摘要:
In a broadband microwave acoustic delay line, two or more transducers are used for energy translation from electromagnetic into acoustic (one type) and reverse (the other type) which are mechanically independent and resonant at acoustic frequencies different from one to the others. Each transducer of one type is connected to a first end of a matching section which constitutes a series resonant circuit tuned at a frequency within the band different from the frequency corresponding to any other transducer. The second ends of the two or more matching sections are connected at the same end of a wideband impedance transformer.
摘要:
In a waveguide to microstrip coupler comprising a metal part fastened to one of the waveguide large walls in which a channel is machined and a strip line within said channel protruding through an opening in said waveguide large wall, the distance between the nonmetalized face of the strip line substrate and the channel wall is set to a value depending on the mid band frequency of the transmitted bandwidth in order to provide a bandwidth equal to 40 percent of the mid band frequency value.
摘要:
The production sequence of the UHF transistors includes at least one ion implantation step for doping the emitter, which takes place after doping of the base, through an emitter window etched from a thin oxide layer closing the base window previously etched from a thick oxide layer. This ion implantation is followed by an anneal in neutral atmosphere while the emitter window remains open, at a temperature lower than 1000*C in the case of silicon. The base is doped either by diffusion or ion implantation. Two further ion implantations are used to degenerate the base contact area and to reduce transversal base resistance.
摘要:
A device for equalizing the electrically equivalent lengths of line sections between successive amplifiers in a digital signal transmission system. It comprises the cascade combination of a plurality of amplifiers, fixed impedance networks and adjustable impedance networks controlled by variable resistances, and includes a feedback path delivering a current to said variable resistances, said current varying according to the average peak amplitude of the output signal of said device. The attenuation provided by the adjustable networks is higher when the equivalent length of the preceding line section is shorter. Means are provided for adjusting the variation ranges of the variable resistors.
摘要:
In order to obtain wide aperture and high directivity radiation patterns from the same antenna, the radiating structure is made of a non magnetic dielectric and a dielectric ferrimagnetic material. The magnetic part is associated with magnetizing coils energized from an aperture control current source. When the antenna is of the rod type, the rod is made of the non magnetic dielectric which is covered at least partly with a magnetic coating. When the antenna is of the spherical type, a magnetic material core is surrounded with a non magnetic dielectric shell.
摘要:
A communication system in which binary coded pulses are translated into multi-level pulses before being transmitted through a communication circuit, at the receiving end of which they are reconverted into binary coded pulses. The binary pulses are grouped into words of n bits, to each of which a (n+1)th-bit of constant value is added. The (n+1) bit words are subdivided into k partial words each having q bits, with (n+1) equal to the product kq. Each one of the partial words is translated into a multi-level pulse of one or the other polarity according to the algebraic sign of the sum of the positive and negative amplitudes of the previously transmitted multi-level pulses. A method for the insertion of synchronization words is described. At the receiving end of the system, the (n+1)th-bit in each group of k partial words is used for controlling the correct restitution of the original binary coded word, by eliminating the ambiguity which otherwise could result from the fact that different multilevel pulses may correspond to identical binary coded partial words, according to their position in the sequence of these words.
摘要:
A microwave integrated circuit operating as an acoustic delay line comprises a substrate, at least an input strip line conductive pattern and an output strip line conductive pattern deposited on said substrate, at least one electroacoustic transducer between said lines and said substrate located so that the acoustic waves propagate within the substrate along a preferred axis.
摘要:
A microwave resonator comprising an insulating substrate plate with a metallized coating entirely covering one of its faces and a metallized ring on its other face, and a microstrip transmission line on the same plate capacitively coupled with said ring. Microwave generators using such a resonator for determining their working frequency and having a Gunn diode located in the central hole of the ring are also described. The substrate plate can be made of a non-magnetic material or, if a variable frequency is desired, of a magnetic material adjustably polarized by D.C. field producing means.
摘要:
Microwave integrated circuits are designed as microstrip patterns on insulating non magnetic substrates with the same crystalline structure as magnetic materials operating in the same frequency band. At X band, solid solutions of ferrites with titanates are described and a garnet-like non magnetic material is preferred at L band. Magnetic parts are set into the substrate.