Other

Northeastern University

Massachusetts Technological Laboratory, Inc.

Hoton How

Carmine Vittoria

Ta-Ming Fang

Yizhou Huang

Yung-Ching Chu

Allan Widom

Disclosed is one method and one apparatus which teach improved techniques in using a shaped bias magnetic field over the active region of a ferrite stripline circulator/isolator circuit. The axial component of the bias field is decreased from the center toward edge, thus it is able to accommodate the accompanying changes in magnetization. This fulfills the requirements that frequencies are scaled with distances thereby warranting broadband operation. Furthermore, the radial component of the bias field is reduced, so as to minimize the generation of non-circulation volume modes. The discontinuity in magnetization distributed over the circulator/isolator active region is reduced, so as to minimize the generation of magnetostatic surface modes. The resultant circulator/isolator performance can thus show a broad bandwidth with improved characteristics in insertion loss and in isolation.

Method and apparatus of obtaining broadband circulator/isolator operation by shaping the bias magnetic field

Disclosed is one method and one apparatus which teach improved techniques in equipping an RFID with security measure. Conventionally an RFID is employed basically to replace the usage of an infrared bar-code label thereby to supply electronic or digital signature and identification. In this sense, the traditional RFID technology is in lack of security and an RFID can be tampered with in an arbitrary manner not to cause an alert. This is no longer true if an RFID is endowed with security. In this invention an RFID, either an active or a passive device, has the ability to memorize its original spatial position so that if the position is changed without authority, an alarm signal is generated.

Method and apparatus for implementing security protection over RFID

Disclosed is a method and an apparatus enabling operation of balanced phase shifts providing uniformity that the insertion loss do not show variation with the derived angles in phase shift. The invention incorporates a resonator supporting nonreciprocal wave propagation. The resonator is divided in two equal parts showing symmetry so that the change in electronic parameters from one part of the resonator counter balances the other part, thereby causing no change to the resonance condition. Amplifiers are thus not needed by the phase-shift operation. Electronically active materials, such as ferrites, ferroelectrics, and/or varactors, are utilized, and the phase shifter device can be fabricated assuming a variety of transmission-line geometries, such as microstrips, striplines, waveguides, coax lines, parallel wires, coplanar waveguides, image lines, fin lines, and slot lines, providing versatility and convenience in applications.

Method and apparatus of obtaining balanced phase shift

Disclosed are one method and one apparatus which enable a non-reciprocal microwave resonator to be coupled in and out at various positions showing the circular symmetry. As such, the transmission phase, but not the amplitude, can be varied, resulting in the operation of a digital phaser. The resonator is electrically connected to two network feeders each of which provides separate phase selectivity. The overall phase selectivity of the phaser is the product of the selectivities of these two network feeders, resulting in a less volume, and hence reduced fabrication costs.

Method and apparatus of obtaining uniform coupling from a nonreciprocal resonator

Disclosed is a method and an apparatus implying nearly 100% security with a tag system showing low cost and compact volume. Like a conventional tag, the disclosed tag system will respond properly to an interrogation signal. In addition, the disclosed tag system is able to monitor the environment local to a merchandise. Whenever the merchandise package is opened and/or impaired, alarm will be generated on the spot. It is almost impossible to disarm the tag system, unless a password is attained. The disclosed tag system shows a high sensitivity, and it does not need an electronic searching machine, or an interrogation gate, to operate. When combined with an electromagnetic transmitter, a smart tag system results, allowing merchandise to be traced on the computer screen, capable of performing discriminative tasks according to the imposed regulation rules on the merchandise IDs.

Method and apparatus of obtaining security tag operation using local magnetic marker

Disclosed is a method and an apparatus enabling water-conditioning processes to be performed using a heater initially equipped with an aquarium tank for the purpose of supplying heat. Instead of allowing heat to propagate globally, reactor housing is introduced in the tank enclosing the heater so as to form a localized hot zone. The temperatures of the hot zone are maintained at high degrees sufficient to initiate various water-conditioning processes with efficiency, including alga control, ammonia control, water-hardness control, and sterilization. The construction of the reactor housing is simple and inexpensive, and its geometry is compatible to a heater which can be purchased commercially. In short, multiple functions are added to a heater installed in an aquarium, performing water-conditioning processes in addition to the basic task of supplying heat, allowing water quality of the aquarium to be improved and maintained.

Method and apparatus of obtaining water conditioning utilizing localized hot zone

Disclosed is a method for improving the sensitivity of a fluxgate magnetometer for which high-order harmonics are detected and utilized in determining a weak external magnetic field expressed in the core region. These harmonic signals are processed coherently so as to increase the signal-to-noise ratio, since noise can only add to the signal incoherently at these harmonic frequencies. Also disclosed is a method for improving the sensitivity of a fluxgate magnetometer for which the technique of waveform autocorrelation is used in determining a weak external magnetic field expressed in the core region. By convolving the gated signal with a waveform duplicating the signal itself, noise content is effectively suppressed, thereby increasing the resolution power of the fluxgate magnetometer.

Fluxgate signal detection employing high-order waveform autocorrelation

Disclosed is a method for establishing and utilizing electronic tracks on roads for ground vehicles so as to ease the driving task with added safety and efficiency. Electronic tracks define traces on roads guiding the movement of a ground vehicle in as much as the same way that railroad tracks confine the movement of a train. Speed control can be achieved by using equipments detecting the driving conditions and the road environment along with the gliding action of the ground vehicle on electronic tracks. Automation in driving is thus possible, at least partially. Electronic map can be constructed consisting of many of the electronic tracks. Based upon both the static and dynamic information on roads, an electronic map is able to configure an optimal route connecting two addresses with the shortest time in traveling.

Electronically tracked road-map system

Disclosed is a method for achieving miniature fluxgate circuits capable of remotely sensing local dynamic magnetic fields. By synchronizing the excitation currents of the sensor core with the time-varying magnetic signals, the sensitivity can thus be improved, thereby enabling dynamic measurements at high speed. Also disclosed is a magnetic recording head device which uses a fluxgate magnetometer to measure a sequence of magnetic digital data bits, capable of providing dual reading and writing functions at high speeds, whose fabrication is fully compatible with the current printing circuit technologies.

Methods of using fluxgate magnetometer on measuring remote and dynamic magnetic signals

Disclosed is a method and two devices for obtaining phase shifts by using a non-reciprocal resonator supporting single-mode operation. As such, wave propagation in the resonator is unambiguous in phase, allowing the phase to be coupled in or out at different positions. This results in novel phase shifter devices of two kinds: One kind of the devices suggests to change the coupling positions by using switches, and the other kind suggests to use a movable port to be driven by a step motor, for example. In this invention the phase-shift function performed by a non-reciprocal resonator invokes no use of a transmission line, none for the adjustment in its electronic properties, including permittivity and permeability. The operation of the disclosed phase shifter devices is uniform, being independent of the phase-shift angles, exhibiting low insertion loss and low return loss. Depending on the purpose of applications, versatile phase shifter devices can thus be fabricated, showing the following advantages, economy, reduced size, fast response, high isolation, minimum internal reflection, and compatibility with the current semiconductor fabrication techniques. This invention favors the fabrication of large phased array systems, where available space, cost, and power dissipation can be of primary concerns.

Method and apparatus of obtaining phase shift using nonreciprocal resonator

Disclosed is a method and a device for obtaining precision data acquisition via hand writing/drawing without requiring the use of a transducer pad, the screen of a monitor, or a scanner. As such, writing/drawing can be applied to almost all kinds of material surfaces, including books, fabrics, labels, etc., with or without showing an ink mark. Graphic and text images can all be effectively processed. Data acquisition function is accomplished by continuously monitoring the orientation of a magnet ball installed at the tip of a magnetomechanical ball-pen device whose outlook resembles a regular pen. When powered by a battery with self data-storage capability, the disclosed method and device allow for a new class of instrumentations that data acquisition function is carried out at the same time whenever hand writing/drawing is applied in the normal manner.

Precision data acquisition using magnetomechanical transducer

A magnetic/acoustic transducer is disclosed. The transducer can be used in security/smart tag applications. The transducer includes a sensor tag made of magnetic metallic glass having a relatively high magnetostriction and a relatively low coercivity. Driving signals are provided by an rf dipole loop antenna. The tag responds to the rf signals and converts the exciting magnetic field into acoustic signals via magnetoelastic coupling. That is, the tag is forced to vibrate in unison with the incident electromagnetic signals generating longitudinal acoustic waves along a length of the tag. This results in radiation of ultrasound waves in air which can then be detected and characterized using an ultrasound microphone or a piezoelectric sensor. The tag is provided having a length equal to one half or one quarter long of an acoustic wavelength so that an acoustic resonance condition is established to maximize the generation of ultrasound waves in air. The measured ultrasound signal is locked in phase with the excitation or reference signal for sensitive long-range detection. The tag can operate in a magnetized or a demagnetized state to stimulate binary signals for security-tag applications. Tags of different length and/or geometry can be deployed in combination so that the tag transducer produces unique and distinguishable frequency spectrums to be used as smart tags.

Method and apparatus for generating and detecting acoustic signals

A new technique is presented which exploits AC Hall effect in the characterization of layered semiconductor structures. The method involves the use of laser signals by means of optical fibers in the presence of a DC magnetic bias field. Upon incidence the polarization of the optical signal is rotated via a Lorentz force due to the AC Hall effect. As such, the reflected waves carry informations on the Hall mobility of the charge carriers. The calculations show that AC Hall reflection coefficient warrants sufficient intensity to be measured. Our theory is complete in the sense that depth profiling has been explicitly incorporated in the formulation.

Method and apparatus for structure characterization of layered

The present invention discloses a frequency tunable filter which includes an electromagnetic (E-M) wave propagation line which includes a microstrip and a ground plane in the substrate for transmitting a sequence of E-M signals via the propagation line. The E-M wave propagation line includes a frequency tuning mechanism, i.e., the magnetic layer, which is capable of utilizing a ferromagnetic anti-resonance frequency response to the E-M signals transmitted via the propagation line for controlling and frequency tuning the E-M signal transmission. In one of the preferred embodiments, the E-M wave propagation line includes a microstrip forming on the top surface of a dielectric or semiconductor substrate for receiving and transmitting the E-M signals and a ground plane forming on the bottom surface of the semiconductor substrate. And, the frequency tuning mechanism includes a ferromagnetic layer formed in the substrate between the microstrip and the ground plane.

Tunable millimeter wave filter using ferromagnetic metal films

An array antenna includes a ferrite substrate having a two-dimensional planar array of antenna elements disposed over a first surface thereof and means for applying an external magnetic field having a magnitude and direction which can be varied at least in a plane in which the antenna elements lie. The amplitude and direction of the external magnetic biasing field is varied to control the relative phases between each of the plurality of antenna elements and to steer the direction of a main antenna beam in two dimensions.

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Belmont, MA, United States of America

Hoton How