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.

Optical frequency synthesizer for precision spectroscopy

Abstract: We have used the frequency comb generated by a femtosecond mode-locked laser and broadened to more than an optical octave in a photonic crystal fiber to realize a frequency chain that links a 10 MHz radio frequency reference phase-coherently in one step to the optical region. By comparison with a similar frequency chain we set an upper limit for the uncertainty of this new approach to 5. 1x10(-16). This opens the door for measurement and synthesis of virtually any optical frequency and is ready to revolutionize frequency metrology.

RF MEMS switches and switch circuits

Abstract: MEMS switches are devices that use mechanical movement to achieve a short circuit or an open circuit in the RF transmission line. RF MEMS switches are the specific micromechanical switches that are designed to operate at RF-to-millimeter-wave frequencies (0.1 to 100 GHz). The forces required for the mechanical movement can be obtained using electrostatic, magnetostatic, piezoelectric, or thermal designs. To date, only electrostatic-type switches have been demonstrated at 0.1-100 GHz with high reliability (100 million to 10 billion cycles) and wafer-scale manufacturing techniques. It is for this reason that this article will concentrate on electrostatic switches.

Wireless position sensor

Abstract: Apparatus for tracking an object includes a plurality of field generators, which generate electromagnetic fields at different, respective frequencies in a vicinity of the object, and a radio frequency (RF) driver, which radiates a RF driving field toward the object. A wireless transponder is fixed to the object. The transponder includes at least one sensor coil, in which a signal current flows responsive to the electromagnetic fields, and a power coil, which receives the RF driving field and conveys electrical energy from the driving field to power the transponder. The power coil also transmits an output signal responsive to the signal current to a signal receiver, which processes the signal to determine coordinates of the object.

IEEE standard for safety levels with respect to human exposure to radio frequency electromagnetic fields, 3kHz to 300 GHz

Abstract: IEEE C95.1-1991 gives recommendations to prevent harmful effects in human beings exposed to electromagnetic fields in the frequency range from 3 kHz to 300 GHz. The recommendations are intended to apply to exposures in controlled, as well as uncontrolled, environments. They are not intended to apply to the purposeful exposure of patients under the direction of practitioners of the healing arts. The induced and contact current limits of IEEE C95.1-1991 are modified in this edition. In addition, field strengths below which induced and contact currents do not have to be measured are specified, spatial averaging and measurement distance requirements are clarified, and more precise definitions for averaging volume and radiated power are provided.

Frequency-modulation spectroscopy: a new method for measuring weak absorptions and dispersions.

Abstract: A new type of wavelength-modulation laser spectroscopy is accomplished by utilizing an external phase modulator driven at radio frequencies large compared to the width of the spectral feature of interest. The spectral feature is probed by a single frequency-modulated (FM) sideband, and the associated absorption and dispersion are measured by monitoring the resulting radio-frequency beat signal. Experimental results are presented for the measurement of Fabry–Perot resonances, I2 vapor absorption lines, and saturation holes in Na vapor.