High-Impedance Surfaces (HIS) comprising lossy Frequency Selective (FSS) are employed to design thin electromagnetic absorbers. The structure, despite its typical resonant behavior, is able perform a very wideband absorption in reduced thickness. Losses the frequency selective surface introduced by printing periodic pattern through resistive inks and hence avoiding soldering of large number lumped resistors. effect resistance FSS dielectric substrate characteristics on input impedance...

A frequency selective radome is presented, acting as a pass band filter at given band, while behaving an absorber above the transmission band. The behavior obtained by metallic FSS realized through compact interdigitated Jerusalem cross element characterized very large rejection used ground plane of thin wideband based on resistive high-impedance surfaces within total reflection outer reduces signature antenna system when illuminated out signals. which comprises designed so to minimize...

The transmission and reflection properties of frequency-selective surfaces (FSSs) are evaluated through a simple accurate first-order circuit approach. approximate analysis, based on the parallel between real structure lumped-LC-network counterpart, is also useful for acquiring physical insights into working principles surfaces. first part paper describes technique computing lumped parameters most common frequency-selective-surface elements. L C representing given element derived only one...

This paper introduces several different design methodologies for multiband artificial magnetic conducting (AMC) surfaces. The begins by investigating the properties exhibited a conventional electromagnetic bandgap (EBG) AMC that consists of frequency selective surface (FSS) on top thin dielectric substrate with PEC back plane. higher-order resonances associated these surfaces have not been discussed in detail to date, as previous research has concerned only exploiting primary resonant...

A design for planar electromagnetic absorbers is presented. The performance of this absorber maintained over a wide incidence angles and both TE TM polarization. composed high-impedance surface comprising an array patches grounded lossy dielectric slab perforated with metallic vias (wire medium). main contribution the paper to demonstrate practically use presence additional resonance when plasma frequency wire medium in substrate close original surface. between FSS ground plane discussed...

A popular absorbing structure, often referred to as Perfect Metamaterial Absorber, comprising metallic periodic pattern over a thin low-loss grounded substrate is studied by resorting an efficient transmission line model. This approach allows the derivation of simple and reliable closed formulas describing absorption mechanism subwavelength structure. The analytic form real part input impedance explicitly derived in order explain why moderate losses sufficient achieve matching with free...

We describe a numerically efficient strategy for solving linear system of equations arising in the Method Moments electromagnetic scattering problems. This novel approach, termed as characteristic basis function method (CBFM), is based on utilizing functions (CBFs)-special defined macro domains (blocks)-that include relatively large number conventional sub-domains discretized by using triangular or rectangular patches. Use these leads to significant reduction unknowns, and results...

A solution for reducing the radar cross section (RCS) of a microstrip antenna based on use frequency selective surfaces (FSSs) is described. The goal accomplished by replacing solid ground plane device with hybrid structure comprising suitable FSS. behavior illuminated wave analyzed using periodic method moments (PMM), and it modeled resorting to transmission-line equivalent circuit. Similarly, propagation quasi-TEM mode along modified feeding line array represented an circuit surface waves....

Numerical techniques based on a time-domain recursive solution of the electric field integral equation (EFIE) may exhibit instability phenomena induced by joint space-time discretization. The above problem is addressed with specific reference to evaluation electromagnetic scattering from perfectly conducting bodies arbitrary shape. We analyze particular formulation method moments which relies triangular-patch geometrical model exterior surface body and operates according...

A novel chipless RF identification based on a multiresonant high-impedance surface is proposed. The structure finite metallic frequency-selective (FSS) comprising 2 × (30 mm 30 mm) or 3 (45 45 unit cells. FSS cell formed by several concentric square loop resonators. thin performs deep absorptions of the impinging signal at resonant frequencies related to If one printed loops in removed, corresponding absorption peak disappears from reflected giving possibility encoding desired bit sequence....

A comprehensive analysis aimed at reducing the radar cross section (RCS) of array antennas, preserving same time their radiating performance, is presented. microstrip slot considered as a test case to illustrate proposed strategy for reduction (RCSR). It shown that remarkable signature can be accomplished over frequency band wide two octaves by employing an periodic resistive elements in front apertures. The monostatic and bistatic RCS structures are investigated both normal oblique...

Low-profile antennas comprising a horizontal dipole above high-impedance surface are analyzed. The emphasis of this paper is on the additional resonances radiating structure caused by waves propagating surface. It shown that such can be favorably used for broadening bandwidth antenna. phenomenon thoroughly modeled exploiting parallel between HIS and waveguide resonator. In second part we discuss homogenized approaches modeling properties antenna with to discussed in first part. As it turns...

An overview of transmission/reflection-based methods for the electromagnetic characterisation materials is presented. The paper initially describes most popular approaches bulk in terms dielectric permittivity and magnetic permeability. Subsequently, limitations aimed at removing ambiguities deriving from application classical Nicolson–Ross–Weir direct inversion are discussed. second part focused on partially conductive thin sheets surface impedance via waveguide setups. All presented...

The advantages of adopting circular polarization in multiple-input-multiple-output (MIMO) systems are illustrated for both line-of-sight (LOS) and multipath propagation. More detail, an analysis the MIMO performance attainable by employing orthogonal circularly polarized (CP) radiators with respect to linearly (LP) ones, has been addressed. At first, accurate is presented aimed at evaluation channel matrix comprehensively including also effects antenna LOS condition. In particular,...

The particle swarm optimization (PSO) is a stochastic strategy that has recently found application to electromagnetic problems. It based on the behavior of insect swarms and exploits solution space by taking into account experience single as well entire swarm. This combined synergic use information yields promising tool for solving design problems require relatively large number parameters. In this letter, problem synthesizing frequency selective surfaces (FSSs) addressed using specifically...

In this letter, the bandwidth of high-impedance surfaces (HISs) is discussed by an equivalent circuit approach. Even if these have been employed for almost 10 years, it sometimes unclear how to choose shape frequency selective surface (FSS) on top grounded slab in order achieve largest possible bandwidth. Here, we will show that conventional approach describing HIS as a parallel connection between inductance given dielectric substrate and capacitance FSS may induce inaccurate results...

Microstrip reflectarray antennas consist of a grounded quasi-periodic array printed elements able to compensate the phase displacement non-coherent electromagnetic excitation generated by feeder. The design is usually accomplished tracing reflection diagram periodic version surface, which analogous high-impedance surface (HIS). Reflection losses this structure are here analyzed through simple equivalent transmission line model. analytical expressions impedance offered HIS (real and imaginary...

An efficient approach for obtaining an active high- impedance surface (HIS) is presented. The novel design allows us to synthesize a tunable HIS by drastically reducing the number of elements employed. conventional loading single varactor each unit cells frequency selective (FSS) overcome connecting FSS feeding network located behind ground plane through metallized vias. A waveguide demonstrator proposed structure has been designed, realized, and tested. In example shown herein, apply group...

This communication aims to demonstrate both theoretically and experimentally that chipless tags can be efficiently detected on metallic platforms by exploiting cross-polar reflection. The employed tag consists of a frequency selective surface (FSS) comprising concentric square loop resonators printed grounded dielectric slab. co-polar reflection amplitude the proposed structure is characterized deep minima in correspondence every resonance, whereas component coefficient exhibits well defined...

A wideband and polarization-insensitive absorber/reflector with multifunctional characteristics is proposed in this communication. The designed structure comprises a switchable layer, an air spacer, metal ground. layer contains active resonant elements, whose switching properties are realized by controlling p-i-n diodes. Bias networks for the diodes integrated into structures no dedicated bias lines required. Thus, negative effect of extra can be alleviated. In order to achieve...

Electromagnetic absorbers for free space and cavity absorption are discussed. Classical configurations described as well more recent designs. The presented layouts able to provide absorbing behaviors spanning from ultra-narrow band ultra-wideband. A comparison among various solutions is both in terms of achievable bandwidth minimum theoretical thickness. problem resonances also addressed. It shown that can be damped by using alternative with respect the classic use lossy magnetic materials.

A novel encoding paradigm for chipless radio frequency identification (RFID) tags based on phase quantization is presented. The most distinctive features of this approach are represented by the low requirement bandwidth and scheme. former achieved using only a multifrequency reading without resorting to ultrawideband systems, whereas latter relies linking information quantized difference between TE TM response tag. mechanism described as well decoding procedure. reliability illustrated...

A chipless RFID sensor exploiting the depolarizing effect of a finite period surface is proposed for rotation monitoring. The information encoded in cross-polar response scatterer, which, turns, depends on orientation tag with respect to probing wave. Preliminary assessment illustrated and critical issues are analyzed future developments.

A novel low-cost null-steering antenna operating at 2.45 GHz is designed by exploiting an asymmetric excitation of two characteristic modes. This compact allows a null shift the radiation pattern changing relative phase between capacitive exciters (CCEs) located above conductive plane. As proof concept, prototype radiator has been realized resorting to discrete shifter in order scan null. The measured patterns prove that proposed design strategy reliable and applicable other kinds...