips on a grounded dielectric slab. The FSS unit is based on two concentric Minkowski loops. The simple circuit model indicates that the combination of loops with different substrate thicknesses can be utilized to realize two adjacent absorption bands. Then, the inner loop is located within the middle...
This paper presents a novel design method for improving bandwidth of sleeve antenna. The proposed design method incorporates dual-sleeve structure and end-loaded technology. Two novel sleeve antennas are designed with operation frequency 0.8GHz∼2.7GHz and 3.1GHz∼10.6GHz based on the proposed method. Simulation results show that the antennas have a 3.4∶1 bandwidth with 10-dB return loss and an omnidirectional...
This paper presents a broadband omnidirectional circularly polarized antenna design using combination of broadband omnidirectional vertically and horizontally polarized radiating elements. The vertically polarized (VP) component is a modified version of ultra-wideband (UWB) monopole antenna and the horizontally polarized (HP) element is a recently-developed omnidirectional HP antenna using planar...
Novel multiband/broadband horizontally polarized omnidirectional antennas (HPOAs) are proposed in this paper. The HPOAs are made up of a metallic cavity and a bent feedline. By shaping the cavity and the feedline, the HPOAs can achieve multiband or broadband performances. A dual-band HPOA, a broadband HPOA, and a compact tri-band HPOA are developed. The impedance bandwidths of the dual-band HPOA for...
A compact hybrid dipole antenna is presented with enhanced bandwidth. The antenna consists of a half-wavelength driven dipole and a one-wavelength parasitic folded dipole. By properly engineering the resonant frequencies of the driven dipole and the parasitic folded dipole, wide bandwidth with S11 ≤ −10 is achieved from 1.82 GHz to 2.27 GHz (450 MHz, 22.7%). The measured results of the proposed antenna...
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