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This paper describes the principles of operation of the Tactical Air Navigation (TACAN) antenna system and compares the performance characteristics of the mechanically rotated with a proposed electronically scanned system. An analysis is provided of the various factors involved in the design of an electronically scanned TACAN antenna. The discussions in this paper serve as an introduction to a paper in this issue which describes the design, fabrication, test, and evaluation of one example of an experimental model of an electronically scanned cylindrical TACAN antenna array [1].

In recent years methods of producing controlled modifications of the ionosphere by use of high-intensity radio-frequency waves have been proposed; some have been tried with inconclusive results. The present paper describes detection of significant (∼30%) changes in the electron temperature in the F2 region produced by absorption of radio-frequency energy propagated at or near the local ionospheric plasma frequency. The radio-frequency source is the 1-Mw cw transmitter and ∼16° beamwidth antenna array described in the accompanying paper by Utlaut [1970]. As shown by the calculations of Meltz and LeLevier [1970], electron temperature increases of ∼35% can be expected within a few tens of seconds after the transmitter, tuned to within 1% of f0F2, is turned on.

The present author suggests a new distribution function for the roots of the complex polynomial corresponding to the nulls of the radiation pattern of a linear antenna array on the unit circle in a complex plane which is more general than the one suggested by the same author in a previous paper. The new distribution function is of the form ψ K =ψ 0 {1+ξK ((ln(ψ m /ψ 0 -1)-lnξ)/(ln m)) }. When ψ 0 and ξ are chosen properly, the suggested distribution includes the following distributions or arrays as special cases: (1) the uniform end-fire arrays; (2) the uniform broadside arrays; (3) the Schelkunoff's distribution in the range of ψ; (4) the Dolph-Tchebyscheff's distribution for number of elements not greater then seven. But the suggested distribution has the advantage of improving all of them, especially for the suppression of side-lobes near-by the main beam which is very important in certain practical applications.Moreover, since the primary patterns of many types of radiating elements fall off with increasing angle from the main maximum so that the wide-angle lobes would be at a lower level than those close to the main beam, it is necessary to design an array pattern in such a way so that the side-lobes should increase in magnetude with increase in angle from the position of the main beam in order to achieve an over-all pattern with side-lobes all equal or approximately equal in magnitude which is useful in many practical applications. Neither Schelkunoff's distribution in the range of ψ nor Dolph-Tchebyscheff's distribution meets this requirement but the suggested distribution does.In this paper, explicit expressions for the relative antenna currents have been put in closed forms convenient for calculation and semigraphical method has been used for all the pattern calculations.

An analytical approach to the design of a super-synthesis antenna array is applied in this paper. It involves isolation and separate optimization of the influence of different parameters on the sampling of the spatial frequency components. The approach requires a detailed understanding of the geometry of tracking by an ensemble of baselines, but it gives a nearly optimum array design without much help from a computer. A feature of this design is that by simply doubling the array elements, the synthesized main beam area of the array is reduced 16 fold. Extensive computations have been used to demonstrate this extraordinary result.

In this paper, a unified formulation is made for the optimization of directivity and signal-to-noise ratio of an arbitrary array, with or without a constraint on the array Q-factor. When there is a constraint, the solution is reduced to that of a polynomial; when there is no constraint, the solution is given in a very simple form. First, it is shown that for a given array geometry there exists a finite permissible range of the Q-factor and this range reduces to zero for large spacings. Second, a detailed comparison between four well-known excitations (uniform, Hansen-Woodyard, optimum cophasal, and optimum) is made and the main results are as follows, 1) The Hansen-Woodyard excitation yields a directivity higher than that of the uniform only when the element spacing is somewhat smaller than a half wavelength (λ/2), but at the price of much higher Q. On the other hand, it is much lower than that of the optimum excitation. 2) For spacing less than λ/2, the optimum excitation is strongly tapered toward the ends of the array and approximately antiphasa (i.e., 0, 180° 0, 180°, ...); whereas for spacing greater than or equal to λ/2, it is nearly uniform and cophasal. 3) For large spacings, the directivity of uniform excitation is nearly optimum. For small spacings, the optimum directivity becomes much higher than all others, but is always associated with an enormously large Q-factor. Therefore in this case a constraint of the Q-factor is important. 4) Hansen-Woodyard and uniform arrays have the interesting property that their sensitivity factors are independent of spacing. The optimization of signal-to-noise ratio is also demonstrated. In particular, the result shows that although an improvement in gain over the uniform excitation is very difficult to realize in practice, a substantial improvement in signal-to-noise ratio is entirely practical. Other numerical results and some extensions of the theory to aperture antennas are also included.

A computer program has been investigated and developed for the calculation of the far field radiation pattern of an antenna array. This paper contains an IBM 360/65 program for the calculation of the far field pattern with accuracy checks on the pattern obtained by using radio stations KXIC and WSUI, both located in Iowa City, Iowa, as assumed normals. Two theories of solving the far field calculation problem with the SDS-92/TR-48 hybrid computer are submitted.

A system consisting of an antenna array and an adaptive processor can perform filtering in both the space and frequency domains, thus reducing the sensitivity of the signal‐receiving system to interfering directional noise sources. Variable weights of a signal processor can be automatically adjusted by a simple adaptive technique based on the least‐mean‐squares (LMS) algorithm. During the adaptive process an injected pilot signal simulates a received signal from a desired “look” direction. This allows the array to be “trained” so that its directivity pattern has a main lobe in the previously specified look direction. At the same time, the array processing system can reject any incident noises, whose directions of propagation are different from the desired look direction, by forming appropriate nulls in the antenna directivity pattern. The array adapts itself to form a main lobe, with its direction and bandwidth determined by the pilot signal, and to reject signals or noises occurring outside the main lobe as well as possible in the minimum mean‐square error sense. Several examples illustrate the convergence of the LMS adaptation procedure to the corresponding Wiener‐optimum solutions. Rates of adaptation and misadjustments of the solutions are predicted theoretically and checked experimentally. Substantial reductions in noise reception are demonstrated in computer‐simulated experiments. The techniques described in this paper are applicable to signal‐receiving arrays for use over a wide range of frequencies.

This paper discusses the design and construction of a branch-fed, variable-phase, 20 to 55 Mc array of 48 log-periodic elements. Phasing to control-beam direction is described and the correction necessary for ionospheric refraction is presented in terms of vertical incidence critical frequency. The array gain as measured by moon-bounce techniques is found to be in good agreement with the theoretical value.

This paper describes the application of a phase changer which, when periodically distributed along a cylindrical conductor, controls the phase of the currents so that the radiation is concentrated in a plane perpendicular to the axis of the conductor. A theoretical analysis is made of a two-element structure, and the results are compared with those obtained by experiment. Further experimental results are given for multi-element structures.

This paper presents a theory for, and a method of designing a thinned or broad-band antenna array by means of unequal spacings. Using the theory of unequally spaced arrays developed by one of the authors, an antenna array can be designed to produce a desired beamwidth and sidelobe level with the average spacing many wavelengths apart. The patterns are expressed in a series of the Anger functions and its sidelobe level is shown to decrease approximately as N^{-0.5}\simN^{-0.4} where N is the total number of elements, and the gain is approximately equal to N . It is also shown that the sidelobe level can be improved by varying the amplitude distribution. Numerical examples are given to illustrate the method.

An electromechanical calculator has been designed for the rapid solution of directional-antenna patterns. After the desired antenna parameters have been set up, the machine automatically draws the field-intensity curve to any desired scale on a sheet of polar co-ordinate paper and indicates the rms value for drawing a circle of the equivalent nondirectional pattern. The fundamental design of the calculator does not limit the number of antennas that can be used in the directional array. As the number of antennas is increased, the greater the degree of control is possible to mould the radiation pattern into the desired shape. Not only is the horizontal directional field-intensity pattern, such as used in broadcast practice, readily available, but the field-intensity contours at any elevation angle can be drawn with equal ease. The vertical radiation characteristics of the several antennas can be selected at will. This makes it possible to explore the solid contour surface of the whole hemisphere in a relatively short time and also determine the total power radiated from the directional-antenna system. The machine is also suitable for calculating the solid contour surface of the radiation pattern from a parallel horizontal antenna array.

The single-ring circular antenna array of axial dipoles is analyzed in this paper. Such an array consists of m parallel dipoles, equally spaced on the circumference of a circle whose radius is ?. The two principal properties with which a designer is concerned are (1) the radiation pattern and (2) the impedance of each element in an array, both of which can be found if the current distribution along the element is known. To synthesize a specified radiation pattern, the voltages at the center of each element must be determined.

It is well known that a linear antenna array with equally spaced elements can be represented by a polynomial whose roots correspond to the nulls of its antenna pattern. Since the linear array has equally spaced elements, its polynomial has only integral powers of the variable, so that the array can be represented by a Z transform. Therefore, the effect of moving roots of the polynomial can be represented as a linear sampled-data system problem, which is solved by using a table of Z transforms or by discrete numerical convolution. In this paper, the quantitative effects on the array and its antenna pattern caused by moving roots of the polynomial are determined, and these effects are utilized for array synthesis to produce desired antenna patterns. Examples illustrating the use of this new synthesis technique include modification of a uniform array to obtain low sidelobes in the antenna pattern and synthesis of an array to produce nulls in its antenna pattern in the directions of discrete and spatially distributed interference sources.

The purpose of this paper is to investigate the signal distortion which results when long, series-fed arrays are used for communication. It is shown that under certain conditions the antenna array can be considered a linear filter, the response of which is a function of frequency as well as spatial coordinates. The distortion accompanying the transmission as measured by the least mean-square difference between the transmitted and the received signals is derived. This expression is evaluated for the case of a uniformly excited array and a rectangular band-pass signal spectrum. In the absence of noise the transmitted signal can be completely recovered in the receiver by employing the proper linear filter. In the presence of noise the signal cannot, of course, be completely recovered. However, a technique for minimizing the distortion, in this case using a pre-filter and a post-filter, is investigated.

In most problems on antenna systems the field at any point is assumed to be one or other of the so-called induction and radiation fields. Actually it is a combination of the two and in some cases the “ static ” electric field has to be considered. All antenna systems are designed to give a specific radiation field in certain directions. It would simplify problems connected with antenna systems and, in particular, beam systems, if the total field at any point in space were expressed in the form of a radiation field. In order to take account of the apparent change in type of field as we recede from the antennae, the equation for such a field must contain two variable factors depending on the distance. One of these governs the phase and the other the amplitude of the total field. In this paper these factors are calculated and curves are plotted giving their values for different distances. The best position for a reflector is then considered and it is found not necessarily to be at a ¼ wave-length behind the transmitter, as is commonly supposed.The method of calculating from the curves the required positions of antennae in a system for any given purpose is shown. Two specific cases are considered. One corresponds to the parabolic reflector and the other to the linear curtain system. It is shown that the envelope of the reflecting antennae when these are tuned is not quite a parabola. In a beam system with a linear antenna array, it is found that good conditions are obtainable if the transmitting antennae are spaced 0.72 wave-length apart and the reflector is in line 1/4 wave-length behind, with the individual antennae midway between the two corresponding antennae of the transmitter.The experimental results of Tatarinoff appear to confirm the theoretical results obtained.

This paper describes a technique for providing phase compensation to signals received at widely-spaced antennas and processed at a central location. Self-compensation is provided for pathlength variations in reference-signal distribution systems. The technique may be adapted to include the measurement and compensation of signal-channel phase variations. Practical systems which require this type of compensation include interferometric systems used for position and position-rate measurements of missiles and spacecraft, interferometers and arrays of antennas used for radio and radar astronomy, and arrays of large-aperture antennas used for deep-space communications.

The theoretical analysis in this paper is based on the assumption that the angles of signal arrival on the mobile receiver are uniformly distributed. From the analysis and experimental studies, we find that if the antenna spacing between two adjacent antennas in a space diversity array is greater than 0.5λ the array configuration does not affect the cumulative distribution curves nor the shapes of the level-crossing-rate (LCR) curves, and only slightly affects the signal level at which the maximum LCR occurs. Hence a three-element array with a triangular shape or a four-element array with a rectangular shape can be considered a good arrangement, provided each side (antenna spacing) is greater than 0.5λ. Two slightly better arrangements than those we just mentioned for improving the signal fading are also proposed for three-branch and four-branch diversity signals, respectively.

This paper describes a system of stagger-tuned high-Q loop antennas designed for 100 kc Loran pulse reception. The individual loop antenna outputs are first added in a summing amplifier followed by a grounded-grid amplifier and a cathode-follower stage before being fed to the receiver. Based upon preliminary theoretical analysis, an experimental antenna array is developed, which confirms its capability of achieving a wide bandwidth with relatively small dimensions. A squaring scheme of obtaining omnidirectional reception property is suggested; and a modified electrolytic tank method, which is adaptable to the present system in synthesizing a given response characteristic, is also described.

An investigation is made concerning the dependence of the array characteristic of a directional ring aerial on its number of elements. It is shown that an odd number of elements is more favorable than an even number in approximating the array characteristic of a similar ring aerial with infinitely many elements. It was previously shown by Page that a similar statement applies to an azimuthly omnidirectional, fading-reducing, concentric ring aerial; this result is contained as a special case in this investigation. The present paper deals especially with the case in which the principal direction of the antenna array is horizontal; the theory for this case is illustrated by a numerical example. Journal of Applied Physics is copyrighted by The American Institute of Physics.

This paper considers the signal phase acquisition problem for arrays of large-aperture steerable antennas. In particular, long-range signal acquisition is considered for those cases in which the signal-to-noise ratio in each antenna-receiver channel is too low to permit signal phase-lock in each individual receiver. Techniques are discussed which promise to extend the array acquisition sensitivity toward that of an equivalent-area single-aperture antenna. Several acquisition methods are analyzed mathematically and an approximate minimum power threshold estimated for each technique. A numerical comparison between the acquisition techniques for various assumed atmospheric conditions is presented which indicates the limitations on array sensitivity imposed by both the transmission medium and the acquisition technique.

In this paper we consider the problem of using signals received at three or four antennas to estimate the direction from which radio-frequency (RF) radiation is arriving. Though the results are couched in the terminology of angle measurements, they are applicable to any ambiguous measurements for which the number of ambiguities is inversely proportional to the accuracy. For an interferometric system the effect of receiver noise is examined. Then the optimum way to process the received waveforms, and the best spacing for the antennas, is determined. Next, signal-to-noise ratio (SNR) requirements are determined which must be met to insure that, with a given probability, the final unambiguous measurement is not in error by more than some specified amount. Finally, a comparison is made between a system which uses unambiguous measurements and a system which uses ambiguous measurements and then resolves the ambiguities.

This paper describes how continuous null tracking of a target may be achieved with a fixed pattern multiple-beam forming network with a resulting improvement in tracking accuracy when compared to beam interpolation techniques. Continuous null tracking is accomplished by cascading a hybrid phasing matrix with a beam combining networks called a steering box. The steering box combines three elementary beams in the proper ratio to form a composite sum-and-difference beam which may be continuously steered throughout the coverage angle. The change in the sum-and-difference patterns as a function of steering angle is derived for different steering loci. It is shown how pattern asymmetry may be minimized or sidelobe fall-off rate maximized by the proper choice of a steering locus. Several physical realizations of steering boxes are discussed including the steering box employed in an experimental electronic scanning radar system.

This paper describes a phase-lock receiver designed to accomplish the arraying of four independently steerable antennas and provides some measured performance data. The results indicate that the performance of such an array will be comparable to that of a single antenna with the same aperture and a conventional phase-lock receiver.

This paper describes a digital-latching phase shifter which combines the electrical advantages of waveguide design with the compactness of a strip transmission-line structure. Two multibit, nonreciprocal, C-band models are described, which combine the electronic drivers and the microwave structure in an 0.8 by 0.8 inch cross section designed specifically for half-wavelength stacking in an antenna array. A new technique of antisymmetric dielectric loading to convert microwave energy from a TEM mode in stripline transmission to a TE-type mode propagating in a dielectrically loaded rectangular waveguide is presented. Data for a one-bit model are presented along with an investigation into an optimum material choice. Temperature stability and peak power capability are also discussed. The performance of two multibit models are presented, including VSWR, insertion loss, and average power characteristics of the final microwave structures. Temperature variation of phase shift and peak power performance of these devices are also presented. Particular attention is given the electronic drivers for the multibit models which must latch the toroids into their remanent states. The driver circuit is designed to permit switching of each bit between states with a single wire trigger. Finally, the advantages of this design over previous miniaturized models are summarized, and further investigations into other features for greater optimization are suggested.

The paper deals with an investigation of the horizontal and the vertical patterns due to a plane array of isotropic radiators arranged along a cardioid. Following a brief theoretical analysis, seve...

This paper is concerned with the problem of arraying Yagi disk or disk on rod surface wave structures having large interelement spacings. It is shown that symmetrical arrays having acceptable sidelobe levels (below 13 db) can be designed using simple array theory and the knowledge of a single-element pattern.

Interference patterns resulting from a system of orderly arranged sources, whether they be radio, light, or sound waves, can be conveniently analyzed by the use of the exponential operator ej. This paper illustrates the application of the exponential operator in the development of the equation for the general antenna array.

There is a continuing practical need for antennas which radiate a pattern which is omnidirectional in azimuth, but with a specified shape in the vertical direction. One example is that of a broadcast station, where the radiated power should be concentrated along the ground. Conventional solutions of this problem make use of an array of colinear elements, or of sectionalized elements, or of top-loaded antennas. The height of the antenna is often of the order of a half-wavelength. Page1 proposed that a circular array be used for this purpose, and showed that an array of several radiators distributed about the circumference of a circle, and with an element at the center, could be made to radiate an omnidirectional pattern in azimuth, with a null at any prescribed vertical angle. In the antenna described by Page all of the elements are driven, which entails complicated matching and phasing networks. It is the purpose of this paper to describe an antenna, similar in geometry to that of Page, in which only the center element is driven. The remaining elements are excited by mutual coupling from the center element, and the desired null in the vertical pattern can be controlled either by varying the length of the parasites, or by inserting a tuning reactance at the center of the parasites.

The phase and amplitude weighting of the waveform received at each element of an antenna array can be adaptively controlled in real time to optimize the antenna pattern for a variety of communication links. In this paper we present the results of experiments conducted with an SHF self-phasing array and with an adaptive UHF null-forming array.

To transmit higher data rates or, conversely, to use present bandwidths over longer distances, the effective radiated power (ERP) from satellites must be substantially increased. Present operational satellites have stationary antennas, which typically radiate energy in nearly all directions; however, as the gain is increased, the necessity of steering the beam arises. In this paper, the application of electronic self-steering techniques to satellite communication systems with high-gain antennas is considered. Two experimental configurations of self-steerable arrays have been designed, fabricated, and tested. The Transdirective Array, a special configuration of the multiple-beam array, utilizes Butler matrices to form a high-gain antenna that receives incident signals from arbitrary directions and processes them with amplification and frequency translation before re-radiating the signals toward other directions. The second model is an example of the class of self-phasing arrays. This group is composed of conformal arrays of elements, each of which has its own electronic circuitry that automatically phases the elements to produce a beam in the direction dictated by a pilot signal from a station desiring to communicate with a transmitting station. In the simplest form of the self-phasing (retrodirective array), the needed phase inversion is derived from a mixing action.

Two-dimensional windows find applications in many diverse fields, such as the spectral estimation of random fields, the design of two-dimensional digital filters, optical apodization, and antenna array design. Many good one- dimensional windows have been devised, but relatively few two-dimensional windows have been investigated. In this paper we show that good two-dimensional windows can be obtained by rotating good one-dimensional windows. That is, if w(x) is a good symmetrical one-dimensional window, then w sub 2(x,y) = w(square root of (x squared + y squared)) is a good circularly symmetrical two- dimensional window.

This paper adds the concept of interelement mutual coupling to a previously presented design technique for aerial arrays. With mutual coupling accounted for, one can realistically design electronically scanned arrays of wire elements that have both maximum gain and a number of independent, steerable nulls in the radiation pattern.