Antenna arrays with hybrid analog-digital signal processing capabilities offer a compromise between the performance of digital arrays and the cost-efficiency of analog arrays with a single radio-frequency (RF) chain. A limitation of hybrid arrays is that the number of independent streams that they can transmit with standard precoding techniques cannot be larger than the number of RF chains. In ...

In this paper, we present a RF directional modulation technique using a switched antenna array for physical layer secure communication. The main idea is that a switching scheme of the switched antenna array is designed according to a spreading sequence for the purpose of spreading spectrum of the transmit signal. The transmit signal is associated with the spreading sequence and the direction of...

AIMS Recurrent arrhythmias after ablation procedures are often caused by recovery of ablated tissue. Robotic catheter manipulation systems increase catheter tip stability which improves energy delivery and could produce more transmural lesions. We tested this assertion using bipolar voltage attenuation as a marker of lesion quality comparing robotic and manual circumferential pulmonary vein abl...

This wireless transponder recovers power and a reference clock from an incident RF signal and returns data on a 900MHz carrier. A multi-stage voltage multiplier/rectifier converts the received low power RF signal to a useful DC voltage and stores the energy on a storage capacitor. The injection locking technique facilitates power efficient generation of a low phase noise 900MHz internal clock f...

Z Technology manufactures NIST traceable instrumentation for the measurement of receive-level RF signal strength over a basic frequency range of 5 to 1000 MHz. Systems can be tailored to meet specific customer requirements and for measurement of specific transmission formats and extended frequency ranges. As an example, custom configurations can be provided with both wideband measurement and GP...

Catheter ablation for septal accessory pathways is occasionally associated with complications, such as atrioventricular block, since the septal region is a complex anatomical structure containing the atrioventricular conduction system. Therefore, we designed a signal separator composed of an inductance-capacitance network with which the local electrogram at the ablation site could be continuous...

In this paper, a novel method for extracting an RF pilot carrier signal in the coherent receiver is presented. The RF carrier is used to mitigate the phase noise influence in n-level PSK and QAM systems. The performance is compared to the use of an (ideal) optically transmitted RF pilot tone. As expected an electronically generated RF carrier provides less efficient phase noise mitigation than ...

PURPOSE To improve ultrahigh field diffusion-weighted imaging (DWI) in the presence of inhomogeneous transmit B1 field by designing a novel semi-adiabatic single-refocused DWI technique. METHODS A 180° slice-selective, adiabatic radiofrequency (RF) pulse of 4 ms duration was designed using the adiabatic Shinnar-Le Roux algorithm. A matched-phase slice-selective 90° RF pulse of 8 ms duration w...

RF spoiling is a well established method to produce T(1)-weighted images with short repetition-time gradient-echo sequences, by eliminating coherent transverse magnetization with appropriate RF phase modulation. This paper presents 2 novel approaches to describe signal formation in such sequences. Both methods rely on the formulation of RF spoiling as a linear increase of the precession angle b...