(1983). A Comparison of Alternative Creep Force Models for Rail Vehicle Dynamic Analysis. System Dynamics: Vol. 12, No. 1-3, pp. 79-83.

A detailed study of a single-layer circuit analog absorber using double-square-loop array reveals that three resonances can be obtained within its operating frequency band. An equivalent model is proposed to explain how these produced and absorption bandwidth widened. Simple guidelines for the design this are then formulated. It shown through measurements fractional 126.8% realized at least 10 dB reflectivity reduction under normal incidence. Furthermore, total thickness only 0.088λL lowest...

A novel design of a transmission window within the absorption band circuit analog absorber, named as frequency-selective rasorber (FSR), is presented. Based on an equivalent model, conditions are formulated to produce passband with small insertion loss and reduce reflection at frequencies below above in meanwhile. Simple guidelines our proposed FSR then developed. With loaded lumped elements, arrays square-loop cross-dipole combined realize its implementation. It shown through measurements...

This paper introduces the concept, theory, and design of 3-D frequency selective rasorbers (FSRs), which have a transmission window transparent to incident electromagnetic wave with two absorption bands located at both sides window. The proposed rasorber consists 2-D periodic array parallel waveguides. characteristics high selectivity are produced by lossless resonators implemented using waveguide metallic post in center. On other hand, obtained lossy constructed loading lumped resistors...

A novel design of an absorptive frequency-selective transmission structure (AFST) is proposed. This based on the a frequency-dependent lossy layer with square-loop hybrid resonator (SLHR). The parallel resonance provided by utilized to bypass path and improve insertion loss. Meanwhile, series used for expanding upper absorption bandwidth. Furthermore, out-of-band frequencies achieved using four metallic strips lumped resistors, which are connected SLHR. quantity elements required in unit...

This letter presents a design of thin and broadband absorbers using two-dimensional (2-D) periodic array double-square loops printed on dielectric substrate. Lumped resistors are inserted into the four sides to absorb incident electromagnetic wave. Simulated measured results for radar cross-section (RCS) finite 2-D in good agreement both show that novel absorber can reduce conducting plate's RCS greatly over wide frequency range.

This communication presents a 3D frequency selective rasorber (FSR) with bandpass filtering response and wideband absorption characteristics. By loading an array of lumped resistors at one side microstrip-line based structure (FSS), multiple resonators, including lossy are constructed. The performance high selectivity is provided by resonators in the substrate region microstrip line. characteristic obtained resistor-loaded air region. All reflected waves can be effectively absorbed...

Three-dimensional (3-D) frequency-selective structures are a recent development that exhibit superior filtering responses compared to conventional two-dimensional (2-D) surfaces. A three-dimensional structure typically comprises periodic array of multimode cavities the modes which and coupling with air can be controlled obtain desired frequency response. Based on their distinct configuration, we seek classify them as separate class high-performance structures, highlight unique features in...

A varactor-tunable second-order bandpass frequency-selective surface (FSS) for microwave frequencies is presented in this article. The FSS composed of three stacked metallic layers. wire grid each layer combination with vias provides the bias varactors. This configuration eliminates need a dedicated network varactors, and thus avoids undesirable responses associated added grid. An equivalent circuit model together an analytical design method provided to simplify procedure FSS. performance...

Tailoring methodology is proposed in this communication to achieve an arbitrary frequency response within a wide absorption band. An ultrawideband (UWB) absorber utilizing multiple resonances the unit cell of 3-D frequency-selective structure utilized as textile for designs. Two types are proposed: one absorptive reflection (AFSR) and other transmission (AFST). These structures have reflection/transmission band prototypes designed, fabricated, measured validate methodology. The first UWB...

A novel frequency selective surface (FSS) exhibiting pseudo-elliptic band-reject response is presented. The proposed FSS consists of a two-dimensional periodic array microstrip lines. For an incident wave linear polarization perpendicular to the printed lines, virtual magnetic walls are formed between Since line shielded with side supports two quasi-TEM modes, effectively forms dual-mode resonator. elliptic thus realized by coupling both modes wideband achieved including higher-order array....

The first demonstration of an optofluidic metamaterial is reported where resonant properties every individual metamolecule can be continuously tuned at will using a microfluidic system. This called random-access reconfigurable metamaterial, which used to provide the tunable flat lens with wavefront-reshaping capabilities.

A new class of three-dimensional (3-D) bandpass frequency-selective structures (FSSs) with multiple transmission zeros is presented to realize wide out-of-band rejection. The proposed FSSs are based on a two-dimensional (2-D) array shielded microstrip lines shorting via ground, where two different resonators in the substrate constructed excited mode. Furthermore, metallic plates rectangular shape and “T-type” inserted air region lines, which can introduce additional provided by Using this...

A novel dual-polarized band-absorptive frequency selective rasorber (FSR) is proposed in this communication. The FSR constructed by two-layer cascaded printed circuit boards, which meander-line square loops with and without lumped resistors loaded on the top bottom surfaces of two substrates. Its operating principle analyzed, an accurate equivalent model presented. prototype has been fabricated, assembled, measured. measured absorption band from 4.8 to 6.81 GHz (34.6%), a thickness λ <sub...

This paper presents a study of sea-water monopole antenna at very high frequency (VHF) band for maritime wireless communications. The consists feeding probe and cylinder held by clear acrylic tube. is loaded with disk on the top to improve excitation TM mode. A theoretical based three-term theory presented, which has not appeared in literature. Commercial software packages ANSYS HFSS FEKO are used simulate this antenna. Experimental results fabricated radius 50 mm show reasonably good...

An isosceles right triangular waveguide with one electric wall and two magnetic walls is proposed to design a triple-mode filter implemented in substrate integrated waveguide. The complete closed-form modal solutions are presented for both transverse modes the resonant frequencies of resonator made short can then be calculated. A structure called quarter-mode (QMSIW) introduced realize compact planar form. Simulated field distributions excited QMSIW good agreement theoretical predictions...

This communication presents a 3-D frequency-selective rasorber (FSR) that has passband with low insertion loss and two absorption bands at both sides of the passband. A lossless lossy resonators are employed in unit cell periodic structure to produce bands, respectively. Utilizing techniques stepped impedance resonator capacitor loading, thickness is reduced. Moreover, loading also frees tuning each resonant frequency resonator, which facilitates FSR design. The multiresonances obtain wide...

A methodology for designing a frequency selective reflector with two-sided absorption bands is proposed. This method based on utilizing multimode resonators inside 3-D unit cell to obtain an absorption-reflection-absorption response. Detailed analysis of this absorptive (AFSR) provided the aid equivalent circuit model reveal operating principle. To show benefit new structure in antenna's radar cross section reduction (RCSR), dual-polarized 3-D-AFSR integrated monopole and dipole antennas are...

A new quasi-elliptic bandpass frequency-selective surface (FSS) is presented by cascading a two-dimensional periodic array of double square loops (DSLs) and an gridded (GSLs). The proposed FSS can be systematically synthesized based on microwave filter theory. control not only the passband characteristics, but also transmission-zero frequencies at both ends passband, thus resulting in high selectivity filtering response. operating principle, detailed synthesis procedure, implementation...

This communication presents a wide-band and low-profile H-plane horn antenna based on ridged substrate integrated waveguide (SIW) with large conducting ground. The is implemented in single thickness of 0.13 λ0 at the center frequency. Despite its low profile, new achieves very wide bandwidth by employing an arc-shaped copper taper printed extended dielectric slab three-step SIW transition. critical for widening operation lowering characteristic impedance so that excellent matching from...

This paper presents the design of a compact and wideband surface wave antenna that exhibits very low profile can be flush-mounted on conformal platform. The proposed comprises tapered grounded ceramic slab, unidirectional launcher, impedance transition. slab is smoothly to transform guided into radiated space over wide frequency range. launcher employs probe-fed parallel plate waveguide with modified parabolic reflecting wall metallic post, which are critical for effectively transforming...

A multilayer structure and magnetic ferrite material are employed to expand the absorption bandwidth of 3-D frequency-selective rasorber (FSR). Resonant-like is used realize loss with high selectivity over a wide frequency band, while proposed achieve multiple peaks at designated frequencies. Combining loaded can bands. Equivalent circuit models utilized understand operating mechanism described guide design selected materials. Two broadband FSRs designed, fabricated, measured. Both designs...

A new single-layer linear-to-circular polarizer is presented in this communication. novel hybrid meander line and loop configuration employed to transform linearly polarized field circularly over a wide frequency band. Numerical simulations indicate that the proposed robust under oblique deflected illuminations. prototype of designed fabricated. Measured results show band axial ratio less than 3 dB ranges from 18 29 GHz with about 3-dB insertion loss.

This article proposes a new method to realize low-profile broadband absorber. The unit cell of the proposed absorber consists two layers: lossy layer with four rotationally symmetric bent metallic strips embedded chipresistors, which is modified from doubly fed dipole antenna, and ground separated by an air spacer. Three resonant modes strip chip-resistors are generated, current in passes through under different it finally consumed, resulting energy dissipation. As result, ultrawideband...

In this article, a novel frequency-selective rasorber (FSR) is proposed, which provides high-efficiency transmission band and broadband radar cross section (RCS) reduction by hybridizing low-frequency diffusion high-frequency absorption. The FSR comprises three layers. A second-order bandpass surface designed as the bottom layer, has reflection-transmission-reflection frequency response, acts an equivalent ground plane for upper layers outside band. circuit analog absorber coding metasurface...