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Four different orientations of a log-periodic dipole array of 11 elements over several types of ground are studied. With the xy-plane always treated as the flat ground, they are called 1) the x-array when dipole elements are parallel with the x-axis and the array axis is parallel with they-axis, 2) the y-array when dipoles are parallel with the y-axis and the array axis is coincident with the z-axis, 3) the z-array when dipoles are parallel with the z-axis and the array axis is parallel with the y-acix, and 4) the z=Ay=array when dipoles are parallel with the x-axis and the array axis makes an angle with the z-axis.
Understand the theory and function of wireless antennas with this comprehensive guide As wireless technology continues to develop, understanding of antenna properties and performance will only become more critical. Since antennas can be understood as junctions of waveguides, eigenmode analysis—the foundation of waveguide theory, concerned with the unexcited states of systems and their natural resonant characteristics—promises to be a crucial frontier in the study of antenna theory. Foundations of Antenna Radiation Theory incorporates the modal analysis, generic antenna properties and design methods discovered or developed in the last few decades, not being reflected in most antenna books...
A numerical method for calculating the scattering and diffraction at an antenna site to be used in a sky-wave communication link is derived. The method of physical optics is used to treat the scattering by the terrain surrounding the antenna site. The terrain is represented by a Gaussian transformation and, as an intermediate step, the reflection points on the terrain are found. The method is compared with the approach based on the numerical solution of an integral equation and good agreement is obtained. It appears that the method will be applicable over the HF range for the majority of terrain encountered in practice.
This book gives a step-by-step presentation of a generalized transmission line method to study the far-zone radiation of antennas under a multilayer structure. Normally, a radiation problem requires a full wave analysis which may be time consuming. The beauty of the generalized transmission line method is that it transforms the radiation problem for a specific type of structure, say the multilayer structure excited by an antenna, into a circuit problem that can be efficiently analyzed. Using the Reciprocity Theorem and far-field approximation, the method computes the far-zone radiation due to a Hertzian dipole within a multilayer structure by solving an equivalent transmission line circuit. ...
MULTIFUNCTIONAL ANTENNAS AND ARRAYS FOR WIRELESS COMMUNICATION SYSTEMS Offers an up-to-date discussion of multifunctional antennas and arrays for wireless communication systems Multifunctional Antennas and Arrays for Wireless Communication Systems is a comprehensive reference on state-of-the-art reconfigurable antennas and 4G/5G communication antennas. The book gives a unique perspective while giving a comprehensive overview of the following topics: Frequency reconfigurable antennas Pattern reconfigurable antennas Polarization reconfigurable antennas Reconfigurable antennas using Liquid Metal, Piezoelectric, and RF MEMS MIMO and 4G/5G wireless communication antennas Metamaterials and metasur...
The main purpose of the report is to establish certain structural properties of a peculiar class of Plane Wave Spectra (PWS) representing an aperture field (or, equivalently of radiation patterns) which make the aperture reactive power equal to zero. To achieve this objective the entire question of the representation of an aperture field through a PWS is reexamined from a novel viewpoint. The Fourier transform (FT) of the transverse electric field on the aperture is considered as a two-dimensional vector field on the wavenumber plane, represented through two scalar functions, which are its coordinates in a chosen vector basis (Section 3). The choice of the latter has an important physical significance since it corresponds to the decomposition of the PWS into two components having differently polarized radiation patterns and different reactive properties. In Section 4, it is shown that the conductance and the susceptance of an aperture can be expressed as integrals (extended over the visible and invisible space) of two quadratic forms (whose explicit expressions depend upon the basis chosen to represent the PWS).
This book presents the fundamental background theory and analytical techniques of antenna design. It deals with a very wide range of antenna types, operating from very low frequencies to millimetre waves.
Measured radiation patterns of a plasma-covered antenna are compared with an approximate leaky wave analysis due to Oliner and Tamir. The results clearly show a shift in the optics ''critical angle'' and the appearance of several side lobes are predicted by theory. The plasma is produced in a He - Xe admixture at 0.4 torr by a capacitively-coupled 10-Mcps cw source and contained in a rectangular pyrex vessel of interior dimensions 8 in. by 4 in. by 5 in. Electron densities in excess of 5 x 10 to the 11th power per cc are measured by a standard microwave interferometer by manually balancing a bridge or automatically by displaying a set of interference ''fringes'' after a pattern is recorded. (Author).
Based on Bahl and Bhartia's popular 1980 classic, Microstrip Antennas, this all new book provides the detail antenna engineers and designers need to design any type of microstrip antenna. After addressing essential microchip antenna theory, the authors highlight current design and engineering practices, emphasizing the most pressing issues in this area, including broadbanding, circular polarization, and active microstrip antennas in particular. Special design challenges, ranging from dual polarization, high bandwidth, and surface wave mitigation, to choosing the proper substrate, and shaping an antenna to achieve desired results are all covered.