Showing papers on "Feed line published in 1971"

Base-band radiation and reception system

Abstract: A base-band transmitter and receiver antenna system for operation in subnanosecond pulse radio systems of the type detecting the presence or range of near-by reflecting objects utilizes directive, dispersionless, broad band traveling wave transmission line radiator and receiver antenna elements arranged cooperatively to limit the effect of base-band energy directly coupled from the transmitter to the receiver.

Differential doppler detection for rf intruder alarm systems

Abstract: An intruder detection system in which an RF transmitter is connected through a length of transmission line to a transmit/receive antenna, both transmitter and antenna are matched to the line. Diode detectors are connected in opposite directions to the line at points spaced a quarter wave length apart. The diodes connect through low-pass filters to the balanced inputs of an AC coupled amplifier which extracts the doppler sine wave from the oppositely traveling transmitted and received waves on the line. The doppler sine wave is squared and the pulses are integrated to trigger an alarm. A band pass filter is so positioned in the line to reduce false alarms by defining a specific radio frequency bandwidth and also allows the detectors to be used to time the transmitter oscillator.

Helicopter uhf antenna system for satellite communications

Abstract: A UHF antenna comprising crossed dipoles in the shape of drooped bow ties, encased by a polyester fiberglass laminated cone, positioned above and rotating with the blades of the helicopter, and orthogonally fed by a coaxial transmission line running through the hollow rotating mast provides an antenna for overhead signal transmission and reception. A coaxial rotary joint is placed inside the mast at the lower end to make a rotating electrical connection with the feed line.

Radio communication transmission system for vehicles

Abstract: A radio communication transmission system for moving vehicles following a track wherein an intermediate frequency communication signal is transmitted on a leaky coaxial cable at a low loss from a ground station. This signal is periodically amplified, if required, to compensate for attenuation, and is also periodically frequency converted into a radio frequency signal which is transmitted along with the aforesaid intermediate frequency signal on the same leaky coaxial cable for uniform leakage therealong for coupling to an antenna on a vehicle traveling adjacent the leaky coaxial cable. A transmitter is provided on the moving vehicle and transmits a second radio frequency signal from the vehicle to couple the signal to the leaky coaxial cable for transmission thereon. This second radio frequency signal is then frequency converted to a second intermediate frequency signal for transmission at a low loss thereafter on the same leaky coaxial cable to a ground station for reception.

Arrangement for the decrease of reflection interferences within networks for pulse transmissions

Abstract: An arrangement for reducing reflection interference within a pulse transmission network which has a main transmission line and a plurality of branch transmission lines which are predominantly capacitively loaded wherein adjacent the connection of a branch transmission line to the main transmission line there is provided a resistor in series with the branch transmission line and having a resistance value equal to the wave resistance of the branch line minus half the wave resistance of the main transmission line.

Balanced Transmission-Line Measurements Using Coaxial Equipment (Correspondence)

Abstract: The availability of commercial precision coaxial hybrids makes measurements on balanced two-conductor transmission lines as easy and as practical as on an unbalanced coaxial system. These hybrids, when used as a balun, transform an unbalanced coaxial system to a balanced shielded system and because of the nature of the balanced shielded system permit the measurement of the characteristics of loads connected thereto by the use of commercial coaxial test equipment. This technique has been successfully used from 600 MHz to 5 GHz, and with presently available components can be used at HF and VHF as well. The theory upon which the measurement technique is based is outlined and some results of an experimental verification included.

Wideband detector for use in coaxial transmission lines

Abstract: Coaxial line apparatus forming a termination and detector for high frequency signals. An input coaxial transmission line has an inner conductor and an outer conductor. The input coaxial transmission line is branched into a load transmission line and a parallel video transmission line. The load transmission line has inner and outer conductors and a matching impedance connected between the inner and outer conductors for terminating the load transmission line. The parallel transmission line has a separate outer conductor and inner conductive means. The inner conductive means include a crystal diode mounted at an angle with respect to the axis of the parallel transmission line outer conductor. The parallel transmission line outer conductor has an apertured portion substantially aligned with the crystal diode so that the crystal diode can be inserted or removed through the apertured portion. The parallel transmission line also includes additional impedances for attenuating relatively high frequency signals.

The shunt-driven circular loop antenna

Abstract: The distribution of current, admittance, and far field of a shunt-driven circular loop antenna are derived and related to those of an equivalent series-driven loop in parallel with a section of transmission line. The effective length of a shunt-loaded receiving antenna is obtained in terms of the corresponding quantity for the series-loaded loop.

Device for producing rectangular voltage pulses of very small width between two outputs

Abstract: The device comprises a first transmission line which can be charged, a second transmission line which constitutes the load line and switching means for connecting one end of the charged line to the load line. The load line is made up of two sections having the same characteristic impedance and the charged line has a characteristic impedance which is very substantially lower than that of the load line.

Radio Interference from Isolated Noise Sources on Overhead Transmission Lines

Abstract: An isolated noise source such as a cracked insulator on a multiconductor overhead EHV transmission line produces an electric field adjacent to the line by two separate paths. One is the transmission of the noise voltage along the line causing a lateral field and the other is the direct radiation from the source acting as a dipole antenna. The theory of natural modes has been applied to determine the line field while ordinary antenna theory has been used in the determination of the antenna field. The calculations have been carried out with a digital computer for a single circuit horizontal line although the program developed is general and applicable in the analysis of a practical line of any configuration and make up. It has been shown that the transmission line functions as an induction umbrella where the line field is strong and outside which the antenna field is predominant.

X-ray topography apparatus

Abstract: This invention provides an improvement in an X-ray topography apparatus for photographing grid distortions of a monocrystalline solid body. In the X-ray apparatus which includes a rotary oscillatory drive in communication with its feed line, the crystalline body to be examined is oscillated along the feed line about an axis in the plane of the feed line and perpendicular to said plane formed by the inciding and refractory X-rays of the apparatus with the crystalline body, the amplitude of the rotary oscillation being set to a sufficiently low value to maintain the level of X-ray diffraction constant, and the improvement comprising an electronic follow-up device in direct communication with the oscillatory drive to continuously readjust the zero point of the oscillation to provide a maximum intensity of the diffracted X-ray beam recorded.