Antenna Theory: Analysis and Design, 3rd Edition. Home · Antenna Theory: Introduction to the Design and Analysis of Algorithms, 3rd Edition · Read more. The third edition of Antenna Theory is designed to meet the needs of electrical .. Antenna Theory: Analysis Design, Third Edition, by Constantine A. Balanis. Introduction. Radiation Pattern. Radiation Power Density. Radiation Intensity. Banmwidth. Directivity. Numerical Techniques.

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Uploaded by: DINO - Download as PDF File . pdf), Text File .txt) or read online. Antenna Theory - Analysis and Design, 2nd Edition contantine a Antennas for All Applications by John D. Kraus & Ronald J. Marhefka 3rd Ed. Because there are so many methods of analysis and design and a plethora of antenna It is based on antenna theory, digital signal processing, networks and .

The outward moving wavefronts are easily identified using the coloring scheme for the intensity or gray scale for black and white monitors when viewing the movie. Each time step is 5 picoseconds while each FD-TD cell is 3 mm on a side. The movie is 37 frames long covering picoseconds of elapsed time.

Antenna Theory - Analysis and Design.pdf

The entire computational space is For this problem the pulse travels in an outward direction and is reflected when it reaches the walls of the cylinder. The reflected pulse along with the radi- ally outward traveling pulse interfere constructively and destructively with each other and create a standing type of a wavefront. The peaks and valleys of the modified wavefront can be easily identified when viewing the movie, using the colored or gray scale intensity schemes.

Sufficient time is allowed in the movie to permit the pulse to travel from the source to the walls of the cylinder, return back to the source, and then return back to the walls of the cylinder.

Each time step is 5 picoseconds and each FD-TD cell is 3 mm on a side. The movie is 70 frames long covering picoseconds of elapsed time. The square cylinder, and thus the computational space, has a cross section of The computational space is The movie is 70 frames long covering picoseconds of elapsed time and is created by taking a picture every third frame.

Each time step is 4. In order to illustrate the creation of the current distribution on a linear dipole, and its subsequent radiation, let us first begin with the geometry of a lossless two-wire transmission line, as shown in Figure 1.

The reflected traveling wave, when combined with the incident traveling wave, forms in each wire a pure standing wave pattern of sinusoidal form as shown in Figure 1. This is indicated in Figure 1. Radiation from each wire individually occurs because of the time-varying nature of the current and the termination of the wire.

If in addition the spacing between the two wires is very small 5 A. The net result is an almost ideal and desired nonradiating transmission line.

However, because the two wires of the flared section are not necessarily close to each other, the fields radiated by one do not necessarily cancel those of the other. Therefore ideally there is a net radiation by the transmission- line system.

Ultimately the flared section of the transmission line can take the form shown in Figure 1. This is the geometry of the widely used dipole antenna.

Antenna Theory Analysis And Design 3rd Ed

Because of the standing wave current pattern, it is also classified as a standing wave antenna as contrasted to the traveling wave antennas which will be discussed in detail in Chapter Thus the fields radiated by the two arms of the dipole vertical parts of a flared transmission line will primarily reinforce each other toward most directions of observation the phase due to the relative position of each small part of each arm must also be included for a complete description of the radiation pattern formation.

If the diameter of each wire is very small d A , the ideal standing wave pattern of the current along the arms of the dipole is sinusoidal with a null at the end. How- ever, its overall form depends on the length of each arm. This is illustrated in Figure 1. Therefore the current in all parts of the dipole does not have the same phase. This is demonstrated graphically in Figure 1. In turn, the fields radiated by some parts of the dipole will not reinforce those of the others.

See Figure 4. For a time-harnronic varying system of radian frequency co — 2: These variations can be obtained by multiplying the current standing wave pattern of Figure 1. His work was first published in [13].

He also showed that light was electromagnetic and that both light and electromagnetic waves travel by wave disturbances of the same speed. In , Professor Heinrich Rudolph Hertz demonstrated the first wireless electromagnetic system.

It was not until that Guglielmo Marconi was able to send signals over large distances. He performed, in , the first transatlantic transmission from Poldhu in Cornwall, England, to St. His transmitting antenna consisted of 50 vertical wires in the form of a fan connected to ground through a spark transmitter. The wires were supported horizontally by a guyed wire between two m wooden poles.

The receiving antenna at St. John's was a m wire pulled and supported by a kite. This was the dawn of the antenna era. Much of this work is captured in the book by Silver [14]. A contributing factor to this new era was the invention of microwave sources such as the klystron and magnetron with frequencies of 1 GHz and above.

While World War II launched a new era in antennas, advances made in com- puter architecture and technology during the s through the s have had a major impact on the advance of modern antenna technology, and they are expected to have an even greater influence on antenna engineering into the twenty-first cen- tury.

Beginning primarily in the early s, numerical methods were introduced that allowed previously intractable complex antenna system configurations to be analyzed and designed very accurately. In addition, asymptotic methods for both low frequencies e. While in the past antenna design may have been considered a secondary issue in overall system design, today it plays a critical role.

In fact, many system successes rely on the design and performance of the antenna. Analysis and design methods are such that antenna system performance can be predicted with remarkable accuracy. In fact, many antenna designs proceed directly from the initial design stage to the prototype without intermediate testing.

The level of confidence has increased tremendously. The widespread interest in antennas is reflected by the large number of books writ- ten on the subject [15].

These have been classified under four categories: Fundamental, Handbooks, Measurements, and Specialized. This is an outstanding collection of books, and it reflects the popularity of the antenna subject, especially since the s.

Because of space limitations, only a partial list is included here [2], [5], [7], [ 16] — [39], includ- ing the first and second editions of this book in , Some of these books are now out of print.

During and after World War II, many other radiators, some of which may have been known for some and others of which were relatively new, were put into service. This created a need for better understanding and optimization of their radiation characteristics.

Many of these antennas were of the aperture type such as open-ended waveguides, slots, horns, reflectors, lenses , and they have been used for communication, radar, remote sensing, and deep space applications both on airborne and earth-based platforms.

Many of these operate in the microwave region and are discussed in Chapters 12, 13, 15 and in [40]. Prior to the s, antennas with broadband pattern and impedance characteristics had bandwidths not much greater than about 2: In the s, a breakthrough in antenna evolution was created which extended the maximum bandwidth to as great as Because the geometries of these antennas are specified by angles instead of linear dimensions, they have ideally an infinite bandwidth. Therefore, they are referred to as frequency independent.

This class of antennas is discussed in more detail in Chapter 11 and in [41]. It was not until almost 20 years later that a fundamental new radiating element, which has received a lot of attention and many applications since its inception, was introduced.

This occurred in the early s when the microstrip or patch antennas was reported. This element is simple, lightweight, inexpensive, low profile, and conformal to the surface. These antennas are discussed in more detail in Chapter 14 and in [42], Major advances in millimeter wave antennas have been made in recent years, including integrated antennas where active and passive circuits are combined with the radiating elements in one compact unit monolithic form.

These antennas are discussed in [43]. Specific radiation pattern requirements usually cannot be achieved by single antenna elements, because single elements usually have relatively wide radiation patterns and low values of directivity.

To design antennas with very large directivities, it is usually necessary to increase the electrical size of the antenna. This can be accomplished by enlarging the electrical dimensions of the chosen single element. However, mechanical problems are usually associated with very large elements.

An alternative way to achieve large directivities, without increasing the size of the individual elements, is to use multiple single elements to form an array. An array is a sampled version of a very large single element. In an array, the mechanical problems of large single elements are traded for the electrical problems associated with the feed networks of arrays.

Arrays are the most versatile of antenna systems. They find wide applications not only in many spaceborne systems, but in many earthbound missions as well. In most cases, the elements of an array are identical; this is not necessary, but it is often more convenient, simpler, and more practical.

With arrays, it is practical not only to synthesize almost any desired amplitude radiation pattern, but the main lobe can be scanned by controlling the relative phase excitation between the elements. This is most convenient for applications where the antenna system is not readily accessible, especially for spaceborne missions.

The beamwidth of the main lobe along with the side lobe level can be controlled by the relative amplitude excitation distribution between the elements of the array. In fact, there is a trade-off between the beamwidth and the side lobe level based on the amplitude distribution.

Analysis, design, and synthesis of arrays are discussed in Chapters 6 and 7. However, advances in array technology are reported in [44] -[48]. A new antenna array design referred to as smart antenna , based on basic technol- ogy of the s and s, is sparking interest especially for wireless applications. This antenna design, which combines antenna technology with that of digital signal processing DSP , is discussed in some detail in Chapter To analyze each as a boundary-value problem and obtain solutions in closed form, the antenna structure must be described by an orthogonal curvilinear coordinate system.

This places severe restrictions on the type and number of antenna systems that can be analyzed using such a procedure. Therefore, other exact or approximate methods are often pursued. Two methods that in the last three decades have been preeminent in the analysis of many previously intractable antenna problems are the Integral Equation IE method and the Geometrical Theory of Diffraction GTD. Numerical techniques, such as the Moment Method MM , are then used to solve for the unknown.

Once the current density is found, the radiation integrals of Chapter 3 are used to find the fields radiated and other systems parameters. This method is most convenient for wire-type antennas and more efficient for structures that are small electrically. One of the first objectives of this method is to formulate the IE for the problem at hand.

The other is the Magnetic Field Integral Equation MFIE , and it is based on the boundary condition that expresses the total electric current density induced on the surface in terms of the incident magnetic field.

The MFIE is only valid for closed surfaces. Advances, applications, and numerical issues of these methods are addressed in Chapter 8 and in [3] and [49]. When the dimensions of the radiating system are many wavelengths, low-frequency methods are not as computationally efficient. However, high-frequency asymptotic techniques can be used to analyze many problems that are otherwise mathematically intractable.

One such method that has received considerable attention and application over the years is the GTD, which is an extension of geometrical optics GO , and it overcomes some of the limitations of GO by introducing a diffraction mechanism. The Geometrical Theory of Diffraction is briefly discussed in Section However, a detailed treatment is found in Chapter 13 of [3] while recent advances and applications are found in [50] and [51]. For structures that are not convenient to analyze by either of the two methods, a combination of the two is often used.

Such a technique is referred to as a hybrid method , and it is described in detail in [52]. This method has also been applied to antenna radiation problems [53] -[56]. A method that is beginning to gain momentum in its application to antenna problems is the Finite Element Method [57] - [6 1 ]. Re sponsible for its success have been the introduction and technological advances of some new elements of radiation, such as aperture antennas, reflectors, frequency independent antennas, and microstrip antennas.

Excitement has been created by the advancement of the low-frequency and high-frequency asymptotic methods, which has been instrumental in analyzing many previously intractable problems. A major factor in the success of antenna technology has been the advances in computer architecture and numerical computation methods. Today antenna engineering is considered a truly fine engineering art.

Although a certain level of maturity has been attained, there are many challenging opportunities and problems to be solved. Phased array architecture integrating monolithic MIC technology is still a most challenging problem. Computational electromagnetics using supercomputing and parallel computing capabilities will model complex electromagnetic wave interactions, in both the frequency and time domains.

Innovative antenna designs. New basic elements are always welcome and offer refreshing opportunities. New applications include, but are not limited to wireless communications, direct broadcast satellite systems, global positioning satellites GPS , high-accuracy airborne navigation, global weather, earth resource systems, and others.

Because of the many new applications, the lower portion of the EM spectrum has been saturated and the designs have been pushed to higher frequencies, including the millimeter wave frequency bands. Java-based interactive questionnaire with answers.

Power Point PPT viewgraphs. IEEE, Vol. Blake, Antennas, Wiley, New York, , p. Miller and J. Schelkunoff and H. Antennas Propagat. Andrew, C. Balanis, and P. Version 4: UK, , Silver Ed. Series, Vol. Jordan and K. Collin and F. Zucker Eds.

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Tang and R. Miller and G. Marhefka and W. Maloney, G. Smith, and W. Scott Jr. Katz, M. Piket-May, A.

Taflove, and K. Anten- nas Propagat. Tirkas and C. II, pp. Jin and J. McGrath and V. Sun and C. Lucas and T.

IEEE Trans. Some of the parameters are interrelated and not all of them need be specified for complete description of the antenna performance. Parameter definitions will be given in this chapter. In most cases, the radiation pattern is determined in the far- field region and is represented as a function of the directional coordinates.

Radiation properties include power flux density, radiation intensity, field strength, directivity, phase or polarization. A convenient set of coordinates is shown in Figure 2.

Antenna Theory - Analysis and Design, 2nd Edition contantine a balanis.pdf

A trace of the received electric magnetic field at a constant radius is called the amplitude field pattern. On the other hand, a graph of the spatial variation of the power density along a constant radius is called an amplitude power pattern. Often the field and power patterns are normalized with respect to their maximum value, yielding normalized field and power patterns.

Also, the power pattern is usually plotted on a logarithmic scale or more commonly in decibels dB. Third Edition , by Constantine A. For an antenna, the a. To demonstrate this, the two-dimensional normalized field pattern plotted in linear scale , power pattern plotted in linear scale , and power pattern plotted on a log- arithmic dB scale of a element linear antenna array of isotropic sources, with a spacing of d — 0. To find the points where the pattern achieves its half-power —3 dB points , relative to the maximum value of the pattern, you set the value of the a.

All three patterns yield the same angular separation between the two half-power points, This is discussed in detail in Section 2. In practice, the three-dimensional pattern is measured and recorded in a series of two-dimensional patterns.

Some are of greater radiation intensity than others, but all are classified as lobes. Figure 2. A description of these programs is found in the attached CD.

Other programs that have been developed for plotting rectangular and polar plots are those of [1] — [3]. In some antennas, such as split-beam antennas, there may exist more than one major lobe. A minor lobe is any lobe except a major lobe. In Figures 2. Minor lobes usually represent radiation in undesired directions, and they should be minimized.

Side lobes are normally the largest of the minor lobes. The level of minor lobes is usually expressed as a ratio of the power density in the lobe in question to that of the major lobe. This ratio is often termed the side lobe ratio or side lobe level. Side lobe levels of —20 dB or smaller are usually not desirable in most applications. In most radar systems, low side lobe ratios are very important to minimize false target indications through the side lobes.

It is evident that this pattern has one major lobe, five minor lobes and one back lobe. The level of the side lobe is about — 9 dB relative to the maximum. A detailed presentation of arrays is found in Chapter 6. For an amplitude pattern of an antenna, there would be, in general, three electric-held components E r , Eg, E j, at each observation point on the surface of a sphere of constant radius r — r c , as shown in Figure 2.

In the far held, the radial E r component for all antennas is zero or vanishingly small compared to either one, or both, of the other two components see Section 3. Some antennas, depending on their geometry and also observation distance, may have only one, two, or all three components.

The radial distance in Figure 2. This term is usually applied to an antenna whose maximum directivity is significantly greater than that of a half-wave dipole.

It is seen that the pattern in Figure 2. An illustration is shown in Figure 2. Other coordinate orientations can be selected.

The omnidirectional pattern of Figure 2. These regions are so designated to identify the held structure in each. Although no abrupt changes in the held configurations are noted as the bound- aries are crossed, there are distinct differences among them.

The boundaries separating these regions are not unique, although various criteria have been established and are commonly used to identify the regions. Reactive near-field region is dehned as "that portion of the near-held region imme- diately surrounding the antenna wherein the reactive held predominates.

If the antenna has a maximum dimension that is not large com- pared to the wavelength, this region may not exist. For an antenna focused at inhnity, the radiating near-held region is sometimes referred to as the Fresnel region on the basis of analogy to optical terminology. If the antenna has a maximum overall dimension which is very small compared to the wavelength, this held region may not exist. In this region the held pattern is, in general, a function of the radial distance and the radial held component may be appreciable.

The far-held patterns of certain antennas, such as multibeam rehector antennas, are sensitive to variations in phase over their apertures. For an antenna focused at inhnity, the far-held region is sometimes referred to as the Fraunhofer region on the basis of analogy to optical terminology. The amplitude pattern of an antenna, as the observation distance is varied from the reactive near held to the far held, changes in shape because of variations of the helds, both magnitude and phase.

A typical progression of the shape of an antenna, with the largest dimension D , is shown in Figure 2. It is apparent that in the reactive near- held region the pattern is more spread out and nearly uniform, with slight variations.

As the observation is moved to the radiating near-held region Fresnel , the pattern begins to smooth and form lobes. In the far-held region Fraunhofer , the pattern is well formed, usually consisting of few minor lobes and one, or more, major lobes. Reactive Near-field Figure 2. Rahmat-Samii, L. Williams, and R. One radian is defined as the plane angle with its vertex at the center of a circle of radius r that is subtended by an arc whose length is r.

A graphical illustration is shown in Figure 2. The measure of a solid angle is a steradian. One steradian is defined as the solid angle with its vertex at the center of a sphere of radius r that is subtended by a spherical surface area equal to that of a square with each side of length r.

Hollis, T.

Lyon, and L. Clayton, Jr.

The infinitesimal area dA on the surface of a sphere of radius r, shown in Figure 2. Refer to Figures 2. Do this a. Compare the two. It is then natural to assume that power and energy are associated with electromagnetic fields.

Since the Poynting vector is a power density, the total power crossing a closed surface can be obtained by integrating the normal component of the Poynting vector over the entire surface. A close observation of may raise a question.

At this point it will be very natural to assume that the imaginary part must represent the reactive stored power density associated with the electromagnetic fields. In later chapters, it will be shown that the power density associated with the electromagnetic fields of an antenna in its far-held region is predominately real and will be referred to as radiation density.

Based upon the definition of , the average power radiated by an antenna radi- ated power can be written as The power pattern of the antenna, whose definition was discussed in Section 2. The observations are usually made on a large sphere of constant radius extending into the far held. In practice, absolute power patterns are usually not desired.

However, the performance of the antenna is measured in terms of the gain to be discussed in a subsequent section and in terms of relative power patterns. Three- dimensional patterns cannot be measured, but they can be constructed with a number of two-dimensional cuts.

Determine the total radiated power. For a closed surface, a sphere of radius r is chosen. To find the total radiated power, the radial component of the power density is integrated over its surface. An isotropic radiator is an ideal source that radiates equally in all directions.

Although it does not exist in practice, it provides a convenient isotropic reference with which to compare other antennas. In addition, it will have only a radial component.

Thus the power pattern is also a measure of the radiation intensity. The total power is obtained by integrating the radiation intensity, as given by , over the entire solid angle of An. A three-dimensional plot of the relative radiation intensity is also represented by Figure 2. The beamwidth of a pattern is defined as the angular separation between two identical points on opposite side of the pattern maximum. In an antenna pattern, there are a number of beamwidths.

Another important beamwidth is the angular separation between the first nulls of the pattern, and it is referred to as the First-Null Beamwidth FNBW. Other beamwidths are those where the pattern is —10 dB from the maximum, or any other value. However, in practice, the term beamwidth , with no other identification, usually refers to HPBW. The beamwidth of an antenna is a very important figure of merit and often is used as a trade-off between it and the side lobe level; that is, as the beamwidth decreases, the side lobe increases and vice versa.

In addition, the beamwidth of the antenna is also Figure 2. If the separation is smaller, then the antenna will tend to smooth the angular separation distance. Example 2. Find the a. Basically the term directivity in the new version has been used to replace the term directive gain of the old version.

In the new version the term directive gain has been deprecated. The average radiation intensity is equal to the total power radiated by the antenna divided by An. If the direction is not specified, the direction of maximum radiation intensity is implied. Write an expression for the directivity as a function of the directional angles 6 and 0.

This may give the reader a better understanding and appreciation of the directivity. To better understand the discussion, we have plotted in Figure 2. We see that both patterns are omnidirectional but that of Example 2. Lorrain and D. Corson, Electromagnetic Fields and Waves, 2nd ed.

Freeman and Co. The values repre- sented by and those of an isotropic source D — 1 are plotted two- and three- dimensionally in Figure 2. For the three-dimensional graphical representation of Figure 2. Outside this range of angles, the isotropic radiator has higher directivity more intense radiation. The three-dimensional pattern of Figure 2.

These patterns are plotted using software developed in [2] and [3], and can be used to visualize the three-dimensional radiation pattern of the antenna. These three-dimensional programs, along with the others, can be used effectively toward the design and synthesis of antennas, especially arrays, as demonstrated in [7] and [8]. The directivity of an isotropic source is unity since its power is radiated equally well in all directions.

In equation form, this is indicated in 2- 16a. The directivity can be smaller than unity; in fact it can be equal to zero.

For Examples 2. A more general expression for the directivity can be developed to include sources with radiation patterns that may be functions of both spherical coordinate angles 6 and f. In the previous examples we considered intensities that were represented by only one coordinate angle 9, in order not to obscure the fundamental concepts by the mathematical details. So it may now be proper, since the basic definitions have been illustrated by simple examples, to formulate the more general expressions.

These can also be used for design purposes. For a rotationally symmetric pattern, the half-power beamwidths in any two perpendicular planes are the same, as illustrated in Figure 2. Read more. Analysis and Design, 2nd Edition. Analysis and Design.

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Lee Eds. We see that both patterns are omnidirectional but that of Example 2. Because of the symmetrical nature of the function, it can be shown that the shaded area in section 1 included in the numerical evaluation is equal to the blank area in section T left out by the numerical method.

If the separation is smaller, then the antenna will tend to smooth the angular separation distance. Another form of a reflector, although not as common as the parabolic, is the comer reflector, shown in Figure 1.

A typical example is TV for which the overall broad- cast reception can be improved by utilizing a high-performance antenna. I would like to thank Craig R.

Antenna Theory and Microstrip Antennas. In fact, many antenna designs proceed directly from the initial design stage to the prototype without intermediate testing.

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