Showing papers on "Coaxial antenna published in 1995"

Single-layer single-patch wideband microstrip antenna

Abstract: A coaxially-fed single-layer single-patch wide-band microstrip antenna in the form of a rectangular patch with a U-shaped slot is discussed. Measurements showed that this antenna can attain 10-40% impedance bandwidth without the need of adding parasitic patches in another layer or in the same layer.< >

Multiple antenna ablation apparatus

Abstract: An ablation apparatus has a multiple antenna device of adjustable length including an adjustable length primary antenna and an adjustable length secondary antenna. The primary antenna has a longitudinal axis, and the secondary antenna is deployed in a direction lateral to the longitudinal axis. The secondary antenna is constructed to be structurally less rigid than the primary antenna. The adjustable lengths of the primary and secondary antennas permits a desired geometric ablation of a selected tissue mass. An adjustable insulation sleeve is positioned on an exterior of one of the primary or secondary antennas. An energy source is connected to the multiple antenna device. A variety of energy sources can be used including RF, microwave and laser.

Multiple-polarization microstrip reflectarray antenna with high efficiency and low cross-polarization

Abstract: This paper presents the study and prototype demonstration of the concepts of antenna focusing, cross-polarization reduction, and multiple-polarization capability of a planar microstrip reflectarray antenna. A square patch with two equal microstrip delay lines connected to its two orthogonal feeding points is used as the antenna element of the planar reflectarray. The length of the delay lines, which varies from patch to patch, is schematically designed to focus the plane wave to the feed point. The measured overall efficiency of the prototype antenna is above 50% in the normal operating band, and in some frequency ranges the efficiency has reached 70%. The experimental patterns show that the measured cross polarization due to special arrangement of the delay lines is quite low at the direction of the main beam. X-polarization and Y-polarization measured data show that the antenna is suitable for multiple-polarization applications (dual linear and dual circular). Surprisingly, the antenna has achieved approximately greater than 7% of gain bandwidth (-3 dB gain drop). These results demonstrate the feasibility of such an antenna for radar and communication system applications. >

Multiple antenna ablation apparatus and method with multiple sensor feedback

Abstract: An ablation apparatus includes an ablation energy source producing an electromagnetic energy output. A monopolar multiple antenna device is included and has a primary antenna with a longitudinal axis, a central lumen and a distal end, and a secondary antenna with a distal end. The secondary antenna is deployed from the primary antenna central lumen in a lateral direction relative to the longitudinal axis. The primary antenna and secondary antennas are each electromagnetically coupled to the electromagnetic energy source.

Analysis of a microstrip reflectarray antenna for microspacecraft applications

Abstract: A microstrip reflectarray is a flat reflector antenna that can be mounted conformally onto a spacecraft's outside structure without consuming a significant amount of spacecraft volume and mass For large apertures (2 m or larger), the antenna's reflecting surface, being flat, can be more easily and reliably deployed than a curved parabolic reflector This article presents the study results on a microstrip reflect-array with circular polarization Its efficiency and bandwidth characteristics are analyzed Numerous advantages of this antenna system are discussed Three new concepts using this microstrip reflectarray are also proposed

Planar inverted F antenna loaded with high permittivity material

Abstract: Enhanced gain of an inverted F antenna loaded with a very high permittivity substrate has been demonstrated. Measurements show that the size of the antenna can be reduced without sacrificing the antenna radiation efficiency. The gain-enhancement mechanism, bandwidth, and antenna radiation gain and patterns are presented and discussed.

Stacked annular ring dielectric resonator antenna excited by axi-symmetric coaxial probe

Abstract: A stacked annular ring dielectric resonator (DR) antenna composed of commercially available dielectric resonators and exited by axi-symmetric coaxial probe is studied computationally using the finite-difference time-domain (FDTD) method. The numerical results are checked against experimental measurements, and good agreement is observed. It is demonstrated that the introduction of air-gaps between the two DR's and also between the driven DR and the ground plane can improve the impedance bandwidth of the antenna significantly. The effects of the air-gaps thickness on the return loss and the bandwidth are discussed. The far-fields are also calculated by applying the electromagnetic field equivalence principle. The antenna produces an end-fire radiation field similar to that of an electric monopole. >

Tunable microstrip patch antennas

Abstract: A patch antenna is provided with one or more tuning strips spaced therefrom and RF switches to connect or block RF therebetween. When RF is connected between the tuning strips and the patch, the tuning strips increase the effective length of the patch and lower the antenna's resonant frequency, thereby allowing the antenna to be frequency tuned electrically over a relatively broadband of frequencies. If the tuning strips are connected to the patch in other than a symmetrical pattern, the antenna pattern of the antenna can be changed.

Single compact dual mode antenna

Abstract: A printed circuit board antenna is provided which includes an electronic switch (38) whereby a single compact radiating structure consisting of a split dipole antenna (10) with associated balun structure (11) may be selectively driven in either of two modes to provide orthogonal polarization and pattern diversity: as a split dipole antenna with a quarter wave balun relying on the split dipole antenna (10) as the radiating element; or as a top-loaded monopole relying on the quarter wave balun structure (11) as the radiating element against a ground plane (12). Orthogonal polarization and pattern diversity are achieved as a result of the mutually perpendicular orientations of the split dipole antenna (10) and its integral balun structure (11).

Meander line loaded antenna

Abstract: An antenna includes one or more conductive elements for acting as radiating antenna elements, and a slow wave meander line adapted to couple electrical signals between the conductive elements, wherein the meander line has an effective electrical length which affects the electrical length and operating characteristics of the antenna. The electrical length and operating mode of the antenna may be readily controlled.

Miniature multi-branch patch antenna

Abstract: A miniature, multi-branch patch antenna suitable for operating in the 1 GHz to 100 GHz frequency range, a method for making same and a communication system using the same is disclosed. In one embodiment, the antenna comprises a planar dielectric substrate, a plurality of conducting antenna elements each having a feed port, a ground plane and a septum located between each conducting antenna element. In a second embodiment, the antenna comprises a planar dielectric substrate, a plurality of conducting antenna elements each having a feed port, a ground plane and a superstrate that is disposed on the plurality of conducting antenna elements and at least a portion of the dielectric substrate. The septum and the superstrate suppress undesirable coupling mechanisms. In a communication system according to the present invention, the miniature, multi-branch patch antenna is coupled to a transmitter and/or receiver.

Frequency-selective antenna with different signal polarizations

Abstract: A slot radiator and a patch radiator are formed in a single antenna which is connected to a handheld, wireless telephone. The antenna can be pivoted to operational positions and excited to radiate linearly-polarized signals or circularly-polarized signals whose radiation patterns are respectively directed azimuthally and elevationally.

Slot antenna arrangement for portable personal computers

Abstract: An antenna arrangement is provided in which a slot antenna is attached to the surface of an equipment case made of a dielectric material, there being provided also a ground plane spaced a small distance apart from the case and behind the antenna. The equipment may be a personal computer, e.g. a notebook computer, and the antenna, which may take the form of a copper foil, may be attached to the lid of the computer by an adhesive on its rear surface. The ground plane may, in this case, take the form of an existing display backplane. The invention provides for the realization of a compact antenna arrangement due to the effect of the case dielectric on the effective electrical length of the slot antenna.

Curved dipole antenna with center-post amplifier

Abstract: An antenna system embodiment of the present invention comprises a curved dipole antenna stood off at its center by a printed circuit board assembly containing a pre-amplifier. The curved dipole antenna is implemented with a single-sided flexible circuit and is anchored at its four free ends to a sheet metal base for a groundplane. The printed circuit board assembly containing the predetermined amplifier is fixed perpendicular to the sheet metal base and has a tab that engages a slot in the center of the single-sided flexible circuit for electrical connection of a pair of orthogonal dipoles patterned on one side of the flexible circuit.

Method, dual rectangular patch antenna system and radio for providing isolation and diversity

Abstract: The present invention provides a method, dual rectangular patch antenna system, and radio for providing isolation and diversity while eliminating the need for a diplexer or a second transmit/receive switch. The dual rectangular patch antenna system comprises a first rectangular patch antenna (202), a second rectangular patch antenna (204), and a switch (206). Receive path diversity is provided by switching between the first rectangular patch antenna (202) and the second rectangular patch antenna (204).

Frequency selective surface integrated antenna system

Abstract: A frequency selective surface integrated antenna is provided which compri a frequency selective surface, including an electrically non-conductive substrate and an electrically conductive layer, mounted to the substrate and having a pattern of apertures; and an antenna integrated in the frequency selective surface.

Broadband coplanar waveguide-coplanar strip-fed spiral antenna

Abstract: A novel broadband coaxial-coplanar waveguide-coplanar strip-fed spiral antenna is presented. The antenna has good radiation patterns and a return loss of better than 10 dB over a wide bandwidth from 0.4 to 3.6 GHz. A DC-3.7 GHz broadband balun was developed for the antenna feed.

Multi-loop antenna

Abstract: A dual loop antenna (100) provides a dual frequency band response. The dual loop antenna (100) is configured on a substrate (102) which includes first and second radiator elements (106, 206) coupled through a common feed element (108).

Characteristics of a low-profile circular disk DR antenna with very high permittivity

Abstract: The fundamental broadside TM110 mode of an aperture-coupled circular dielectric resonator antenna is studied. By using high-dielectric-constant material, the DR antenna can be made low-profile with a relatively low resonant frequency. The return loss, radiation characteristics, antenna gain and beamwidth of the configuration are measured and discussed.

A dual‐frequency antenna using a single patch and an inclined slot

Abstract: Results on a dual-frequency microstrip patch antenna fed by using an inclined slot in the ground plane of a microstrip line are described. The frequencies of operation are determined by choosing the dimension of the rectangular patch and by adjusting the inclination angle of the slot. The antenna is easy to construct and results obtained from an antenna designed to operate around 9 and 12 GHz are presented. © 1995 John Wiley & Sons. Inc.

Multi-resonance horizontal-U shaped antenna

Abstract: A novel design of high frequency hidden hand-held antenna which includes two metal arms above a lower arm of finite ground plane. By properly choosing the lengths of these arms and the separations between them, the bandwidth can be broadened more than 20%. Thus, it is suitable for personal mobile communication applications. A full wave equivalent circuit analytic model is also developed to analyze and optimize the geometrical configuration including the lengths and separations between the arms. Numerical analyses for current distribution on the conductor surface and various antenna characteristics such as input impedance and radiation patterns are computed by the use of the analytical models. Experimental results and numerical computations all confirm that better performance characteristics including broadened antenna bandwidth are achieved by this novel antenna.

Dual frequency planar antenna at S and X bands

Abstract: A new configuration of patch antenna is introduced, which provides a dual-band operation. This structure consists of an S-band cross patch with four square patches printed in the empty spaces among the arms of the cross. These patches provide a subarray working at X-band. This structure is simple to design and offers the advantage that it can be printed on a single-layer. An array geometry designed by using the above structure, is suggested. This can be suitable for satisfying the requirements of a typical dual-frequency SAR antenna.

Communications apparatus with antenna switching based on antenna rotation

Abstract: An electronic device includes a host component having a first antenna; and a radio unit that may be connected to the host component and that has a second, rotatable antenna. The radio unit also includes a switch that is triggered by rotation of the second antenna to activate either the first antenna or the second antenna.

Low profile TEM mode slot array antenna

Abstract: A low profile slot antenna is provided which includes first and second oppositely disposed metallic plates with a dielectric layer disposed therebetween. An array of horizontal and vertical radiating elements are formed in the first metallic plate. An array of horizontal coupling slots and an array of vertical coupling slots are formed in the second metallic plate. The antenna further includes a planar feed network electrically coupled to the coupling slots. The feed network is connected to a conductive waveguide tube located at the central portion of the antenna. Orthogonal probes couple the waveguide tube to a transceiver. Accordingly, the slot antenna may operate to transmit and receive linearly polarized energy. The antenna may further include a polarization converter for converting between linear and circular polarization so as to allow for antenna operation with single or dual circular polarization energy. The polarization converter may include a pair of Meanderline polarizer sheets disposed above the metallic plates, or alternately may include use of a ninety degree hybrid coupler.

Magnetic core element for antenna, thin-film antenna, and card equipped with thin-film antenna

Abstract: A magnetic core element for use in a thin antenna. The magnetic core element has a thickness of 25 μm or less and is made of a particular amorphous alloy strip or a particular nano-crystalline alloy strip. A thin antenna having a laminated magnetic core made of the magnetic core elements is highly resistant to deformation and has a high Q-value.

Multi-staged antenna optimized for reception within multiple frequency bands

Abstract: An antenna suitable for use at subscriber sites in a television distribution system having a high front-to-back ratio and optimized for reception within multiple frequency bands. The antenna is comprised of multiple tapered antenna stages including a primary antenna stage for receiving a primary frequency band and a coupling antenna stage for matching the impedance of the primary antenna stage to either a coaxial cable or downconverter electronics. The multiple antenna stages are alternatively formed from either a stamping of a metal sheet or a double sided printed circuit board.

Wireless electronic module

Abstract: A wireless electronic module includes a folded monopole antenna having an antenna port impedance which is reactive at the RF frequency of operation and which conjugately matches the reactive impedance of the electronic circuit which connects to the antenna port. A grounded shield is interposed between the antenna and the electronic circuit to reduce RF losses at the antenna.

Efficient, dual-polarization, three-dimensionally omni-directional crossed-loop antenna with a planar base element

Abstract: A self-contained system containing an antenna, a circuit board, and a power source. The antenna consists of two loop elements mounted perpendicular to each other on a circular metal plate that acts both as part of the radiating system and as a shield between the circuitry and the radiator. The circuit board includes a transmitter, a receiver, and other circuitry for storing information and executing software. The antenna has a high gain, is omnidirectional in two orthogonal polarizations, and has a high degree of isolation between the two loop elements. To achieve omnidirectionality, in one mode, the antenna operates by using each loop element in a time-sequence of brief on/off states. In another mode, the transceiver uses both loop elements simultaneously with the signals on the two loop elements in phase quadrature.

Quadrifilar helix antenna

Abstract: A quadrifilar helix antenna for use in satellite communications comprises four conductive elements arranged to define two separate helically twisted loops, one slightly differing in electrical length than the other, to define a cylinder of constant radius supported by itself or by a cylindrical non-conductive substrate. The two separate helically twisted loops are connected to each other in such a way as to constitute the impedance matching, electrical phasing, coupling and power distribution for the antenna. In place of a conventional balun, the antenna is fed at a tap point on one of the conductive elements determined by an impedance matching network which connects the antenna to a transmission line. The matching network can be built with distributed or lumped electrical elements and can be incorporated into the design of the antenna.

Microstrip antenna array

Abstract: An antenna for a base station in a mobile radio communication system with at least one base station and at least one mobile station is disclosed. The antenna comprises a microstrip antenna array with a matrix of microstrip patches with at least two columns and two rows. In addition, a plurality of amplifiers is provided wherein each power amplifier is connected to a different column of microstrip patches. Finally, beamformers are connected to each power amplifier for determining a direction and shape of narrow antenna lobes generated by the columns of microstrip patches.