Showing papers on "Monopole antenna published in 1971"

Amplitude modulation using phased-array antennas

Abstract: An antenna system for producing an amplitude modulated signal at a receiver by properly varying the spatial amplitude distribution of the antenna beam. The antenna beam variation is accomplished by varying the relative phase of a phase-array antenna at the desired modulation rate. A variable DC bias signal is applied to each element of the antenna which is used to steer the beam in angle. An AC signal is also applied to each element which will qppear as AM modulation at a distant receiver.

Receiving antenna for miniature radio receiver

Abstract: Receiving antenna for miniature radio receiver formed by conducting U-shaped member having substantially parallel elongated arms which form sides of the housing of the receiver and a connecting portion which forms one end of the housing. When the receiver is in the normal position for use, the arms are positioned vertically with the connecting portion at the top, and the U-shaped member acts as an inductive loop antenna to detect the H-field of the electro-magnetic wave. A reactance network, which is capacitive in the frequency range of interest, is connected to the open ends of the arms. The reactance network can be adjustable to tune the antenna for various frequencies, the antenna having been found suitable for use in the frequency range from 148 to 173 megacycles.

Physically small combined loop and dipole all channel television antenna system

Abstract: A low cost, physically small, all channel television antenna system is provided for reception in high signal strength areas. The antenna is characterized by a loop having a pair of separated gaps, one of which is a feed gap and the other an impedance termination gap for operating as a directional reception antenna at the low and high VHF television frequency bands. Inboard the loop is placed a television band UHF dipole antenna. The input terminals of the dipole antenna and the feed terminal of the loop antenna are each coupled to a combiner with a single output from the combiner.

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.

Serpentine antenna mounted on a rotatable capacitive coupler

Abstract: This disclosure teaches an antenna including a conductor disposed in a serpentine arrangement defined by a plurality of undulations, wherein the amplitude or size of the undulations determines the directivity of the antenna, and wherein the undulations function to cancel mutual inductance parameters of the antenna while increasing the capacitive reactance thereof, to yield broadband characteristics. The antenna can take a variety of shapes, as for example the undulations may all fall entirely in a common plane and generally define a circle, a square, or an ellipse, etc.; or, such undulations may be arranged to form a ring or other three-dimensional object. The said shape of the antenna and its disposition with the earth''s surface also contribute to the directivity of the antenna.

Dipole antenna arrangement for radio with separate speaker-microphone assembly

Abstract: A speaker microphone assembly, used with a portable radio unit containing receiving and transmitting equipment for receiving and transmitting radio signals, includes a housing with a helical antenna element mounted to the top wall to form one element of a dipole antenna. A coaxial cable having inner and outer conductors is connected from the portable unit equipment to the speaker microphone housing. The center conductor is connected to the helical antenna and the outer conductor is terminated in the housing at a first point which is ground potential. A second outer conductor surrounds and is insulated from the first outer conductor, and is connected to the first outer conductor at the first point. The second outer conductor extends for a predetermined length along the first outer conductor to form the other element of the dipole antenna.

Multiturn loop antenna

Abstract: The invention is a multiturn loop antenna of an efficient design suitable for use singly, in arrays, or for inductively exciting radiating currents on a structure - the surface and the elements radiating to achieve optimum system performance. The antenna may be fed balanced or unbalanced and its input impedance may be either capacitive or inductive. In a preferred embodiment for omnidirectional coverage the antenna is positioned in a dielectric or ferrite filled cavity; the antenna may be a single element for linear polarization or a pair of multiturn loops at right angles to each other and with 90* phasing to effect circular polarization.

Multi-function antenna coupler

Abstract: The antenna coupling circuit facilitates simultaneous reception and transmission of information carrying radio signals through a common antenna A single filter having a plurality of helical resonator sections forms the harmonic filter of the transmitter, the preselector of the receiver, and a duplexer for connecting both the transmitter and receiver to a single antenna A first plurality of the helical resonator sections are connected between the antenna and the input stage of a receiver which passes the band of frequencies to be received while reflecting the frequencies to be transmitted A second plurality of helical resonator sections are connected between the output of a transmitter and the antenna which passes the frequencies to be transmitted while reflecting the frequencies to be received The coupling between individual helical resonators is arranged to discriminate against frequencies higher than the passband All of the cells of the filter circuit are mechanically connected together to form an integral compact structure

Terminator for spiral antenna

Abstract: : The patent describes a spiral antenna wherein its radiating elements terminate in Archimedean spirals.

Bandwidth extension for dipole antennas by conjugate reactance loading

Abstract: Periodically loaded transmission line theory is employed to indicate a loading scheme for broad banding a linear dipole antenna. A conjugate reactance load element (negative inductance) is suggested and a design concept developed. Numerical techniques are used to solve Hallen's integral equation, and it is shown that a broad-band (8:1 frequency range) dipole with broadside radiation and VSWR < 2 can be realized.

Automatic level measuring and control system

Abstract: A single length of insulated, stranded steel cable extends vertically through a bin or other material container and functions as a radiating antenna for an electrical signal transmitter. The reactance of the antenna, which varies as a function of the level of material in the container adjacent the antenna, is inductively linked to an oscillator circuit in the transmitter. The transmitter''s signal is altered in frequency with changes in the antenna''s reactance is combined with that of a constant frequency reference signal. The frequency of the resulting difference signal is employed to form a remote indication of the material level and to provide control information for automatically maintaining or varying material levels.

Shielded end-fire antenna

Abstract: The in ention is for an antenna comprising an end-fire radiator in a shielded structure. A specific case is an axial-mode helical antenna in a conical horn which produces a circularly polarized pencil beam with low sidelobe level over a 2-to-1 bandwidth with a gain in the order of four times that of a simple helix.

Method and means of improving reception of vehicular window-mounted antenna

Abstract: Method of and means for improving the receptive qualities of a window- or windshield-mounted antenna of an automotive vehicle, by providing a closed annular conductive screen extending about, exteriorly of, adjacent, and in fixed relation with the antenna secured to the surface of a window or windshield, and in grounding such screen from a point thereof to a selected point of the vehicle or the coaxial cable lead-in from antenna to receiver.

Antenna element including means for providing zero-error 180{20 {11 phase shift

Abstract: A system including an antenna, such as a phased array radiating element including a dipole, is provided including a digital phase shifter. The 180* bit of the digital phase shifter is implemented by reversing the polarity of the signal in the antenna.

Analysis of the excitation of the Earth-ionosphere waveguide by a satellite-borne antenna. II

Abstract: An analytical approach is outlined to obtain the fields near the earth's surface for a long wave transmitting antenna on a satellite. The medium is divided into slabs, each of which is characterized by a dielectric tensor. To simplify the calculations, a planar model is considered in which the d.c. magnetic field is vertical. An explicit derivation is given for a three-layer planar model: the lowest layer, up to ca. 70 km, represents the earth–ionosphere waveguide, the second layer may represent the D region; and the third layer is the one containing the satellite, which is idealized by a vertical electric dipole. Emphasis is placed on the relative launching efficiency of a satellite-borne antenna as compared with a ground-based antenna of the same strength. For sake of simplicity the antenna is idealized as an electric dipole and all sheath effects are neglected.

Magnetic antenna having a block or circuit components therein

Abstract: An antenna for a receiver comprising a magnetic core in the form of a thin layer having a thickness less than 50 microns superposed on a casing of a receiver or on a block of components of the receiver, and a winding wound on said magnetic core and connected electrically to the components in the casing or in the block, the winding serving as the antenna for the receiver. A receiver which comprises said antenna.

Antenna mast misalignment detector

Abstract: An antenna misalignment detector has two electrolytic transducers mounted on a mast carrying the antenna perpendicular to each other in the same horizontal plane. The antenna is mounted on a mast. The square root of the sum of the squares of the output from the transducers is generated and compared with a predetermined reference so that an alarm sounds when the antenna is misaligned along a vertical axis to the ground.

Antenna system for vhf and uhf radio direction finders

Abstract: An antenna system for a VHF and UHF radio direction finder comprises a loop antenna formed by turns which are arranged on an elongated magnetodielectric core. The antenna system has also an omnidirectional antenna member and a switch means which shapes the resultant directivity pattern by adding up signals from the loop and omnidirectional antennas and changing the position of this pattern discretely by 180 DEG in the horizontal plane to obtain its mirror image. The omnidirectional antenna is made in the form of a closed turn arranged on the core of the loop antenna so that it is substantially perpendicular to the turns of the loop antenna. A portion of the closed turn is disposed in the direction of the longitudinal axis of the core is elevated above the core surface through a known distance whereby the magnitude of the signal from the omnidirectional antenna is such that the two resultant directivity patterns of the antenna system intersect only at two points in a horizontal plane.

Combined multi-polarization loopstick and whip antenna

Abstract: A RECEIVING ANTENNA ASSEMBLY FOR MITIGATING SIGNAL FADING AND CANCELLATION CAUSED BY THE DEGRADING EFFECTS OF MULTIPATHS AND SCATTER IN JUNGLE, MOUNTAIN OR URBAN ENVIRONMENTS WHICH ANTENNA HAS THREE MUTUALL-PERPENDICULAR, MULTI-POLARIZATION FERRITE LOOPSTICKS FOR SENSING H FIELD SIGNAL ENERGY AND A WHIP ANTENNA FOR SENSING E FIELD SIGNAL ENERGY, AND SELECTION MEANS FOR CHOOSING AMONG THE SIGNAL ENERGIES SENSED BY THE FERRITE LOOPSTICKS AND THE WHIP ANTENNA.

Double ridged wave guide feed for signal antenna

Abstract: A microwave antenna system comprising a balanced two-arm spiral antenna or pyramidal antenna is directly fed at its center pole by a double ridged wave guide.

Inconspicuous vehicle mounted radio antenna

Abstract: A conductive rod is mounted in spaced relationship to the outer body of an automotive vehicle to provide a decorative ornament for the vehicle and to provide an inconspicuous antenna for a radio receiver contained within the vehicle. The capacitance developed between the conductive rod and the vehicle body tunes the rod to act as a quarter wavelength antenna. An adjustable connector assembly couples the conductive rod to the radio receiver so as to match the output impedance of the antenna to the input impedance of the radio receiver.

A new analysis of the sandwich-wire antenna

Abstract: It is hypothesized that the exact shape of the center conductor of a sandwich-wire antenna, provided it is of fairly simple form, is not important in determining the radiating properties of the antenna. An analysis is therefore made by standard principles of a sandwich-wire antenna having a particularly simple shape for the center conductor. This approach leads to an explicit formula for the structure attenuation constant in terms of its geometrical parameters which may be used for design purposes. Experimental measurements which support the theory and justify the shape-independence hypothesis are presented.

Radiation from a short dipole or monopole near a thick conducting cylinder of resonant length

Abstract: Using a theoretical-numerical technique involving the magnetic field integral equation, the radiation fields are determined for configurations comprised of a centrally located dipole and a thin quarter-wave monopole near conducting cylinders of finite lengths. Such configurations are important since they give measures of the radiation effects of fuselages of aircraft or other structures which the cylinders may model. The radiation fields are determined in the three principal planes for wavelengths passing through the resonant length of the cylinder, i.e., L \approx \lambda . The radiation patterns for both the dipole and monopole sources when normalized with respect to one another are similar to within approximately 1 dB. The vertically polarized patterns in the horizontal plane (the plane orthogonal to the dipole axis and containing the cylinder axis) show small deviations from their near omnidirectional characteristics for cylinder electrical lengths of 0.5, 1.0, and 1.5\lambda . On the other hand, the cross polarized component (the horizontal component) in the same plane shows a substantial enhancement of the intensity of the lobe structure at resonance. The patterns are compared to those acquired experimentally in an anechoic chamber and close agreement is demonstrated.

Collapsible high gain antenna

Abstract: A lightweight small high gain antenna which is capable of being packaged in a collapsed form and automatically expanded when in use. The antenna includes a cylindrical housing having a rod with a piston adjacent one end extending therethrough. Attached to the outer end of the rod in a normally collapsed state is a helical wire coil. When the gas producing means is activated the piston and rod are shifted outwardly to expand the wire coil. A latch means is provided for holding the helical coil in the expanded position.

Antenna having a combined dipole and loop portion

Abstract: An antenna which in one embodiment is formed from a plate and which has openings formed therein wherein the opening comprises one-eighth to seven-eighths of the total area of the plate and which forms a composite antenna having a dipole and loop portion. The antenna may also be formed in printed circuit form as a thin foil upon a supporting member and may be directly mounted on a television set, for example.

Wide band dipole antenna with capacitive reactance added to arms

Abstract: A wide-band antenna comprising a dipole antenna mainly consisting of a pair of linearly arranged antenna arms and a capacitor disposed at a prescribed one point on each of said paired arms equally spaced from the center of a feeding portion.

Rudimentary horn antenna

Abstract: Preliminary results obtained from an investigation of the impedance and radiation properties of a novel broadband linearly polarized antenna called the rudimentary horn are reported. When properly designed the antenna is found to be capable of maintaining its desirable radiation and impedance characteristics over a 10:1 band of frequencies.

Electromagnetic fields at points near pulse-excited linear antenna

Abstract: For a finite-length cylindrical monopole antenna mounted vertically on a perfectly conducting ground plane and driven by a dc pulse, the time variation of the electric and magnetic field intensities at points located at distances of the order of the monopole length from the antenna has been computed. The ratio of the monopole length to its radius was assumed to be 904, the source impedance 300 ohms, and the pulse length was taken to be equal to four tenths the time required for pulse transmission to the end of the antenna.

Collinear dipole antenna

Abstract: A collinear dipole array antenna including feed means whereby the dipoles are energized in phase independent of frequency over the operating frequency range.

Monopole antenna above a hemisphere

Abstract: Antenna imaging by a finite ground is investigated analytically and numerically by considering a conical monopole antenna above a finite hemispherical ground of variable radius. The ratio Y_{t}/Y_{t \infty} of the terminating admittance of the antenna over a finite to that over an infinite ground is evaluated and plotted versus the ground radius for various monopole lengths. The plots provide a quantitative measure of the effectiveness of finite screens in imaging antennas.