Different Types Of Antennas Research Articles

Comparative study of high-performance GPS receiving antenna designs

The FAA decision allowing the use of the global positioning system (GPS) as a radio navigation and landing help system in the United States commercial airports boosts the need for a high-performance GPS receiver which provides the demanded precision. The design of the receiving antenna is one of the most important parts in the design process, as it has to face significant challenges including uniform coverage of all satellites and the rejection of the multipath signals. The rejection of the multipath signals is accomplished by specifying restrictive criteria to the GPS antenna. This includes a high rejection of the cross-polarized signals and a radiation pattern with a sharp slope for low-elevation angles; that is, near the horizon. The feasibility of using different types of antennas to satisfy restrictive criteria such as dual-frequency coverage (L1 and L2 frequencies), -15 dB cross-polarization rejection, and a beamwidth of more than 130/spl deg/ is discussed. The antenna designs examined in this study include patch antennas, helical antennas, and conical spiral antennas. Two different receiver designs were also examined including a single-antenna system with a hemispherical coverage and an antenna array which may provide independent sectoral coverage or the desired beamwidth. It is shown that a design based on a conical spiral antenna backed with absorbing material may be used to satisfy all the desired specifications. This result was confirmed experimentally.

Optimal spatial separator of signals and interference in radio communication channels. 1. Numerical simulation

We propose an optimal algorithm for separating signals with angular manipulation from interference of any type, which is based on the space-time procession of signals. The basic characteristics of such a separator are studied by the method of numerical simulation for different types of antennas with two and three spacing branches: the dependences of separation efficiency on the angular spacing of the signal and interference sources, on the power of signals received, on the separator parameters, on the interference and signal types, etc. It is shown that the considered adaptive receiver can suppress interference efficiently in an ideal communication channel.

A study of three-half-turn and frame antennae for ion cyclotron range of frequency plasma heating in the URAGAN-3M torsatron

Numerical and experimental results of Alfvén wave heating of plasmas in the frequency range below the ion cyclotron frequency ( ω < ω ci ) are presented. Two different types of antenna were used for plasma production and heating: a frame type antenna (FTA) conventionally used in the URAGAN-3M device and a three-half-turn antenna (THTA) proposed recently to avoid the deleterious effects of conversion of fast wave to slow wave in the plasma periphery and to perform plasma core heating more effectively. Numerical modeling of electromagnetic field excitation in the URAGAN-3M plasma by the FTA and THTA was performed using a one-dimensional code. The results of calculations showed better performance of the compact THTA compared with the FTA for the case of a high density plasma (approximately 10 13 cm −3 ). When using the THTA, the experiments performed showed the possibility of dense plasma production (more than 2 × 10 13 cm −3 ) and heating, which had not been obtained earlier in the URAGAN-3M. Shifting the power deposition profile deeper inside the plasma body with the THTA resulted in modification of the plasma density profile and an improvement in plasma confinement.

Arrays: A software package for analysis of antenna arrays

This article describes a software package useful for the instruction of antenna array theory. The program provides the radiation pattern of different types of antennas, the array factor of linear, two-dimensional and three-dimensional arrays, and the total radiation pattern. The elements of the array are isotropic source, Hertzian dipole, straight thin wire dipole, and finite line source with uniform current distribution. The user has the freedom to choose one of the supported element types or to provide the pattern of an antenna element based on experimental or calculated data. This article serves as a tutorial for selected examples as well as a quick guide for the use of this software.

Understanding antennas for radar communications and avionics, by Benjamin Rulf and Gregory A. Robertshaw, Van Nostrand Reinhold

This book is an attempt to introduce electromagnetic applications to personnel with a non-electrical- engmeering background. The topics covered range from introduction of wave theory to different types of antennas. As the authors indicate, the objective of this book is not to confuse the non-specialist with detailed analysis, but to introduce him to the concepts of electromagnetics with regard to antenna applications. This book will certainly aid many electromagnetic specialists in tailoring courses for non-electromagnetic engineers. Specific topics in each of the 14 chapters are identified next.

Computer aided design of array processing techniques in NDE

This chapter is concerned with different types of antenna and antenna screening to prevent external interference (shielding). The difference between monostatic and bistatic is explained and the basic common antennas (bowtie, horn, and snake) are described and illustrated. There is also a short description of different types of borehole antenna and the reason for antenna arrays. The necessity for shielding is explained and a quick guide to the depth capability of a GPR based on its dimensions given. Advice on sensitive sites and potential sources of external interference as well as the detection of aboveground signals is also given.