Topic
Radio frequency
About: Radio frequency is a research topic. Over the lifetime, 44413 publications have been published within this topic receiving 448181 citations. The topic is also known as: RF & radio frequency.
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TL;DR: An RF-DC power conversion system is designed to efficiently convert far-field RF energy to DC voltages at very low received power and voltages and is ideal for use in passively powered sensor networks.
Abstract: An RF-DC power conversion system is designed to efficiently convert far-field RF energy to DC voltages at very low received power and voltages. Passive rectifier circuits are designed in a 0.25 mum CMOS technology using floating gate transistors as rectifying diodes. The 36-stage rectifier can rectify input voltages as low as 50 mV with a voltage gain of 6.4 and operates with received power as low as 5.5 muW(22.6 dBm). Optimized for far field, the circuit operates at a distance of 44 m from a 4 W EIRP source. The high voltage range achieved at low load current make it ideal for use in passively powered sensor networks.
766 citations
TL;DR: In this paper, a Pentacene-based thin-film integrated circuit with polymeric shadow masks and powered by near-field coupling at radio frequencies of 125 kHz and above 6 MHz has been demonstrated.
Abstract: Pentacene-based thin-film integrated circuits patterned only with polymeric shadow masks and powered by near-field coupling at radio frequencies of 125 kHz and above 6 MHz have been demonstrated. Sufficient amplitude modulation of the rf field was obtained to externally detect a clock signal generated by the integrated circuit. The circuits operate without the use of a diode rectification stage. This demonstration provides the basis for more sophisticated low-cost rf transponder circuitry using organic semiconductors.
753 citations
Patent•
10 Nov 2004
TL;DR: In this paper, a method for tracking an object, including positioning a radio frequency (RF) driver to radiate an RF driving field toward the object, and fixing to the object a wireless transponder that includes a power coil and at least one sensor coil.
Abstract: A method is provided for tracking an object, including positioning a radio frequency (RF) driver to radiate an RF driving field toward the object, and fixing to the object a wireless transponder that includes a power coil and at least one sensor coil. The method also includes receiving the RF driving field using the power coil and storing electrical energy derived therefrom. A plurality of field generators are driven to generate electromagnetic fields at respective frequencies in a vicinity of the object that induce a voltage drop across the at least one sensor coil. A digital output signal is generated at the wireless transponder indicative of the voltage drop across the sensor coil, and the generation of the digital output signal is powered using the stored electrical energy. The digital output signal is transmitted from the wireless transponder using the power coil, and the transmission of the digital output signal is powered using the stored electrical energy. The digital output signal is received and processed to determine coordinates of the object.
728 citations
Patent•
28 Sep 1998TL;DR: A radio frequency identification device comprises an integrated circuit including a receiver, a transmitter, and a microprocessor as discussed by the authors, where the receiver and transmitter together define an active transponder.
Abstract: A radio frequency identification device comprises an integrated circuit including a receiver, a transmitter, and a microprocessor. The receiver and transmitter together define an active transponder. The integrated circuit is preferably a monolithic single die integrated circuit including the receiver, the transmitter, and the microprocessor. Because the device includes an active transponder, instead of a transponder which relies on magnetic coupling for power, the device has a much greater range.
720 citations
TL;DR: In this paper, the authors used vector field-sensing electric and magnetic triaxial antennas to estimate the orbital angular momentum (OAM) of radio beams, assuming ideal (noiseless) conditions and that the beam axis is known.
Abstract: Recent discoveries concerning rotating (helical) phase fronts and orbital angular momentum (OAM) of laser beams are applied to radio frequencies and comprehensive simulations of a radio OAM system are performed. We find that with the use of vector field-sensing electric and magnetic triaxial antennas, it is possible to unambiguously estimate the OAM in radio beams by local measurements at a single point, assuming ideal (noiseless) conditions and that the beam axis is known. Furthermore, we show that conventional antenna pattern optimization methods can be applied to OAM-generating circular arrays to enhance their directivity.
700 citations