Showing papers on "Monopole antenna published in 1983"

Rectangular dielectric resonator antenna

Abstract: An antenna which consists of a resonant rectangular parallelepiped dielectric on top of a ground plane is described. Calculated radiation patterns and measured impedances are presented, and the effects of feed probe length variations are discussed.

Single-element rectangular microstrip antenna for dual-frequency operation

Abstract: The letter describes a single-element rectangular microstrip antenna which can operate simultaneously for two different frequency bands.

Rectangular microstrip patch antennas with infinite and finite ground plane dimensions

Abstract: The rectangular microstrip patch antenna has been extensively analyzed with regard to its input impedance and resonant frequency, both for infinite and finite ground plane dimensions. For infinite ground planes existing formulas have been compared and improved parameters presented. The influence from the side current radiation has been discussed as well. For finite ground plane dimensions the contribution from the ground plane edge diffraction has been accounted for in an equivalent radiation conductance and an equivalent diffraction susceptance. Formulas for these parameters have been developed on the basis of different theories. They are valid under the condition that only one of the ground plane dimensions are finite at the same time. Experimental investigations are carried out to test the accuracy of the developed formulas, showing good accuracy under the given conditions.

Double tuned, coupled microstrip antenna

Abstract: A first antenna for radiating a signal at a predetermined frequency employing at least one 1/4 wavelength microstrip resonator positioned below a metal 1/4 wavelength radiator. A circularly polarized antenna including a 1/2 wavelength radiator electromagnetically coupled to a 1/4 wavelength resonator is further disclosed.

Integrated receiver antenna device

Abstract: An integrated receiver antenna device comprising a pair of antenna elements providing a spiral antenna for receiving radio frequency signals over a broadband of frequencies with an extended high frequency limit and providing high sensitivity over the broadband of frequencies. The elements each have first and second ends and provide a pair of interwound conductive windings with their first ends positioned proximate to each other at the center of the antenna for providing sensitivity at the high frequency limit of received radio frequency signal, while the second ends of the elements are displaced from the first ends and positioned at the periphery of the antenna. A detector mixer unit is connected between and positioned proximate to the first ends of the antenna elements for deriving radio frequency signals received by the antenna elements and receiving an input signal for providing an oscillating signal at the detector mixer unit for producing an output signal.

Frequency independent shielded loop antenna

Abstract: An antenna is disclosed that is especially useful for radiating and receiving non-sinusoidal electromagnetic waves. The antenna is an efficient and distortion-free radiator of electromagnetic pulses that do not use a sinusoidal carrier. The antenna's size is independent of frequency and the antenna, therefore, can be of small size relative to the wavelength of the radiated electromagnetic waves. When used for reception of electromagnetic wave energy, the antenna performs with low distortion. The basic concept underlying the invention is the modification of the Hertzian electric dipole into an antenna structure that can carry large currents without requiring a large driving voltage. Antennas for the transmission or reception of sinusoidal waves achieve that goal by employing resonant structures. The invention achieves the same result by changing the Hertzian electric dipole into a loop that forms a Hertzian magnetic dipole and preventing the undesirable magnetic dipole radiation by shields of conducting and absorbing materials.

Printed circuit balun with a dipole antenna

Abstract: A coplanar printed circuit balun for connecting an unbalanced feedline to a balanced dipole antenna.

Coaxial dipole antenna with extended effective aperture

Abstract: A coaxial dipole antenna includes a first radiator which is approximately one quarter wavelength long. A second radiator exhibits length less than one quarter wave length and is coupled to the feed port by a reactive element which has an electrical reactance which is insufficient to increase the electrical length of the second radiator to one quarter of the wavelength. The length of a dipole antenna is substantially shortened while an effective aperture of one half wavelength is maintained by causing a portion of the transceiver housing to radiate in phase with the antenna.

Microstrip antenna with circular ring

Abstract: A radar antenna is shown in a first embodiment to have a ground plane and a feed line on opposite sides of a dielectric sheet and a ring-shaped antenna element on another dielectric sheet to form a microstrip assembly wherein such antenna element is capacitively coupled to the feed line. In a second embodiment the radar antenna has a parasitic antenna element on still another dielectric sheet, such parasitic antenna element being in register with the ring-shaped antenna element.

A Holographic Surface Measurement of the Texas 4.9-m Antenna at 86 GHz

Abstract: An instrument has been built which allows the electromagnetic measurement of the surface accuracy of a large millimeter-wavelength antenna. The University of Texas 4.9-m radio telescope has been measured with this technique at 86.1 GHz to an accuracy of 4 ?m at the surface. Our technique is an interferometric one which is fast, accurate, and able to measure the whole antenna surface at once. While the technique is illustrated by its use on a large antenna, it could be used in a near-field measurement of a smaller antenna. Several antenna surface maps are presented. A comparison of run-to-run repeatability was made. The technique itself was tested by deforming the antenna surface in a known way and subsequently detecting the deformation.

Microstrip antenna and antenna array

Abstract: A microstrip antenna comprises a first dielectric layer having a permittivity of 2.5-12.5 carrying the ground plane on one face and a feeder-resonator on the opposite face; a second dielectric layer thereover having a permittivity of 2.2-2.5 and carrying on its outer face a radiator electromagnetically coupled to the feeder-resonator; and spacing means spacing the second dielectric layer from the first a distance of up to seven times the thickness of the first, and providing a permittivity between the two dielectric layers which is approximately that of air. Matching of the antenna is obtained by varying the spacing between the two dielectric layers. The gain of the radiating element is better than 7.5 dbi for bandwidth of 15%. Sidelobe level is less than 15 dB in azimuth and elevation plan. The radiation pattern of the antenna is symmetric in both azimuth and elevation plan.

A new MIC slot-line aerial

Abstract: The design and performance of a new microwave integrated circuit (MIC) slot-line antenna is presented. The new antenna has a narrower beam for the same order of gain as that of the conventional MIC dipole and resonator antennas. The antenna operates in X -band with a gain of 6 dB and a sidelobe level of 10 dB. It can be easily integrated with other MIC components.

Omnidirectional, circularly polarized, cylindrical microstrip antenna

Abstract: A microstrip cylindrical antenna comprised of two concentric subelements on a ground cylinder, a vertically polarized (E-field parallel to the axis of the antenna cylinder) subelement on the inside and a horizontally polarized (E-field perpendicular to the axis) subelement on the outside. The vertical subelement is a "wraparound" microstrip radiator. A Y-shaped microstrip patch configuration is used for the horizontally polarized radiator that is wrapped 1.5 times to provide radiating edges on opposite sides of the cylindrical antenna for improved azimuthal pattern uniformity. When these subelements are so fed that their far fields are equal in amplitude and phased 90° from each other, a circularly polarized EM wave results. By stacking a plurality of like antenna elements on the ground cylinder, a linear phased array antenna is provided that can be beam steered to the desired elevation angle.

A Multi-Element Microstrip Antenna for Local Hyperthermia

Abstract: A multi-element microstrip antenna applicator designed for microwave local hyperthermia is described Design criteria for such a microstrip antenna array are presented Various antennas were built and compared Experimental measurements of heating patterns show the multiple microstrip spiral antenna provides controlled heating over a large area

Dielectric and width effect on H -plane and E -plane coupling between rectangular microstrip antennas

Abstract: Theory and numerically computed results are presented for mutual coupling between two rectangular microstrip antenna patches. E -plane alignment and H -plane alignment are the two patch orientations considered. The s -parameter matrix element s_{11} is used to study the mutual coupling. Extensive results are provided for s_{11} covering several relative substrate dielectric constants, antenna patch widths, and antenna patch separations. Results are also given for resonant frequency, resonant impedance behavior, and radiation pattern at resonance.

Phase scanned microstrip array antenna

Abstract: A microstrip array antenna, including spaced radiator elements supplied w microwave power and separated from an underlying ground reference plane by a layer of dielectric material, in which the antenna beam is phase scanned by periodically closing switching devices connected between the reference plane and at least one null point of each radiator element. In one embodiment, the radiator elements are identical rectangular patches disposed along a path, each patch having a length parallel to the path of one-half wavelength and a width transverse to the path not exceeding one wavelength in the underlying dielectric material at the antenna operating frequency. The patches are connected in series to receive microwave power by conductive strip elements whose widths are selected to effect a desired distribution of radiated microwave power from the patches.

Spiral antenna deformed to receive another antenna

Abstract: A spiral antenna has a plurality of interleaved radiating elements winding outwardly in a spiral pattern about a common axis. The spiral pattern is deformed at outer regions of the antenna to define one or more circumferentially disposed concavities in the body of the antenna. Each concavity is adapted to receive another antenna such as a spiral antenna or horn antenna.

Vertical antenna with improved artificial ground system

Abstract: The present invention relates to vertical antenna systems employing an improved artificial ground system. In a low frequency design, the artificial ground system provided is in the form of a counterpoise or ground screen that is provided with an efficient, economical and practical electrical radial wire design. A high frequency design is also provided in the form of an integral antenna structure. This high frequency integral design entails a vertical antenna, a counterpoise in the form of a metal plate, a ground plate, and wherein said metal plate forming the counterpoise is insulated from the ground plate. In either type of antenna system, the counterpoise functions to collect antenna return currents and direct them back to the feed point of the antenna in an efficient and effective manner.

Three element low profile antenna

Abstract: A low profile antenna is provided which includes a counterpoise above which are situated three parallel oriented L-shaped elements. Each of the elements includes leg and foot portions. One common end of the leg portions of the elements are electrically coupled together and to an antenna trimming stub. The remaining end of the middle element constitutes the feedpoint of the antenna together with the remaining ends of the other two elements. The dimensions of the counterpoise top surface are selected to be substantially less than one wavelength at the desired operating frequency of the antenna. In this manner, the antenna generates or is responsive to radio frequency waves exhibiting two polarizations.

Antenna with BNC-type coaxial connector

Abstract: An antenna comprises an antenna body telescopically movable between a fully retracted position and a fully extended position and having a free end. A BNC-type coaxial receptacle is mounted to the free end of the antenna body. A mounting base receives the BNC-type coaxial receptacle when the antenna is in the fully retracted and completes an electrical ground circuit to the BNC-type receptacle.

Formulation for wire radiators on bodies of translation with and without end caps

Abstract: A formulation, based on the method of moments (MM), is presented for active and passive wire radiators attached to, or near, a broad class of bodies and surfaces, including open or closed cylinders of arbitrary cross section as well as finite flat or curved panels. The development expands the utility of the MM theory for various antenna problems. The analysis incorporates a special junction basis set for the antenna attachment points. Total domain and piecewise continuous expansion functions are used on the surfaces. The formulation is primarily intended for prediction of radiation patterns of wire antennas (such as monopoles and loops) on asymmetric bodies of translation, open or closed (capped). The present method has shown satisfactory agreement with published data in the prediction of antenna input impedances as well.

High-power VLF transmitter facility utilizing a balloon lofted antenna

Abstract: A 100-kW transportable very low-frequency (TVLF) transmitter facility has been used for magnetospheric wave-injection experiments from sites in Alaska, New Zealand, and Norway. A unique feature of the TVLF facility is the antenna which is a conducting cable lofted to an altitude of 1500 m by a 1000-m3helium balloon. The antenna is driven at its base as a monopole above a ground plane. The antenna cable also serves as the balloon tether. The lowest operating frequency in this configuration is 6.6 kHz, at which the radiated power is 100 W. At the highest operating frequency used in the experiments, 21 kHz, the radiated power is 10 kW. In Norway power lines were used as antennas. The minimum operating frequency was then 1 kHz and the radiated power is estimated to be about 0.5 W. The components and performance of the TVLF facility used with the balloon lofted antenna are described.

Non-resonant coaxial monopole antenna

Abstract: A relatively short broad band monopole coaxial antenna is provided with a center conductor and an outer radiator. The antenna is mounted above a ground plane and comprises a bare outer radiator portion adjacent the ground plane and a portion remote from the ground plane which is covered with a variable thickness microwave absorbent material. The signal to be transmitted is applied to the base of the monopole antenna adjacent the ground plane. Non-radiated signals propagate up the antenna. The high frequency components are absorbed by the microwave absorbing material. A tip matching network and a base matching network are coupled between the outer conductor and the ground plane for attenuating and matching the low frequency components of the non-radiated signals. The resulting monopole coaxial antenna has no undesirable reflections and has the appearance of infinite effective length antenna.

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.

Antenna with coaxial connector

Abstract: An antenna defines a coaxial connector receptacle when the antenna is in a fully retracted position

Frequency sharing antenna

Abstract: PURPOSE:To obtain the equivalent efficiency among antennas with use of each exclusive primary antenna by piercing a horn antenna through the area at the center of a print antenna where no radiating element is formed. CONSTITUTION:For higher frequencies, a primary reflector 1 is irradiated by a horn 9 for high frequencies which is piercing through a hole drilled at the center part of a print antenna 13 where no irradiating element 16 is formed. Then the reflector 1 reflects two radio waves of high and low frequencies radiated from the antenna 13 to the spaces along radio wave routes 7 and 7' respectively.

Circularly polarised printed antenna with wide axial-ratio bandwidth using strip dipoles and slots

Abstract: A circularly polarised series-fed printed-array antenna having a wide axial-ratio bandwidth (for an axial ratio of less than 3 dB) is realised by combining strip dipoles with slots. To form a free-space dipole, i.e. a complementary radiator to a slot, the strip dipole is constructed by modifying the strip radiator of the circularly polarised antenna presented in a previous paper. Several experiments verify that the strip dipole behaves like a free-space dipole. Next, a design procedure of the circularly polarised printed antenna with a wide axial-ratio bandwidth is described. On the basis of the design procedure, two types of the array antenna having different strip-dipole spacings are made and measured at S-band. An axial-ratio bandwidth of about 27% is obtained for the three sets of the radiators, although the actual gain is less than 0 dBi because the impedance matching is neglected.

Tuneable antenna with inductive coupling at input

Abstract: A whip antenna system for surface vehicles or the like. The antenna system's tuner has an LC tank circuit, into whose inductor is inserted a coil that is connected to the vehicle's transmitter/receiver, the coil being field coupled to the tank circuit's inductor. The inserted coil provides sufficient reactance that the vehicle need not serve as a counterpoise, thus providing an antenna of comparable size but electrically less close to the ground (i.e. one that has better "seeing"), and useable with non-metallic vehicles (e.g. fiberglass boats).