Revealing radiationless sources with multi-harmonic mantle cloaking

A general formula for the scattering suppression of simultaneous cylindrical harmonic waves is reported for a bare dielectric cylinder. A proper surface impedance condition is imposed at the boundary between dielectric and background regions, revealing a parity-time condition for the internal electromagnetic field in order to be nonradiating. Depending on the maximum number M_max of cylindrical harmonic waves to suppress along the azimuthal variable phi, such surface impedance function profile reveals several higher order nonradiating modes. The determination of M_max is consistent with the degrees of freedom of the scattered fields. Moreover, the multi-harmonic mantle cloaking technique automatically generates radiationless sources suitable for the implementation with metal-dielectric metasurfaces or all-dielectric metamolecules

Optimized Design and Multiphysics Analysis of a Ka-band Stacked Antenna for CubeSat Applications

Nowadays, the use of CubeSats for telecommunications and interplanetary missions is ever-increasing, thanks to their appealing low-cost character, as well as the space environment, which poses challenging multiphysics constraints on the antenna design. In this framework, the use of Ka-band for communication is explored. We present the design of a stacked patch antenna working across the down- and uplink Ka-bands. Materials and geometry of the radiator have been selected by accounting for the trade-off between electromagnetic, thermal and mechanical requirements. The design of the antenna is performed with a particle swarm optimization algorithm developed to control the bandwidth and matching. A bandwidth of [email protected] GHz has been obtained, with a gain around 8 dB. Furthermore, a multiphysics thermal analysis is performed to verify the operational stability of the optimized array, mounted on a 1 U satellite, in a case-study mission. The temperature patterns in the array are evaluated during the orbital period, and the influence of the operative temperature on the antenna responses and gain was considered. We found that the thermal loads can affect the antenna matching. However, thanks to the optimized design, the proposed stacked antenna can operate from −100 ∘ C to 100 ∘ C, with an almost constant gain. Finally, following a damage-tolerant approach, the level of mechanical deformation, which could be induced on the communication system, was studied. The stress analysis reveals that the stacked geometry can be used in a space mission. From the investigation of the strain and displacement field, we found a negligible impact on the antenna performance

Design of a Low-Profile Dual Linearly Polarized Antenna Array for mm-Wave 5G

This work proposes a dual linearly polarized antenna array for 5G mm-wave band, which is designed to be compatible with planar printed circuit board technology. The proposed antenna is engineered with a focus on simplifying the antenna geometry and eliminating any critical issues that may arise in antenna manufacturing. The proposed antenna has been evaluated, finding a 7% impedance bandwidth centered around 27.28 GHz. Additionally, the beam steering capability of the antenna is found to cover a ±30% angular width for both linear polarizations. These findings highlight the potential of the proposed antenna for use in 5G mm-wave band applications, where compatibility with planar printed circuit board technology and simplified antenna geometry are essential design requirements

A Low-profile Shared Aperture Antenna for FR1 and FR2 5G Frequency Bands

Shared-aperture antennas are attracting a wide interest in last of years, due to their inherent compactness and low-profile layout. More specifically, in this work a shared-aperture antenna for FR1 and FR2 frequency bands is proposed. The difference in size between the radiating elements operating the two frequency bands can be exploited to embed different antennas in the same area. A 4×4 patch array for FR2 is embedded inside a FR1 shaped patch antenna. The antenna system is designed by preserving a low-profile architecture suitable for planar technology. The performance of the antenna system are evaluated for both the bands achieving a 10-dB bandwidth equal to 0.14 GHz (3.8 %) for FR1 and to 2.32 GHz (8.6 %) for FR2. In FR2, a ±30° steering capability along the H plane is shown

Transverse circular polarized bessel beam launchers for near-field applications, by using a RLSA with an inward Hankel aperture distributions

International audienc

RLSA Bessel beam launchers using Hankel waves

International audienceIn this paper the focusing capabilities of a radiating aperture taking on an Hankel-like distribution are demonstrated. In the case of an infinite aperture distribution, an analytical approach is followed. In the case of an inward Hankel wave, the ideal non-diffractive Bessel beam shape is observed for the longitudinal z-component of the electric field in a conical region close to the axis of symmetry of the aperture. In the finite case, an asymptotic approximation is used to evaluate the diffractive contributions due to the aperture truncation and to verify the conclusions of the infinite case. A radial waveguide loaded with annular slots is therefore designed and optimized as a practical implementation of the proposed Bessel beam launcher validating the theoretical results

A Low-Phase-Noise and Area-Efficient Quad-Core VCO Based on Stacked Two-Port Inductors

In this paper, a quad-core oscillator is presented, which exploits a novel stacked two-port inductor topology to couple four oscillator cores. The topology guarantees excellent low-phase-noise performance, while overcoming the drawbacks of multi-core oscillators in terms of power consumption and silicon area occupation. Three different 19.125-GHz quad-core VCOs were designed in a fully depleted silicon on insulator CMOS technology to demonstrate the high design flexibility of the proposed solution that allows power consumption and area occupation to be traded off according to the specific requirements. Although the quad-core VCO design was aimed at 77-GHz automotive radar, the proposed topology can be profitably exploited in RF/mm-wave wireless communication systems

Analysis and design of CP Bessel beam launchers

In this paper the focusing capability of a radiating aperture implementing an inward traveling wave current distribution directed along a fixed unit vector is investigated. In particular, it is shown that such a current distribution generates a field profile with its transverse component (with respect to the normal of the radiating aperture) taking the form of a zero-th order Bessel profile. As a practical implementation of the theoretical analysis, a circular-polarized (CP) Bessel beam launcher, made by a radial parallel-plate waveguide loaded with several slot pairs and arranged on a spiral pattern, is designed and optimized. The designed launcher performance agrees with the theoretical model and exhibits an excellent polarization purity

Green's function for grounded anisotropic liquid crystal substrate

In this paper, a procedure to calculate the dyadic impedance (or admittance) Green's function for a grounded layer of LCs is briefly presented. To validate the theoretical procedure, an example of dispersion calculation of a grounded layer of LCs is presented, showing excellent agreement with the simulations made with a commercial software

Design of Dual Circularly Polarized Sequentially-Fed Patch Antennas for Satellite Applications

In this paper, we present the design and fabrication of two dual circularly polarized (CP) patch antennas that can be profitably used as feeders for reflector systems normally adopted for satellite applications. In the first part of the manuscript, we propose the optimization of a dual-CP patch antenna, loaded by a fence of passive monopoles around it to increase antenna gain for high elevation angles. To achieve dual-CP operation mode, the circular patch has been sequentially-fed by three pins, whose mutual phase-shift is equal to 120 ∘ . The antenna feeding network was placed on the antenna back and designed using microstrip technology. Two different input ports provide both right-hand (RH) and left-hand (LH) circular polarizations. A prototype of such an antenna was fabricated and measured at f = 8 . 25 GHz. Furthermore, to test the versatility of the proposed single radiating patch, in the second part of the manuscript, we present the results of geometrically scaling at f = 2 . 2 GHz (higher UHF band) and this was used as a building block for the design of a dual-CP sequentially-fed 2-by-2 array antenna. The results for both the proposed antennas are satisfactory in terms of impedance bandwidth, broad radiation pattern, gain and cross-polarization rejection, thus they can be profitably used as feeders for reflectors at relatively low frequencies