Abstract: The present invention provides a communication terminal that enables precise communications with optimum receive sensitivity at any time regardless of any change in peripheral environments of an antenna thereof. The communication terminal including means for transmitting and receiving radio waves is provided with a training mechanism for enabling the communication terminal itself to conduct training mode for tuning receive sensitivity, and switching mechanism for switching between normal communication mode and the training mode. The communication terminal is particularly useful as a communication terminal for automobile in the Intelligent Transport System or the like.

Abstract: By switching a mode signal, capability of a drive circuit in a latch circuit can be improved than in a normal mode. Accordingly, even if a small leakage occurs in a blown portion of a fuse element, blow is correctly identified. In this manner, by improving drivability of the latch circuit, incorrect determination of fuse blow state can be avoided. Thus, a semiconductor device unlikely to make incorrect determination of fuse blow state can be provided.

Abstract: A planar conductor has a first port and a plurality of second ports. A conductive planar region is electrically coupled between the first port and the plurality of second ports. The planar region includes a first region adjacent to the first port, a third region adjacent to the second ports, and a second region between the first region and the third region. Each region has a corresponding greatest width. The greatest width of the second region is less than each of the greatest widths of the first and third regions. Irregular lateral edges of the planar conductor conduct prevent concentrations of an electrical signal at the lateral edges to more uniformly drive devices that are connected to the planar conductor.

Abstract: A controllable two-phase network for production of two output signals at two loads with identical load impedances from an input signal from a source containing a phase path for production of a first output signal, and an amplitude path for production of a second output signal, from the input signal. The phase path contains a trimming resistance and a trimming capacitance in order to influence the phase shift between the input signal and the first output signal. The amplitude path contains a compensation circuit for matching the amplitude of the second output signal to the amplitude of the first output signal. In particular, the two-phase network is designed such that the two output signals have the same amplitude, and the phase of the first output signal has a constant phase shift with respect to that of the second output signal.

Abstract: A transmission line adapter for high speed interface. A receiver receives input signals via a transmission line. An active termination circuit is selectively connected to the transmission line in parallel with the receiver according to a receive condition. A self-terminated driver circuit outputs a first voltage and a second voltage according to output data. A selective circuit for selectively connects the self-terminated driver circuit to the transmission line when output of the self-terminated driver circuit is a first voltage, and selectively connects the self-terminated driver circuit or the active termination circuit to the transmission line when the output is a second voltage.

Abstract: Apparatus for providing a controllable impedance at a reference plane in a circuit comprises a unidirectional transmission line loop having first and second input/output terminals. The first input/output terminal is connected to the reference plane and an amplifier is located in the transmission line loop to amplify signals passing in a direction from the second input/output terminal to the first input/output terminal. A variable tuned circuit couples the second input/output terminal to a terminating device.

Abstract: A high power switchable power combiner includes a plurality of input ports and a plurality of matching elements. The matching elements are arranged to be used in combination when more than two of the input ports are connected. A thermally conductive dielectric member may be provided between the inner conductor of the combiner and the conductive housing thereof to provide a thermal path to dissipate heat from the center conductor.

Abstract: A power splitter that has a small package size and repeatable electrical characteristics. The power splitter includes a low temperature co-fired ceramic (LTTC) substrate with several layers. Electrical components such as resistors, capacitors and ground planes are integrated within the LTTC substrate. A binocular core transformer is attached to the upper surface of the LTTC substrate and is electrically connected to the resistors, capacitors and ground plane. The transformer provides impedance matching and dividing functions. The LTTC substrate has electrically conductive vias extending through the layers. The vias are used to connect the power splitter to terminals on outer surfaces of the substrate and to make electrical connections between the layers of the LTTC substrate. The power splitter circuit requires only one transformer.

Abstract: A microphone assembly includes one or more transducers positioned in one or more housings. A processing circuit is coupled to the transducer for outputting an electrical signal such that the microphone in combination with the processing circuit very effectively cancels noise. The microphone assembly can be employed in a vehicle accessory.

Abstract: Briefly, in accordance with one embodiment of the invention, a combiner may include transmission lines to couple a receive port and a transmit port to an antenna at a common junction. Shunt admittance elements may be utilized at the transmit and the receive ports to isolate one of the transmit and the receive ports from the antenna by shunting the at least one of the transmit and the receive ports to a power supply potential such as a ground reference. During a transmit mode, the shunt admittance element at the receive port may shunt the receive port to the power supply potential, thereby isolating the receive port from the antenna. During a receive mode the shunt admittance element at the transmit port may shunt the transmit port to the power supply potential, thereby isolating the transmit port from the antenna.

Abstract: In signal sources having a high impedance, typically a capacitive “signal source” such as capacitor-microphone capsules, it is common practice to use amplifier circuits that include means for coupling signals and determining operating points in addition to the actual amplifier having a high-resistance, non-inverting input. For setting the operating points of the signal source and the amplifier, separate bias-voltage sources are provided; these are coupled to the signal source and the non-inverting input, respectively, of the amplifier via a coupling impedance. At least one coupling capacitance is disposed in the signal path between the signal source and the non-inverting input of the amplifier. To attain a considerable noise gain without the disadvantage of very high idle times in this type of amplifier circuit, it is proposed that the coupling impedances be formed from a nonlinear resistance (D1, D2 or D3, D4) and an ohmic resistance (R3 or R4) connected thereto in series.

Abstract: A radio communication apparatus is provided, which realizes a desired impedance matching state between a retractable antenna and a circuit connected thereto in both a situation where the antenna environment is similar to a free space and a situation where the antenna environment is dissimilar from a free space.

Abstract: The invention concerns an impedance transforming device that includes a dielectric circuit board substrate. The substrate has at least one region that has a relative permeability or a relative permittivity different from a remaining portion of the substrate. In order to control the permeability and permittivity, in this way, meta-materials can be used to selectively modify portions of the substrate. A transmission line transformer is disposed on the substrate and coupled to the region.

Abstract: An apparatus for communication of electric or electromagnetic signals over air includes a transmitter or receiver and a coupler. The coupler has a capacitive circuit connected with an air-core or dielectric-core transformer. The capacitive circuit resonates with the transformer at a preselected frequency. The coupler eliminates noise and is matched to the characteristic impedance of the air at the preselected frequency, which linearizes communication and allows high-speed data and voice communication over long distances.

Abstract: In an information processing apparatus, a transmission distortion of a signal transmitted between a module and a controller is reduced. A plurality of modules and a controller controlling the modules are mounted on a circuit board. A bus line connects the controller to the modules, the bus line including a main line and a plurality of branch lines each of which is branched from the main line and is connected to a respective one of the modules. Impedance matching elements are provided to the main line of the bus line so as to match a characteristic impedance between the controller and each of the modules. Each of the impedance matching elements is located behind a branch point of one of the branch lines connected to the respective one of the modules with respect to the controller.

Abstract: A mini BNC connector, which provides a better signal transmission quality and can be fabricated conveniently, includes a metal outer casing with two locating cylinders and a joining chamber communicating with the two cylinders, two insulators fitted in the locating cylinders respectively with each of the two insulators having a piercing hole, two terminals joined to the piercing holes respectively with a tail section respectively extending to the joining chamber, two conductors connected to the tail sections respectively and a further insulator having two through holes joined to the conductors respectively and fitting with the inner side of the joining chamber so as to fix the conductors.

Abstract: A broadband impedance matching integrated circuit apparatus comprising an alternating current ground plane, a direct current ground plane positioned proximate to the alternating current ground plane, a first conductive transmission line positioned a distance from the alternating current and direct current ground planes, a dielectric material layer with a thickness positioned on the first conductive transmission line, a second conductive transmission line positioned on the dielectric material layer wherein the first and second conductive transmission lines are electrically interconnected to behave as an electromagnetically coupled tapped autotransformer.

Abstract: A micromachine switch for use in a millimeter wave circuit and a microwave circuit is simpler in structure than conventional micromachine switches. The micromachine switch has first and second high-frequency signal lines (1b, 1a), cantilever (11) fixed to an end of the first high-frequency signal line (1b) and extending to a position above second high-frequency signal line (1a), first insulating means (15) disposed on second high-frequency signal line (1a), second insulating means (14) disposed in an area where cantilever (11) and second high-frequency signal line (1a) confront each other, and first control signal line (2) connected between an end of second high-frequency signal line (1a) and first insulating means (15), for applying a control signal.

Abstract: A phase detector which determines the phase based upon the output signals from a power coupler. The power coupler outputs a first signal and a second signal. The first and second signals are input to a magnitude detector which determines the magnitude of the relative phase between the first and second signals. The first and second signals are also input to a sign discriminator which determines the sign of the phase between the first and second signals.

Abstract: A circuit for dynamically combining/splitting power amplifier outputs having at least four power input ports. The input ports are joined by a 360 degree transmission line having three switches spaced 90 degrees apart. Two coupled line circuits are connected to the transmission line. The coupled line circuits are placed in parallel and each of the coupled line circuits selectively provides either 50 Ohms or 70.7 Ohms impedance.

Abstract: A waveguide apparatus for bidirectional distribution of signals includes: (a) a first conductive element parallel with a reference plane; (b) a second conductive element in spaced parallel relation with the first element; (c) a first coupling locus situated in the first element; and (d) second coupling loci arrayed in the second element. Each second coupling locus includes an aperture traversing the second element at a lineal distance from the first coupling locus in a lineal plane perpendicular with the reference plane and containing a line from the first coupling locus. Each aperture has a major and a minor axis. The major axis establishes an installation attitude with respect to the lineal plane. The lineal distance and the installation attitude for each aperture are selected to distribute electromagnetic signals having substantially equal power.

Abstract: The present invention provides a mechanism for supporting high digital bandwidth in a multi-drop bus system. A first device of the system is electrically coupled to a bus. Multiple receiving devices are coupled to the bus through associated electromagnetic couplers having coupling coefficients in a specified range. The geometries of the electromagnetic couplers are selected to reduce variations in the coupling coefficients with changes in the relative positions of the coupler components.

Abstract: A power splitter/divider may be used with a paralleled amplifier. The power splitter/divider includes a common port and a distribution structure for distributing equal-amplitude samples of the applied signal from the common port to four cascades of artificial transmission lines. The impedances of the sections of artificial transmission line are stepped, in order to provide an impedance transformation between the individual ports and the impedance presented to the common port. When there are four cascades, each presents an impedance of 200 ohms to the common port, for operation in a 50-ohm system. Each artificial transmission line of each cascade includes at least two planar, spirally disposed elongated conductors, spaced to provide mutual coupling between turns. In at least some of the artificial transmission lines, discrete capacitors aid in forming pi sections of transmission line.

Abstract: To avoid VSWR degradation associated with using a fixed impedance matching transformer in an RF power amplifier combiner, the transformer is configured as an adjustable-impedance matching transformer, that maintains a relatively low voltage standing wave ratio at the combiner's output port, as the number of amplifiers is changed. The adjustable impedance transformer may comprise a section of transmission line conductor and an adjacent dielectric medium, the dielectric constant of which is controllably variable. The dielectric medium may comprise a shaped dielectric element, that is positionable relative to the transmission line conductor, so as to provide a variable dielectric constant and thereby allow the effective impedance of the transformer to be varied among respectively different values based upon the number of amplifiers being combined.

Abstract: A single-input/multiple output power splitter having internal feedback circuitry. A separate amplifying circuit, such as a transistor, is used to drive each of the outputs. The transistors may be arranged in a common source/emitter amplifying configuration in which the gates/bases are connected together as an input node. Each transistor has an associated feedback circuit including passive circuit elements, such as resistors. The passive circuit elements are connected between the drain/collector of its corresponding transistor and a common intermediate connecting node to which all feedback resistors are also connected. The common intermediate node is connected to the single input via a separate input resistor.

Abstract: A standard, high performance CATV signal splitter that operates at high signal levels with greatly reduced intermodulation distortion. The circuit retains the presently accepted performance standards for RF signal splitters while reducing the unacceptable distortion resulting from the higher signal levels currently encountered in applications such as Internet communication. The improved signal splitter circuitry reduces or eliminates signal distortion due to magnetization of the ferrite core material. Such core magnetization occurs in prior art signal splitters when the high permeability ferrite core of the transformer is exposed to random electrical spikes, power surges, and static charge build-up. In the present invention, a tuned circuit is added in the output balance section of a prior art signal splitter to confine the transformer performance to the narrower range of CATV frequencies.

Abstract: A device for transmitting electromagnetic signals across a structure including functional modules organized so that two-for-one redundancy is obtained, in the case of signals that are transmitted by electromagnetic waveguides, includes a waveguide, an input end of which receives signals intended to be fed to one or the other of two functional modules organized so that two-for-one redundancy is obtained, and the other end of which is short circuited. It includes two electric field sampling units, each of which is adapted to feed one of the modules and which are disposed at respective distances from the short circuited end of the waveguide that are equal to one quarter of the wavelength of the signals transmitted by the waveguide or an odd number multiple thereof. Each module has an output connected to a single-pole switch or combiner transmitting signals from either or both of the two modules downstream of the device.

Abstract: This invention relates broadly to rf coupling circuits enabling any platform-mounted antenna system and its associated standard broadcast-communications radio receiver, to also be used in conjunction with a navigational receiver. An exemplary embodiment of the invention is an antenna coupler for coupling a broadcast communications antenna with a broadcast communications receiver and a navigation receiver. The coupler includes independent rf paths for coupling the broadcast communications antenna to the broadcast communications receiver and to the navigation receiver.

Abstract: An RF signal divider useful in the 250 to 2500 MHz range includes an RF input connection and a plurality of RF output connections. A resistive path connects each RF output connection from an RF output connection with a impedance ZL to a common node with an impedance ZQ. An input impedance transformer couples an RF input connection with an input impedance ZL to the common node. This RF signal divider is characterized by good insertion loss variation and isolation over the entire frequency range and by a minimal circuit area.

Abstract: A power combiner circuit for RF signals includes a multi-path network for conveying a plurality of RF signals over a selected path or paths, to a common node. A switched RF impedance transformer connects between the common node and an RF load. The switched RF transformer switches between first and second transformation functions depending upon the number of network paths that are selected.

Abstract: The invention comprises a low-noise amplifier of the type comprising a transistor exhibiting a saturation phase for signals of high amplitude. According to the invention, at the output of the amplifier is arranged a load impedance referring back to this output an optimal impedance for maximizing the power at the output of the transistor and an open circuit in the reception frequency band. Thus, the entire parasitic signal is “boxed in” by the load impedance. Particular application in the field of bidirectional transmissions, especially transmission systems linking a terminal comprising the device according to the invention with at least one satellite or a terrestrial base station.

Abstract: A power splitter/divider may be used with a paralleled amplifier. The power splitter/divider includes a common port and a distribution structure for distributing equal-amplitude samples of the applied signal from the common port to four cascades of artificial transmission lines. The impedances of the sections of artificial transmission line are stepped, in order to provide an impedance transformation between the individual ports and the impedance presented to the common port. When there are four cascades, each presents an impedance of 200 ohms to the common port, for operation in a 50-ohm system. Each artificial transmission line of each cascade includes at least two planar, spirally disposed elongated conductors, spaced to provide mutual coupling between turns. In at least some of the artificial transmission lines, discrete capacitors aid in forming pi sections of transmission line.

Abstract: The prior art has a problem in which an isolation between output terminals is deteriorated when a thin film resistor is used as an isolation resistor. Such being the case, in a power divider/combiner comprising an input terminal, two output terminals, two branch lines each connecting the input terminal and one of the output terminals and having a line length that is ¼ of a set wavelength or a multiple of integer of half a wavelength and ¼ of the set wavelength, and an isolation resistor connected to between the output terminals, there is provided an improved power divider/combiner further comprising a transmission line interposed between each of the output terminals and the branch lines. Consequently, even when using the isolation resistor having a length that can not be ignored as compared with a wavelength of a high-frequency signal in use, the isolation between the output terminals can be ensured.

Abstract: A data transmission circuit for transmitting a data stream includes a voltage supply terminal, a resistively terminated, controlled-impedance transmission line and an inductor coupled between the voltage supply terminal and the controlled-impedance transmission line.

Abstract: A termination circuit for unused wires in an unshielded twisted pair (UTP) cable in a local area network (LAN) device. In an eight wire UTP cable, four wires may be unused. The four unused wires are shorted to each other at a point of termination which is electrically connected to ground across a terminating resistive element having a resistance value in a range of about 0.36 to about 0.62 of a differential impedance of the UTP cable, e.g., 36 to 62 ohms for a UTP cable having a differential impedance of 100 ohms.

Abstract: An interface system for interconnecting a personal computer to audio input ports of a home stereo system. An illustrative embodiment of the invention comprises impedance transformers for improving the impedance match between an audio output port of the PC and the higher impedance audio input ports of the stereo system. An elongated low voltage, low impedance cable has coupling devices at each end, the coupling devices being dimensioned and arranged to establish respective signal paths through the cable by electrically interconnecting the audio output port and the corresponding low impedance windings of the first and second impedance transformers. The illustrative interface system further includes additional coupling devices dimensioned and arranged to accommodate electrical connections between corresponding high impedance windings of the first and second impedance transformers and the first and second audio input ports of the home stereo system.

Abstract: An approach for impedance matching a transmission line includes using the actual line impedance. According to one example embodiment, the impedance of a line connecting first and second nodes is calibrated by first driving the line to a steady-state voltage using a first current having a magnitude greater than zero, driving the current to a zero magnitude from the first node and therein inducing a voltage transient. The resultant voltage level on the line at the first node is then measured and analyzed relative to a reference voltage. The result of the comparison is then used to adjust the conductance at the second node.

Abstract: In a power divider/combiner, two quarter wavelength lines are connected to a first I/O terminal. A first transmission line is connected between the other end of one of the quarter wavelength lines and one of the second I/O terminals, a second transmission line is connected between the other end of the remaining quarter wavelength line and the remaining second I/O terminal, a third transmission line is connected between an absorption resistor and the one of the second I/O terminals, and a forth transmission line is connected between the absorption resistor and the remaining second I/O terminal. Assuming that the characteristic impedance at the I/O terminals is Z0, the characteristic impedance of each of the four transmission lines is set to {square root over (2)}·Z0.

Abstract: The present invention provides a system and device for a network hub that includes a single valued resistor placed in series with each transmission line such that reflected and other unwanted waves in the transmission line are rapidly dampened to prevent interference and errors in transmission. The present invention also provides a method and system for determining an appropriate single valued resistor serially placeable within a transmission line in a network such that reflected and other unwanted waves in the transmission line are rapidly dampened to prevent interference and errors in transmission. The present invention locates the single valued resistors on a network hub board. The present invention further provides resistors having resistance of approximately 22 ohms for use with a wide range of impedance transmission lines and signal baud rates.

Abstract: Difference frequency impedance transformation circuits for power amplifiers can change the impedance presented to an input of a power amplifier at a frequency that is a function of a difference between the receive and transmit frequency ranges. The difference frequency impedance transformation circuit may, therefore, reduce the noise at the difference frequency which may otherwise be mixed with the transmit frequencies to produce noise in the receive frequency range. In particular, difference frequency impedance transformation circuits can include a first circuit that conducts the first signals to an input of the power amplifier. A second circuit is electrically coupled to the input of the power amplifier and changes the impedance presented to the input of the power amplifier at the difference frequency. Related power amplifier systems, wireless user terminals, and methods are also disclosed.

Abstract: A high speed digital signal connection interface with reduced cross talk includes a multiple pin connector with disconnectable header and receptacle portions. The header is attached to a first set of signal carrying wire pairs communicating with a first signal processing unit. The receptacle is attached to a second set of signal carrying wire pairs communicating with a second signal processing unit. Within each of the first and second wire pair sets is a first wire pair subset carrying digital signals travelling in a first direction between the signal processing units, and a second wire pair subset carrying digital signals travelling in a second direction between the signal processing units. The first and second wire pair sets are attached to the corrector such that adjacent pin pairs of the connector carry only signals travelling in the same direction and such that connector pin pairs carrying signals travelling in opposite directions are not adjacent to each other.

Abstract: A high power combiner arrangement with improved isolation between input ports for high power applications. In particular, in accordance with high power combiner arrangement, power combining logic is combined with a series of isolators such that at least one isolator is inserted between each power source, i.e., a signal source, and a corresponding input port to the power combining logic. The number of isolators inserted is determined as a function of the isolation requirements of the overall application. Advantageously, the degree of isolation achieved by the high power combiner is directly proportional to the number of inserted isolators placed between each power source. Furthermore, the insertion of a number of high power circulators between each power source and the power combing logic facilitates the achievement of higher isolation between the power sources with minimal degradation in signal characteristics.

Abstract: A device for transmitting electromagnetic signals across a structure including functional modules organized so that two-for-one redundancy is obtained, in the case of signals that are transmitted by electromagnetic waveguides, includes a waveguide, an input end of which receives signals intended to be fed to one or the other of two functional modules organized so that two-for-one redundancy is obtained, and the other end of which is short circuited. It includes two electric field sampling units, each of which is adapted to feed one of the modules and which are disposed at respective distances from the short circuited end of the waveguide that are equal to one quarter of the wavelength of the signals transmitted by the waveguide or an odd number multiple thereof. Each module has an output connected to a single-pole switch or combiner transmitting signals from either or both of the two modules downstream of the device.

Abstract: A dual-frequency matching circuit of the present invention comprises an output terminal to which a load is connected, an input terminal through which an input signal is input to the load, a series resonance circuit, which is composed of a series capacitor and a series inductor connected in series to the series capacitor and disposed in such a manner that it is connected in series to the load when observed from the input terminal side, and a parallel resonance circuit, which is composed of a parallel capacitor and a parallel inductor connected in parallel to the parallel capacitor, and disposed in such a manner that it is connected in parallel to the entire portion of the load and the series resonance circuit when observed from the input terminal side.

Abstract: An impedance matching circuit for a set-top box includes a diplexer at a preceding stage having a given output impedance, and a network interface having a given input impedance different from the output impedance of the diplexer. The impedance matching circuit is connected between the diplexer and the network interface, and matches the output impedance of the diplexer to the input impedance of the network interface. Further, the impedance matching circuit includes a transformer having a primary coil and a secondary coil connected to the network interface, a first resistor for connecting an output end of the diplexer to an end of the primary coil of the transformer, a second resistor for connecting another output end of the diplexer to another end of the primary coil of the transformer, and a third resistor connected in parallel with the primary coil of the transformer.

Abstract: A high power combiner arrangement with improved isolation between input ports for high power applications. In particular, in accordance with high power combiner arrangement, power combining logic is combined with a series of isolators such that at least one isolator is inserted between each power source, i.e., a signal source, and a corresponding input port to the power combining logic. The number of isolators inserted is determined as a function of the isolation requirements of the overall application. Advantageously, the degree of isolation achieved by the high power combiner is directly proportional to the number of inserted isolators placed between each power source. Furthermore, the insertion of a number of high power circulators between each power source and the power combing logic facilitates the achievement of higher isolation between the power sources with minimal degradation in signal characteristics.

Abstract: A device for decreasing the number of antennas on a combat vehicle that accommodates several communications terminals has a combiner-separator module for coupling each pair of communications terminals to the same antenna. Each module has one master gate for connecting the antenna and two slave gates for connecting the communications terminals, coupled by way of a transformer stage. The gates are direct-current decoupled from the transformer stage and the master gate is connected to each slave gate by way of a bypass that transmits only a direct current and provides an antenna voltage.

Abstract: A system and method for constructing a resistance integrated coupler adapted to be coupled between a data bus and a terminal device. The system and method includes the steps of calculating a desired resistance of a set of data-bus windings, wherein the desired resistance is substantially (1.5×Zo), wherein Zo is a selected data bus cable nominal characteristic impedance; winding the set of data-bus windings to form a first part of the resistance integrated coupler using a specified amount of high resistance wire, the specified amount of high resistance wire having a total resistance substantially equal to the calculated desired resistance; and winding a set of terminal device windings to form a second part of the resistance integrated coupler. The resistance integrated coupler is constructed substantially in accordance with the guidelines of MIL-STD-1553B.

Abstract: According to the configuration the present power splitter, it is possible to reduce the characteristic impedance of a transmission line constituting a directional coupler by setting the impedance of a first terminal pair constituted of an input port 7a and a second output port 7d of a 6-dB branch-line-shaped directional coupler 7 to a value smaller than a reference impedance Z0 (50 &OHgr; in general) and setting the impedance of a second terminal pair constituted of an isolation port 7b and a first output port 7c of the directional coupler 7 to Z0. Therefore, it is possible to increase the number of splits and reduce loss, as compared with conventional cases.

Abstract: ? Device for cancelling the effects of the reflection in a signal transmission system (10) including a driver (12) and a plurality of n receivers (14, 16) wherein signals are sent according to a multipoint topology from the driver to the receivers, each receiver having an internal capacitance and sending back reflection signals to the driver each time a signal is transmitted thereto by the driver. The device comprises circuit means causing the signal resulting from the sequential reflections due to a given receiver and then due to the driver to have the same magnitude but the reverse sign as the sum of all signals received in the given receiver resulting from the reflections due to all receivers, and the net linking the driver to each receiver comprises delay means (40) enabling the propagating time of a signal sent from the driver to this receiver to be identical for each receiver, whereby the total sum of all reflection signals arriving in the given receiver at the same time is equal to zero.