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The backfire antenna described combines the structural advantages of a single endfire with the high gain of a reflector antenna. With its principal application in the gain range between 15 and 30 dB where ordinary endfire antennas become impractically long and paraboloidal antennas too expensive, it should prove to be especially advantageous for telemetry and radio astronomy applications in the 100- to 2000-MHz frequency range. The high gain of the backfire is based on the high-amplitude standing-wave field distribution formed between two planar reflectors. The space between the reflectors acts like an open resonating cavity that in basic configuration and function resembles a Fabrey-Perot laser cavity. An S-band model of a 4.0-wavelength backfire produces a gain of 23.5 dB at its optimum frequency, which corresponds to the gain of an equal-size paraboloidal antenna of 60% efficiency. Patterns show a very low side- and backlobe level over a frequency range of 1.25 to 1. Design information for these backfire antennas is given. Compared with an optimized equal-length Yagi, the backfire antenna produces an increase in gain of more than 8 dB. To achieve a gain of this magnitude with an ordinary array, one of two recently built antennas for satellite applications uses 16 Yagis, each 2.0 wavelength long, to produce a gain of 22.4 dB, and another uses 36 cavity-backed slots to produce 21.2 dB. These results emphasize the advantages of the single-element backfire antenna, whose 23.5 dB gain is achieved through a simple structural design that does not depend on the complicated feed systems that are necessary components in multielement arrays. (Author).
The short backfire (SBF) antenna consisting of a large reflector illuminated by a dipole feed and smaller disk reflector produces a gain of 15 dB above isotropic. As an array element it has been efficiently adapted for various configurations of high-gain antennas producing gains of up to 25 dB, with a single SBF element capable of replacing four to six elements of a conventional multidipole array. Farfield patterns and directivity measurements are presented for a single element and for a twin element mounted on a common reflector. Optimized dimensions for both cases are discussed for possible application to more complex types of antennas.
A backfire antenna is described which incorporates a dielectric slow-wave structure in place of the parasitic directors of earlier models. Using previously investigated optimum dimensions, this antenna uses new techniques of energizing in a cross polarized sense. Measurements of far-field patterns, directivity, and isolation between primary planes are given. (Author).
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.
Describes the VHF and UHF antennas for the 30-3000 Mhz range that have been developed over the past 50 years, including many designs that have not previously been treated in detail, and several new uses for old designs. Among the topics are methods of predicting and measuring the performance of antennas, and how it is affected by the local environment, both normal and adverse, and by the structures on which the antennas are mounted, both fixed and mobile (including humans). Addressed primarily to practicing antenna engineers; the basic theory is assumed to be known except for the less known types. Distributed by INSPEC. Annotation copyright by Book News, Inc., Portland, OR