Two-Dimensional Time-Domain Antenna Arrays for Optimum Steerable Energy Pattern with Low Side Lobes

This document presents the synthesis of different two-dimensional time-domain antenna arrays for steerable energy patterns with side lobe levels. The research is focused on the uniform and nonuniform distributions of true-time exciting delays and positions of antenna elements. The uniform square array, random array, uniform concentric ring array, and rotated nonuniform concentric ring array geometries are particularly studied. These geometries are synthesized by using the well-known sequential quadratic programming. The synthesis regards the optimal true-time exciting delays and optimal positions of pulsed antenna elements. The results show the capabilities of the different antenna arrays to steer the beam in their energy pattern in time domain and how their performance is in frequency domain after the synthesis in time domain

Design of beam-forming networks for scannable multi-beam antenna arrays using CORPS

This paper deals with the design of beam-forming networks (BFN) for scannable multibeam antenna arrays using Coherently Radiating Periodic Structures (CORPS). This design of CORPS-BFN considers the optimization of the complex inputs of the feeding network by using the Differential Evolution (DE) algorithm. Simulation results for different configurations of CORPS-BFN for a scannable multibeam linear array are presented. The results shown in this paper present certain interesting characteristics in the array factor response for the scannable multibeam linear array and the feeding network simplification for the design of BFN based on CORPS.This work was supported by the Mexican National Science and Technology Council, CONACyT, under grant J50839-Y and the Science and Technology Council of Tamaulipas Mexico (COTACyT) under Grant 2007-C13-73901

Simplifying the feeding network for multi-beam circular antenna arrays by using corps

An innovative way to analyze the design of beam-forming networks (BFN) for scannable multi-beam circular antenna arrays using the CORPS (Coherently Radiating Periodic Structures) concept is introduced. This design of CORPS-BFN considers the optimization of the complex inputs of the feeding network by using the Differential Evolution (DE) method. Simulation results for different configurations of CORPS-BFN for a scannable circular array are presented. The results shown in this paper illustrate certain interesting characteristics in the behavior of the array factor for the scannable circular array. The most significant aspect that is unique to this proposal is the simplification of the feeding network based on CORPS.This work was supported by the Mexican National Science and Technology Council, CONACyT, under grant 127919 and the Science and Technology Council of Tamaulipas Mexico COTACyT under grant 2007-C13-73901 and 108166

Important Teacher Qualities for Integrating Blended Learning in Higher Education

Blended learning is widely accepted in Peruvian higher education for a number of reasons, including the fact that it allows students more leeway to accommodate their own unique schedule and learning needs. The present qualitative research investigates the qualities of effective teachers that are crucial to the successful implementation of blended learning from the vantage point of experts, who can gain valuable insight into the causes of organizational problems and the best strategies for resolving them. There are seven positive characteristics of blended learning teachers, such as the ability to recognize the need for pedagogical change or the confidence to incorporate technology into learning processes, and four negative characteristics, such as a lack of familiarity with blended learning or anxiety about students use of technology. Blended learning in higher education is investigated here to identify the factors that influence it

Multiobjective Synthesis of Steerable UWB Circular Antenna Array considering Energy Patterns

True-time delay antenna arrays have gained a prominent attention in ultrawideband (UWB) applications such as directional communications and radar. This paper presents the design of steerable UWB circular array by using a multiobjective time-domain synthesis of energy pattern for circular antenna arrays. By this way we avoid individual beamforming for each frequency in UWB spectrum if the problem was addressed from the frequency domain. In order to obtain an energy pattern with low side lobe level and a desired main beam, the synthesis presented is performed by optimizing the true-time delays and amplitude coefficients for the antenna elements in a circular geometry. The method of Differential Evolution for Multiobjective Optimization (DEMO) is used as the optimization algorithm in this work. This design of steerable UWB circular arrays considers the optimization of the true-time exciting delays and the amplitude coefficients across the antenna elements to operate with optimal performance in the whole azimuth plane (360°). A comparative analysis of the performance of the optimized design with the case of conventional progressive delay excitations is achieved. The provided results show a good performance for energy patterns and for their respective power patterns in the UWB spectrum

Synthesis of volumetric ring antenna array for terrestrial coverage pattern

This paper presents a synthesis of a volumetric ring antenna array for a terrestrial coverage pattern. This synthesis regards the spacing among the rings on the planes X -Y, the positions of the rings on the plane X -Z, and uniform and concentric excitations. The optimization is carried out by implementing the particle swarm optimization. The synthesis is compared with previous designs by resulting with proper performance of this geometry to provide an accurate coverage to be applied in satellite applications with a maximum reduction of the antenna hardware as well as the side lobe level reduction.This work was supported by the Mexican National Science and Technology Council, CONACyT, under Grant no. 127919