Abstract: A modular solid-state radar transmitter apparatus for producing waveforms whose amplitude may be varied over time. The transmitter achieves pulse modulation on either an intrapulse or pulse to pulse basis, while at the same time reducing stress on individual solid-state modules. Intrapulse modulation and pulse to pulse modulation can be produced with the disclosed modular solid-state transmitter because the number of modules and the sequence in which they are activated is selectable. These selections provide the various desired levels of transmitted power and thus effectively achieve modulation. In order to achieve this intrapulse modulation, a variable combiner is introduced whose coupling factor is coordinated with the module activations. In one embodiment, variable combining is accomplished by the use of RF switching logic for combining pairs of signals in parallel. In this case, RF switches are programmed to act as a conventional combiner when all modules are active.

Abstract: An over the horizon communications system includes a transmitter for generating a signal to be communicated, an acoustic source located on the earth in a direction from the transmitter that the communication is to take place which is capable of providing periodic variations in the density of the atmosphere, and means for directing the transmitter at the variations to cause the signal to be redirected over the horizon to a point of reception. The point of reception may be a radar target and the signal may be returned, or the point of reception could be a communication receiver.

Abstract: A radio frequency power divider/combiner having a pair of conductive plates between which the dominant E-type mode is produced by symmetrical excitation at a central point preferably by means of a coaxial line having its outer conductor attached to the first of these plates, and its inner (center) conductor passing freely therethrough and attaching to the second of these parallel plates in an impedance matching flareout. A plurality of uniformly distributed collectors each in the form of a loop feeding the coaxial branch port provides for low loss. The entire assembly is in the form of a thick disc with radially extended branch ports about its perimeter and a common excitation feed extending normally from the surface of the first plate. Resistors are provided between adjacent portions of the end-on loops for the suppression of circumferential current components corresponding to undesired modes.

Abstract: An improved and modified hybrid-ring coupler using distributed, quarter-wave length, tuning element to achieve the proper phasing between signal paths. Extra line lengths have been added to accommodate the addition of a third port so the device is a three-way combiner/divider. Two isolation ports accommodating external isolation resistors are provided. Instrumentation is preferably in microstrip medium.

Abstract: An integrated planar antenna array comprising at least two separate interleaved arrays separately controllable and responding to separate frequency bands. Both arrays operate with substantially the same phase center and substantially within the same effective aperture. The first array or subarray comprises spaced linear, slotted-waveguide arrays and the second subarray includes a meander line occupying the space between each of the waveguides of the first array. Scan systems are shown for independent operation of the two arrays. An alternative for the second subarray is shown in the form of slotted, square-coaxial, linear arrays in the spaces between the waveguides of the first subarray.

Abstract: A planar array and associated apparatus providing polarization agility in radar systems. The array is composed of first and second pluralities of generally parallel, slot-radiator, linear arrays. The first group of linear arrays has radiator slots oriented at 45.degree. with respect to the axial (lengthwise) dimension of the linear arrays. The second group also has 45.degree. slots, but they are rotated 90.degree. with respect to the slots of the first group. First and second groups are interleaved, each group being excited in parallel, the first group directly from a transmit/receive port and the second from the same port but through a controllable phase shifter. The setting of the phase shifters of the array comprising the first and second groups of interleaved linear arrays produces a corresponding operating polarization. Each linear array is a length of coaxial transmission line with rectangular or square outer conductor, the slots being cut into the walls thereof.

Abstract: A slotted-waveguide linear array in which a pattern of slots in a narrow wall of a first waveguide forms the aperture of the array. A second waveguide runs parallel to the first guide, the other narrow wall of the first waveguide being a common wall with the second waveguide. The pattern of coupling holes through this common wall couples energy between the waveguides.A feed arrangement, preferably including a 180.degree. hybrid, has two of its ports connected one each to the first and second waveguides, the difference port, when driven, providing 180.degree. phase feed of the two waveguides so that the presence of the second waveguide is substantially nil. Thus, a single beam is formed as if the second waveguide were not present. The feed also provides for excitation of the waveguides through a mutual hybrid in-phase relationship when the sum port of the hybrid is driven, in which case the beam is angularly separated from the original beam.

Abstract: The invention involves in-phase power splitting from an input into separate pairs of paralleled input variable circuits which may be linear amplifiers or linear controlled attenuators. The outputs of these circuits feed the input branches of a pair of 180.degree. hybrid circuits, the outputs of those hybrids providing the inputs of a 3 db quadrature coupler. An output of this coupler then provides the overall output which is shifted in phase with respect to the original input as a function of the gain control signal applied differentially between the variable circuits of the aforementioned pairs as the cosine of the desired phase angle in respect to the first pair of circuits and in accordance with the sine of the desired phase angle at the control terminals of the second pair of circuits.

Abstract: A 180.degree. microwave phase-bit device implemented in a stripline medium with integral transitional coupling into a waveguide by means of an H plane loop within the waveguide. The device is particularly well suited for use in digital diode phase shifters attached to waveguide feed networks, such as in the case of corporate feed of plural antenna elements within a phased array. The device is shown both independently and in connection with diode phase shifters providing intermediate values of phase shift such as 22.degree., 45.degree. and 90.degree.. PIN type radio frequency diodes would normally be used to provide the necessary switching function.

Abstract: An integral element/phase shifter for use in a phase scanned array. A non-resonant waveguide or stripline type transmission line, series force feeds the elements of an array. In the embodiments shown, four RF diodes are arranged in connection within the slots of a symmetrical slot pattern in the outer conductive wall of the transmission line to vary the coupling therefrom through the slots to the aperture of each individual antenna element. Each diode thus controls the contribution of energy from each of the slots (at a corresponding phase) to the individual element aperture and therefore determines the net phase of the said aperture. Three species of the invention are shown, the first and second involving RF diodes in the slots of waveguide broad and narrow walls respectively, and the third having slots through the shield plane of a stripline. The invention facilitates array phase scanning without the need for separate, and relatively more expensive, discrete phase shifters for each antenna element.

Abstract: An electronic scan system with excitation arrangement for producing a directive radiation pattern from a circular or cylindrical array at a predetermined pointing angle.The circular or cylindrical array provides random beam pointing. An RF input-output port feeds an equal amplitude distribution network providing as many outputs as there are elements of the array employed at any given time. An equal number of phase shifters is included, and gross beam positioning is effected through selection of the contiguous element group to be excited by means of RF switching. The phase shifters may then be controlled to provide the specific beam pointing or scan desired within the selected sector. The antenna elements of the array are fed through a passive interconnecting matrix responsive thereto, said matrix providing inherent amplitude taper across the effective aperture.