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We present a new technique for designing low-profile circularly-polarized reflectarrays with broadband true-time-delay (TTD) responses and linearly-polarized feeds. The proposed reflectarray exploits the unit cells of ground-plane-backed, anisotropic miniaturized-element frequency selective surfaces as its spatial time-delay units (TDUs). Each TDU is composed of a stack of non-resonant rectangular-shaped...
In this paper, new ultra-wideband (UWB) stop-band frequency selective surface (FSS) is proposed. The frequency band, over which flat stop-band response is achieved, covers the entire band from 3 to 12GHz. The proposed FSS constitutes with compact size unit cells printed on one side of dielectric substrate. Providing good candidate for Ultra wide-band applications and an optimized solution for integration...
In this paper, design of a broadband circularly polarized dielectric resonator antenna (DRA) operating in the L-band is proposed. Antenna is cylindrically shaped and it is fed by a microstrip line through two concentric slots with an inner and outer perturbations. VSWR and 3-dB axial ratio bandwidths of the designed antenna are respectively, 40% and 6% while 6-dB axial ratio bandwidth before the cavity...
We show how the bandwidth over which power can be transferred from multiple radio-frequency sources to multiple loads scales with the number of sources and loads. Our principal tools include broadband multiport matching upper bounds on the integral over all frequency of the logarithm of a suitably defined power reflection ratio. We also characterize matching structures whose bandwidth scale as the...
An aperture coupled circular patch antenna is presented for dual circular polarization at Ka-band. Two microstrip lines are used to excite a circular patch through two slots to generate a broadband RHCP and LHCP radiation with high isolation between them. An aperture coupling is employed to provide a wide beamwidth axial ratio. The proposed antenna is a good element candidate to be considered for...
A broadband linearly polarized magnetoelectric (ME) dipole antenna with broad beamwidth in both E-plane and H-plane is presented. By employing four L-shaped dipole arms and inclined sidewalls along the E-plane edge of the ground plane, wide half power beamwidth of 100 ± 6 ° and wide pattern bandwidth from 1.9 to 2.7 GHz are obtained, as well as nearly identical E-plane and H-plane radiation patterns...
A tri-layered chiral metasurface is proposed and demonstrated to exhibit broadband asymmetric transmission of linearly polarized electromagnetic waves in two opposite directions. The full wave simulation shows that the proposed metasurface can rigorously satisfy the asymmetric transmission (AT) theorem and can achieve cross-polarization conversion with high efficiencies for linearly polarization waves...
In this work we present a leaky wave antenna (LWA) radiating in circular polarization (CP) by means of a broadband multilayered polarizer. The polarizer is designed independently of the LWA antenna without affecting its behaviour. The achieved axial ratio (AR) is kept below 2 dB within a bandwidth of 31% ranging from 26.7GHz to 35.5GHz. All results are verified via full-wave simulations over an angular...
A radio-frequency source generally can be closely matched to a load only over a restricted bandwidth. One measure of the maximum possible bandwidth is the Bode-Fano bound. Although the bound is often a good measure of the maximum bandwidth, there exist certain loads for which the bound is loose, and therefore cannot be attained by any matching network. We present a method to tighten the Bode-Fano...
In this paper, a novel broadband flexible metamaterial absorber is proposed. The unit cell of the absorber is consisted of loaded high-impedance surfaces (HIS) on a flexible polyethylene terephthalate (PET) substrate and a metallic ground plane seperated by a dielectric layer. Losses in the high-impedance surface are introduced by printing the periodic pattern through resistive inks and hence avoiding...
In this work, we propose an optimal design for the crescent-slot nanoantenna for energy harvesting applications. By tuning the axial ratio of the two ellipses comprising the antenna, the band and field intensity of the nanoantenna can be controlled. Full wave electromagnetic simulations using COMSOL and HFSS have been carried out to show the efficiency of this approach.
This paper presents a broadband LNA MMIC design with 0.1um GaAs pHEMT process. The peak power gain of 22dB with 3dB bandwidth of 31GHz from 73GHz to 104GHz, and the minimum noise figure of 3.6dB at 82GHz have been achieved by the 4-stage LNA. The input and output return loss is less than −10dB within full W-band. This well-designed LNA with a compact size of 1.75×0.55mm2 will be utilized for passive...
Considering a broadband co-frequency and co-time full duplex (CCFD) transceiver, which transmits and receives at the same time and frequency resources, the previous studies propose many self-interference cancellation algorithms in the radio frequency (RF) domain, but lack their performance analysis. Therefore, we make an attempt to analyze the optimal self-interference cancellation performance in...
A novel broadband metamaterial absorber based on cross dumbbell-shaped 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 12.1 GHz under the normal incidence, equivalent to a relative absorption bandwidth...
In this paper, a broadband perfect metamaterial absorber was designed in microwave frequency band, which was based on flexible materials. The flexible materials can be used in radomes, sensing, cloaking and other microwave applications. This absorber is polarization insensitive owing to the high — degree symmetry of structure. Simulation results show that the proposed absorber has high absorption,...
In this paper, a novel single-layer broadband subwavelength multi-resonance element is proposed to design a dual circularly polarized (CP) reflectarray with a dual linearly polarized (LP) feed. The simulated results show an adequate phase range over 3600 and low mutual coupling between the two orthogonal polarizations of the element. Also, a superior bandwidth performance has been verified, compared...
One of the research projects of Multi-Beam Klystrons (MBKs) is to extend its bandwidth. The bandwidth of the MBKs strongly depends on its peak power and the cathode loading. In some applications, an S-band MBK with peak power of 30∼50kW, bandwidth of 10%, efficiency of more than 25%, and the lifetime of more than 3000 hours is needed. In order to realize wide bandwidth at low peak power, the S band...
Large super markets have a great variety of goods and different supermarkets may have different distribution of commodity. Most of the customers find it difficult to stand in long queue for billing the purchased products. This causes waste of time and wrong billing for wrong customers. This project provides a great solution to all these problems. Most recently LIFI is new emerging technology in the...
TV White Spectrum utilization has become a major concern in the field of communication sector throughout the world. This research paper focuses on utilizing the TV White Spectrum for Wireless Broadband Internet Connectivity (WBIC) on the basis of availability. For reference, a practical scenario has been considered. The scenario represents the TV White Spectrum of Bangladesh Television (National Television...
This work introduces an alternative architecture of a GNSS signal simulator, where the multiple GNSS services in the full GNSS bandwidth from L5 to L1 are generated and mixed in digital form. The digital-to-analog conversion and up-conversion to L-band is then applied to the single compounded wideband digital signal. The digital signal generation and mixing is implemented on a pair of strong GPUs...
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