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A new type of antenna design is described that could be applied to radar antennas for surveillance or navigational purposes. Compared with antennas in current use large reductions, typically 50-70% in cross sectional size and overall weight, should be obtainable with this antenna design. (Author)

An array of fan-shaped segments arranged in a spiral-like manner is described. The fan-shaped segment, which may consist of a board of stripline or microstrip, contains several radiating elements phased by the Huggins or I.F. method. The fields produced by single segments are calculated and the characteristics of the radiated beams are given. Quantitative expressions for the field produced by spiral arrays are derived and examples of field patterns and beam properties are given. A method is presented for coupling the outputs of an array of segments to feed a circular array to obtain conformal scanning. When used in this latter manner, the dimensions of an array of segments can be greatly reduced.

The patent relates to a reciprocal corporate microwave feed network. A matrix is connected between a selector switch and an antenna ring array. The matrix divides microwave energy from sender apparatus and produces a tapered phase distribution to a selectively predetermined sector of the array. The active or energized array sector forms a highly directive beam which is normal to the array sector. The matrix is circularly symmetric and can feed any sector of the array as selected by an input switch. The beam is step scanned over 360 degrees with the number of steps being determined by switching and matrix circuitry.

The patent describes a high frequency, corner reflector antenna comprising two screens of vertical wires positioned at right angles to each other and two active elements located there-between. The device is operable over a frequency bandwidth of 4:1 and can provide an azimuth pattern beamwidth of 45 degrees. The active elements comprise moderate-Q radiators tunable over a 2:1 frequency range whereby two frequencies can be transmitted simultaneously without the use of multicouplers.

The patent describes a method and apparatus for obtaining automatic retrodirective performance from circularly symmetric arrays, and circular continuous aperture antennas. Phased mode sets are provided by a multimodal feed network as a result of modal interconnection methods. All modes in a particular mode set become in phase in the direction of an incoming signal, and as a result, a beam is made to reradiate in that direction. The method is applicable to two and three-dimensional retrodirective systems and includes both active and passive devices. Also, the reradiated beam width, beam power, and other reradiated beam characteristics including sidelobe functions, are capable of being controlled and adjusted.

The analysis of finite planar arrays of slots is developed. This analysis includes as special cases the linear array of slots with weak coupling and the linear array with strong coupling. This strong coupling case has not been available heretofore in the literature. Likewise the analysis of the finite planar array is presented for the first time in this report. The degenerate or special case of the linear array with the weak coupling of slots is presented with experimental confirmation of results. The experiments of others were used to verify the finite planar array analysis. A complete and error free program has been written in Fortran IV language during this study. This program will enable the sponsor to fully utilize the advanced methods of calculation of array performance without the necessity of making expensive experimental models of planar arrays. This type of early design calculation also makes it possible to avoid 'blind spots' in the projected array performance. The analysis may be adapted to arrays using other than slot elements through the use of the same basic approximation methods as well as with full use of reciprocity and symmetry., See also Part 1, AD-918 224L.

The report contains the results of a program to develop and build an electronically steerable MIC linear array with a single MIC receiver front end and the necessary array feed structure. The linear array consisted of four modules in a single housing bolted to a second housing containing four cylindrical waveguide antennas. Phase shifters for beam steering and polarization diversity were tight-coupled meander line, nonreciprocal ferrite structures flux driven to obtain effectively 4-bit operation. A varactor tuned MIC Gunn oscillator was investigated for use as the local oscillator. A new design approach consisting essentially of lumped tuning elements was used. A mathematical model for this approach was generated and computerized. A new design approach in phase shifter flux drivers using standard commercial components was derived. (Modified author abstract)

A modified dual feedhorn antenna assembly for the air route surveillance radar (ARSR-2) was evaluated on a comparison basis with the normal feedhorn in attaining optimum radar coverage. Data indicated that ground clutter at close-in radar ranges was significantly reduced by use of a high-angle antenna beam (passive feedhorn) resulting in improvement in signal-to-clutter response at these ranges. Installation of the dual feedhorn antenna assembly as a field modification is considered feasible. (Author)

A study was made to investigate the feasibility of utilizing a single reflector aperture radiating at UHF, L-band, and C-band frequencies. Radiation measurements were performed at UHF (335 MHz) and at L-band (1200 to 1600 MHz). The feasibility of an integrated L-band and C-band feed system was established; however, no measurements were made on the C-band characteristics because it was an optional requirement. Two types of L-band feeds were evaluated: a cavity-backed open-sleeve dipole, and a probe-excited coaxial cavity. The measured VSWR and patterns of these feeds are shown. The cavity-backed dipole feed was incorporated into a 6-ft parabolic reflector to determine the reflector antenna performance at L-band with and without the presence of a UHF dipole mounted at the vertex of the reflector. With the UHF dipole mounted at the vertex of the reflector and as a prime-focus feed, the UHF radiating characteristics were measured. Concepts for integrating a C-band system with the L-band feeds are provided. (Author)

Eight short backfire (SBF) elements aligned on a common planar reflector form a highly efficient fan-beam array capable of yielding a maximum gain of approximately 24 dB. The influence of parameter variations on the array patterns and directivity was experimentally determined by varying the frequency. Normalized design parameters for highest efficiency and for circular polarization capability are tabulated. All array dimensions are given in wavelengths so that each application can easily be scaled for any desired frequency. (Author)

The report discusses the efforts carried out to determine the feasibility of a dual feedhorn configuration to be employed with the doubly-curved ASR-5 antenna reflector. The feedhorn geometry is modified to provide a tilted up, receive only, second elevation plane pattern in addition to the normal elevation plane pattern of the original design. The intent of this terminal radar antenna modification program is to produce separate antenna two-way coverage patterns for the close-in and long-range capabilities of the radar system. It is intended that the close-in coverage will be obtained by transmission on the normal (low) beam and reception on the second (high) beam. The long-range coverage will be obtained by both transmission and reception on the normal beam. It is expected that the antenna will be tilted down one or more degrees from the typical unmodified ASR-5 design elevation angle., See also Volume 1, AD-781 348.

The objective of the program is to produce separate antenna two-way coverage patterns for the close-in and long range capabilities of the terminal radar system. The feedhorn geometry of the ASR-5 antenna was modified by adding a separate receive only feedhorn and polarizer. The close-in coverage was obtained by transmission on the normal (low) beam and reception on the second (high or tilted-up) beam. The long range coverage was obtained by both transmission and reception on the normal beam. This program was divided into two phases. Phase I involves the work performed to determine the feasibility of a dual feedhorn configuration to be employed with an ASR-5 antenna. Phase II concerns the design and test of the hardware to be delivered to the FAA for evaluation with an ASR-5. (Modified author abstract), See also Volume 2, AD-781 349.

Presents mathematical analysis of the antenna., Edited trans. of Novye Razrabotki Elementov Radiotekhnicheskikh Ustroistv. Respublikanskii Mezhvedometvennyi Sbornik (USSR) n1 p150-154 1972, by Victor Mesenzeff.

The report details the design and fabrication of a C-band (6.4-8.9 GHz) cylindrical array with 360 degree azimuth coverage and an elevation beam squinted out of the azimuth plane. The array was designed using computer program calculations to determine such parameters as allowable element spacing, allowable squint angle (without grating lobes) and element positional tolerance. The element phase and amplitude excitation errors which were acceptable were also determined by the computer program. The array arrangement sleected was eight rows of eight elements staggered and stacked in a cylindrical configuration. The element type selected was a 'fat dipole' over a cup reflector which exhibited a 42% bandwidth. The feed network was a series of microcircuit power dividers arranged with one input and 64 outputs which exhibited an octave bandwidth. (Modified author abstract)

The report contains a description of the results of experiments performed at the RAT SCAT Site, a ground plane radar cross section range, to examine the operational feasibility of measuring arbitrary targets with circular polarization and, in addition, measuring linear scattering matrices. A calibration procedure compatible with the RAT SCAT facility is presented. Elliptical polarization was used to facilitate the establishment of circular polarization at the target point. Experimental data is presented on the magnitude of polarization degradation as a function of target size and time. Relative phase measurements, along with the necessary amplitude measurements, were used to determine the linear scattering matrix of a complex target. Finally, two annotated schemes compatible with present RAT SCAT equipment for obtaining the linear scattering matrix are described.

The concepts of geometric optics as applied to a spherical reflector are discussed in detail. The caustic surface of a spherical reflector is examined, with particular emphasis on the advantages of complex number notation, and representation in terms of the height of the incoming ray and the arc length along the caustic. The focal region within the caustic curves is studied, and the importance of the circle of least confusion is pointed out. The use of wavefront constructions as an alternate approach is illustrated. The functional relationships are develop5d for the path-length to a field point on a concentric surface in the focal region, its spherical coordinates, and the height of incoming rays. Computations are summarized on graphs. Finally, the relationship between stationary phase and path-length is mentioned.

A commutator for circular antenna array is described using multi- throw switches fed in parallel through a power divider. The excitation phases of the elements can be controlled by phasing elements located between the power divider and the switches. In applications requiring excitation of only a few radiators at a time, each phasing element might simply be a diode together with tuning reactances. Application of the commutator and phasing scheme to a step- scanned antenna for LES-5 or 6 is described.

An experimental model of the variable-coverage communications antenna system for the LES-7 spacecraft is described. Consisting of a waveguide lens, a 19-horn feed cluster, and a combiner switch, the system will permit selection of the antenna pattern that best matches a desired coverage on earth. The coverages realizable are of many sizes and shapes, and extend from that of a 3 deg pencil beam to a full hemisphere. A computer study of this antenna system gave results in good agreement with measurement. The salient features of this study are also described.

The effects of various support structures on the radiation patterns of a Cassegrainian antenna have been investigated experimentally. Detailed two- dimensional contour plots of the wide-angle radiation are presented primarily for support member dimensions up to about one wavelength. We show that the disturbing effects decrease rapidly for perpendicular polarization when the dimensions are decreased below wavelength/2. Furthermore, the on-axis geometrical shadowing due to the support members does not give the correct level and shape of the wide-angle radiation. Account must be taken of the polarization and orientation of the members relative to the antenna axis. The performance of dielectric members is shown to be generally poorer than that of metallic members. The alternative of supporting the subreflector with a thin- wall axial dielectric cylinder is shown to be electrically acceptable for thicknesses of the order of 0.01 wavelength. The data presented should be useful in designing and evaluating various types of support structures for Cassegrainian and front-fed reflectors.

The design parameters for a practical X-band electronic 360 degree scanning antenna have been evolved. The antenna employs two geodesic Luneberg lenses and a secondary radiator in conjunction with a switching network consisting of latching circulators arranged in a tree-type configuration. The general technique also is applicable to a sector scan system. A complete mechanical layout has been made of a typical model with the following theoretical characteristics: an azimuth beamwidth of 3.8 degrees, an adjacent beam overlap of 2 dB, an insertion loss of less than 3 dB, a peak power handling capability of 20 KW minimum, and an average power capability in excess of 100 watts. This type of scanning antenna has the advantage that the gain, beamwidth, side-lobe level, and cross-over points of adjacent beams are constant with scan angle. In addition, the beam positions are stable because they are determined by the mechanical position of the feeds and consequently are insensitive to changes in operating conditions. (Author)

Matrix methods are applied for solutions of a variety of problems involving arrays of wire antennas. The versatility of matrix methods for this application is emphasized. It is shown that once the array geometry and the positions of the feed points are known both scattering and radiation problems can be handled by appropriate matrix manipulations. Problems in both array design and analysis are discussed along with examples involving beamwidth and sidelobe reduction, gain maximization, and use of parasitic elements and parallel conducting ground planes. It is pointed out how attention can be changed easily from one problem to another through very simple changes in program instructions or data input. (Author)

Progress is reported on a program to develop dielectric elements for use in lightweight, highly-transportable satellite communications antennas. Dielectric elements investigated in order (1) to determine the dielectric element type most applicable to the transportable array problem and (2) to further reduce this element to useable hardware. The remaining portion of the program will consist primarily of the design, fabrication, and testing of an array model to demonstrate transportability features. The dielectric element investigations indicated that several types of dielectric elements are applicable. These elements were projected into possible array configurations which were evaluated and compared on the basis of transportability. As a result of these evaluations and comparisons, the reflector antenna with a Dielectric Cassegrain Feed has been found to be most applicable for use in highly-transportable systems and is more completely developed than the other dielectric element types. The Cylindrical Dielectric Antenna and the Dielectric-Loaded Reflector have been found to have some desirable characteristics for transportable applications. (Author), Continuation of Contract DA36 039AMC03310E. See also AD-613 932.

A new technique was presented for linear array design using a form of limited amplitude tapering. It was shown that desirable pattern characteristics can be achieved using an amplitude distribution that is uniform over all but a few of the outermost pairs of array elements resulting in a partially uniform array. This method applies equally well to broadside and endfire arrays and can be used to place pattern nulls in one or more specified directions or to eliminate virtually all radiation over one or more sectors of space. When compared with Dolph-Chebyshev arrays corresponding to the same sidelobe levels, partially uniform arrays provide a simpler excitation scheme in general and, in some cases higher directive gain and a lower maximum-to-minimum excitation ratio. Both theoretical and experimental examples are given. (Author)

General methods of parameter calculation for antenna-feeder systems are briefly explained and the design of common types of antennas (e.g.) dipole slot, array, axisymmetrical, horn, and reflecting antennas are discussed. The methods of antenna directional pattern position control in antenna arrays are also described., Edited trans. of mono. Volume 1, Proektirovanie Antenno-Fidernykh Ustroistv, Moscow/Leningrad, 1966 p1-648. See also Volume 2, AD-693 009.

The invention consists of a device for nonmechanical oscillation or swinging of the pattern of directionability of multioscillator antennas, which has a number of controlling phase shifters connected into the feed channels of the oscillators, which is distinguished by the fact that for the purpose of obtaining sufficiently high efficiency of the antenna while using phase shifters with relatively little efficiency or reduction of the number of controlling factors, the connecting of the basic feed channel with the oscillators is effected by means of single-type dividers of power with three inputs into two terminal ones of which there are connected phase shifters with opposite directions of the phase change, the said phase shifters being controlled by one and the same factor (voltage, current, or common mechanical drive). (Author), Unedited rough draft trans. of Russian patent 154,301, appl. no. 768,151/26-9, 9 Mar 62. Legibility of this document is in part unsatisfactory. Reproduction has been made from best available copy.

For multibeam operation of an antenna, it is necessary for some of the feeds to be displaced from the axis of symmetry. The effects of such displacement are investigated for the double-spherical Cassegrain reflector. Aperture blocking, phase error, radiation pattern, aperture efficiency, beam-width and sidelobe level are studied as functions of the displacement angle xi. An attempt to improve the performance of the antenna by tilting the feed through an angle zeta is made, and a practical feed pattern is used to evaluate the system. The results indicate that very narrow beamwidth and reasonably low sidelobes can be obtained, which are essential for multibeam antennas. The decrease of the aperture efficiency due to a displacement and a tilt of the feed is studied in detail for different reflector sizes and feed pattern. (Author)

This report covers the design, development, fabrication and testing of four antenna horns (L, S, C and X-Band), which essentially have had their back lobes reduced by a factor of 25 db. The lobe reduction was achieved by erecting metal flanges on the E-edges (of the horn aperture) and covering the forward surface of these flanges with a microwave energy absorbing material. (Author)

This technical note describes and gives the results of a limited investigation of a type of undirectional, vertically polarized, log-periodic antenna referred to as a log-periodic folded monopole array. The objective of the study was to learn enough about the new structure so that a comparison of its performance could be made with the other possible array elements, namely the zigzag and coaxial fed monopole array antennas. From the impedance data, it appears that the impedance characteristics of this type structure are not naturally good, and that a more careful investigation would have to be conducted to determine if there were any modifications which would improve its performance. It was decided that since this type structure offered no great advantage over the zigzag or coaxial fed monopole array it would not be worthwhile going into an investigation in an attempt to improve its impedance performance at this time. It is interesting to note that this structure represents the first time, to the author's knowledge, that a folded monopole has been incorporated in the design of a log-periodic structure. Since this structure was conceived several other investigators have had varying degrees of success using folded monopoles or dipoles in the design of log-periodic structures.

This report describes the investigations conducted during a program to investigate the applicability of endfire, dielectric radiating elements in easily transportable satellite communications antenna arrays. Investigations of the applicability of these elements as primary feeds for lenses and reflectors are also described. The program has provided a new and workable theory that is applicable to a wide range of element sizes and materials and has resulted in the development of the Foamrod Antenna which has an order of magnitude greater gain than conventional end-fire dielectric elements. An Array Design Plan was written which describes an array equivalent to a thirty foot diameter parabolic antenna. For a feasibility model, a 16-element array was designed for electrical performance equivalent to a 15 foot diameter paraboloid. In the area of feeds for reflector antennas, some promising results have been obtained., Legibility of this document is in part unsatisfactory. Reproduction has been made from best available copy, See also AD-429 052.

The objective of the study is to perform calculations and accumulate data that will show the interrelations among various performance parameters of a flat-plate reflector and support system capable of positional adjustment in three dimensions, and to estimate the cost of such a system. The report includes investigations of various plate designs, support structures, and drive-positioning methods, all of which are designed to meet a nominal set of conditions. The relationship between the cost and reasonable deviations from these conditions is also delineated. From these investigations and related studies of power consumption, soil conditions, etc., sufficient data are available to permit the preparation of a set of system-design specifications. (Author)

A wideband, circularly polarized antenna system has been developed for use on spin-stabilized synchronous satellites. The satellite is assumed to be a right-circular cylinder of 84-in. diam and 77.3-in. height. The antenna consists of two circular arrays of 12 radiating elements equally spaced around the circumference of the satellite. The axial spacing between the two arrays is 40 in. The basic radiating element is a crossed dipole with flat open sleeves, and the VSWR is less than 2.5:1 over a 1.8:1 frequency band (225 to 400 MHz). Both the dipoles and sleeves are of wire-grid construction for minimization of solar cell shadowing. The electrical performance of the antenna is established on the basis of half-scale model measurements. It is shown that the antenna can provide an EOE gain (gain in the direction of the edge of the earth) of more than 9.3 dB from 225 to 250 MHz and at least 8.5 dB from 250 to 400 MHz.

Efforts were directed toward an engineering study program for a post-attack, survivable antenna installation. The purpose of the program was to determine the feasibility of an air supported, integrated, radome-antenna con figuration that can be packaged in a small volume, stored underground in a hardened enclosure, and capable of being quickly and automatically erected. Performance characteristics are to be comparable to a conventional 25 by 18 foot parabolic reflector. The results of the study and test program show that an antenna system consisting of a rotatable feed inside a non rotating inflatable structure that serves as both a radome and a reflector is feasible. An inflatable structure can be fabricated to a specified contour, surfaced with a reflector consisting of closely spaced parallel conductors, and after inflation maintain this contour such that it will successfully meet radiation and environmental requirements. Also an inflatable antenna of this type can be practically stowed in and deployed from a hardened enclosure de signed to withstand nuclear attack.

The ability to rapidly scan a highly directive antenna beam has been made possible by recent advances in the art of microwave phase shifting. This report describes an experimental C-band phased array antenna. The antenna is composed of eight subarrays which may be arranged in several configurations to investigate the effects of a full array. Each subarray contains a reactive power divider, 48 ferrite phase shifters and their electronic drivers, and a radiating structure. The radiating structure has been designed to provide some compensation for impedance variation with scanning. The design and fabrication of the components are discussed in detail, and test results of the array are presented and analyzed.

The results of measurements of intermodulation (IM) interference taken aboard USS MOUNT WHITNEY, USS BLUE RIDGE, and USS IWO JIMA are presented. In addition, the results of laboratory tests of connectors that were interference sources aboard BLUE RIDGE are reported. IM interference levels measured aboard MOUNT WHITNEY were determined to be lower than those aboard USS FOX (DLG 33), which was previously considered to have the lowest topside- generated rfi levels among active Fleet warships. Interference levels at hf and vhf on BLUE RIDGE were found to be higher than MOUNT whitney levels but still lower than those on FOX. UHF IM interference measurements taken aboard BLUE RIDGE indicated serious sources of interference in PHASOR 90 transmitting systems. Substituting connectors not having nonlinear material for the Prodelin cable connectors and in the PHASOR 90 power divider was proposed as a corrective measure. By applying new measurement techniques, important sources of topside- generated interference were located and identified aboard IWO JIMA. A plan of minimum topside rfi control measures for LPH-class ships was devised which, while not reducing levels to those of FOX, will effect a major improvement at minimum cost.

An investigation was made of the utility of a portion of a spherical Luneberg lens between 2 plane reflectors as a lens of reduced size and weight. If the reflectors pass through the center of the sphere, the resulting system produces several perfectly focused radiation beams, each appearing to originate from a virtual source on the surface of the full sphere. The virtual source positions and the position, beamwidth, and gain of the beams are accurately predicted from the spherical wedge angle and the source position. When the wedge angle is pi/p, where p is an integer, rays with p reflections form the beam having the greatest gain and a displacement from the wedge bisector equal to the source displacement. For applications in which only this principal beam is desired, the gain of the unwanted beams can be reduced by absorption, reflection, or illumination taper. Scanning is achieved by moving the feed along the surface of the spherical wedge; if p is an odd integer, scanning can be obtained by moving the wedge past a fixed feed. Experimental data were taken on a 2-dimensional X-band model having a value of p = 1. Satisfactory agreement existed with the predicted performance regarding beam position, beamwidth, and gain. The single, undesired beam was minimized by the use of absorbing material.

A thorough summary is presented of the theory of large array antennas, with emphasis on electronic scanning (phased array) radar applications. The treatment is comprehensive, covering the theory of error-free arrays of isotropic radiators, arrays of real radiators, and the effects of errors on array patterns and properties. A survey is presented of methods of feeding and phasing large arrays. The understanding and presentation of useful, approximate results is emphasized, will all but the most vital or simple derivations referenced to an extensive bibliography.

The scanning characteristics of a near-field Cassegrainian antenna excited with a relatively small planar array are investigated theoretically and experimentally. The analysis uses both geometrical optics and scalar diffraction theory. The technique is a viable approach to the problem of modifying an existing high-resolution dish radar for limited scan capability. Feed requirements can be satisfied by virtually any planar array concept, i.e., phase scanning, frequency scanning, multiple-beam-forming networks, etc. The scan range is roughly approximated by a fixed angular field of view; hence, the number of beamwidths scanned with electrically large apertures can be very high. Further, the system is free from the coma lobes usually associated with off-axis beams from a paraboloid. Design curves are presented from which one can determine the secondary characteristics - gain, scan loss, sidelobes, etc. - for a given array/reflector configuration.

Part I. Rod antennas with integrated tunnel diodes. A rod is cut in 2 parts and joined again by a complex impedance. This impedance is produced by a tunnel diode, shunted by a short circuited line of variable length. Current distribution and input impedance are calculated and measured. Amplification factor and mutual coupling between 2 parallel antennas are treated theoretically. A method for measuring the mutual coupling is developed. Part II. Scimitar antennas. For better understanding the radiation diagram, the electrical and magnetical near field and the current distribution on the scimitar is measured. To improve the broadband matching of the input impedance and the radiation diagrams new forms of scimitars were tested (radiation diagram, input impedance, near field and current distribution).

The report summarizes the results of absolute gain and radiation pattern measurements on two large aspect ratio reflectors with various primary feed systems. The width-to-height ratios of the reflectors approximated 7.2 to 1 and the focal lengths were approximately one-quarter of the large dimension. The antennas were polarized with the primary feed E-field parallel to the large dimension of the reflectors., NRL Problem 52R08-37.

An experimental investigation was conducted to determine whether the degradation in electrical performance commonly observed with reduced-height helical-wound vertical dipoles can be avoided. A new design approach has been explored which helped define a major cause of this degradation. Data obtained during this investigation supports a working hypothesis that losses associated with circulating currents in the capacitance between turns of a helically wound, electrically short vertical dipole greatly reduce antenna bandwidth and efficiency. A six-foot-high experimental model was constructed and tested as a replacement for the 10-foot whip of Antenna AS-1729( )/VRC. The design of this foreshortened model minimized circulating current losses throughout the operating band of 30 to 76 Mc and resulted in an average efficiency of 90% compared to the 10-foot whip.

An experimental program to demonstrate the feasibility of combining a coaxial probe monopulse organ pipe scanner with a wide angle two-dimensional constrained lens is described. The antenna system which was built and tested to prove this feasibility operates in the 5250 mcs to 5750 mcs range. It produces a half power beamwidth of 2 degrees in azimuth by 4 degrees in elevation which can be scanned =36 degrees from broadside in the azimuth plane. Variations of the measured radiation characteristics with frequency and angle of scan are summarized in graphical form. Design data and typical monopulse sum and difference patterns are presented. The test results show that such a lens- scanner antenna system is practicable for wide angle scanning in one plane.

This report consists of an examination of post-1950 rotary joint designs for use at X-, C-, and S-bands. Among the topics discussed are single and multichannel rotary joints with coaxial line or rectangular waveguide inputs. Since the simplest waveguide rotary joints incorporate transitions from rectangular to circular waveguide or from rectangular waveguide to a coaxial line, calculations are included on the relative power-handling capabilities of circular waveguide, rectangular waveguide, and coaxial line when subject to the conditions necessary for proper functioning of a rotary joint. A detailed examination is made of rectangular waveguide joints of the coaxial line, circular waveguide, coaxial mode converter, and of the annular varieties. It is shown that, in the circular waveguide variety, either a circularly polarized H(11) mode or an E(01) mode can be used. Methods of avoiding undesirable performance due to resonances in the circular waveguide are discussed. Methods are described of using circular waveguide rotary joints for dual-channel applications.

This report is concerned with a survey of the presently available literature concerning broadband antennas, in order to determine the capabilities and the limitations of the various techniques which have been investigated. In the first part the present state of the theory of frequency independent antennas is discussed. The experimental work on these structures is then briefly reviewed. In Section II, a parallel treatment is made for log periodic antennas. Section III is mainly concerned with the theoretical question of the bandwidth limitation of an antenna 'small' in terms of wavelength.

This report gives the derivation of equations for the ray trace analysis of an antenna consisting of a parabolic dish with a phased array in front of it. The derivation gives the equations for ray tracing in a form suitable for digital computer use. A number of rays from a plane wavefront can be traced through the antenna system to a feed point on the antenna axis. The rays are straight lines, and specular reflection is assumed at the dish. The phased array returns the reflected rays to the feed point (which is assumed to lie between the dish and phased array). The major features provided by the analysis and the computer program are the relative phases and path lengths of the rays from the wavefront to the feed point (tabulation and computer plots), the total number of rays, the number obscured by the phased array, the number that arrive at the phased-array plane and lie within the phased array itself, a computer-generated plot of the starting points on the wavefront of the rays used in tracing, a plot of the locations of those rays that arrive at the phased- array plane, and an outline of the phased array.

Research concerned a study of flush-mounted broadband antennas of LP (log-periodic) design. Some of the types of designs for flush-mounted antennas which have been attempted are shown. A typical example is given of a class of structures which is fabricated by starting with a planar LP structure which has a satisfactory but bidirectional pattern, i.e., it radiates symmetrically in both hemispheres above and below the antenna. In order to have the energy radiating in the top half alone, the lower portion is usually blocked off with a series of cavities or even a single cavity. Most of these have been found to exhibit poor performance as broad-band antennas. Another configuration is shown that seemingly looks like a dual of the LP dipole antenna. This will not work because the transmission line at the input would be essentially short-circuited by the shunt loops as they got smaller and smaller to satisfy the scaling conditions. There may be ways of getting around this, but a direct approach would be preferable and it is the purpose of this paper to outline one such approach.

The property shown by dielectric blocks of concentrating the energy of electromagnetic waves is similar in many respects to the operation of an ordinary glass optical lens. The energies considered have a much lower frequency than that of light, and the wave lengths are generally such that the lenses have dimensions of the order of a wave length, for the more usual applications. In this they differ radically from optical lenses. A definite phase relationship is found to exist between the energy in the lens and that of free space, and if in the design of the lens, this relationship is not respected, the lens will not yield its maximum concentrating power, or gain. The energy velocity in a lens approaches that of light with a decreasing cross section. The side walls of a lens are found to be effective energy gatherers. The thinner the lens the longer it can be made so as to increase its exposed area. An increased gain results. The index of refraction of the lens material plays a role in this action by its effect on the lens velocity. Experimental data correlating their different properties are given in the following with tentative supporting theories where possible. Dielectric losses contribute a small and usually negligible effect in the operation of all lenses, but this effect has been disregarded to simplify as far as possible the following data., Presented to Univ. of Paris, Science Faculty, 5 Dec 1946.

The shallow-cavity crossed-slot antenna is a UHF radiator designed primarily for use on a high-speed aircraft operating as the airborne terminal in a satellite-to-air communications link. The requirements, design analysis and performance characteristics are described. The antenna's shallow profile makes it attractive either as a 'paste-on' or flush-mounted type radiator. Near-hemispherical radiation coverage is provided.

The complete pattern of a parabolic reflector antenna was calculated using the singly-diffracted rays of the geometrical theory of diffraction, with proper corrections for the forward and real axial directions. Excellent agreement with experimental patterns can be expected, if the aperture blockage is not significant. The solution has the usual advantages of a solution based on the geometrical theroy of diffraction, namely, it is obtained in the form of simple functions, its computation cost is low, it is directly related to the radiation mechanism of the antenna and so it can be readily used in the design problem, and it can be easily extended and modified as the need arises.

A point-source compact antenna range was modified by installing a range reflector having a more accurate surface contour and by shielding the reflector edge and its feed with absorbing material. Stray radiation measurements and pattern measurements were made within the band from 8.2 to 12.0 GHz using a 30-inch paraboloidal test antenna. Results are compared with those obtained on a previously constructed range, and they demonstrate that the range performance was improved. Measured maximum stray radiation levels on the modified range vary from about -44 db to about -58 db with respect to the collimated radiation. Radiation patterns compare very favorably with those measured on a 700-foot outdoor antenna range.