Abstract: There is disclosed herein a linearly polarized mat-strip phased antenna array wherein the antenna array is phased by incorporating in series relationship one or more mat-strip loaded line type phase shifters in the mat-strip power division distribution network for the mat-strip dipole elements and/or a combined mat-strip dipole element and phase inverter. Two embodiments are illustrated.

Abstract: A circular phased array system is described which utilizes a lens feed to simplify the problem of commutating the RF distribution system through 360* of steering of the antenna beam. The lens feed consists of a circular parallel-plate radial transmission line with a central set of probes and a ring of peripheral probes. The peripheral probes are coupled via switches to an array of radiating elements arranged in a circle. The central set of probes can be energized and phased to produce electromagnetic energy with an amplitude distribution within the parallel-plate line in any given direction. By selective settings of phase and amplitude of the energy coupled to the central set of probes to achieve the proper energy distribution to the peripheral probes and by operating the switches to determine which radiating elements are coupled to the peripheral probes, a desired directive antenna pattern with low side lobes is provided.

Abstract: This relates to a mat-strip dual circularly polarized phased antenna array with independent steering of both right hand circularly polarized and left hand circularly polarized antenna beams. This is obtained by superimposing in a common aperture two linearly polarized phased arrays with their dipole element axis in space quadrature and by setting one polarizer over both linearly polarized arrays. The two circularly polarized antenna beams can be independently and simultaneously scanned, operated in transmit or receive, operated at different frequency and be designed for different bandwidth, gain and slidelobe characteristics. The beams are oppositely polarized through the use of a single polarization device interposed over orthogonal linear arrays. The linearly polarized arrays are phased by a separate phase shifter coupled to the mat-strip power division distribution network of each of the arrays, by providing one or more mat-strip phase shifter which can be controllably connected into the distribution network and/or by controlling the manner in which the distribution network is connected to the mat-strip dipole elements of the array.

Abstract: An instantaneous, omnidirectional direction finding system for locating an incoming wave over a complete 360° arc in space employing a circular antenna array and a fixed phase shifting network for deriving from said array a differently time phase shifted signal for each different spatial direction. The array observes all spatial directions continuously, as opposed to a sequential angular scanning technique. In a preferred system, the phase shifting network provides a plurality of output modes wherein the incoming wave is defined by different phase displaced signals that are compared and quantized to obtain a digital code representing direction.

Abstract: An improved transmission line network includes signal coupling and combining sub-networks for interchange of high frequency energy between elements of a planar lineal antenna array and a monopulse radar transmitter and receiver having sum and difference channels.

Abstract: A beam forming network is disclosed interconnecting one of a plurality of input terminals with a corresponding number or a different number of antenna elements of an antenna array. The beam forming network may be used in conjunction with such an antenna array to receive waves and to provide outputs corresponding thereto, or to radiate waves in response to a selected input signal properly applied. More specifically, each of the plurality of terminals which serve as output ports when receiving and input ports when transmitting, is coupled by a plurality of delay lines to each of the antenna elements. In a radiating system, a signal is applied to one of the input terminals which is coupled to each of the antenna elements through such delay elements that the waves radiated from each of the antenna elements are delayed by specified amounts which cause the direction of the composite wave or beam formed by the waves derived from all antenna elements to be directed along a line disposed at a particular angle with respect to the axis of the antenna array. In one embodiment of this invention, the antenna elements may be disposed in a linear array, which allows selection of beam directions in a plane containing the line of radiating elements, whereas in other embodiments of this invention, the antenna elements may be disposed in two or threedimensional arrays, which allows selection of beam directions representing various combinations of azimuth and elevation angles relative to the array axis.

Abstract: Grating lobe suppression in an electronically scanned antenna array is realized by adding odd mode power to the fundamental even mode power that normally drives each radiating element of the array. The odd mode power is maintained .+-. 90.degree. out of phase with the even mode power at each radiating element aperture. The ratio of even mode power to odd mode power is varied as a function of main beam displacement from broadside. One class of circuit for automatically accomplishing the required functions utilize waveguide power dividers and phase shifters. An alternative embodiment comprehends the use of passive, reciprocal linear circuitry to perform the power division. In some circuits the phase difference between adjacent radiating elements is used to derive odd and even mode signals.

Abstract: The analysis of an antenna array may be reduced to the solution of a set of linear equations. For large arrays, the solution of the set of equations requires considerable computer time. This communication shows how the matrix properties arising in the special case of a linear equally spaced array can be exploited to devise an efficient method for solving the set of equations.

Abstract: An electronically steerable antenna array comprising phased element antennas has essentially uniform gain for small scan angles. An idealized shape of element pattern in the array environment is closely approached by controlling the complex mutual coupling among the element antennas for pattern shaping. The resulting element-in-array pattern has a nearly flat top, steep sides, and also has low sidelobes in the angular regions where grating lobes of the array factor can appear upon steering. Consequently, the antenna array has high and almost constant gain over a limited range of steering angles in all directions from the principal mechanical axis of the planar array, and has low sidelobes and low grating lobes.

Abstract: A phase alignment system for a self-phasing antenna array is described. A single time-shared processor sequentially phase aligns each array element with a suitable reference signal. This technique is applicable to a self-phasing array in which the random phase of the signal received at each array element is slowly varying (bandlimited). Individual antenna signals are summed and the phase of the signal from a selected one of those antennas is compared to the phase of the sum (reference) and a variable phase shift is introduced into that selected one antenna output to bring that output into closer conformity with the phase of the sum. This process is repeated sequentially for the entire group of antennas and optionally the sequential comparing and adjusting may be interrupted, maintaining the phase-shifts for the several antennas at their most recent value, and the antenna array employed for a transmitter to thereby provide a transmission radiation pattern substantially the same as the reception sensitivity pattern as it existed just prior to the interruption.

Abstract: A linear antenna array receives incoming microwave signals which are coup to a wide-angle, microwave lens to produce a received beam pattern in azimuth. The beam pattern is crystal detected and log video amplified to produce an output signal comprising directional information in the amplitude level. The directional information is processed in a logic processor which converts information into binary voltage levels which are gated to appropriate switch drivers and to automatically decide the discrete received beam detecting target signal and to activate a switch which will enable ECM signals to be transmitted to radiate in the desired transmit beam. ECM signals which are gated through the switch apparatus by inputs from the logic processor are coupled to a second microwave lens apparatus which forms a beam pattern to be transmitted which is retro-directive with respect to the received beam pattern. The beam is transmitted by a linear antenna array.

Abstract: 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*, with the number of steps being determined by switching and matrix circuitry

Abstract: An antenna array for the TACAN navigational guidance system has a plurality of cylindrically arranged antenna elements. Each element is excited with a modulated radio frequency signal, the modulation pattern for each such element having a predetermined phase relationship with reference signals. The modulation signal for all antenna elements are stored in digital form in a memory which may comprise a "read only" memory. The memory is digitally addressed to successively provide outputs in binary coded form, these outputs representing the modulation signal for each of the antenna elements in sequence. The outputs of the memory are converted to analog form to provide modulation signals for each of the antenna elements in incremental steps.

Abstract: A device for reradiating rf energy into shadowed areas behind mountains, for example, said device comprising a passive antenna array without reflectors or transmission line and having a plurality of half-wave dipole antennas spaced from each other by electrical insulators, the dipoles being arranged in strings and the strings being arranged in vertically closely spaced rows between side-support members

Abstract: A new class of antenna array lattices is examined and classified by using the formalism of the space point groups. The space symmetries of the current excitations and their resulting patterns are investigated. A new procedure for designing orthogonal antenna field patterns is developed.

Abstract: The feasibility of obtaining broadband time delay steering of a simple antenna array has been investigated. An array of two archimedean spirals was fabricated and scanned by ferroelectric time delay devices made of a polycrystalline ceramic containing 68.5% SrTiO3 and 31.5% PbTiO3. A 29° beam (zero bias; 3.1 GHz) was scanned to 36° off broadside with a bias voltage applied on one of the time-delay devices. For radiation patterns recorded at 3.1 GHz the beam steering is approximately a linear function of the applied bias voltage. Radiation patterns recorded over a broad frequency range show that the beam scanning is relatively independent of frequency. With a fixed bias voltage of 200 volts applied on one of the time delay devices, a beam steering of 23 ± 2° was obtained over the frequency range of 2.8 to 3.6 GHz. For a 120 volt bias setting, the array was steered to 9 ± 1° from broadside over the frequency range of 2.6 to 3.8 GHz. A quality factor is defined for comparing the efficiencies of different fer...

Abstract: A pair of back-to-back and interlaced antenna arrays, including end-fire parasitic directors, are supported by a common structure and perform almost independently with very little coupling or interaction despite their proximity. Each antenna array may provide an omnidirectional radiation pattern.

Abstract: : The concept of array ambiguity plot is introduced, and it is shown that there are exactly five distinct topological cases for antennas arranged in a plane. Some examples are given, including all regular polygon arrangements. The remainder of the paper is concentrated on those antenna arrays having a two- dimensional lattice point topology for their array ambiguity plots, as they appear to have the most forgiving tolerance requirements. Angle processing implementation and measurement tolerances for ambiguity resolution are discussed. It is shown that, for a given tolerance and region within which antennas are to be located, the ambiguities of the plot move away exponentially with number of antennas if they are placed judiciously. It is therefore possible to obtain the advantages of wide baseline systems which are ambiguity-free with just a few antennas. The one-dimensional antenna array situation is treated, it being a special case of the theory.

Abstract: A circuit for providing accurate timing pulses to steer an antenna array. A Gunn device coupled at the input of each transmitting element supplies a single pulse at predetermined time intervals to the element enabling time delay steering of the antenna array.

Abstract: A commutated antenna array for a Doppler type radio navigation beacon system in which there are reference and main arrays. A limited number of additional elements are added to the main array on a semi-random basis and an adjustment in the commutated reference cycle is made in accordance with main array element spacing. Multi-path problems resulting from use of wide antenna spacing in the main array of a commutated reference Doppler Beacon are reduced.

Abstract: The invention relates to a logarithmic, periodical antenna array with dipoles of varying length attached to a boom, surrounding feeders in contact with the radiator elements of the dipoles. The antenna preferably has adjustable operating direction. In order to enable the use of the antenna for two different frequency ranges, each half-wave dipole has a central portion protruding from the boom and surrounded by two tubular collinear members separated by a gap. The inner member is only secured to the boom, and the outer member only to the end of the arm. Free outside and along it, at least one of the tubular members has a metal member, only attached to the end of the tube at the gap. In the lower frequency range the current distribution half-wave reaches between the outer tubular members in each dipole pair, and in the higher frequency range the outside metal members will give one current distribution half-wave over each radiator element in a dipole pair.

Abstract: A new formula for calculating the directivity of a phased antenna array with limited scan angle is presented. The elements are directive and have interelement spacings so large that grating lobes appear.

Abstract: A broad-band antenna element and beam-forming matrix have been developed for reception of signals at 25-100 MHz. The element is a zig-zag log-periodic antenna with a nominal impedance of 430\Omega and a VSWR of less than 1.9. The matrix utilizes time-delay gradients to obtain frequency-independent beam positions and also allows several different beam positions to be monitored simultaneously. Observations of natural radio sources using a 16-element array have verified its usefulness.

Abstract: : The purpose of the study was to investigate the potential advantages which may accrue to HF antenna array systems by employing adaptive beamforming techniques. Data for the study were obtained using a CW transmitter located in Bearden, Arkansas and an eight element, narrow band (31.25 Hz) receiving array in Los Banos, California. The Bearden signal was presumed to be an undesired interference. The individual array element signals were combined using tapped- delay-line filters for purposes of rejecting the Bearden signal while simultaneously forming a beam in the direction of a weak desired signal. It was shown that adaptive adjustment of the delay line weights provided better than 25 db improvement over conventional beamforming methods. The adaptive time constant was measured as 27,000 adaptations for each 3 db improvement, corresponding to a real time rate of less than 100 msec for special purpose digital hardware.