Showing papers on "Feed line published in 1983"

Analysis and optimized design of single feed circularly polarized microstrip antennas

Abstract: Analysis and optimized designs are presented of three types of single feed circularly polarized microstrip antennas, namely, a diagonal fed nearly square, a truncated-corners square and a square with a diagonal slot. The Green's function approach and the desegmentation methods are used. The resonant frequencies are calculated for two orthogonal modes which together yield circular polarization. Optimum feed locations are determined for the best impedance match to a 50 \Omega coaxial feed line. Axial-ratio bandwidths, voltage standing-wave ratio (VSWR) bandwidths and radiation patterns are evaluated and verified experimentally.

An imaging beam waveguide feed

Abstract: A pseudo-frequency-independent beam waveguide feed has been designed and built to accommodate a new liquid-helium-cooled millimeter wave radio astronomy receiver in the side cab of the Crawford Hill 7-m antenna. This enables the antenna to be tilted without tilting the liquid-filled receiver. Comparison with the old vertex-cab feed indicates very little measured transmission loss through the beam waveguide. The frequency independence is based upon the Fresnel zone imaging principle. Design procedures and practical bandwidth limitations are explained. An explicit expression for the third-order term of an offset reflector surface clarifies the approximation of a lens by an offset reflector.

Choosing Line Lengths for Calibrating Network Analyzers

Abstract: Equations, examples, and a table are given to help choose the best length for a precision transmission line which is used in some methods for calibrating a network analyzer. One line will cover a frequency range of about 10:1. Two lines will cover a range of about 65:1.

Measurement of the current flow in an electric power transmission line by detection of infrared radiation therefrom

Abstract: Passage of current through a power transmission line causes infrared radiation therefrom. The construction of a high-tension (HT) line with counterwound helical conductors for current around a supporting core minimizes the surrounding magnetic field, reducing the skin resistance of the line per unit length as compared to its bulk resistance per unit length. Infrared radiation from the I2 R losses in the line is thus linearized, and the current in the line can be indirectly measured by sensing the infrared radiation from the line itself using infrared detectors.

TEM horn antenna: input reflection characteristics in transmission

Abstract: The reflection coefficient of open-ended, parallel-plate transmission lines of different TEM-wave impedance, Z0, have been observed using an impulsive source waveform and a sampling oscilloscope. When converted to the frequency domain the results support the theoretical analysis of mode conversion and reflection due to Weinstein. Reflection from a smoothly tapered Z0 within the feed line is also considered, showing that good pulse-optimised antennas can be designed on these two principles.

Radio receiver apparatus for vehicle

Abstract: A vehicle radio receiver apparatus constitutes an antenna device including an antenna element and also a radio receiver integral with the antenna device so as to receive a signal from the antenna element The radio receiver includes a tuner circuit directly connected to the antenna element, a high-frequency amplifier circuit for amplifying the reception signal tuned into by the tuner circuit, and an audio signal converter for detecting and low-frequency amplifying a high-frequency amplified signal and for producing an audio signal A tuning control signal and a volume control signal are respectively supplied from a control unit to the tuning circuit and the audio signal converter circuit of the radio receiver This control unit is arranged separately from the radio receiver and receives volume control and tuning control operating signals from an operating section which has a tuning control knob, a volume control knob and the like The operating signals are transmitted to the antenna element and to the radio receiver through the transmission line

Device for uniformly distributing liquid, viscous or foamed liquors

Abstract: The device for uniformly distributing liquid, viscous or foamed liquors operates with a distributor which has a central feed line, its outlet lines leading to a receiver being arranged concentrically or at an equal angle to the centre axis of the central feed line. The cross-section of the feed line and the total of the cross-sections of the outlet lines must correspond. Preferably, the central feed takes place via a vertically arranged feed section upstream of the distributor. The distributor is preferably connected to a foam generator via the central feed line. The distributor can be designed as a further foaming device and is preferably connected to a receiver which is designed as a charging device.

Log-periodic antenna

Abstract: A log-periodic antenna comprises two arrays of dimensionally tapered radiating elements disposed in the E-plane and each fed by a balanced line consisting of the inner conductors of two coaxial cables. In one embodiment the elements of each array are dipoles and in another embodiment are formed of continuous conductive strips in zig-zag patterns on non-conductive support members. Each array preferably has two sets of elements disposed in planes, respectively, which converge toward the smaller end of the array with vertically aligned radiating elements of each set projecting in opposite directions from the array axis. Periodic gain dropout anomalies across the antenna operating band are eliminated by use of a shielded feed line. In another embodiment having advantage in direction finding, the sets of elements of each array are located on associated opposite sides of a right rectangular pyramid. These pyramidal arrays are used in pairs for direction finding.

Optimizing antenna interface for automobile radio receivers

Abstract: An automatic signal optimizing interface for connection between the antenna of an automobile radio receiver and the receiver itself processes the RF signal received by the antenna and provides an improved output signal to the automobile receiver which is optimized for distortion free reception. The output signal is limited to the desired frequency band to eliminate interfering signals, and is maintained within the optimum dynamic range of the receiver, even under reception conditions in which the received antenna signal itself is excessively high or undesirably low. The interface therefore permits superior performance by the radio receiver by optimizing the signal supplied to the radio and by preventing intermodulation distortion which otherwise commonly results from overloading of the front end of the radio receiver by excessively strong received signals. The optimizing interface operates independent of the radio receiver, and therefore is amenable to after market or OEM use in conjunction with substantially all existing automobile radio receivers. Operation of the signal processing circuitry of the interface is automatic so that no user intervention or monitoring is required, and is sufficiently rapid and of sufficient range and resolution to compensate for nearly all adverse reception conditions encountered in both urban and rural areas.

Transition between rectangular and relatively large circular waveguide for a UHF broadcast antenna

Abstract: A high power TV antenna for operation at the ultra high frequency (UHF) frequency F includes a radiating antenna located at the top of a tower structure (often hundreds of feet high), a transmitter at the bottom of the tower and a main circular waveguide transmission line of diameter Dl between the transmitter and the antenna carried by the tower; the feed to and/or from the transmission line including transition sections such that wave propagation in the transition sections is below cutoff for the TM01 mode while it is above cutoff for the dominant TE11 mode while wave propagation in the main circular waveguide transmission line of diameter Dl is substantially totally in the dominant TE11 mode even while it is above cutoff for the TM01 mode, whereby the transition sections tend to inhibit wave propagation in the system in the undesired TM01 mode.

Microwave directional antenna employing surface wave mode

Abstract: A microwave directional antenna, particularly for the millimeter-wave range, comprises a dielectric line with line discontinuities, affixed to a metallic ground plane. The dielectric line is a radial waveguide extending about a center where the feed is provided. A mode launcher is located at this center. In a preferred embodiment, the boundary of the dielectric line circumscribes a circle; the line discontinuities are preferably embodied as metallic strips arranged on the dielectric guide on circles about the center.

Aircraft trailing ball antenna

Abstract: An antenna, suitable for being deployed from an aircraft or other vehicle and characterized by broadband, omnidirectional radiation/reception is provided by a coaxial transmission feed line that is terminated by an electrically conductive ball that is electrically and mechanically connected to an extension of the center conductor of the coaxial line, and by a telescopically adjustable sleeve choke having the end adjacent the ball conductor, electrically bonded to the outer conductor of the coaxial line. The choke is adjusted in length to form a matched counterpoise to the ball radiator. The diameter of the ball, the gap length corresponding to the length of the inner conductor between the ball and the terminus of the outer conductor of the line, as well as the length of the sleeve choke, are selected so that the diameter of the ball is greater than one-quarter of the midband wavelength and less than five eighths of the midband wavelength, the gap length between the ball radiator and the terminus of the outer coaxial conductor is less than one-eighth of the midband wavelength, and the choke length is approximately equal to the midband wavelength.

Device for draining/purging liquid/gas remaining in loading arm

Abstract: PURPOSE:To realize considerable labour saving by adopting semiautomatic liquid draining and gas purging through the use of push-button switch when each of operations of nitrogen gas valve and gas escape valve is started. CONSTITUTION:Push-button switch 36 is pressed to open N2 gas valve AV-6 and gas escape valves AV-4 and AV-5. Then, N2 gas from nitrogen gas source 24 will simultaneously fill the shore side feed line 3 and shore side return line 13 via feed line 22 and lines 26, 28 and loading arms 1, 17, and will be further led to flare lines 10, 16. Accordingly, simple operation can secure reliable operation as only push-button switch 36 needs to be operated everytime shore side valves AV-1 to AV-6 are started in operation.

UHF broadcast antenna on a tower with circular waveguide carrying RF energy up the tower to the antenna with polarization adjustments and exclusions

Abstract: In an ultra high frequency (UHF), high power broadcast television (TV) antenna system that includes a radiating antenna located at the top of a tower structure many hundreds of feet high, a transmitter at the bottom of the tower and a circular waveguide transmission line between the transmitter and the antenna carried by the tower, an undesired polarization mode that is transverse to the desired polarization mode for which the antenna system is adjusted is excluded at the top of the tower structure at the end of the circular waveguide transmission line so that the undesired polarization mode does not energize the radiating antenna and, in particular, the undesired polarization mode does not energize the antenna and produce a ghost image in a TV receiver after reflecting from the bottom end of the circular waveguide transmission line back up to the antenna and does not add a standing wave in the circular waveguide transmission line.

Low impedance coplanar microwave transmission line

Abstract: A small, very low impedance coplanar waveguide microwave transmission line. A composite coplanar waveguide transmission line section composed of a plurality of interleaved fingers (14, 16, 21, 23) is coupled between input and output transmission line sections. Alternate ones of the interleaved fingers are connected to a main conductor (12) of the input and output transmission line sections and to a metal ground plane layer (11). The composite transmission line section may be connected either in cascade with the input and output transmission line sections or in a shunt arrangement. Composite characteristic impedances of less than two ohms are realized.

Coaxial transmission lines and components

Abstract: In this Chapter an account will be given of the main types of transmission line so that a sound choice can be made for any desired system. In many cases the system will require the use of such devices as balancing units, power splitters, hybrids, etc. These are grouped under the heading 'line components'. They are discussed in this Chapter because many of them are built up from lengths of transmission line and because without them neither transmission line nor antenna could function in the desired manner.

RF receiver utilizing a multiple echo delay line

Abstract: A rf receiver includes a multiple echo delay line, a switch, an rf activity detector, and a measurement receiver. A received rf signal initially impinges on the delay line but after a brief delay the detected rf signal actuates a switch, which disconnects the delay line from the input and connects it to the input of the measurement receiver, which receives and processes the multiple signal echos from the delay line.

The high power, long pulse ion cyclotron resonance heating system for textor

Abstract: An ICR heating experiment on TEXTOR at the 3 MW rf power level with maximum pulse lengths of 3 s will start in 1983. The transmitter set-up consists of two independent 1.5 MW systems tunable in the frequency range 25-29 MHz. Each system is constituted by the following items: 1°) The low power excitation which provides appropriately shaped rf pulses 2°) The power amplifier whose construction and test procedure are described in a companion paper. 3°) The transmission line and antenna two-stub tuning system made of pressurized 6″ 1/8 and 9″ rigid coaxial line components. 4°) The antenna of the shielded strip-line type to be installed along the machine's hot liner (up to 500°). The antenna is coupled to the pressurized transmission line by means of an interface which includes: a) A coaxial line section under high vacuum with ceramic vacuum feedthroughs at both ends and a fixed stub through which cooling is introduced and which also will lower the VSWR of the line. b) A flexible line section which takes up the thermal expansion of the liner and constitutes the heat barrier between the antenna and the water cooled line section.

Arrangement for supplying antenna voltages, which are unbalanced and balanced with respect to earth, of different frequency ranges to an unbalanced output

Abstract: The invention relates to an arrangement for supplying voltages of various frequency ranges, which are unbalanced and balanced with respect to earth, to an unbalanced output, preferably for broadcast reception at low, medium, high and very high frequencies with a resonant transformer which exhibits at the base of the antenna, which is unbalanced with respect to earth, a winding having at least one tap for the unbalanced output, preferably for connecting the inner conductor of a coaxial cable. In this arrangement, the invention consists in that a further winding tap is connected to one half of an open dipole, the other half of which is connected to an additional winding which is connected to earth at the other end and which is wound in parallel with a part winding of the resonant transformer. The part winding with the parallel additional winding is a familiar balancing element which transfers the balanced dipole voltage without attenuation to the unbalanced output. The transformation ratio of the unbalanced voltages remains unchanged in the low, medium and high frequency ranges. It is advantageous if all windings are tightly coupled to one another on a ring core having high permeability and the least possible losses. The arrangement according to the invention can also be used in a simple manner in a dipole which is mounted set up insulated on the unbalanced antenna. Its lower part consists of a tube through which the balanced feed line with a characteristic impedance of 75 ohms is conducted from the arrangement according to the invention at the lower end of the tube to the open dipole.

Harmonics filtration device for a radio transmitter

Abstract: not available for EP0013223Abstract of corresponding document: US4286238A harmonic filtering device placed in a high frequency line connecting a radio transmitter to its load with at least one cell in parallel on the line, constituted by an anti-resonant circuit (at the transmission frequency of the transmitter) in series with a resistor, whose value is approximately 1/20th of the characteristic impedance of the line. This cell is made of a coaxial line with four conductors in which inset elements (short-circuit, capacitor, load) form the inductor and the capacitor of the anti-resonant circuit and the resistor. The resistor of this cell has no effect at the transmission frequency of the transmitter and creates insulation between the load and the transmitter for harmonic frequencies.

Delay line and mutual coupling considerations for MST radar antenna arrays

Abstract: Basic antenna theory which states that the field radiated from an antenna array is equal to the sum of the currents flowing in each element of the array is discussed. The feedline distribution system guarantees the proper amplitude and phase of the current for each element of an array. The difference in electrical lengths of the feedlines to the elements has to equal the desired phase angle. The current for voltage delay in a transmission line is equal to the transmission line electrical length in only a few special cases, when the transmission line is terminated in its characteristic impedance or when the transmission line's electrical length is a multiple of 90 degrees.

A feed system for a multibeam antenna at 20/30 GHz

Abstract: A Feed System is presented capable of handling two indipendent Communication Channels at 20 GHz and One RF Sensing Signal at 27 GHz. The trade off results for the feed at 20 GHz show that a smoothed wall conical horn with shaped profile operating on the TE_{11} mode is the best compromise between electrical performance and mechanical constraints. A special OMT is described which allows the introduction of the RF Sensing signal at 27 GHz without the excitation of spurious modes. Furthermore the RF Sensing port present enough directivity to minimize power loss.