Antennas and Propagation, IRE Transactions on
The Transactions ceased publication in 1962. The current retitled publication is IEEE Transactions on Antennas and Propagation.
Latest Published Articles

Microwave lens matching by simulated quarterwave transformers
Dec10 2012 
Analysis of a terminatedwaveguide slot antenna by an equivalent circuit method
Dec10 2012 
Surface currents excited by an infinite slot on halfplanes and ribbons
Dec10 2012 
A mechanically simple Foster scanner
Dec10 2012 
Some data for the design of electromagnetic horns
Dec10 2012
Popular Articles

The equiangular spiral antenna
Jan06 2003 
Guided waves on sinusoidallymodulated reactance surfaces
Jan06 2003 
Partially reflecting sheet arrays
Jan06 2003 
Plasma simulation by artificial dielectrics and parallelplate media
Jan06 2003 
The impedance properties of narrow radiating slots in the broad face of rectangular waveguide: Part ITheory
Jan06 2003
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Popular Articles (April 2015)
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1. The equiangular spiral antenna
Publication Year: 1959 , Page(s): 181  187
Cited by: Papers (114)  Patents (3)A circularly polarized antenna is described which makes possible bandwidths that a few years ago were considered to be impossible. The design of the antenna is based upon the simple fundamental principle that if the shape of the antenna were such that it could be specified entirely by angles, its performance would be independent of wavelength. Since all such shapes extend to infinity it is necessary to specify at least one length for an antenna of finite size. The one length in this antenna, the arm length, need only be of the order of one wavelength at the lowest frequency of operation to obtain operation essentially independent of frequency, and the geometry of the antenna allows this arm length to be spiraled into a maximum diameter of one half wavelength or less. Antennas have been constructed that have an essentially constant radiation pattern and input impedance over bandwidths greater than 20 to 1. View full abstract»

2. Guided waves on sinusoidallymodulated reactance surfaces
Publication Year: 1959 , Page(s): 201  208
Cited by: Papers (66)  Patents (4)A rigorous solution is derived for the propagation characteristics and field distributions of waves guided by a plane surface which possesses a surface reactance modulated sinusoidally in the propagation direction. The explicit field amplitudes and the determinantal equation for the propagation wavenumber are expressed in a continued fraction form which is rapidly convergent for all values of modulation. Numerical results are obtained for both surface wave (modal) and leaky wave (nonmodal) solutions. The relevance of these studies to highgain modulated surfacewave antennas is discussed. View full abstract»

3. Partially reflecting sheet arrays
Publication Year: 1956 , Page(s): 666  671
Cited by: Papers (205)  Patents (2)Multiple reflections of electromagnetic waves between two planes are studied, and the increase in directivity that results by placing a partially reflecting sheet in front of an antenna with a reflecting screen is investigated at a wavelength of 3.2 cm. The construction and performance of various models of such arrays is discussed. Thus, for example, a "reflexcavity antenna" with an outer diameter of and an overall length of only is described which has halfpower beamwidths of and in the and planes, respectively, and a gain of approximately 14 db. It is shown that larger systems produce considerably greater directivity but that their efficiency is poor. View full abstract»

4. Plasma simulation by artificial dielectrics and parallelplate media
Publication Year: 1962 , Page(s): 82  95
Cited by: Papers (95)  Patents (4)A plasma in the absence of dc magnetic fields is representable, from the electromagnetic viewpoint, as a lossy dielectric with a complex index of refraction whose real part is less than one. Its electrical properties, such as propagation constant and intrinsic impedance, can be simulated by microwave structures, such as artificial dielectrics of lossy metallic rods, and by  plane parallelplate guides. Design techniques are presented for application to the modeling of plasma media. Examples include problems of radiation from antennas on a plasmacoated ground plane, with magnetic line sources and electric aperture radiators simulated by parallelplate guides and rodded media, respectively. Radiation patterns of these models show good agreement with established theory. Waveguide measurements on the rodded media also confirm the expected propagation and impedance characteristics. View full abstract»

5. The impedance properties of narrow radiating slots in the broad face of rectangular waveguide: Part ITheory
Publication Year: 1957 , Page(s): 4  11
Cited by: Papers (28)Theoretical results, valid at and away from resonance, for the impedance properties of the rotated series slot, the displaced series slot, and the longitudinal shunt slot have been derived by the use of variational expressions coupled with certain stored power considerations. The additional influence of finite wall thickness, an appreciable factor, is taken into account by a microwave network treatment. The results for the zerothickness resistive elements become identical with those of Stevenson when the slot length is made equal to a half wavelength. The theoretical derivations are presented in Part I. In Part II, comparison is made with experimental data both previously available and specially taken in this connection. The effect of wall thickness and the distinction between slots of rounded and rectangular ends are also considered. The agreement between theory and measurement is reasonably good. View full abstract»

6. The Archimedean twowire spiral antenna
Publication Year: 1960 , Page(s): 312  323
Cited by: Papers (151)  Patents (4)A pair of equally excited but oppositely sensed Archimedean twowire spirals situated close to one another in the same planea doubletis used to generate a linearly polarized field in which the direction of polarization and phase are controlled or varied independently of each other by rotation of the spiral radiators. An array of these doublets can be made to scan by rotation of the several spiral elements; an eightdoublet array which was made to scan over an sector with small amplitude variation is discussed. A doublet fed from a ring network can be employed as a polarization diversity circuit. A virtual doublet is achieved by placing a single spiral in a fight angle trough. A preliminary scanning array comprising four spirals in a trough was made to scan . The possibility of using a parasitic spiral in conjunction with a driven spiral for obtaining linear polarization of variable direction and phase is indicated. Also, a brief simplified analysis of the twowire Archimedean spiral is presented, which leads to the concept of higherorder modes of radiation. View full abstract»

7. The impedance propeties of narrow radiating slots in the broad face of rectangular waveguide: Part IIComparison with measurement
Publication Year: 1957 , Page(s): 12  20
Cited by: Papers (63)First Page of the ArticleView full abstract» 
8. Leakywave antennas I: Rectangular waveguides
Publication Year: 1959 , Page(s): 307  319
Cited by: Papers (66)  Patents (1)A microwave network approach is employed for the description and analysis of leakywave antennas. This approach is based on a transverse resonance procedure which yields the complex propagation constants for the leaky waves. A perturbation technique is then applied to the resonance equation to obtain results in simple and practical form. These procedures are illustrated by application to a number of practical leaky rectangular waveguide structures. Very good agreement is obtained between the theoretical results and the measured values. View full abstract»

9. The slot antenna with coupled dipoles
Publication Year: 1960 , Page(s): 136  143
Cited by: Papers (21)The problem of an array consisting of a slot antenna and two symmetricallylocated cylindrical dipoles is formulated. The approximate distribution of the current along each antenna is obtained by a method of iteration. The radiation function, the coupling coefficients between the slot and the dipole, the relation between the magnetic current in the slot and the electric current in the dipole, and the input impedance of the slot in the presence of the dipoles have been obtained. An experimental setup for measuring the radiation patterns is described and measured and theoretical patterns are displayed. View full abstract»

10. On the guided propagation of electromagnetic wave beams
Publication Year: 1961 , Page(s): 248  256
Cited by: Papers (118)Any field in a halfspace can be described by a continuous spectrum of cylindrical waves. If this spectrum comprises substantially only waves whose propagation constant is very close to the plane wave propagation constant, the field can be resolved into a set of elementary wave beams which are characterized by Laguerre polynomials. They satisfy orthogonality relations like the wave modes in a waveguide. The elementary beams or "beam modes" can be reiterated and guided by reconstituting the crosssectional phase distribution at certain intervals. Reiterative beams are utilized in the beam waveguide. The finite size of the phase resetting devices effects a modification of the reiterative beam modes and causes diffraction losses. These losses decrease very rapidly with increasing diameter of the phasing devices. View full abstract»

11. Van Atta reflector array
Publication Year: 1960 , Page(s): 436  438
Cited by: Papers (46)The Van Atta reflector array is an array in which the elements are interconnected to reradiate received energy back in the direction of arrival. Scattering cross section measurements on a fourbyfour Van Atta array of sixteen dipoles are presented. This array reflects over a wider angle than the typical corner reflector, but is sensitive only to incident waves in the frequency band of and having the polarization of the dipoles. View full abstract»

12. The radiation characteristics of a zigzag antenna
Publication Year: 1958 , Page(s): 191  194
Cited by: Papers (3)The radiation properties of a single zigzag antenna are reported. This is a special type of broadband travelingwave antenna which, when properly designed, produces a strong axial beam of radiation. The radiation pattern has a halfpower beamwidth of in the plane and in the plane; the corresponding sidelobe ratios are 10.5 db and 17.5 db down, respectively, in the two planes. Approximate expressions for the radiation fields are also given and compared with the experimental values. The broadband property of the antenna is studied by measuring the radiation patterns over a range of frequencies. The performance of the antenna is compared with the Yagi antenna. The high directivity of the antenna can be utilized advantageously in the vhf and uhf ranges. The results of impedance measurement also are reported. View full abstract»

13. On cross coupling in multiplebeam antennas
Publication Year: 1962 , Page(s): 548  557
Cited by: Papers (67)  Patents (1)In general, the beam patterns of a multiplebeam antenna system may overlap. The degree of overlap is usefully defined by a crosscorrelation type of integral which includes phase factors as well as polar diagrams in the description of the beams. It is shown that when beam overlap exists, conservation of energy implies the unavoidable existence of cross couplings between the feed lines, and a related limitation on the radiation efficiency (or correspending receiving cross section) of any single beam. Quantitative relationships are derived describing these limitations, and examples given. The implied character of the scattering matrix, comprised of the array of crosscoupling factors, is also discussed with especial emphasis on lossless, reciprocal systems. View full abstract»

14. Theory of unequallyspaced arrays
Publication Year: 1962 , Page(s): 691  702
Cited by: Papers (97)  Patents (4)Although recently unequallyspaced arrays have been shown to be useful, the theory has not been fully developed, except for the use of matrices, computers, or the perturbation method. This paper presents a new approach to the unequallyspaced array problem. It is based on the use of Poisson's sum formula and the introduction of a new function, the "source position function." By appropriate transformation, the original radiation pattern is converted into a series of integrals, each of which is equivalent to the radiation from a continuous source distribution whose amplitude and phase distribution clearly exhibit the effects of the unequal spacings. By this method, it is possible to design unequallyspaced arrays which produce a desired radiation pattern. This method is effective in treating arrays of a large number of elements, and unequallyspaced arrays on a curved surface. Three examples are shown to illustrate the effectiveness of the method. The problem of sidelobe reduction for the array of uniform amplitude, which was attacked by Harrington, is treated by our method. A numerical example is shown for 25db sidelobe level. Also, the problem of secondary beam suppression is attacked with the use of the Anger function. The interesting problem of azimuthal frequency scanning by means of an unequallyspaced circular array is also shown, using the method of stationary phase. View full abstract»

15. Design of circular apertures for narrow beamwidth and low sidelobes
Publication Year: 1960 , Page(s): 17  22
Cited by: Papers (86)  Patents (5)This article extends a method of antenna design described in an earlier article by the same author. A family of continuous circular aperture distributions is developed in such a way as to involve only two independent parameters, , a quantity uniquely related to the design sidelobe level and a number controlling the degree of uniformity of the sidelobes. An asymptotic approach to the condition of uniform sidelobes thus becomes possible. A companion article by Robert Hansen contains aperture distribution tables and examples. View full abstract»

16. Multiple beams from linear arrays
Publication Year: 1961 , Page(s): 154  161
Cited by: Papers (50)  Patents (4)The problem of devising a passive RF transmission line feed system to provide independent multiple outputs from a linear array is considered. It is shown that a lossless, matched feed network is possible only for uniform aperture distribution. The general feed system for connecting inputs to elements is shown to consist of conventional hybrid junctions with associated phase shifters. In order to increase the possible number of elements in the array, the problem of finding applicable junctions more complex than the hybrid is considered. Junctions with three inputs and three outputs and with four inputs and four outputs are derived for use in multiple feed networks, expanding the number of elements in the array to . View full abstract»

17. Log periodic dipole arrays
Publication Year: 1960 , Page(s): 260  267
Cited by: Papers (80)  Patents (3)A new class of coplanar dipole arrays is introduced. The antennas described provide unidirectional radiation patterns of constant beamwidth and nearly constant input impedances over any desired bandwidth. The broadband properties are achieved by making use of the principles of log periodic antenna design. Models are discussed which are capable of providing 8 to 9db directive gain with an associated input standing wave ratio of 1:2:1 on a 75ohm feeder, and this performance is independent of frequency. The freespace properties of several of these arrays have been measured and the results are presented. The antenna configuration is simple, permitting practical methods of fabrication, and the design should prove useful in many applications. It makes possible, for example, the construction of "allwave" rotatable beams of very low cross section for use in the hf to uhf spectrum. View full abstract»

18. New circularpolarized frequencyindependent antennas with conical beam or omnidirectional patterns
Publication Year: 1961 , Page(s): 334  342
Cited by: Papers (21)A conical beam may be obtained from balanced equiangular spiral antennas by constructing an antenna with more than two spiral arms and symmetrically connecting these arms to provide a suppression of the radiated fields on the axis of the antenna. The angle of this conical beam can be controlled and, with proper choice of parameters, confined to the immediate vicinity of the azimuthal ( ) plane. An antenna with four symmetrically spaced arms can provide a radiation pattern that is within 3 db of omnidirectional circularly polarized coverage in the azimuthal plane. The standingwave ratio of this antenna referred to a 50ohm coaxial cable is less than 2to1 over the pattern bandwidth. This fourarm version retains the wide frequency bandwidths of the basic conical logspiral antenna, and it provides a coverage which heretofore has been difficult to obtain even with narrowband antennas. View full abstract»

19. Microwave antennas derived from the cassegrain telescope
Publication Year: 1961 , Page(s): 140  153
Cited by: Papers (73)  Patents (5)A microwave antenna can be designed in the form of two reflecting dishes and a feed, based on the principle of the Cassegrain optical telescope. There are a variety of shapes and sizes available, all described by the same set of equations. The essential performance of a Cassegrain doublereflector system may be easily analyzed by means of the equivalentparabola singlereflector concept. Techniques are available for reducing the aperture blocking by the sub dish of the Cassegraln system: one method minimizes the blocking by optimizing the geometry of the feed and sub dish; other methods avoid the blocking by means of polarizationtwisting schemes. The former method yields good performance in a simple Cassegrain antenna when the beamwidth is about or less. The latter methods are available for any application not requiring polarization diversity, and an optimized set of polarizationoperative surfaces has been developed for these twisting Cassegrain antennas. Experimental results, presented for practical antennas of both types, illustrate the feasibility of these principles. A number of unusual benefits have been obtained in the various Cassegrain antenna designs, and additional interesting features remain to be exploited. View full abstract»

20. The unidirectional equiangular spiral antenna
Publication Year: 1959 , Page(s): 329  334
Cited by: Papers (40)  Patents (1)Circularly polarized unidirectional radiation, over a bandwidth which is at the discretion of the designer, is obtainable with a single antenna. The antenna is constructed by wrapping balanced equiangular spiral arms on a conical surface. The nonplanar structure retains the frequencyindependent qualifies of the planar models, and, in addition, provides a single lobe radiation pattern off the apex of the cone. Practical antennas have been constructed with radiation patterns and input impedance essentially constant over bandwidths greater than 12 to 1 and there is no reason to assume that these cannot be readily extended to more than 20 or 30 to 1. View full abstract»

21. A new method for obtaining maximum gain from yagi antennas
Publication Year: 1959 , Page(s): 379  386
Cited by: Papers (45)  Patents (1)In conventional Yagi design, optimum performance requires separate adjustments in a number of parametersthe array length and the height, diameter, and spacing of the directors and reflectors. By introducing the notion of a surface wave traveling along the array, it is possible to demonstrate experimentally the interrelationship between these parameters. With this, the gain then depends only on the phase velocity of the surface wave (which is a function of the height, diameter, and spacing of the directors) and on the choice of the reflector. Thus, maximum gain for a given array length, for any director spacing less than , can be obtained by suitable variation of the parameters to yield the desired phase velocity. A design procedure that provides maximum gain for a given array length is presented. View full abstract»

22. Array factors with nonuniform spacing parameter
Publication Year: 1962 , Page(s): 131  136
Cited by: Papers (43)An algorithm is formulated to describe the construction of arrays whose individual antenna elements are to be distributed nonuniformly over an aperture. From the distribution to which the algorithm is equivalent, a distribution of array factor values is inferred. It is also shown how the individual array factor values may be statistically described when the element placement is statistically described. An array of antenna elements can be nonuniformly distributed so as to produce an array factor with a single major lobe from onefourth the elements required by a uniform distribution at a sacrifice of 5 db in sidelobe level and no sacrifice in main beamwidth. View full abstract»

23. Reciprocity theorems for electromagnetic fields whose time dependence is arbitrary
Publication Year: 1960 , Page(s): 68  73
Cited by: Papers (13)Two reciprocity theorems are derived which are valid for fields whose sources may have arbitrary time dependence. The first theorem involves the electromagnetic potentials, and the second is in terms of the electric and magnetic fields directly. In both cases, it is necessary to make use of the advanced as well as the retarded solutions to Maxwell's equations. Some properties of the theorems are discussed, and, as an application, the second theorem is used to derive a variational expression for scattering of electromagnetic waves from a perfect conductor. View full abstract»

24. Circularly polarized slot radiators
Publication Year: 1957 , Page(s): 31  36
Cited by: Papers (30)  Patents (4)A pair of narrow slots crossed at right angles and located at the proper point in the broad wall of a rectangular waveguide will radiate a circularly polarized wave. Some of the results of a study of the properties of such slots is presented. The study was undertaken with the aim of obtaining information useful in design of a circularly polarized linear array. Some of the properties of the slot pairs are as follows: 1) They are inherently matched, independent of the slot length. 2) When the slot arms are made resonant, approximately 75 per cent of the incident power is radiated, with a vswr of 1.12. 3) When fed from one end of the waveguide, the slots radiate righthand circular polarization; from the other end, lefthand. In using these slots in linear arrays the power radiated is varied by changing slot length, since position and orientation are fixed by the requirements of circular polarization. The slots must be separated by a guide wavelength, so waveguide loading or other complicated schemes must be used to reduce the slot spacing. View full abstract»

25. Angular accuracy of a phased array radar
Publication Year: 1961 , Page(s): 268  275
Cited by: Papers (33)One type of phasedarray radar of current interest employs an array of separate receiving elements, each followed by an individual amplifier. These individual signals are combined coherently to form one or more receiving beams for searching, tracking, or performing both functions simultaneously. This paper presents an approach to the theory of angle measurement with a phased array of this type. In the onedimensional problem considered here, the receiving antenna consists of a linear array of individual antennaamplifier elements. The receivernoiselimited case is considered, in which accuracy is limited by the additive normally distributed noise present in each channel. An expression is derived for the limiting accuracy of angular measurement when a single set of samples is available. This set of samples is obtained simultaneously, one sample from each channel. Next, two methods of implementing the angular measurements are discussed. These are amplitude comparison monopulse and a coherent or phase comparison technique. For large signaltonoise ratios and for either a square law or a linear envelope detector, the accuracy of amplitude comparison monopulse approaches the theoretical limit. The same accuracy can be achieved with the coherent technique by proper weighting of the individual signals. View full abstract»

26. On the beam deviation factor of a parabolic reflector
Publication Year: 1960 , Page(s): 347  349
Cited by: Papers (19)First Page of the ArticleView full abstract» 
27. Phase centers of microwave antennas
Publication Year: 1956 , Page(s): 597  600
Cited by: Papers (16)This paper is concerned with the location of the phase centers of microwave antennas. The inadequacy of conventional aperture theory for the accurate description of phase centers is discussed. Formulas are developed and, for numerical indications, calculations are made for paraboloidal reflectors of different ratios and a class of primary patterns which provide an approximate representation of a great many common feeds. The results are presented in graphical form to provide useful design information and show the dependence of principal and plane phase center location on feed and dish parameters. Contrary to the prediction of aperture theory, it is shown that the phase centers of axially symmetric antennas are not in the aperture plane, but they are dispersed about it. View full abstract»

28. The travelingwave linear antenna
Publication Year: 1961 , Page(s): 324  329
Cited by: Papers (48)  Patents (1)It is shown experimentally that an essentially travelingwave distribution of current can be produced on a linear antenna by inserting a resistance of suitable magnitude onequarter wavelength from the end of the antenna. A theory for the resistivelyloaded dipole antenna is formulated on the basis that the inserted resistors (one in each arm) can be replaced by equivalent generators and that the resulting triplydriven antenna can be solved by the superposition of singly and doublydriven dipoles. Approximately 50 per cent of the power is dissipated in these resistors. With a travelingwave distribution of current on an antenna available, the properties of this antenna are then investigated and compared with those of the conventional linear antenna. It is found that the input impedance of the travelingwave antenna remains essentially constant as a function of antenna length, whereas that of the conventional linear antenna varies considerably. It is also shown that the input impedance of the travelingwave antenna varies only slightly over a 2 to 1 frequency band. The directional properties of the travelingwave and conventional dipole are compared, and it is shown that a minor lobe does not appear in the radiation pattern of the travelingwave dipole until it is much longer than the conventional dipole. Also, it is shown that where the directional properties of the conventional dipole are quite sensitive to a change in frequency, those of the travelingwave dipole are not. View full abstract»

29. Space tapaering of linear and planar arrays
Publication Year: 1962 , Page(s): 369  377
Cited by: Papers (68)  Patents (2)The recent activity in electronically scanned arrays has stimulated interest in means of reducing both the quantities of elements required for a given size aperture and the number of different types of transmitters which would be necessary in an array using an illumination taper. One method of doing this is presented in this paper. The conventional amplitude tapered array is simulated by varying the spacing of equally excited elements, hence the name "space tapering." Space tapered arrays with predictable gains, beamwidths, and sidelobe levels can readily be designed using graphical techniques and simple mathematics. Reduction in the number of elements of from 50 to 90 per cent for moderate and large size planar arrays are possible while retaining good pattern characteristics. Although only linear and circular planar arrays are discussed, the technique can be applied to other planar and three dimensional arrays. View full abstract»

30. Linear arrays with variable interelement spacings
Publication Year: 1962 , Page(s): 137  143
Cited by: Papers (48)Optimum broadside arrays with constant spacings, i.e., DolphTchebycheff arrays, use relatively many elements and are often difficult to realize in practice due to mutual coupling effects. To overcome these disadvantages a variety of arrays with widely and variably spaced elements have been designed using both analog and digital computer techniques. These arrays all have many fewer elements than DolphTchebycheff arrays with the same beamwidth and sidelobe level. One of the arrays designed has 21 elements and is 76 wavelengths long when used as a broadside array. The 3db beamwidth is 0.74 degree, the sidelobe level 7.4 db. The array has perfect steerability in a 1.8:1 bandwidth with no interelement spacing smaller than onehalf wavelength in this band. A DolphTchebycheff array with the same beamwidth and sidelobe level uses 53 elements, and the steerability is not perfect even at a single frequency. View full abstract»

31. On the gain and beamwidth of directional antennas
Publication Year: 1958 , Page(s): 219  225
Cited by: Papers (44)A formula is given for the maximum gain of a class of antennas having fields expressible as a finite number of spherical wave functions. This maximum gain can be achieved for arbitrarily polarized radiation fields, and it can be related to antenna size by requiring the near fields to be small in magnitude. Also, the radiation field is in the form of a polynomial, so that patterns optimum in the Tchebycheff sense can be defined. Formulas for the relationship of beamwidth to sidelobe level are given. View full abstract»

32. Optimum feeds for all three modes of a monopulse antenna II: Practice
Publication Year: 1961 , Page(s): 454  461
Cited by: Papers (20)  Patents (3)In an amplitudemonopulse antenna whose main aperture is illuminated by a feed, it is desired to control the feed excitation independently in the sum, azimuth difference, and elevation difference modes. It is possible to describe a feed system, comprising an infinite array of radiators and hybrid junctions, which demonstrates the principle of complete independent control of the three modes. There are several practical feeds which approach a hypothetical ideal one in varying degrees. One representative type is the "twelvehorn feed;" although it has some disadvantages, it is versatile and quite useful. However the most attractive type for many applications appears to be one having a combination of multiplehorn excitation in one plane and multimodewaveguide excitation in the other. With a simple form of the "multihornmultimode" feed, the ideal is substantially realized, and a major improvement in monopulse performance can be obtained. View full abstract»

33. A triangular arrangement of planararray elements that reduces the number needed
Publication Year: 1961 , Page(s): 126  129
Cited by: Papers (43)  Patents (2)In this paper, it is shown that by arranging the elements of a beamscanning planar antenna array in a triangular pattern rather than a rectangular pattern, the number of elements needed in the array is reduced. (The number of elements needed in an array is determined from the requirement that no spurious beams form in the array pattern.) The reduction in the number of elements depends upon the solid angle over which the main beam is positioned. If the main beam is positioned within a constant angle about the array normal, then the number of elements can be reduced by 13.4 per cent by arranging the elements in a pattern of equilateral triangles rather than in a square pattern. If the main beam is positioned within a "pyramid," centered about the array normal, then the reduction is usually less than 13.4 per cent. Graphs are included showing for both element arrangements the solid angle over which the main beam can be scanned without the formation of spurious beams. View full abstract»

34. Surfacewave luneberg lens antennas
Publication Year: 1960 , Page(s): 508  515
Cited by: Papers (11)It is demonstrated that a surfacewave structure having isotropy in the plane of the structure can be operated as a lens. The index of refraction is given for a dielectric slab on a ground plane, a bed of metal posts on a ground plane and a parallelplate structure with one plate filled with holes. The necessary radial variations in index for several Lunebergtype lenses are given. These include the conventional Luneberg lens, Gutman's modification, the rimfed Luneberg adapted to a spherical surface and a modification adapted to a spherical surface and collimation of the rays at an arbitrary angle with respect to the plane on which the lens is mounted. An approximate analysis of surfacewave lenses based on optics is described. View full abstract»

35. Pattern limitations in multiplebeam antennas
Publication Year: 1962 , Page(s): 430  436
Cited by: Papers (21)It is shown that in a lossless passive antenna radiating multiple beams from a common aperture, the radiation pattern and the crossover levels cannot be specified independently. This is due to a requirement that the beams must be orthogonal in space. It is also shown that this limitation can be overcome by using multiple apertures, lossy networks, or active networks. Suitable arrangements for obtaining low sidelobes with satisfactory crossover levels are described. View full abstract»

36. Theory of the cornerdriven square loop antenna
Publication Year: 1956 , Page(s): 393  407
Cited by: Papers (3)The general problem of determining the distribution of current and the driving point impedances of a square loop or frame antenna is formulated when arbitrary driving voltages are applied at each corner or when up to three of these voltages are replaced by impedances. The loop is unrestricted in size and account is taken of the finite crosssection of the conductors. Four simultaneous integral equations are obtained and then replaced by. four independent integral equations using the method of symmetrical components. These equations are solved individually by iteration and firstorder formulas are obtained for the distributions of current and the drivingpoint admittances. By superposition the general solution for the abritrarily driven and loaded loop is obtained. Interesting special cases include a cornerreflector antenna and the square rhombic (terminated) antenna. An application of the principle of complementarity permits the generalization of the solution to the square slot antenna in a conducting plane when driven from a doubleslot transmission line at one corner. View full abstract»

37. Surfacewave propagation on coated or uncoated metal wires at millimeter wavelengths
Publication Year: 1962 , Page(s): 246  254
Cited by: Papers (16)  Patents (1)The properties of surface waves guided by an uncoated cylinder of finite conductivity (Sommerfeld wave) or by a perfectly conducting cylinder with a dielectric coating (Goubau wave) have been analyzed theoretically for frequencies in the millimeter and submillimeter wavelength regions. Previous analysis by Goubau for lower frequencies provided the primary basis for this investigation. For wire sizes which provide low loss propagation above about 100 kMc, the approximations used by earlier workers are not sufficiently accurate to provide useful results. More accurate solutions for some of the properties have been obtained for wires of circular cross section by the use of fewer or different approximations. Numerical values have been calculated for attenuation, powerhandling ability, and radial extent of the region of principal power flow. The results show that above 70 kMc the significant field extent is reasonable and the attenuation may be orders of magnitude smaller than for rectangular waveguide. Consideration was also given to the problem of surfacewave propagation on wires of elliptical cross section, but in this case the solutions for the field components must normally be expressed in the form of infinite series of products of the radial and angular Mathieu functions. Numerical results are therefore extremely difficult to obtain for elliptical wires. View full abstract»

38. Impedance properties of complementary multiterminal planar structures
Publication Year: 1959 , Page(s): 371  378
Cited by: Papers (38)Booker has shown that Babinet's principle, properly extended to electromagnetic fields, leads to a simple relation between the impedances of two planar complementary structures. A relation, which generalizes this result, is found between the impedance matrices of two complementary terminal structures. This relation is applied to the particular terminal structures having fold symmetry and to those that are also selfcomplementary. In the latter case the impedance matrix is real and entirely determined by the number of terminals. It is therefore independent of the exact shape of the elements composing the structure and of the frequency. By connecting in groups the terminals of such a structure various impedance levels, all frequency independent and real, may be achieved. Structures having their terminal pairs in different locations in the plane are also considered. A selfcomplementary twoport structure is found to be equivalent, from the impedance point of view, to a length of lossy transmission line having a characteristic impedance of ohms. View full abstract»

39. Nonresonant slotted arrays
Publication Year: 1958 , Page(s): 360  365
Cited by: Papers (11)  Patents (1)The distribution of slot conductance of nonresonant arrays is obtained by considering the array as a continuous line source. Distributions of conductance per unit length for three Taylor aperture distributions are thus obtained. However, the discreteness of the array is retained for a discussion of secondorder beams and for the development of a method leading to their suppression. The performance of an experimental array is described. View full abstract»

40. Theory of ferrites in rectangular waveguides
Publication Year: 1956 , Page(s): 531  537
Cited by: Papers (16)Reciprocal and nonreciprocal propagation of electromagnetic energy in an infinitely long rectangular waveguide partially filled with one or two ferrite slabs is described.Methods for obtaining exact solutions of the transcendental equations usually encountered in these boundary value problems are demonstrated for several structures. Calculations are carried out for a lossless ferrite and the phase constant is plotted as a function of the ferrite slab thickness. The cutoff conditions for the lowest TE mode are evaluated in terms of the ferrite slab thickness. New modes, not associated with the empty waveguide modes, are analyzed as ferrite dielectric modes, their propagation characteristics are discussed and the rf electric and magnetic field patterns are plotted. The rf electric fields are plotted for all reciprocal and nonreciprocal modes and the appropriate field configurations are used to explain the operation of ferrite cutoff isolators, the fielddisplacement isolator, the fielddisplacement circulator, and the nonreciprocal phase shifter. Solutions above ferromagnetic resonance are shown and the fields are plotted. A brief comparison of the operation of dispersive devices at high and low frequencies is made. The calculations are extended to include absorption loss, and nonreciprocal attenuation is plotted as a function of slab position near resonance. View full abstract»

41. The rectangular loop antenna as a dipole
Publication Year: 1959 , Page(s): 53  61
Cited by: Papers (9)An integral equation for the current in a rectangular loop of wire is derived for a loop that is driven by two generators located at the centers of one pair of opposite sides. The EMF's are equal in magnitude and in phase in the sense that they maintain currents in the generators that are in the same direction relative to the coordinate system and, therefore, in opposite directions from the point of view of circulation around the loop. An approximate solution is obtained for the distribution of current around the loop and for the drivingpoint impedance. It is shown that the solution for the rectangle of wire reduces to that of the symmetrically driven folded dipole when one dimension is made electrically small and to a section of transmission line driven simultaneously at both ends when the other dimension is made small. The loop that is electrically small in both directions is also examined. View full abstract»

42. Radiation from a tapered surface wave antenna
Publication Year: 1960 , Page(s): 577  586
Cited by: Papers (7)Utilizing results obtained previously for the propagation of electromagnetic waves along a plane surface having a linear spatial variation of surface admittance, an approximate analysis of the radiation properties of a certain twodimensional tapered surface wave antenna is carried out. The radiating structure consists of a surface waveguide of finite length having a linear susceptance variation, inserted between a feeding surface waveguide with constant susceptance, and a perfectly conducting plane. The separate junction effects at the input and output ends of the taper are evaluated approximately for the case where the taper susceptance variation is gradual, and their combined influence on the radiation pattern is discussed. View full abstract»

43. Folded dipoles and loops
Publication Year: 1961 , Page(s): 171  187
Cited by: Papers (16)In Section I the theory of linear arrays consisting of two or more closely spaced elements that are interconnected by lumped reactances is reviewed. Specific application is made to twoelement endloaded folded dipoles and monopoles constructed of conductors with different diameters, to series tuned threewire folded dipoles and monopoles, and to a threewireline reactor and impedance transformer. In Section II the circular folded dipole or Halo antenna is treated. View full abstract»

44. Endfire slot antennas
Publication Year: 1955 , Page(s): 81  86
Cited by: Papers (7)  Patents (3)The conditions for endfire radiation from a travelingwave slot are discussed. These are that the phase velocity of the traveling wave be equal to or less than the velocity of light in free space and that the aperture be excited with a strong longitudinal component of electric field. Practical ways of achieving these conditions are mentioned and an approximate analysis based on partially dielectricfilled waveguide theory is used to determine the aperture fields as a function of the antenna geometry. Farfield pattern characteristics are discussed. It is found that the actual pattern may differ considerably from that predicted by simple theory. This is attributed primarily to two things, a finite ground plane and the discontinuity produced by the abrupt aperture opening. Two practical discontinuity minimizers are described. The ground plane effect is analyzed by applying Huygens Principle, and a simple procedure is described for determining the firstorder effect. The problem of obtaining pencilbeam radiation in the horizontal (plane of the ground plane) pattern is solved quite simply by using wideaperture antennas which can be made to operate satisfactorily over better than a 2:1 band. The efficiency and vswr of a practical antenna, with sidelobes in the horizontal pattern at least 20 db down, have been measured over a 2:1 band. The efficiency varied from 65 per cent at the highfrequency end of the band to 55 per cent at the low end. The vswr was less than 1.4 over the band. View full abstract»

45. An experimental study of the diskloaded folded monopole
Publication Year: 1956 , Page(s): 27  28
Cited by: Papers (2)Data is presented to show the reduction in size and increase in radiation resistance and bandwidth of the diskloaded folded monopole as compared with a diskloaded monopole of the same electrical length. The ratio of diameters of the folded part to the diameter of the driven part was varied for one series of impedance measurements and the axial spacing between the driven part and folded part was varied for another series. The resonant radiation resistance and resonant length may be varied almost independently. The radiation resistance depends upon the ratio of diameter of the folded part to the diameter of the driven part, and the resonant length depends upon axial spacing. The radiation resistance multiplication factor relative to a diskloaded monopole of the same electrical length is approximately the same as the multiplication factor of a folded dipole relative to a dipole. The diskloaded folded monopole has a greater bandwidth than an unloaded monopole of the same wavelengthtodiameter ratio. Where the effective diameter1 of the folded antenna is Â¿2DdS, its radiation pattern is essentially that of an unloaded monopole. View full abstract»

46. Solution of problems in electromagnetic wave theory on a high speed digital calculating machine
Publication Year: 1956 , Page(s): 276  280
Cited by: Papers (1)This paper contains references to several problems in electromagnetic wave theory which have been solved by numerical methods. In particular, it treats the methods and machines employed by groups at the University of Michigan, Willow Run Research Center, and at the U. S. Naval Proving Ground, Dahlgren, Virginia, in obtaining on a highspeed computing machine a numerical solution for the radar cross section of a prolate spheroid. At the University of Michigan the work was under the direction of K. M. Siegel, while R. A. Niemann was responsible for that done at the Naval Proving Ground. View full abstract»

47. Analysis of a terminatedwaveguide slot antenna by an equivalent circuit method
Publication Year: 1956 , Page(s): 16  26The pattern in a halfspace of a slot in the wall of a waveguide is a function of the terminating impedance. The description of the far fields in such a configuration is simplified considerably by the adoption of a network viewpoint, whereby the halfspace is represented approximately by two (or more) spherical transmission lines, the feeding waveguide by a single uniform transmission line, and the slot by a coupling network which is directly analogous to that for a hybrid junction. For a given waveguide termination, the spherical mode voltages are computed by a simple network calculation, and the gain pattern is obtained by modal synthesis. The slot equivalent circuit parameters are obtained readily by simple measurements or from available theoretical formulas. Described in detail both theoretically and experimentally is a symmetric rectangular slot cut in either the broad or narrow face of a rectangular waveguide. View full abstract»

48. A theoretical limitation on the formation of lossless multiple beams in linear arrays
Publication Year: 1961 , Page(s): 350  352
Cited by: Papers (29)  Patents (3)It is well known that through the use of lenses, several independent beams can be formed from a single antenna, with each beam having essentially the gain corresponding to the aperture of the lens. Recently, feed systems have been developed for linear arrays which achieve similar performance through the use of directional couplers. In this paper it is shown that the shape of the beams which can be formed from an equispaced array by such a feed matrix is not arbitrary, unless one is willing to accept losses in addition to normal plumbing losses. It is shown that the array space factors associated with the individual beams must be such that they are mutually orthogonal over a period of the spacefactor pattern. View full abstract»

49. Linear Arrays with arbitrarily distributed elements
Publication Year: 1960 , Page(s): 222  223
Cited by: Papers (75)  Patents (2)A linear array with general arbitrarily distributed elements is discussed. A matrix relationship is found between the elements of the array and its farzone pattern. The lower bound of the stored energy and the factor of the array are found. A figure of merit for the array is defined. View full abstract»

50. A theoretical analysis of the multielement endfire array with particular reference to the YagiUda antenna
Publication Year: 1956 , Page(s): 441  444
Cited by: Papers (2)Self and mutual impedances of a multielement antenna system are discussed, and a method of approximation for these impedances is shown. The impedances derived by this method are applied to a theoretical analysis of the multielement parasitic endfire array. Various characteristics of the YagiUda antenna computed by the theory are given in charts, and a procedure for designing the YagiUda antenna is shown. Comparisons between the theory and experimental results are also discussed. View full abstract»
Aims & Scope
The Transactions ceased publication in 1962. The current retitled publication is IEEE Transactions on Antennas and Propagation.
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Aims & Scope
Includes theoretical and experimental advances in antennas, including design and development, and in the propagation of electromagnetic waves, including scattering, diffraction, and interaction with continuous media; and applications pertaining to antennas and propagation, such as remote sensing, applied optics, and millimeter and submillimeter wave techniques.
Persistent Link: http://ieeexplore.ieee.org/servlet/opac?punumber=8234 More »
Frequency: 12
ISSN:
00961973
Subjects
 Fields, Waves & Electromagnetics
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 ( 1955  1962 ) Antennas and Propagation, IRE Transactions on
 ( 1952  1955 ) Antennas and Propagation, Transactions of the IRE Professional Group on