Abstract: The present invention introduces an RFID system that comprises a two-dimensional antenna configuration having a dipole in combination with a loop antenna or a second dipole with their dipole axes at approximately a 90.degree. angle to one another. The pattern of two dipole antennas combined with the pattern of a single loop antenna, allows the sequential combination of the patterns to represent a nearly spherical antenna pattern in three dimensions, while the antennas reside in a two-dimensional plane. The presence of multiple antennas also allows for a method to switch among the multiple antennas to find the antenna or combination of antennas that create(s) the strongest RF communication link thereby enabling more efficient transmitted power or more directional reception coverage. Improving efficiency can be further improved by taking this concept one step further by adding multiple antennas into the interrogator unit.

Abstract: A pen-enabled computer system in which the digitizer sensor loop array is employed as a radio frequency antenna for receiving signals from an external signal source such as a wireless keyboard or wireless local area network interface. This radio frequency datalink arrangement allows for greatly enhanced freedom of movement when using external system components, as well as reduced component count and weight.

Abstract: An antenna coupling device is disclosed for connecting, substantially inductively, a first antenna to a second antenna, whereat the antenna coupling device comprises a loop antenna (4) with two poles (15, 16). The loop antenna (4) is arranged to surround the first antenna and is connected to the second antenna via both of its poles (15, 16). Such an antenna coupling device connected via a cable (5) to an external antenna by the action of threading the antenna coupling device onto a helical antenna (2) of a hand-portable telephone (1) is used inside a vehicle for improving transmission and reception conditions of the hand-portable telephone (1).

Abstract: The present invention introduces an RFID system that comprises a two-dimensional antenna configuration having a dipole in combination with a loop antenna or a second dipole with their dipole axes at approximately a 90.degree. angle to one another. The pattern of two dipole antennas combined with the pattern of a single loop antenna, allows the sequential combination of the patterns to represent a nearly spherical antenna pattern in three dimensions, while the antennas reside in a two-dimensional plane. The presence of multiple antennas also allows for a method to switch among the multiple antennas to find the antenna or combination of antennas that create(s) the strongest RF communication link thereby enabling more efficient transmitted power or more directional reception coverage. Improving efficiency can be further improved by taking this concept one step further by adding multiple antennas into the interrogator unit.

Abstract: An antenna system comprises a stack of elements that include a GPS patch antenna on a groundplane with an associated low-noise amplifier (LNA), a first Faraday shield of flat ribbon cable covering a first ferrite rod magnetic field antenna, a second ferrite rod magnetic field antenna separated from and orthogonal to the first ferrite rod magnetic field antenna, a second Faraday shield of flat ribbon cable covering the second ferrite rod magnetic field antenna and having a LNA for each of the ferrite rod magnetic field antennas. A third Faraday shield is positioned between the first and second ferrite rod magnetic field antennas. All the Faraday shields are connected to ground such that there are no loops that may act as shorted turns to avoid desensitizing the ferrite rod magnetic field antennas.

Abstract: An antenna for reception of signals in a plurality of frequency bands employed in portable and vehicular communications is constructed of a dielectric layer disposed on a metallic plate which serves as a ground plane. Microstrip antenna elements in the form of a planar radiator encircled by a loop radiator are disposed upon the dielectric layer. A rod radiator oriented normally to the plate extends through the patch radiator and the dielectric layer, and is surrounded by a dielectric cylinder which insulates the rod radiator from the planar radiator and the plate. The planar radiator may be configured as a patch radiator, a spiral radiator, or a crossed dipole radiator. Also, one or more additional layers of patch radiator elements may stacked upon the patch radiator to provide a stacked microstrip radiator. Terminals are positioned about the planar radiator for extracting orthogonal components of a circularly polarized electromagnetic signal.

Abstract: An antenna for a wide bandwidth electromagnetic field polarized in a predetermined direction at right angles to the field propagation direction includes plural metal elements that are not resonant in the bandwidth. The metal elements are excited to transduce an electric field in the polarization direction over the bandwidth range. The plural elements have an extent in the polarization direction no greater than an order of magnitude of the shortest wave length in the bandwidth. A structure between the element, which may be either a coil or parallel electrodes which derive a displacement current, transduces a magnetic field having lines of flux at right angles to the polarization and propagation directions. The electric and magnetic fields are excited by power from the same source with phases so that in an interaction region of the field between a pair of the metal elements there is E.times.H synchronism and a radiation Poynting vector having rotational E and H fields to transduce the electromagnetic field.

Abstract: A broadband, polarization diversity, monopulse antenna comprising a body celed current array and radial arm-coupled log periodic loop antenna in combination with associated mode forming, beam forming and feed networks.

Abstract: A resonant antenna suitable for transmission and for reception over a broad range of frequencies combines electric and magnetic multipoles generated by linear and loop elements respectively. The minimum requirement is one electric and one magnetic dipole and one electric and magnetic quadrupole. The electric elements are driven in time quadrature with the magnetic elements. The elements of the minimum requirement lie in the same plane and along the same axis. The minimum number of elements for a free standing antenna is three loops and three dipoles. Maximum transmission and reception occur only in the same direction along the axis. The size of the antenna is reduced by introducing a ground conductor or plane along the antenna axis and eliminating the half elements on one side thereof and is further reduced by introducing a second ground plane normal to the first at the midpoint of its length and eliminating the quarter elements on one side.

Abstract: An EMI filter for use in a low frequency radio receiver. The device is inserted in the signal line between the receiver and its antenna to provide both common mode and differential mode filtering of out-of-band interfering HF signals which are picked up on the antenna as well as on the signal line and attendant cable shields.

Abstract: A receiving antenna for use in proximity to an antenna having a circular radiating magnetic field includes at least one antenna having a null spatial sensitivity pattern along at least one axis, oriented with the circular radiating antenna located in said null pattern. In a preferred embodiment, the antenna having spatial sensitivity is three orthogonally oriented loop antennas, arranged to be insensitive to signals from the circular radiating antenna and sensitive to TE and TM signals from a remote location.

Abstract: A broadband multi-element antenna is presented. The antenna comprises a monopole centrally disposed within a cavity of the body, and a plurality of antenna elements disposed at ninety degree increments about the periphery of the cavity. A plurality of isolation traps are connected between selected pairs of the antenna elements. The isolation traps are half-wavelength transmission lines which permit excitation of the respective plurality of elements by input signals which are of equal amplitude and 180.degree. out-of-phase but are short circuits between the respective pairs for in phase signals parasitically induced from the monopole. Additionally, switching traps are connected to respective ones of the antenna elements. The switching traps comprise quarter-wave transmission lines which are switchable to ground and selectively provide a short circuit of signals at the respective ones of the elements for changing the radiation pattern of the antenna.

Abstract: Active interrogation devices which can be moved in a track direction relative to passive response devices transmit electrical energy to the response devices with the aid of ferrite rod antennae which are each arranged in the track direction and are contained in each interrogation device and each response device. In the response devices, this energy feeds a transmitting device by which an item of data assigned to a response device can be transmitted in the form of an electrical response signal to a frame antenna of each interrogation device and each response device to the interrogation device. The antenna arrangements can therefore be designed to be relatively narrow in the track direction without the signal for the data transmission exhibiting phase jumps.

Abstract: A three-element directional/omnidirectional antenna adapted for use in both transmitting and receiving modes. Crossed loop antennas are mounted on top of a monopole whip antenna and are electrically coupled thereto. Each of the loop antennas consists of an outer larger primary loop and an inner secondary loop joined at its base to the primary loop. Both the primary and secondary loops are interrupted at their top ends opposite the point where they join the monopole antenna. A tuning capacitor is coupled between the two halves of each of the primary loops, while a coaxial antenna feeds the two secondary loops. The coaxial cables feeding the secondary loops pass through a dual ferrite choke disposed within the monopole antenna.

Abstract: An improved antenna tuning circuit for a long and a medium wave AM radio receiver is disclosed. The antenna tuning circuit of the present invention comprises a tuning coil wound around a ferrite core, a variable capacitor connected in parallel with the tuning coil, and a field effect transistor. One end of the tuning coil is connected to the gate electrode directly or through an impedance means, while the other end of the tuning coil is grounded. The output signal of the antenna tuning circuit is taken out from a selected one of the source or drain electrode of the field effect transistor, whereby the signal to noise ratio may be remarkably improved.

Abstract: A broadband antenna element capable of operating over greater than an octave band of frequencies is disclosed. The element comprises an open-ended rectangular waveguide section having a loop radiator, formed by shorting an insulated probe to one of the broad walls of the waveguide section, disposed therein. Notches are provided in the narrow walls and flanges are provided on the broad walls of the waveguide section for matching purposes. The insulated probe extends through a hole formed in the rear wall of the waveguide section to connect with a stripline feed network.

Abstract: An automatic direction finding (ADF) system including a direction finding antenna array which connects to a radio receiver to process an audio output signal selectively illuminating a segment of a segmented circular visual directional display indicating the direction from which the received signal arrived. In an FM version, the ADF system electronically switches between antennas in the direction finding antenna array alternately incorporating vector information onto the received carrier in a manner that can be phase detected to produce an audio frequency signal within the normal pre-audio bandpass of the receiver. The audio frequency is then demultiplexed to produce separate vector signals. These separate vector signals are then processed for selectively illuminating a segment of the segmented circular visual directional display.

Abstract: Coupling an outer antenna with a radio receiver having a bar antenna is achieved by connecting the outer antenna to a coupling coil which is able to be removably mounted on a bar core of the bar antenna and by mounting the coupling coil on the bar core with such an orientation of the coupling coil that the signal received at the outer antenna does not cancel the signal received at the bar antenna. The connection between the outer antenna and the coupling coil may be made by the use of a coaxial cable with the outer conductor of the cable being not grounded to function as a ground plane. A series circuit of a switch and a resistor may be connected in parallel with the coupling coil to selectively reduce the quality factor Q of the bar antenna.

Abstract: A directional loop array antenna for very low frequency (VLF) reception. array comprises four closely spaced loop antennas forming a unidirectional reception pattern with a main beam of less than 43.degree. between half power points. The array combines two double loop coaxial antennas dispersed with their axis parallel along 45.degree. lines. The signal from one double loop array is delayed sufficiently such that a unidirectional reception pattern is formed.

Abstract: An omnidirectional antenna array comprising a ferrite antenna inductively coupled to one leg of a loop antenna that lies in a plane parallel to the long axis of the ferrite antenna. The output signal may be taken from either of the antennas.

Abstract: A guidance system for aircraft and ships, which system comprises at least two localizer antenna arrangements which are spaced in elevation above a reflecting surface, at least two distance measuring antenna arrangements which are spaced in elevation above the reflecting surface, and at least two glide slope antenna arrangements which are mounted vertically above each other, the guidance system being such that the localizer antenna arrangements are at a mean height of at least 21/2 wavelengths above the reflecting surface and are fed with signals having the same radio frequency but having a phase difference, the distance measuring antenna arrangements are at a mean height of at least 25 wavelengths above the reflecting surface and are fed with signals having the same radio frequency but having a phase difference, and the glide slope antenna arrangements are fed with signals having the same radio frequency but two different frequencies of amplitude modulation to give by reflection from the reflecting surface at

Abstract: A combined loop, sense and communications antenna for aircraft automatic direction finding radio receiver and communications transceiver. A blade-like antenna and a loop antenna are combined in a unitary, streamlined housing of insulating material. The blade antenna serves the dual purpose of providing sense signals to the ADF receiver and of providing a transmitting and receiving antenna for the communications transceiver.

Abstract: A compact transmitting and receiving antenna has dual feeds permitting magnetic and electric dipole radiation. The antenna includes a loop antenna disposed within a loop shield and a mast. The loop shield is insulated from ground and a feed is provided to it and the mast to excite these as an electric monopole. The shield becomes part of the monopole antenna and provides the benefits of top-loading. An isolation transformer permits the simultaneous transmission of monopole and dipole radiation. The transformer converts an unbalanced coaxial feed line to the balanced loop antenna and isolates the monopole feed voltage from the loop antenna feed. To eliminate the affect of the monopole feed on the loop feed, and vice versa, the components on the high side of the monopole feed (the loop shield and mast) are driven in common mode (voltage) by the monopole feed, and will not couple the loop antenna feed through the transformer windings.