Showing papers on "Feed line published in 1972"

Notch filter network

Abstract: A duplex arrangement of filter networks has, on the transmitter side, a quarter wave cavity resonator tuned to the transmitter carrier frequency and coupled to the coaxial transmission line in quarter wave spaced relation. A variable quarter wave reactance section is similarly coupled to the line and coacts with the resonator to create a condition of anti-resonance at the receiver frequency. On the receiver side, a quarter wave resonator and a variable quarter wave section are similarly coupled to the transmission line a quarter wave from the antenna connection, the resonator being tuned to the receiver frequency, and the reactance section coacting with the resonator reactance to create a condition of anti-resonance at the transmitter carrier frequency. A line connecting the resonator to the transmission line can be of the same characteristic impedance or, if greater attenuation at a greater frequency separation is desired, of a lower characteristic impedance than that of said transmission line.

Cylindrical antenna in a rectangular waveguide driven from a coaxial line

Abstract: The problem of a cylindrical antenna in a rectangular waveguide driven from a coaxial line, where the antenna spans the entire guide height, is analysed, and the admittance evaluated. An experimental investigation shows the theory to be very accurate.

High-frequency waveguide feed in combination with a short-backfire antenna

Abstract: A high-frequency waveguide feed in combination with a short-backfire antenna having a cavity and multiple reflectors to permit high power handling capabilities and high frequency applications. An open end of a waveguide is used as the primary radiator in the antenna cavity. The waveguide intrudes into the cavity from behind the larger reflector plate. The polarization response of the antenna is determined by the type of waveguide chosen.

Radio frequency antenna system

Abstract: Tactical radio navigation systems provide distance measuring information to an interrogating aircraft in response to pairs of interrogation pulses received at a beacon transponder, the system also provides bearing and identification information. The transponder receives pairs of interrogation pulses which are decoded into a single pulse for operation of a reply transmitter. Bearing, distance and identification determining signals are generated by the reply transmitter and its antennas. A single antenna functions to both receive the interrogation pulses and radiate the position determining signals. To provide the required bearing information, the antenna radiates pulses from a central antenna array that is stationary with respect to a support housing. These pulses are modulated at a 15 Hz frequency by parasitic elements rotating around the stationary central array. Further modulation of the transmitted pulses at a 135 Hz frequency, superimposed on the 15 Hz frequency, is provided by additional parasitic elements also rotating about the central antenna array. Both the low band frequency parasitic elements and the high band frequency parasitic elements have a configuration to provide improved radiation from the antenna above the horizontal. Also to improve the antenna radiation pattern, the 135 Hz parasitic elements are positioned on a rotating drum of a dielectric material, such as fiberglass. To still further improve the amount of radiation energy above the horizontal reference, radio frequency chokes are coupled to the central antenna array in the feed line from the signal transmitter.

Radio frequency switch employing reed switches and a quarter wave line

Abstract: An antenna switching relay for selectively switching an antenna to a transmitter or a receiver of a radio transceiver includes a pair of normally open reed switches and a quarter wave transmission line. In the receive mode, the reed switches are open and the antenna is connected to the receiver through the quarter wave transmission line. In the transmit mode, the reed switches are closed and the antenna is connected to the transmitter through one of the reed switches, while the other reed switch shorts out the receiver end of the transmission line, thereby causing an open circuit to be reflected to the antenna terminal thereof.

Directional filter using meander lines

Abstract: A frequency-selective directional coupler is provided which comprises a fast-wave transmission line placed in proximity to a slow-wave transmission line. The fast wave line can be a waveguide, strip-line, or microstrip line which follows a fairly direct path between two points. The slow wave line can be a helix or a meander line.

Blocking capacitor for a thin-film rf transmission line

Abstract: A blocking capacitor is formed in the center conductor of a thin-film RF transmission line which is situated over a metal conductor and insulated from the center conductor and outer conductors of the transmission line. The distributed capacitor so formed couples RF signals over a broad frequency range while blocking DC and very low frequency signals on the transmission line.

Electrical switchgear apparatus operating with pressurized gaseous arc-quenching medium

Abstract: Electrical switchgear apparatus using a pressurized arc-quenching and insulating gaseous medium particularly SF6 wherein the gas is maintained at high pressure in a switching chamber and is transferred to an adjacent low-pressure chamber during a switching operation, and wherein the gas is supplied to the switching chamber from a storage container via a high-pressure supply line, then returned via a low-pressure return line from the low-pressure chamber to a compressor for re-compression and feed back via a feed line into the storage container. To prevent condensation of gas in its high-pressure state which may become trapped in the gas supply line between the storage container and the switching chamber, and also similarly trapped in the gas feedback line between the compressor and the storage container, vent lines are provided. A first vent line including a flow restrictor and non-return valve interconnects the gas supply line and the low-pressure return line, and a second vent line including a flow restrictor interconnects the gas feedback line with the low-pressure return line.

Periodic antenna adapted for handling high power

Abstract: A periodic antenna includes a plurality of quarter wavelength resonant, radiating elements spaced along a feed line positioned above a ground plane. Adjacent ones of the resonant elements are separated from each other by a distance substantially less than a quarter wavelength of the operating frequency of the elements and are positioned to extend from the feed line in a direction away from the ground plane. Substantially 180*phase shift is provided between adjacent ones of the elements by including quarter wavelength, shunt distributed parameter slow-wave delay lines between adjacent ones of the elements. The delay lines are located inside of an electrically conducting sleeve that comprises the feed line.

Precision distributed parameter delay line

Abstract: A precision distributed parameter delay line for use in high speed circuitry requiring very precise nanosecond delay intervals. The delay line, in one preferred embodiment, comprises a section of coaxial cable transmission line having a central conductor and a coaxially aligned conductive sheath with the sheath preferably being insulated over its length. The section of coaxial cable tranmission line functions as a low impedance delay element of extremely small outer diameter whose length may be adjusted to provide delays of from tenths to hundreds of nanoseconds. The nature and size of the delay line is such as to make it extremely adaptable to being coiled so as to significantly reduce the amount of space which it occupies. A very short section of coaxial cable transmission line of similar design and impedance characteristics is coupled to the input and/or output ends of the coaxial cable transmission line section central conductor to improve the rise time and provide an extremely high delay to rise time ratio, low insertion loss, low characteristic impedance and is adaptable for use over a wide frequency bandwidth. The delay line may also take the form of a printed circuit of the microstrip type transmission line comprised of an elongated, preferably undulating conductive strip separated from a conductive ground plane by a suitable dielectric with input and output terminals being located a spaced distance from the extremities of the undulating conductive member to provide the characteristics set forth hereinabove while taking advantage of microconductor techniques to further reduce the size and allow dual-in-line delay line packages. Both of the above embodiments may be modified accordingly to provide a tapped delay line having the desirable characteristics set forth herein.

Reducing the Response of Single-Phase Transmission Lines to Electrical Noise

Abstract: The reception of unwanted noise can be drastically reduced in a single-phase transmission line by employing 2N, N = 1,2,. ., conductors with alternate wires connected in parallel. The cross section of the line forms a regular polygon. The advantage of the four-wire line over the two-wire line for discrimination against noise is exhibited.

Low loss modulation system for use with antenna array

Abstract: An antenna array has paired radiating elements which are modulated in phase opposition. Such modulation is accomplished by means of semiconductor modulator elements, one of such elements being connected to the feed line for each of the paired antenna elements. Modulation signals are fed to the paired semiconductor elements in phase opposition relationship to vary the effective impedance of such elements accordingly, thereby causing the power fed to one of the associated paired antenna elements to increase while that to the associated paired element is decreasing, this in accordance with the modulation signal, the sum of the power radiated by the paired elements remaining constant. Power losses are thereby minimized.

Regenerative radio-frequency wire detector

Abstract: A regenerative radio-frequency wire detector is disclosed which incorpora a radio antenna and a radio receiver connected thereto. A radio transmitter is timely energized by an output signal from the aforesaid radio receiver which, in turn, causes the transmitting of electromagnetic energy within the environment ambient to the wire to be detected. A commercial radio station or other source is employed as a covert initial energizer of the wire to be detected. When so energized, said wire re-radiates electromagnetic energy to the receiving antenna which starts the regenerative processing within the system loop constituting the radio receiving antenna, the radio receiver, the radio transmitter, the transmitting radio antenna, the wire, and the environmental medium or mediums within which it is disposed. Due to the amplification effected by the aforesaid regeneration process, the detection of marine mine command wires, for example, is facilitated.