Abstract: An antenna array comprising at least three interferometer pairs of antenna elements with selected spacings made to form a single beam which is readily scannable. All spatial frequencies generated by a signal and intercepted by the array are derived from a signal processing technique applied to the array. The array samples space in the spatial frequency domain while the signal processing technique utilizes real time convolution of functions in the spectral frequency domain. Summation of the appropriate spatial frequencies is equivalent to a Fourier transform operation, yielding the location of the signal source in space. Resolution and freedom from interference of the interferometer system is equal to that of a fully filled array of the same aperture size containing element spacings of one-half wavelength.

Abstract: A directional loop array antenna for very low frequency (VLF) reception. array comprises four closely spaced loop antennas forming a unidirectional reception pattern with a main beam of less than 43.degree. between half power points. The array combines two double loop coaxial antennas dispersed with their axis parallel along 45.degree. lines. The signal from one double loop array is delayed sufficiently such that a unidirectional reception pattern is formed.

Abstract: An antennae feed or take-off for a plurality of antennae where the transmission line, connecting the antennae to the termination of the line, is in a closed loop whereby signal flows either direction and transmission line phase shifts are largely compensated.

Abstract: An antenna system having an array of radiating elements arranged in element modules is provided with coupling networks, one associated with each element module, each network having an input port. Each coupling network provides coupling between its input port and elements in the associated element module, as well as independent coupling between its input port and selected elements associated with other modules in the array.

Abstract: An antenna for a hand-held radio transceiver includes first and second elements extending from the radio's case. The first element is comprised of a pair of series coupled members having electrical lengths of one-half and one-quarter wavelength, respectively, with the free end of the second member being coupled to the transmitter output. The second element couples to the radio's electrical ground and is configured to form a transmission line with the second member. The effective electrical length of the second element, including the influence of the elements parasitic coupling to the radio, is adjusted to be one-quarter wavelength.The resulting antenna structure minimizes surface currents across the radio's body, thereby substantially eliminating power loss caused by absorption in the user's body.

Abstract: The present invention provides several new and useful improvements in steering and control of phased array antennas having a small number of elements, typically on the order of 5 to 17 elements. Among the improvements are increasing the number of beam steering positions, reducing the possibility of phase transients in signals received or transmitted with the antennas, and increasing control and testing capacity with respect to the antennas.

Abstract: In any array antenna system having a coupling network interconnecting a plurality of element groups, the coupling network is provided with phase adjustments to shift the angular location of the effective element radiation pattern. An effective technique for this phase adjustment in a microstrip coupling network makes use of a field altering structure positioned adjacent the microstrip.

Abstract: The object of this invention is to provide a method for a new nonuniformly spaced array with nonuniform amplitudes for sonar, seismic, and electromagnetic applications, where the optimum positions and the optimum amplitudes of the array elements along its axis are systematically determined in order to produce a radiation pattern with specified sidelobe positions (directions) in the radiation pattern. By specifying the sidelobe positions (directions) in the radiation pattern one controls the beamwidth and the sidelobe level value of a directive pattern, and certain other characteristics of other radiation patterns. This method is based on the present invention by which the radiation pattern of a symmetric nonuniformly spaced array with nonuniform amplitudes is expressed rigorously by a constant plus a determinant, where the specified sidelobe positions (directions) of the radiation pattern are introduced explicitly into the determinant in a simple form.

Abstract: An interleaved antenna array is disclosed in conjunction with an improved multiple transmitter antenna system for simultaneously generating two independent groups of composite radiation patterns for two separate pluralities of independent radio devices. A first plurality of isolated independent radio transmitters is coupled, without any signal cancellation, to each and every one of a first plurality of independent antenna elements which form a first group of composite radiation patterns for these transmitters. A second plurality of transmitters is likewise coupled to a second plurality of antenna elements which create a second group of composite patterns for these transmitters. The antenna elements of the first and second pluralities are alternately circumferentially disposed about a central axis and each produces a 90.degree. half power beam width radiation pattern which is directed radially away from the central axis. First and second combining networks produce 90.degree.

Abstract: The object of this invention is to provide a method for a new nonuniformly spaced array with nonuniform amplitudes for sonar, seismic and electromagnetic applications, where the optimum positions and the optimum amplitudes of the array elements along its axis are systematically determined in order to produce a radiation pattern with specified zeros (nulls) in the radiation pattern. By specifying the zeros (nulls) of the radiation pattern one controls the beamwidth and the side-lobe level of a directive pattern, and certain other characteristics of other radiation patterns. This method is based on the present invention by which the radiation pattern of a nonuniformly spaced array with nonuniform amplitudes is expressed rigorously by a determinant, where the specified zeros (nulls) of the radiation pattern are introduced explicitly in the determinant in a simple form.

Abstract: A single antenna array having a phase shifter at the input of each antenna lement and fed by a multifrequency input for simultaneously generating at least two beams. When the different excitation frequencies are simultaneously inputted into the phase shifters, a separate phase increment is introduced into each radiator for each frequency. The result is a separate beam output from each frequency input, the beams being generated simultaneously but at different beam pointing angles.

Abstract: The present invention relates to thinned linear, planar and three-dimensional phased antenna array configurations which have the antenna or sensor elements positioned in a pseudorandom manner as prescribed by the equation based on difference sets. The present antenna array permit thinning factors well below one-half while retaining the sidelobe level characteristics of arrays with much higher thinning factors.

Abstract: An antenna combiner 2.sup.n antenna element system with switchable variable delay line length broadband beam and null steering through 360.degree. in azimuth.

Abstract: Disclosed are array antenna systems wherein the effective element pattern is modified by means of coupling circuits to closely conform to the ideal element pattern required for radiating the antenna beam within a selected angular region of space. Use of the coupling circuits in the embodiment of a scanning beam antenna significantly reduces the number of phase shifters required as compared to prior art array antennas.

Abstract: An Isolation Differential Combiner which accepts signals from two spaced vertical whip antenna elements and which are then combined through delay lines so that the resulting said reception pattern is a cardioid signal pattern at the combiner outputs. The isolation of the two signals is accomplished by connecting wide-band balanced transformers as hybrids. The differential component of the two signals present at the hybrid combiner is available at each secondary winding of each wide-band balanced transformer.

Abstract: A Doppler VOR beacon comprising a central antenna modulated with a reference wave and a ring of omnidirectional antennas radiating sidebands of a sub-carrier amplitude modulation of the carrier commutated around the ring of antennas to simulate a rotating source, in which the central antenna in comparison with the ring antennas has a higher gain towards the horizon and over a predetermined angle above the horizon. The central antenna may comprise a vertically stacked array, the elements of which may be Alford loops.

Abstract: Antenna having a selectively rotatably extendable sensitivity pattern provided by an array of three or more dipole antenna units, each of substantially equal mechanical length and located at the corners of a substantially regular polygon having the same number of sides as the number of units in the array and switching means having connections to each dipole unit to selectively energize at least one of said units and interpose an electrically-lengthening inductive reactance in at least two other units located, with respect to the direction in which the sensitivity is to be extended, behind and on either side of an energized unit to serve as parasitic reflectors extending the lobe of sensitivity of an energized unit in the selected direction.

Abstract: A low height, high efficiency antenna system in which a plurality of radiating elements are spaced to induce mutual radiation resistance in each other and the elements radiate using constant current which is obtained with a parallel folded element that receives the current prior to the radiating element, and since the current is moving in opposite directions in the folded element all but the constant current component is cancelled. The edge of the supporting tower can be used as one or two legs of the folded element.

Abstract: A multi-rod broadband antenna consisting of a plurality of elementary radiators arranged as directrices of a cylinder each consisting of a conductor surrounded with a ferromagnetic core designed so that each one has a resonant frequency value different from any other one, the resonant frequency values being related so as to form a series. The arrangement of the rods around the cylinder is such that the frequency values of two adjacent rods do not correspond to two adjacent terms of the series.