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A simplified circuit-model approach is presented in this work to analyze the behavior of a novel broadband varactor loaded phasing line, specifically designed to improve the frequency performances of aperture-coupled reflectarray cell, and able to offer a useful degree of frequency agility. The proposed approach provides a simple but effective demonstration of the enhanced frequency performances of...
Lorentz reciprocity imposes constraints on radiation and scattering. For instance, a reciprocal antenna in a reciprocal medium will have identical radiation patterns in transmission and reception; therefore, in a dense environment a directive antenna will be prone to ‘hear’ its own echoes. Likewise, a scattering matrix in reciprocal medium will be symmetric, implying particularly that a metasurface...
In summary, we showed a novel approach to conduct difficult CP-gain measurements at mm-wave frequencies using a practical and simple yet affordable method. The proposed method eliminates the need of moving expensive equipment and also reduces the cost of alignment set-up or downconverter probes. Since there is no phase relation between the two steps of the measurements, the method proves to be increasingly...
This contribution investigates the path reduction factor (PF) on terrestrial links, a typical element of rain attenuation prediction models, introduced to take into due account the spatial inhomogeneity of rainfall. A large number of PF values are calculated by simulating the interaction of a hypothetical terrestrial link with a set of realistic rain fields synthesized by MultiEXCELL. The dependence...
A compact range wireless access system in the 60 GHz-band has been proposed for multi-Gb/s data transfer. A prototype GATE (Gigabit Access Transponder Equipment) was made to evaluate the coverage as well as the system performance of received power, bit-error rate (BER) and signal-to-noise ratio. Originally, the double-layer corporate-feed waveguide slot arrays with different number of elements were...
While our log transform reconstruction algorithm provides significant advantages over competing algorithms because of its ability to converge to a unique, global solution without utilizing a priori information, the process still requires a modest amount of regularization which naturally tends to smooth the image and sometimes blur important features. We have integrated this overall technique with...
In this contribution, we present the design of a 400-element electronically reconfigurable transmitarray working in Ka-band with 180° phase-shifting unit-cells. The sequential rotation technique is applied to generate a circularly-polarized beam over a broad frequency band. The proposed configuration exhibits a broadside gain of 20.3 dBi at 29.0GHz and cross polarization discrimination of 30.0 dB...
The generation of propagating Bessel beams is typically limited to optical frequencies with bulky experimental setups. Recent work has shown that Bessel beams can be generated at microwave and millimeter wave frequencies using a planar, leaky-wave antenna. In this work, a system comprised of two coupled Bessel beam launchers is presented. By employing a mode-matching technique, a complete solution...
With Advanced Driver Assistance Systems (ADAS) getting always more sophisticated, the related Virtual Prototyping platforms have to propose a very high level of accuracy with improved flexibility regarding vehicles, sensors, environments and scenarios. In this paper a new strategy is introduced for RADAR sensors modeling aimed at allowing high accuracy while limiting the related development efforts.
In this paper we present two indoor measurement campaigns performed using millimeter-waves massive arrays in a corridor and in an office room. In particular, we characterize the delay spread of the backscattered channel responses which can be exploited in future personal radars applications for indoor localization and mapping.
A polarization reconfigurable antenna using metasurface superstrate is proposed in this paper. The proposed antenna consists of a planar coupling slot with an array of metallic rectangular patches with PIN diodes which can be view as a reconfigurable metasurface superstrate, and a DC bias controlling circuit. When the PIN switches are OFF, the antenna can produce left-hand circular polarized (LHCP)...
An efficient numerical method related to the accurate modeling of 2D electromagnetic wave scattering by comb-like graphene strip gratings was developed. The proposed Nystrom-type numerical analysis is based on the hyper-singular integral equations (IEs) obtained using the zero-thickness resistive-sheet boundary conditions in combination with the quadrature formulas of interpolation type. Unlike FDTD,...
A novel Electromagnetic Band Gap (EBG) structure based on an off-shifted periodic metasurface is presented here. This technique can be employed for packaging of electrical circuits and gap waveguide technology. The proposed structure is easy to manufacture since it only requires drilling holes in metallic plates, reducing the cost when compared to previous works based on other textured surfaces.
Two different array of dipoles above infinite electric ground plane are optimized for bandwidth using particle swarm optimizer, concept of self and mutual impedances and impedance quality factor. It is found that it is the interaction of mutual radiated power that limits the bandwidth, rather than stored energies.
We present the experimental demonstration of the first terahertz isolator (working frequency > 1 THz), obtained using the non-reciprocal electromagnetic properties of graphene under magnetostatic bias. The presentation will cover in detail the design, fabrication and measurement of the device. The isolator operated in reflection for circularly polarized waves, showing two bands at 3 and 7.5 terahertz...
This article presents a DC model for graphene field effect transistor with improved accuracy for wireless communications. The model takes into account the mobility difference between electron and hole, accurately modelling the carrier transport in the graphene channel. In addition, the variations of mobility against carrier density is also included in this model. Excellent agreement has been achieved...
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