Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

A Wideband High-Gain Circularly-Polarized Dielectric Horn Antenna Equipped With Lamé-Axicon Stacked-Disk Lens for Remote Sensing, Air Traffic Control and Satellite Communications

A wideband high-gain circularly polarized (CP) shaped dielectric horn-lens antenna (SDHLA) operating in the frequency band between 6.7 and 18.2 GHz [fractional impedance bandwidth (FIBW) of 92.4%] with a 3-dB axial-ratio in the frequency range from 8.1 to 16.3 GHz [fractional axial-ratio bandwidth (FARBW) of 67.2%], is presented. The antenna, composed of a suitably shaped dielectric horn, integrated with a super-ellipsoidal-axicon dielectric lens made out of stacked thin dielectric disks, is mounted on a printed circuit board (PCB) where a microstrip line terminated with a wideband radial stub is used to excite a S-shaped slot through which the circular polarization is achieved. Parameterized 3D Lamé curves, describing the horn and lens profile, are used to optimize the antenna design. The antenna features a peak realized gain exceeding 13.1 dBi that is beneficial in a variety of applications, such as digital video broadcasting (DVB), remote sensing, weather monitoring, satellite communications, and air traffic control. The full-wave electromagnetic solver CST Studio Suite™, based on a locally conformal finite integration technique (FIT), was employed to design and characterize the antenna whose performances were found to be in good agreement with the experimental measurements.</p

A Comparison between Multiple-Input Multiple-Output and Multiple-Input Single-Output Radar Configurations for Through-the-Wall Imaging Applications

The performances of a multiple-input multiple-output (MIMO) radar, employing 16 equivalent antennas, and multiple-input single-output (MISO) radar, employing 10 antennas, for through-the-wall imaging applications are analyzed. In particular, imaging algorithms based on the Fourier transform (FT) and the multiple signal classification (MUSIC) available in the literature are compared with the FT-MUSIC hybrid algorithm recently developed by the authors. Three different investigations have been performed. The first, performed analytically, refers to a scenario in which a point scatterer is placed in free space, and the second, addressed numerically using the CST full-wave software, refers to a scenario in which two targets are present, while the last was executed in a real scenario where a metal panel is placed behind a tuff wall. All the algorithms and radar configurations were found to be suitable for accurately reconstructing the position of the investigated target. In particular, applying the FT technique, the MISO configuration has a lower cross-range half-power beamwidths (HPBW) than the MIMO one, while the range HPBW is the same for the two radar configurations. Despite the different number of elements present in the two radar configurations, similar range and cross-range HPBW are obtained for both configurations when MUSIC and FT-MUSIC techniques are employed. The field of view for FT and FT-MUSIC is about 45°, while it is less than 15° for the MUSIC algorithm. The HPBWs obtained with the experimental setup are very close to those obtained in the analytical study. Finally, the proposed experimental MISO radar acquires the data in half the time required by the MIMO one. The numerical results, confirmed by the experimental measurements, seem to indicate in the FT-MUSIC technique the one that provides the best performance for the considered radar configurations

A full-wave analysis of the parasitic coupling between right-angle mitered bends microstrip discontinuities

A full-wave analysis of the parasitic coupling effects between right-angle mitered bends microstrip discontinuities is presented. The full-wave analysis is performed by means of the spectral domain approach (SDA) which allows to include the effects caused by the surface and volume waves excited by the discontinuity. Using the computed field quantities, the scattering parameters of the structure are obtained and used to derived an equivalent circuit suitable to model the dispersive effects and the parasitic coupling caused by the microstrip discontinuities. The analysis is carried out by varying the electrical and geometrical parameters that characterize the considered structures. © 2012 IEEE

Near field synthesis based on multi-port antenna radiation matrix eigenfields

The attainable performances of a general formulation employing radiation matrix eigenfields of multi-port antennas to synthesize near-field distributions are investigated. Field synthesis performed on open or closed surfaces, proximate to or enclosing an antenna array, either based on both electric and magnetic target field distributions or just the former, are presented to illustrate key features of the synthesis technique and its sensitivity with respect to realistic random magnitude and phase variations of the array excitation profiles. Guidelines to perform synthesis and steering of complex near-field distributions are then suggested. Propagation characteristics of diffraction-resistant Bessel, OAM Bessel and Airy beams in their actual finite-energy implementation when they are excited by finite-size antenna arrays are finally investigated

A novel wideband multi-permittivity composite dielectric resonator antenna for wireless applications

A novel high-gain dielectric resonator antenna (DRA) for wideband wireless applications is presented. The antenna is composed of a hollow cylindrical dielectric resonator (DR) inside which an assembly of two dielectric truncated cones having different permittivities are inserted. A suitable probe excitation system and an air gap, realized between the base of the first truncated dielectric cone and the ground plane, are used to further increase the antenna bandwidth. A full-wave commercial software based on the finite integration technique (FIT) has been used to analyze and design the antenna, while the singularity-extraction method (SEM) has been adopted to extract information about the main resonant processes taking place in the proposed radiating structure

Energy-based representation of multiport circuits and antennas suitable for near-and far-field syntheses

An energy-based representation suitable for the electromagnetic characterization of linear multiport circuits and antenna systems, as well as for the optimization of antenna beamforming and near-field radio frequency-focusing performances, is presented. Radiation, ohmic, dielectric power loss, and reactive power storage are described in the concise matrix form, yielding respective eigenmodes and eigenfields that rigorously account for all energetic processes. Noteworthy eigenfields orthogonality properties are illustrated and employed to maximize (minimize) active power flow through, or to synthesize fields on, arbitrary surfaces. Applications of the proposed formulation include multiport antennas, microwave-sensing devices, microwave hyperthermia applicators, through-the-wall imaging, and wireless power transfer systems. The numerical results illustrate features and performance advantages of the proposed formulation as applied to multiport antennas and lead to define some basic design guidelines

A Numerical Procedure for the Analysis of EMC/EMI Problems in Radio Communication Systems Operating in Complex Environments

An efficient combined full-wave/high-frequency procedure useful to evaluate the spatial distribution of the electromagnetic field excited by radio sources operating in complex environments is presented. The procedure is based on a full-wave technique for the evaluation of the field distribution excited within a volume surrounding the radiating sources, and a dedicated high-frequency technique useful to model the propagation and interaction of the electromagnetic field with electrically penetrable objects forming the operative environment. In this way, it is possible to determine, with a reduced computational burden, the field distribution from the source location to the far-field region while keeping a high numerical accuracy. Using the proposed procedure, it is possible to evaluate the performance of mobile radio communication systems taking into account the impact of the operative environment, which is in turn essential to identify safety areas in compliance with the electromagnetic compatibility (EMC) regulations. Numerical examples aimed to predict potential EMC/EMI issues which could be caused by a mobile communication system operating in a complex scenario modeling a crisis area are also reported

An Electromagnetic Characterization of Indoor Radio Environments in Microwave WLAN Systems

Phoenix, A