1 

Green's function of an infinite slot printed between two homogeneous dielectrics  Part II: Uniform asymptotic solution
This second part of a twopaper sequence deals with the uniform asymptotic description of the Green's function of an infinite slot printed between two different homogeneous dielectric media. Starting from the magnetic current derived in Part I, the dyadic green's function is first formulated in integral form in both spectral and spatial domains; next, the asymptotic solution for the vector potential is evaluated asymptotically. The asymptotic rayfield is structured in three contributions: a spherical wave radiated by the source (space wave), a conical leaky wave, and a lateral wave. These contributions are first introduced by the stationary phase method applied to the spacedomain radiation integral. From this approach it is seen that the lateral wave contribution is negligible in actual configurations. Next, a rigorous uniform asymptotic evaluation of the radiated field is formulated in the spectral domain by using a steepest descent path deformation which accounts for the vicinity of the pole to the saddle point. Through this rigorous asymptotics, the domain of existence of the leakywave is found to be limited by a conical shadow boundary which deviates from that defined by the stationary phase regime. Along this conical shadow boundary, phase matching occurs between space and leaky wave, which facilitates the transition mechanism between the two wave types. This transition occurs inside a conical transition region with elliptical cross section. The interference between space and leaky waves from the near to the far zone are discussed by means of illustrative examples, which also confirm the accuracy of the asymptotics.

[Abstract]

2 

Green's function for an infinite slot printed between two homogeneous dielectrics  Part I: Magnetic currents
This sequence of papers presents an analytical closed form for the Green's function of an infinite slot printed between two different homogeneous dielectrics. This first part is devoted to the derivation of the slot magnetic current and to the discussion of the relevant physical implications. The Fourier spectrum of the magnetic current is derived by solving in analytical form, under small width approximation, the integral equation (IE) representing the continuity of the magnetic field trough the slot axis. The accuracy of the result is validated trough a fine meshing Method of Moments. From the consequent spectral expression, a closed form approximation of the leakywave propagation and attenuation constants is derived. An asymptotic expression for the current is also obtained by steepest descent path evaluation of the pertinent spectral integral. Analytical expressions of the quasi static (reactive) contribution is given for both elementary dipole and delta gap excitations. The asymptotic, uniform closed form approximation for the field in every space point will be formulated and discussed in the second part of the paper.

[Abstract]

3 

Optimized basis functions for slot antennas excited by coplanar waveguides
A method is proposed for the analysis of slot antennas excited by coplanar waveguides. First, a standard integral equation for the continuity of the magnetic field is formulated. Then the appropriate equivalent magnetic currents of the method of moments are represented in terms of entiredomain basis functions which synthesize the resonant behavior of the slot and the field in proximity of the feeding source and of the bends. In order to define these basis functions, canonical geometries are identified, whose Green's functions have been found analytically. The accuracy and the effectiveness of the method in terms of convergence rate and number of unknowns is demonstrated by comparison with a standard fine meshing fullwave analysis.

[Abstract]

4 

LeakyWave Slot Array Antenna Fed by a Dual Reflector System
Planar leakywave antennas (LWAs) have received much attention in the recent years [1] for applications in the millimeterwave ranges. In particular the compatibility with printed circuit board technology (PCB) and the low profile are the strongest features of these antennas. Mono dimensional planar leakywave antennas, as in [2], are characterized by a fun beam; then, array solutions or twodimensional planar leakywave antennas are needed to radiate a pencil beam. An array solution of mono dimensional planar leakywave antennas would have the disadvantages of acumber some feeding network accompanied by a probable low efficiency. On the other hand twodimensional leakywave antennas have the advantage of absence of the feeding network, but they are less flexible for beam shaped designing. The pencil beam leakywave antenna presented here, an array of slots etched on one plate of a parallel plate waveguide (PPW) is fed by a dual offset Gregorian reflector system realized by vias connecting the two plates of the PPW. The antenna is shown in Fig.1.

[Abstract]

5 

LeakyWave Slot Array Antenna Fed by a Dual Reflector System
A leakywave slot array antenna fed by a dual offset Gregorian reflector system is realized by pins in a parallel plate waveguide. The radiating part of the antenna is composed by parallel slots etched on one side of the same parallel plate waveguide. The dual offset Gregorian reflector system is fed by an arrangement constituted by two vias and a grid, also constituted by pins. Also this feed arrangement realizes a leaky type of radiation, this time inside the parallel plate waveguide.Aprototype of the antenna has been designed, manufactured and successfully tested. The low profile, low cost and high efficiency of the antenna render it suited for a variety of radar or telecom applications

[Abstract]

6 

ProblemMatched Basis Functions for Microstrip Coupled Slot Arrays based on Transmission Line Green+s Functions (TLGF)
A method is proposed for the analysis of arrays of linear printed antennas. After the formulation of pertinent set of integral equations, the appropriate equivalent currents of the Method of Moments are represented in terms of two sets of entire domain basis functions. These functions synthesize on one side the resonant behavior of the slot, microstrips or dipole and on the other side the field in proximity of the feeding source and of the discontinuities. In order to define these basis functions, canonical geometries are identified, whose Green's functions have been found in semianalytical form. The accuracy and the effectiveness of the method in terms of convergence rate and number of unknowns is demonstrated by comparison with a standard fine meshing fullwave analysis. The method is extremely convenient for large arrays where the details of the feed are very small in terms of the wavelength. Since the proposed solution is independent on the dimensions of these details, it provides a dramatic reduction of the number of unknowns with respect to a standard fine mesh analysis.

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[Abstract]

7 

Dispersion properties of an array of slots etched at the interface between two infinite dielectric materials
An array of long slots, oriented along x, etched on a ground plane that separates two infinite dielectric materials constitutes the basic canonical problem investigated in this article. In a single slot structure, the direction of radiation and the attenuation constant could be directly linked to the dominant leaky wave pole (kxlw) that dominates the pertinent Green’s Function (GF) spectrum in the longitudinal direction, x. In a multi slot problem, the number of poles that appear in the GF is equal to the number (N) of slots composing the array and in view of this two problems arise. First, how to locate efficiently these N poles in the kx spectrum of the GF parameters. Secondly to asses which of these poles are significant, i.e. dominate the behaviour of the array.

[Abstract]

8 

Non Resonant Slots for Wide Band 2D Scanning Arrays
A novel type of broadband integrated array scanning in one plane is proposed. Such arrays are aimed to meet the requirements typically set for airborne Synthetic Aperture Radars, while allowing the highest degree of integration between the T/R modules and radiating elements. The array is composed by broadband leakywave slot elements radiating by means of a wedge shaped dielectric lens. As a preliminary step this paper is focused on a finite number of infinite slots radiating in an infinite medium of the same permittivity of the lens. The problem is studied through a very efficient semianalytical spectral domain procedure based on the assumption of small width of the slots in terms of a wavelength. © 2005 IEEE.

[Abstract]

9 

Leaky Wave Radiation of a DipoleExcited Slot Line Printed on an Artificial Plasma


10 

LeakyWave Slot Array Antenna Fed by a PinMade Planar Dual Offset Gregorian Reflector System
This work proposes a leakywave slot array antenna fed by a dual offset Gregorian reflector system realized by pins in a parallel plate waveguide. The radiating part of the antenna is composed by parallel slots etched on one side of the same parallel plate waveguide. The dual offset Gregorian reflector system is fed by an arrangement constituted by two vias and a grid, also constituted by pins. A prototype of the antenna has been designed, manufactured and successfully tested. The low profile, low cost and high efficiency of the antenna render it suited for a variety of radar or telecom applications

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[Abstract]

11 

Wide band scanning arrays based on leaky wave radiation
A novel type of broadband integrated array scanning in one plane is proposed. Such arrays could be used for next generation airborne Synthetic Aperture Radars, or even UWB scanning arrays for automotive applications. The array is composed by broadband leakywave slot elements radiating by means of a wedge shaped dielectric lens. The highest degree of integration between the T/R modules and radiating elements is allowed by these systems. As a preliminary step this paper is focused on a finite number of infinitely slots radiating in an infinite medium of the same permittivity of the lens. The problem is studied through a very efficient semianalytical spectral domain procedure based on the assumption of small width of the slots in terms of a wavelength.

[Abstract]

12 

ProblemMatched Basis Functions for Microstrip Coupled Slot Arrays Based on Transmission Line Green's Functions (TLGF)
Problem matched basis functions are proposed for the method of moments analysis of printed slot coupled microstrips. The appropriate equivalent currents of the integral equation kernel are represented in terms of two sets of entire domain basis functions. These functions synthesize on one hand the resonant behavior of slots, microstrips or dipoles and on the other hand the field in proximity of the feeding source and of the discontinuities. In order to define these basis functions, canonical geometries are identified, whose Green's functions have been found in semianalytical form. The accuracy and the effectiveness of the method in terms of convergence rate and number of unknowns is demonstrated by comparison with a standard fine meshing fullwave analysis. The method is extremely convenient for large arrays, where the subwavelength details should be treated together with large global dimensions. Since the proposed solution is independent of the dimensions of these details, it provides dramatic reduction of the number of unknowns and improvement of condition number.

[Abstract]

13 

ProblemMatched Basis Functions for Microstrip Coupled Slot Antennas based on Transmission Line Greens Functions
A general algorithm for the analysis of microstrip coupled leaky wave slot antennas was discussed. The method was based on the construction of physically appealing entire domain Methods of Moments (MoM) basis function that allowed a consistent reduction of the number of unknowns and of total computation time. The basis function obtained were solutions of an integral equation that represented the boundary conditions of a physical problem and had adequate contents of local reactive energy. The procedure could also be used as a matrixcompression technique when the basis function were reviewed as ruling the group of the subdomain unknowns

[Abstract]

14 

Multi sector PCSEBG antenna for low cost high directivity applications
This work proposes a new topology of antenna based on the use of Planar Circular Symmetric EBG with different periodicities. These periodicities are used to impose different propagation velocities of the dominant surface waves on different zones of the same dielectric substrate. The control of the dispersion characteristics guides the design together with the definition of a centered feed suitable to excite the surface waves. One prototype has been designed, manufactured and tested to prove the concept. © 2007 IEEE.

[Abstract]

15 

Reflector Surface Modelling : A European Collaboration
article 
2007

Author: 
Albani, M
·
Balling, P.
·
Ettorre, M.
·
Gerini, G.
·
Maci, S.
·
Pontoppidan, K.
·
Sipus, Z.
·
Sjöberg, D.
·
Vecchi, G.
·
Vipiana, F.

Keywords: 
Physics · Reflector antennas · Frequency selective surface · Interpolation · Antenna feeds · Antenna phased arrays · Optimisation

The topic of this paper is the work carried out in Work Package 2.32 of the EU network ACE. This work package is concerned with the modelling of the surfaces of modern reflector antennas. In particular the problems associated with homogenisation of periodic structures are described together with an application example. An accurate MoM solutions for periodic structure is presented. A new, fast and very efficient interpolation technique for frequency selective surfaces is introduced and linked to high frequency techniques to speed up radiation calculation processes. (5 pages).

[Abstract]

16 

Experimental Demonstration of a Dielectric Dome Antenna with Reduced Profile and Wide Scanning Capability
A wide scanning dome antenna with reduced profile is presented in this contribution. The minimum height of the dielectric lens is derived from its geometrical configuration and imposed in the design. The antenna is analysed using inhouse ray tracing and physical optics tools. Because of the presence of the lens, the phase distribution of the elements is not linear and is derived from the ray distribution over the array using a Zernike polynomial expansion. The maximum scanning angle of the illuminating array is 60° and, due to the combination with the lens, the field of view is enlarged to 70° with similar performance in all planes. A demonstrator of the lens was manufactured and combined with an available phased array working in Kuband. The active reflection coefficient is not significantly affected by the presence of the lens thanks to the matching layer on both the dielectric surfaces. The measured radiated patterns are in excellent agreement with the theoretical prediction, and they then validate the analysis tools. The active element patterns of the dome antenna are rotationally symmetric, showing how the radiating performance is almost independent on the plane of scanning. Moreover, the gain for scanning wider than 60° is significantly improved compared to the standalone array. © 2019 European Microwave Association (EuMA).

[Abstract]

17 

Widescan dielectric dome antenna with reduced profile
article 
2017

Author: 
Gandini, E.
·
Silvestri, F.
·
Benini, A.
·
Gerini, G.
·
Martini, E.
·
Maci, S.
·
Viganò, M.C.
·
Toso, G.
·
Monni, S.

Keywords: 
2015 Observation, Weapon & Protection Systems 2015 Nano Technology · RT  Radar Technology OPT  Optics · TS  Technical Sciences

In this contribution, a dielectric dome antenna design in Kaband is presented. The dome antenna is based on the combination of a phased array and a dielectric lens. The goal of the combination of these structures is to enlarge the field of view of the antenna. In particular, the array is considered to be able to scan up to 60º and the lens is used to enhance the field of view up to 80º. To this end, the optimization variables of the antenna are the shape of the dielectric lens, its thickness, its dielectric constant and the phase distribution over the array. The optimization procedure is based on a raytracing technique. In order to quantify the performance of the dome antenna, a physical optics code was developed to calculate the radiation patterns. The results show good quality patterns over the considered scanning range. The dielectric dome solution is not frequency dependent, and therefore, the bandwidth of the antenna will only be limited by the phased array.

[Abstract]

18 

Deflecting superstrate solutions for widescanning array
article 
2017

Author: 
Silvestri, F.
·
Gerini, G.
·
Gandini, E.
·
Monni, S.
·
Viganò, M.C.
·
Benini, A.
·
Martini, E.
·
Maci, S.
·
Toso, G.

Keywords: 
Electronics · Dome antennas · Phased array · Satellite communications · Satellite communication systems · Scanning antennas · Beam deflectors · Design considerations · Fractional bandwidths · Ka band · Scan angle · Scanning array · Superstrates · Antenna phased arrays · High Tech Systems & Materials · Industrial Innovation · Nano Technology Observation, Weapon & Protection Systems · OPT  Optics RT  Radar Technology · TS  Technical Sciences

Design considerations on a widescanning array antenna for oncraft satellite communications are presented in this paper. For this type of application, a scanning coverage of 80° over a 15% fractional bandwidth in Kaband is required. A solution based on a passive superstrate illuminated by a phased array is recognized as the most encouraging. Two kinds of structures are investigated: A flat solution and a flattened dome. The dome is represented as a surface with an optimized phase shift distribution in order to obtain high performances up to the extreme scan angles. A good gain profile is achieved in both cases.

[Abstract]

19 

DragOnFly: electronically steerable low drag aeronautical antenna
article 
2017

Author: 
Silvestri, F.
·
Benini, A.
·
Gandini, E.
·
Gerini, G.
·
Martini, E.
·
Maci, S.
·
Vigano, M.C.
·
Geurts, M.
·
Toso, G.
·
Monni, S.

Keywords: 
Beam deflector · Dome antennas · Antenna arrays · Antenna phased arrays · Antennas · Bandwidth · Domes · Drag · Microwave antennas · Satellite antennas · Steerable antennas · Antenna architecture · Beam deflectors · Design considerations · Electronic beam scanning · Fractional bandwidths · Large scan angle · Planar phased arrays · Satellite communications · Scanning antennas · Infostructures · Information Society · 2015 Observation, Weapon & Protection Systems 2015 Nano Technology · RT  Radar Technology OPT  Optics · TS  Technical Sciences

This paper presents design considerations for the development of widescanning antennas for oncraft satellite communications. A scanning coverage of 80° is required for this application over a 15% fractional bandwidth in Kaband. A solution based on a phased array illuminating a passive superstrate is identified as the most promising. A fullyelectronic beamscanning is considered in order to reduce the overall thickness of the antenna architecture by avoiding mechanical rotational supports. This is beneficial for the application since a reduced thickness corresponds to a lower drag. Two kinds of superstrates were investigated, a flat solution and a flattened dome. In both cases, the deflecting structure is illuminated by a phased array and is represented as a surface characterized by an optimized phase shift distribution that allows to maintain a high gain level up to very large scan angles. A flatter gain profile compared to a typical cosine scan loss for planar phased arrays was achieved in both cases. Attention was devoted to the minimization of the thickness, which was significantly reduced in comparison to classical dielectric dome solutions.

[Abstract]

20 

The Electromagnetic framework of 'Nanoarchitectronics'
article 
2019

Author: 
Ahopelto, J.
·
Benini, A.
·
Bilotti, F.
·
Casali, B.
·
Chazelas, J.
·
Gerini, G.
·
Hao, Y.
·
Herbertz, K.
·
Maci, S.
·
Massa, A.
·
Pierantoni, L.
·
Torres, C.M. sotomayor
·
Treyakov, S.
·
TriponCanseliet, C.
·
Vardaxoglou, Y.
·
Vecchi, G.
·
Zayats, A.

Keywords: 
Electromagnetism · Nanoelectronics · Cognitive structures · Electromagnetic spectra · Emerging technologies · Engineering applications · High tech industry · Interdisciplinary research · Multidisciplinary systems · Roadmap · Nanosystems · High Tech Systems & Materials · Industrial Innovation

'Nanoarchitectronics' (NTX) denotes a new interdisciplinary research area at the crossroad of Electromagnetics and Nanoelectronics. This new technology will develope reconfigurable, adaptive and cognitive structures with unique physical properties, and engineering applications in the whole electromagnetic spectrum. This FET project funded by the European Framework of Research 'Horizon 2020', gathers thirteen universities, research centers and hightech industries, belonging to eight European countries, combining concepts of multidisciplinary systems in a huge frequency range.

[Abstract]
