Showing papers on "Feed line published in 1973"

Radio frequency communication systems

Abstract: A radio communication system suitable for use in tunnels and mines uses a leaky radiating transmission line connected between a transmitter and a receiver to transmit radio frequency signals to a local receiver. Unidirectional repeaters are located in the transmission line and a return path is provided by a normal wire carrying demodulated signals from the receiver to the transmitter.

Line time base in television receiver

Abstract: A line time base in a television receiver including a symmetrical limiter for cutting off the line flyback pulses from which the reference signal for the synchronizing circuit is derived. As a result a slice is obtained whose duration and amplitude is constant and independent of the load on the EHT generator.

Microwave transmission line and devices using multiple coplanar conductors

Abstract: Three coplanar conductive surfaces on the top surface of a dielectric substrate form a microwave transmission line having first and second transmission modes used in the construction and operation of various microwave devices, such as amplifiers and directional couplers.

Polarizing feed apparatus for biconical antennas

Abstract: Apparatus is disclosed for feeding a single biconical antenna of the type having an upper and a lower cone which are connected to a coaxial feed line, the apices of said cones being in close proximity. The apparatus comprises means for vertically feeding said antenna, the vertical feed means being located at the apices of the cones. Means are also provided for horizontally feeding the antenna, the horizontal feed means being located in the vicinity of the apices of said cones. This combination of feed apparatuses permits the utilization of the vertical, horizontal, slant linear and circular polarization without the necessity of an external polarizer.

Signal transmission system over bidirectional transmission line

Abstract: A signal transmission and receiving system. A transmission line is bidirectional along its length. An impedance element terminates each end of the transmission line. Line drivers each have an output circuit connected at a respective point on the transmission line. Each line driver has a first state presenting an open circuit and a second state for applying a current signal on the transmission line. A receiver has an input connected to the transmission line and responds to the presence or absence of a voltage signal exceeding a predetermined threshhold caused by any one of the line drivers for forming corresponding output signals. Each line driver is characterized in the second state for changing the current on the transmission line so as to change in a predetermined direction the voltage level, if any, on the transmission line caused by current from another line driver.

Transmission line coupling and combining network for high frequency antenna array

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.

Dielectric directional antenna

Abstract: A dielectric directional antenna using a wedge shaped dielectric with conducting exciters on each of the angular sides. One or both of the exciters can be triangular with side indentations and one exciter can be a ground conductor with a coaxial line feeding the exciters. A three-terminal amplifier can be connected to the conductors and the feed line.

Balanced line driver, line receiver system

Abstract: The problem dealt with here is that of preventing erratic behavior of a line receiver when an open occurs in the balanced transmission line feeding the receiver, or when the power supply for the line driver goes off. In the present circuit, bias currents are applied to the transmission line in such a way that the potentials due to these currents are the same on both conductors of the line. A resistor network, responsive to the interruption in bias current flow through one or both conductors or to a change in the path taken by such current flow, places the input circuit of the receiver at a voltage indicative of a given binary value.

Refrigeration system with head pressure control

Abstract: A receiver between the condenser and the flow control device in a refrigeration system stores liquid refrigerant under pressure which is fed through a check valve to the high pressure liquid refrigerant feed line upstream of the flow control device. A pressure regulation valve bypasses the check valve to permit high pressure liquid refrigerant to enter the receiver from the feed line when line pressure exceeds receiver pressure. A vapor flow control line fluid couples the receiver to the evaporator downstream of the flow control device and a pressure regulation valve in this line insures maintenance of proper pressure differential between the line and the receiver.

Full-duplex digital transmission line system

Abstract: A finite drive impedance, unbalanced transmission line system for transmitting only the differentiated transitions of a binary level digital signal is disclosed. The transmission line arrangement includes two identical, balanced-bridge transceivers at opposite ends of a coaxial cable whose alternating current (AC) transmission line characteristics are utilized to maintain waveform timing, i.e., the spacing between the differentiated transitions, independent of transmission line length. Integrated circuit (IC) transistor-transistor-logic (TTL) is utilized for the active elements.

Log periodic pole mounted marker beacon antenna

Abstract: An ILS marker beacon antenna of the type wherein a pair of parallel conductors form a balanced transmission line and support a plurality of lateral radiators of graded lengths. An unbalanced RF transmission line extends through one of the conductors to the apex feed point of the antenna with one conductor of the unbalanced line connected to one of the pair of conductors and the other conductor of the unbalanced line connected to the other of the pair of conductors for flow of RF current from the feed point along the balanced transmission line to the radiating elements. An electrically small dipole monitor antenna mounted on the parallel conductors terminates the balanced transmission line by short circuit in a region near the back of the log periodic antenna to prevent back radiation and monitor antenna operation.

Transmission line theory for an insulated linear antenna in a fluid- or air-filled borehole

Abstract: Using a transmission line theory, expressions for the propagation constant and characteristic impedance of a borehole antenna are derived. Both air-filled and fluid-filled holes are considered. The required modal equation is solved by a rapidly convergent iterative method. Some data for the input impedance and effective dipole moment for the terminated line are then provided. It appears that the presence of conducting fluid in the hole will not seriously impair the effectiveness of the radiating structure, but the voltage gradients in the insulation will be increased markedly.

Traffic surveillance system

Abstract: A traffic-surveillance system comprises a radar equipment coupled to a transmitter/receiver antenna. This antenna is formed by a transmission line including an elongate hollow conductor with leakage losses, such as a slotted coaxial cable or waveguide, producing along its length an electric radiating field. Any metallic mass, such as a vehicle, located within that field reflects part of the radiated energy which is then picked up by the line. Part of the reflected energy is absorbed in the characteristic impedance of the line while the remainder is conveyed to the radar equipment where it is processed to yield the required information concerning the vehicle.

Practical feed network design for antenna arrays

Abstract: Computational procedures have recently been developed which accurately determine the excitation (including mutual coupling effects) at each element of a closely spaced array enabling it to perform in some desired manner. A procedure for designing a transmission-line feed network capable of realizing these required excitations is described. The result is a narrow-band feed system composed simply of a transmission line together with a small number of stubs. A comparison between theoretical and experimental results is given.

NASA/JPL deep space network 64 meter diameter antenna dual frequency feed system

Abstract: To support the Mariner 1973 X-band experiment, it was necessary to implement a dual-frequency microwave feed system for the Cassegrainian-fed DSS 14 64-m antenna. This system must be capable of simultaneous low noise reception at S- and X-bands and high power transmission at S-band. The design and measured perfromance of the DSS 14 reflex feed system is described.

Transient Response of an Asymmetric Cylindrical Antenna

Abstract: The time-domain transient response of a thin dipole antenna is discussed in terms of element lengths and the surge impedances of the transmission line and element terminals. Theory and measurements show that, unlike symmetric configurations, asymmetry in the element lengths, together with appropriate mismatch of the transmission line, produces radiation proportional to the first time derivative of the signal voltage, and replica reception proportional to the incoming field.