Book contents
- Frontmatter
- Contents
- Preface
- CHAPTER 1 INTRODUCTION
- CHAPTER 2 AN APPROXIMATE ANALYSIS OF THE CYLINDRICAL ANTENNA
- CHAPTER 3 THE TWO-ELEMENT ARRAY
- CHAPTER 4 THE CIRCULAR ARRAY
- CHAPTER 5 THE CIRCUIT AND RADIATING PROPERTIES OF CURTAIN ARRAYS
- CHAPTER 6 ARRAYS WITH UNEQUAL ELEMENTS; PARASITIC AND LOG-PERIODIC ANTENNAS
- CHAPTER 7 PLANAR AND THREE-DIMENSIONAL ARRAYS
- CHAPTER 8 TECHNIQUES AND THEORY OF MEASUREMENT
- Appendix I Tables of ΨdR, T(m) or T′(m) and self- and mutual admittances for single elements and circular arrays
- Appendix II Summary of the two-term theory for applications
- Appendix III Summary of formulas for the curtain array
- Appendix IV Tables of admittance and impedance for curtain arrays
- Appendix V Programme for Yagi-Uda array
- References
- List of symbols
- Index
CHAPTER 3 - THE TWO-ELEMENT ARRAY
Published online by Cambridge University Press: 24 May 2010
- Frontmatter
- Contents
- Preface
- CHAPTER 1 INTRODUCTION
- CHAPTER 2 AN APPROXIMATE ANALYSIS OF THE CYLINDRICAL ANTENNA
- CHAPTER 3 THE TWO-ELEMENT ARRAY
- CHAPTER 4 THE CIRCULAR ARRAY
- CHAPTER 5 THE CIRCUIT AND RADIATING PROPERTIES OF CURTAIN ARRAYS
- CHAPTER 6 ARRAYS WITH UNEQUAL ELEMENTS; PARASITIC AND LOG-PERIODIC ANTENNAS
- CHAPTER 7 PLANAR AND THREE-DIMENSIONAL ARRAYS
- CHAPTER 8 TECHNIQUES AND THEORY OF MEASUREMENT
- Appendix I Tables of ΨdR, T(m) or T′(m) and self- and mutual admittances for single elements and circular arrays
- Appendix II Summary of the two-term theory for applications
- Appendix III Summary of formulas for the curtain array
- Appendix IV Tables of admittance and impedance for curtain arrays
- Appendix V Programme for Yagi-Uda array
- References
- List of symbols
- Index
Summary
The method of symmetrical components
An array is a configuration of two or more antennas so arranged that the superposition of the electromagnetic fields maintained at distant points by the currents in the individual elements yields a resultant field that fulfils certain desirable directional properties. Since the individual elements in an array are quite close together— the distance between adjacent elements is usually a half-wavelength or less-the currents in them necessarily interact. It follows that the distributions of both the amplitude and the phase of the current along each element depend not only on the length, radius, and driving voltage of that element, but also on the distributions in amplitude and phase of the currents along all elements in the array. Since these currents are the primary unknowns from which the radiation field is computed, a highly complicated situation arises if they are to be determined analytically, and not arbitrarily assumed known, as in conventional array theory.
In order to introduce the properties of arrays in a simple and direct manner, it is advantageous to study first the two-element array in some detail. The integral equation (2.11) for the current in a single isolated antenna is readily generalized to apply to the two identical parallel and non-staggered elements shown in Fig. 3.1. It is merely necessary to add to the vector potential on the surface of each element the contributions by the current in the other element.
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- Arrays of Cylindrical Dipoles , pp. 70 - 94Publisher: Cambridge University PressPrint publication year: 1968
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