Multiple-antenna systems that operate at high rates require simple yet effective space-time transmission schemes to handle the large traffic volume in real time. V-BLAST, where every antenna transmits its own independent substream of data, has been shown to have good performance and simple encoding and decoding. Yet its drawbacks include its inability to work with fewer receive antennas than tr...

Circular Polarization is a method in which the electric field of the passing wave does not change the strength but only changes direction in a rotary manner. Circular polarization may be referred to as right-handed or lefthanded, and clockwise or anti-clockwise, depending on the direction in which the electric field vector rotates. Circular polarization is often used erroneously to describe mix...

In this paper, performance of relay assisted wireless link is evaluated using VBLAST in the presence of rayleigh fading where source is equipped with two transmit antennas, relay is equipped with multiple transmit and multiple receive antennas, and destination has multiple receive antennas. The input information are modulated using QPSK or 16 QAM or 64 QAM modulator and modulated information ar...

The high-frequency performance of the reflector antennas is mainly limited by the surface. It has been shown that distortions on different regions of the reflector surface can have different effects on the radiation performance. In other words, degradation of the radiation pattern due to the presence of surface distortions is sensitive to the location and behavior of the surface distortion prof...

Top-hat monopole antennas loaded with radially layered dielectric are analyzed using the finite-difference time-domain (FDTD) method. Unlike the mode-matching method (MMM) (which was previously used for analyzing these antennas) the FDTD method enables us to study such structures accurately and easily. Using this method, results can be obtained in a wide frequency band by performing only one ti...

Introduction: Communication between mobile phones and antenna BTS (Base Transceiver station) is carried by electromagnetic waves that have energy, according to their nature. Increasing use of mobile phones because of the proliferation of antennas the concerns about them are proposed in society. In the present study the correlation between distance from the BTS antennas and the ...

Many types of GNSS antennas have been developed in recent years to make them suitable for different applications. Since their designs and performance requirements vary depending on their application, they have been grouped into six different categories in this book: 1. The design and performance of each type of antenna will be described here and throughout the rest of the book. This chapter dis...

Future radiotelescopes need to have high sensitivity. With the limits of receiver sensitivity being reached this can only be achieved by increasing collecting area. Because of this, next generation telescopes will have hundreds if not thousands of large antennas. The large number of antennas greatly increases the possible array configurations or ways of locating the antennas. In this paper a va...

This report addresses the problem of using directional antennas in ad hoc routing. Although the problems with utilizing directional antennas have been visited in the past, the research has been confined mostly to issues related to medium access control. To determine whether directional antennas are beneficial to ad hoc networks, it is necessary to evaluate the impact of directional antennas on ...

There are various patch antennas used for Wi-Fi and Wi-MAX applications. But, the problems with them are low gain, low power handling capacity and hence, conventional yagi-uda antennas are used. Conventional yagi-uda antennas are used in applications where high gain and directionality are required. Generally, number of directors are added to increase gain of these antennas. But, here we present...