Topic
Radiation pattern
About: Radiation pattern is a research topic. Over the lifetime, 32982 publications have been published within this topic receiving 393682 citations.
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TL;DR: In this paper, the physical limitations of omni-directional antennas are considered and the potentiality of a broad band width of an antenna with the maximum dimension of 2a has been shown.
Abstract: The physical limitations of omni‐directional antennas are considered. With the use of the spherical wave functions to describe the field, the directivity gain G and the Q of an unspecified antenna are calculated under idealized conditions. To obtain the optimum performance, three criteria are used, (1) maximum gain for a given complexity of the antenna structure, (2) minimum Q, (3) maximum ratio of G/Q. It is found that an antenna of which the maximum dimension is 2a has the potentiality of a broad band width provided that the gain is equal to or less than 4a/λ. To obtain a gain higher than this value, the Q of the antenna increases at an astronomical rate. The antenna which has potentially the broadest band width of all omni‐directional antennas is one which has a radiation pattern corresponding to that of an infinitesimally small dipole.
1,954 citations
Book•
01 Jan 1949
TL;DR: This book discusses microwave antenna design problems, circuit relations, reciprocity theorems, and antenna measurements - techniques.
Abstract: * Chapter 1: Survey of microwave antenna design problems * Chapter 2: Circuit relations, reciprocity theorems * Chapter 3: Radiation from current distributions * Chapter 4: Wavefronts and rays * Chapter 5: Scattering and diffraction * Chapter 6: Aperture illumination and antenna patterns * Chapter 7: Microwave transmission lines * Chapter 8: Microwave dipole antennas and feeds * Chapter 9: Linear-array antennas and feeds * Chapter 10: Waveguide and horn feeds * Chapter 11: Dielectric and metal-plate lenses * Chapter 12: Pencil-beam and simple fanned-beam antennas * Chapter 13: Shaped-beam antennas * Chapter 14: Antenna installation problems * Chapter 15: Antenna measurements - techniques * Chapter 16: Antenna measurements - equipment
1,504 citations
TL;DR: The mutual resistance condition offers a powerful design tool, and examples of new mobile diversity antennas are discussed along with some existing designs.
Abstract: The conditions for antenna diversity action are investigated. In terms of the fields, a condition is shown to be that the incident field and the far field of the diversity antenna should obey (or nearly obey) an orthogonality relationship. The role of mutual coupling is central, and it is different from that in a conventional array antenna. In terms of antenna parameters, a sufficient condition for diversity action for a certain class of high gain antennas at the mobile, which approximates most practical mobile antennas, is shown to be zero (or low) mutual resistance between elements. This is not the case at the base station, where the condition is necessary only. The mutual resistance condition offers a powerful design tool, and examples of new mobile diversity antennas are discussed along with some existing designs.
1,423 citations
01 Dec 1947
TL;DR: In this paper, a simple formula for the more fundamental properties of small antennas and their behavior in a simple circuit is given for 1-Mc operation in typical circuits, which indicates a loss of about 35 db for the I.R.E. standard capacitive antenna, 43 db for a large loop occupying a volume of 1 meter square by 0.5 meter axial length, and 64 db for an antenna loop of 1/5 these dimensions.
Abstract: A capacitor or inductor operating as a small antenna is theoretically capable of intercepting a certain amount of power, independent of its size, on the assumption of tuning without circuit loss. The practical efficiency relative to this ideal is limited by the "radiation power factor" of the antenna as compared with the power factor and bandwidth of the antenna tuning. The radiation power factor of either kind of antenna is somewhat greater than (1/6π) (Ab/l2) in which Ab is the cylindrical volume occupied by the antenna, and l is the radianlength (defined as 1/2π wavelength) at the operating frequency. The efficiency is further limited by the closeness of coupling of the antenna with its tuner. Other simple formulas are given for the more fundamental properties of small antennas and their behavior in a simple circuit. Examples for 1-Mc. operation in typical circuits indicate a loss of about 35 db for the I.R.E. standard capacitive antenna, 43 db for a large loop occupying a volume of 1 meter square by 0.5 meter axial length, and 64 db for a loop of 1/5 these dimensions.
1,249 citations
TL;DR: In this article, a simple formulation to compute the envelope correlation of an antenna diversity system is derived, which does not require the computation nor the measurement of the radiation pattern of the antenna system.
Abstract: A simple formulation to compute the envelope correlation of an antenna diversity system is derived. It is shown how to compute the envelope correlation from the S-parameter description of the antenna system. This approach has the advantage that it does not require the computation nor the measurement of the radiation pattern of the antenna system. It also offers the advantage of providing a clear understanding of the effects of mutual coupling and input match on the diversity performance of the antenna system.
1,004 citations