Closed-Form Expressions for the Design of Ladder-Type FBAR Filters

Filters based on film bulk acoustic resonators (FBARs) promise to improve the performance of actual filters, however, to the authors' knowledge, their systematic implementation is not straightforward. This letter presents a collection of closed-form expressions for the systematic design of ladder-type filters using FBARs. The procedure is validated against the work of other authors, finding a very good agreement between results     

On the testing of the magnetic field integral equation with RWGbasis functions in method of moments

For electromagnetic analysis using method of moments (MoM), three-dimensional (3-D) arbitrary conducting surfaces are often discretized in Rao, Wilton and Glisson basis functions. The MoM Galerkin discretization of the magnetic field integral equation (MFIE) includes a factor Ω₀ equal to the solid angle external to the surface at the testing points, which is 2π everywhere on the surface of the object, except at the edges or tips that constitute a set of zero measure. However, the standard formulation of the MFIE with Ω₀=2π leads to inaccurate results for electrically small sharp-edged objects. This paper presents a correction to the Ω₀ factor that, using Galerkin testing in the MFIE, gives accuracy comparable to the electric field integral equation (EFIE), which behaves very well for small sharp-edged objects and can be taken as a reference     

Integral equation MEI applied to three-dimensional arbitrarysurfaces

The authors present a new formulation of the integral equation of the measured equation of invariance (MEI) as a confined field integral equation discretised by the method of moments, in which the use of numerically derived testing functions results in an approximately sparse linear system with storage memory requirements and a CPU time for computing the matrix coefficients proportional to the number of unknowns     

Dual-Band Mixer Using Composite Right/Left-Handed Transmission Lines

The concept of composite right left-handed transmission lines provides for one additional degree of freedom in realizing arbitrary dual-band frequency response devices. In this letter, an arbitrary dual-band operation mixer, based on the classical balanced mixer topology is proposed. The prototype demonstrates the mixer performance for a ratio of 2.5 between the two operation bands (860 MHz and 2,150 MHz). The conversion losses are better than 8.5 dB in both bands.     

Processing of biological motion point-light displays by baboons (Papio papio).

Humans apply complex conceptual judgments to point-light displays (PLDs) representing biological motion (BM), but how animals process this kind of display remains uncertain. Four baboons (Papio papio) were trained to discriminate BM from nonbiological motion PLDs using an operant computerized test system. Transfer tests were given after training with novel BM stimuli representing humans or baboons (Experiment 1), with inverted PLDs (Experiment 2), and with BM stimuli in which body parts had been spatially disorganized (Experiment 3). Very limited transfer was obtained with the novel and inverted displays in Experiments 1 and 2, but transfer was much higher after spatial disorganization in Experiment 3. It is suggested that the baboons did not retrieve and interpret the articulated shape of the human or monkey body from the BM PLD stimuli, but rather focused their attention on the configural properties of subparts of the stimuli. Limits in perceptual grouping and restricted abilities in picture-object equivalence might explain why the baboons did not map BM PLD displays onto what they represent. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contrasting the edge- and surface-based theories of object recognition: Behavioral evidence from macaques (Macaca mulatta).

This study assessed the contribution of edge and surface cues on object representation in macaques (Macaca mulatta). In Experiments 1 and 2, 5 macaques were trained to discriminate 4 simple volumetric objects (geons) and were subsequently tested for their ability to recognize line drawings, silhouettes, and light changes of these geons. Performance was above chance in all test conditions and was similarly high for the line drawings and silhouettes of geons, suggesting the use of the outline shape to recognize the original objects. In addition, transfer for the geons seen under new lighting was greater than for the other stimuli, stressing the importance of the shading information. Experiment 3, using geons filled with new textures, showed that a radical change in the surface cues does not prevent object recognition. It is concluded that these findings support a surface-based theory of object recognition in macaques, although it does not exclude the contribution of edge cues, especially when surface details are not available. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

More accurate size contrast judgments in the Ebbinghaus Illusion by a remote culture.

The Ebbinghaus (Titchener) illusion was examined in a remote culture (Himba) with no words for geometric shapes. The illusion was experienced less strongly by Himba compared with English participants, leading to more accurate size contrast judgments in the Himba. The study included two conditions of inducing stimuli. The illusion was weaker when the inducing stimuli were dissimilar (diamonds) to the target (circle) compared with when they were similar (circles). However, the illusion was weakened to the same extent in both cultures. It is argued that the more accurate size judgments of the Himba derive from their tendency to prioritize the analysis of local details in visual processing of multiple objects, and not from their impoverished naming. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Figure of merit for multiband antennas

This communication defines a figure of merit for multiband antennas that gives an objective quantification of the similarities between radiation patterns at the different antenna operating bands.     

Method of moments enhancement technique for the analysis of Sierpinski pre-fractal antennas

The numerical analysis of highly iterated Sierpinski microstrip patch antennas by the method of moments (MoM) involves many tiny subdomain basis functions, resulting in a very large number of unknowns. The Sierpinski pre-fractal can be defined by an iterated function system (IFS). As a consequence, the geometry has a multilevel structure with many equal subdomains. This property, together with a multilevel matrix decomposition algorithm (MLMDA) implementation in which the MLMDA blocks are equal to the IFS generating shape, is used to reduce the computational cost of the frequency analysis of a Sierpinski based structure.     

Comparison of grouping abilities in humans (Homo sapiens) and baboons (Papio papio) with the Ebbinghaus illusion.

This research comparatively assessed grouping mechanisms of humans (n = 8) and baboons (n = 8) in an illusory task that employs configurations of target and surrounding circles arranged to induce the Ebbinghaus (Titchener) illusion. Analyses of response behaviors and points of subjective equality demonstrated that only humans misjudged the central target size under the influence of the Ebbinghaus illusion, whereas baboons expressed a more veridical perception of target sizes. It is argued that humans adopted a global mode of stimulus processing of the illusory figure in our task that has favored the illusion. By contrast, a strong local mode of stimulus processing with attention restricted to the target must have prevented illusory effects in baboons. These findings suggest that monkeys and humans have evolved modes of object recognition that do not similarly rely on the same gestalt principles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)