~ Planar and Corner Reflector Arrays ~
Planar- and corner-reflector arrays began life as antenna designs for both HF and low-VHF service. The physical structure of such arrays is simple, even if very large at the original frequencies of use. The planar reflector (technically, a 180° corner reflector) remains in use today as a VHF and UHF antenna element in conjunction with a wide variety of fed or driven elements. The corner reflector once served not only radio amateurs, but also deep fringe television viewers in the days before cable and satellite service. Both types of reflector-arrays deserve renewed attention for numerous applications. The systematic examination of these of these arrays in this volume aims to improve our understanding of their properties and their potentials.
fter a general introduction to the subject and the basic notions underlying
both types of reflectors, chapters 2 through 6 provides detailed studies of flat-surface
reflectors. Systematic antenna modeling exercises easily uncover some of the requirements
and potentials of planar reflector arrays. The proper size of a flat-panel reflector
depends upon the size of the driving array. Driver assemblies may range from simple
dipoles up to complex arrangements, such as double rectangles and batwing wide-band
structures. The user may choose a desired feedpoint impedance by selecting an appropriate
space between the driven array and the reflector surface. Nevertheless, the popular notion
that screens and solid surface reflectors, on the one hand, and reflectors composed of
spaced rods, on the other, are equivalent turns out to have serious flaws. Rod reflectors
have parasitic properties as well as reflective properties based on optical principles.
The differences are critical to the use of certain types of driving arrays.
Chapters 7 through 12 cover the ins and outs of corner reflectors through systematic modeling. Corner reflectors restrict the possible driver assemblies because the distance between the driver and the reflector surface is more complex. The corner array derives most of its potential from the size of the reflector along the axis of the driving element and along the surface of each side of the reflector. The best corner reflectors turn out to have a limited size parallel to the driver, but are capable of increasing gain until the side dimensions grow very long. Once more, rod and screen or solid surface reflectors have divergent properties due to parasitic effects that occur with rod-based reflectors. Some experimenters have increased the gain of rod-based corner reflectors by selective changes in the rod lengths. Other potentials include increasing gain though variations from the industry-standard 90° corner to narrower angles and by re-shaping the outer ends of the reflector. The 2-plane (sometimes called the 2-dimensional) corner reflector is capable of a wide operating bandwidth by use of a special bent fan-driving (Brown-Woodward) element. The final chapter covers the development of the 3-dimensional (or 3-surface) corner reflector and includes very recent developments for simplifying construction of this high-gain reflector array.
Planar and Corner Reflector Arrays has 316 pages of text with hundreds of illustrations. It also describes easy techniques for modeling the arrays using features available in full-command versions of NEC-2 and NEC-4.
* * * Below is an index
of the chapter titles found in this book
* * *
Titles of Contents
|1||Introduction to Planar- and Corner-Reflector Arrays|
|Part 1||Planar Reflector Arrays|
|2||The Planar Reflector and the Dipole|
|3||Phased Dipoles and Rectangles|
|4||Bobtails and Diamonds|
|5||Rod or Bar Reflectors|
|6||Complex and Special Drivers|
|Part 2||Corner Reflector Arrays|
|7||A Systematic Look at Planar Reflector Sides|
|8||A Non-Systematic Look at Some Corner Variations|
|9||Rod-Based Corner Reflectors|
|10||Variations on Standard Corner Reflectors|
|11||The Very-Wide-Band Corner Reflector|
|12||3-Dimensional Corner Reflectors|
|ABOUT THE AUTHOR
Considered an expert on antennas, L. B. has published over a dozen books, with works on antennas for both the beginner and the advanced student. Among his books are a basic tutorial in the use of NEC antenna modeling software and compilations of his many shorter pieces. His articles have appeared in virtually every amateur radio publication, with translations of some into several languages. Retired Professor from the University of Tennessee at Knoxville, L.B. is Technical & Educational Advisor to the ARRL and Technical Editor for antenneX.
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