The subject of enhancing microstrip patch antennas directivity, using either a frequency selective surface (FSS) or a double-negative (DNG) metamaterial slab, has been investigated by a number of researchers in recent years. The purpose of this paper is to show that we can also achieve the same goal by using a much simpler design for the superstrate, namely a dielectric slab, whose performance ...

The design of time-invariant beamformers is often posed as an optimization problem using practical design constraints. In many scenarios it is sufficient to assume that the microphones have an omnidirectional directivity pattern, a flat frequency response in the range of interest, and a 2D environment in which wavefronts propagate as a function of azimuth angle only. In this paper we consider a...

The directivity index is a parameter that is commonly used to characterize the performance of directional hearing aids, and is determined from the measured directional response. Since this response is different for a hearing aid worn on a person as compared to when it is in a free field, directivity index measurements of hearing aids are usually done under simulated real-ear conditions. Details...

Horn antennas can result in good impedance matching between the waveguide and free space due to the gradual increase in the aperture size. In this paper, a novel plasmonic sectoral horn nanoantenna based on using lens in the aperture is proposed. It is investigated that in addition to improvement of the directivity, the reflection coefficient is also reduced using the proper lens structure. The...

The Wenchuan earthquake of 12 May 2008 is the most destructive earthquake in China in the past 30 years in terms of property damage and human losses. In order to understand the earthquake process and the geo-morphological factors affecting the seismic hazard, we simulated the strong ground motion caused by the earthquake, incorporating three-dimensional (3D) earth structure, finite-fault ruptur...

Dolph-Chebychev arrays are known to exhibit the best compromise between sidelobe level and directivity. However, they place a constraint on the null locations. Any attempt to impose nulls or get them deeper will impact the directivity/sidelobe level trade-off. In this work, null placement in Dolph-Chebychev arrays through element position perturbation is carried out based on Taguchi method whil...

This paper gives an analysis of operation of a self-phased array under conditions of multipath propagation (either reflections or jamming signals). A general method for the calculation of directivity of such an array has been proposed. Influence of reflections by way of the pilot signal channel as well as by way of the primary signal channel is taken into account. Some limitations of the approa...