A 270-GHz Tuner-Less Heterostructure Barrier Varactor Frequency Tripler

A tuner-less heterostructure barrier varactor (HBV) frequency tripler has been designed, fabricated, and tested. A conversion efficiency of 7.2% and output power of 6.5 mW were measured at 270 GHz with 90 mW of input power. The performance of this tuner-less HBV tripler is comparable with other HBV frequency multipliers reported in the literature that utilize mechanical tuners to optimize their performance     

ECG Enhancement by Adaptive Cancellation of Electrosurgical Interference

A technique utilizing a combination of adaptive noise canceling and conventional signal processing is developed to enhance electrocardiographic monitoring in the operating room by reducing the noise interference that is created by an electrosurgical instrument. Significant amounts of interference are eliminated by radio frequency shielding, passive and active low-pass filtering, and optical isolation. A digital adaptive canceler using the least mean-square algorithm of Widrow and Hoff is used to reduce the remainder of the interference, yielding an improvement in signal-to-noise ratio of approximately 110 dB. Clear electrocardiograms have been obtained with electrocautery equipment in operation.     

Terahertz detector utilizing two-dimensional electronic fluid

We report on the first implementation of a terahertz detector utilizing two-dimensional (2-D) electronic fluid in a high electron mobility transistor (HEMT) operating at 2.5 THz. The terahertz radiation induced a dc drain-to-source voltage proportional to the radiation intensity. The measured dependencies of the detector responsivity on the gate bias are in good agreement with the gate bias dependence of the normalized responsivity predicted by the detector theory. This result shows the potential for developing a new family of electronics devices-plasma wave electronics devices-operating at terahertz frequencies     

Analysis of an octagonal micromachined horn antenna forsubmillimeter-wave applications

An analysis is presented of a new horn antenna, fabricated by a novel micromachining technique, that uses crystallographic etching of silicon and ultraviolet lithography of an ultra-thick photoresist (SU-8). The horn was found to have low cross-polarized field levels and a predicted Gaussian coupling efficiency of 92.5%. The horn shape is governed by the crystal planes of the silicon substrate and the thickness of the photoresist and has up to four independent design parameters that allow a wide range of antenna patterns. A design for the horn that yields symmetric beam patterns was investigated by computer analysis, microwave scale modeling, and measurements of a micromachined horn at 585 GHz. The major features of the 585-GHz beam patterns agree well with the computer-generated and scaled beam patterns. We have thus demonstrated a new micromachinable horn that has great potential for integration into array structures