A novel approach to broadband log-periodic antenna design is presented, where some of the most powerful evolutionary algorithms (EAs) are applied and compared for the optimal design of wire log-periodic dipole arrays (LPDA) using NEC (Numerical Electromagnetics Code). The target is to achieve an optimal antenna design with respect to maximum gain, gain flatness, Front to Rear ratio (F/R) and SW...

It is known that in two-dimensional periodic arrays of dislocations the summation of the periodic image fields is conditionally convergent. This is due to the long-range character of the elastic fields of dislocations. As a result, the stress field obtained for a doubly periodic array of dislocation dipoles may contain a spurious constant stress that depends on the adopted summation scheme. In ...

A comprehensive simulation of ultra-wideband signal propagation in indoor environments is presented. The simulation is based on time-domain electromagnetic modeling of transmitting and receiving antennas and the analysis of wave propagation through indoor channels using the time-domain uniform theory of diffraction. The antennas are a pair of TEM horns which are modeled as arrays of vee dipoles...

micrornas (mirnas) are short, endogenous non-coding rnas that function as guide molecules to regulate transcription of their target messenger rnas. several methods including low-density qpcr arrays are being increasingly used to profile the expression of these molecules in a variety of different biological conditions. reliable analysis of expression profiles demands removal of technical variati...

Very high wind loads represent one of the major problems for ultralarge-scale 5G base station arrays in sub-6 GHz band, where dozens or even hundreds antennas are used. An ultracompact dual-polarized cross-dipole antenna with an extremely small overall projected area is presented. The reduced by employing miniaturized cross dipoles and replacing traditional ground plane a defected structure (DG...

The power loss and electromagnetic energy density of a metamaterial consisting of arrays of wires and split-ring resonators are investigated. We show that a field energy density formula can be derived consistently from both the electrodynamic (ED) approach and the equivalent circuit (EC) approach. The derivations are based on the knowledge of the dynamical equations of the electric and magnetic...

In this article, the particle swarm optimization algorithm is used to calculate the complex excitations, amplitudes and phases, of the adaptive circular array elements. To illustrate the performance of this method for steering a signal in the desired direction and imposing nulls in the direction of interfering signals by controlling the complex excitation of each array element, two types of arr...

A compact dual-band dual-polarized antenna is proposed in this paper. The two pair dipoles with strong end coupling are used for the lower frequency band, and cross-placed patch dipoles are used for the upper frequency band. The ends of the dipoles for lower frequency band are bent to increase the coupling between adjacent dipoles, which can benefit the compactness and bandwidth of the antenna....