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the exploitation of Extremely High Frequency (EHF) bands (30-300 GHz) for broadband transmission over satellite links is a hot research topic nowadays. In particular, the Q-V band (30-50 GHz) and W-band (75-110 GHz) seem to offer very promising perspectives. This paper aims at presenting an overview of the current status of research and technology in EHF(More)
—The growing demand for broad-band wireless communication links and the lack of wide frequency bands within the conventional spectrum, causes us to seek bandwidth in the higher microwave and millimeter-wave spectrum at extremely high frequencies (EHF) above 30 GHz. One of the principal challenges in realizing modern wireless communication links in the EHF(More)
A unified formulation of spontaneous (shot-noise) and super-radiant emissions in electron devices is presented. We consider an electron beam with an arbitrary temporal current modulation propagating through the interaction region of the electronic device. The total electromagnetic field is presented as a stochastic process and expanded in terms of(More)
1098-4402= We report experimental studies of the spectral linewidth and chirp characteristics of the mm-wave rf radiation of the Israeli Electrostatic-Accelerator free electron laser (EA-FEL), along with theory and numerical simulations. The simulations, matching the experimental data, were carried out using a spacefrequency-domain model. EA-FELs have the(More)
It is well known that electrons passing through a magnetic undulator emit partially coherent radiation: `Undulator Synchrotron Radiationa. Radiation from electrons, entering the undulator at random, adds incoherently. If the electron beam is periodically modulated (bunched) to pulses shorter than the radiation wavelength, electrons radiate in phase with(More)
Single mode operation was exhibited on the Israeli tandem free-electron laser (FEL). This enabled judicious measurements of narrow spectral linewidth, frequency chirp, and relaxation-oscillation effects. Exact 3D simulations of the FEL oscillator showed good agreement with the measurements, and permitted an estimation of the fundamental Schawlow-Towns(More)
OBJECTIVE To evaluate the relationship between the presence of microorganisms at the time of cesarean at different sites of the genital tract and the development of postpartum endometritus. METHODS One-hundred thirty-three healthy women who delivered by cesarean were enrolled in this prospective study. Cultures were obtained during the surgery and on days(More)
An experimental project aimed at demonstrating Free Electron Maser (FEM) operation with prebunching is under way at Tel-Aviv university. The FEM utilizes a 1.0 A prebunched electron beam obtained from a microwave tube. The electron beam is bunched at 4.87 GHz and is subsequently accelerated to 70 keV. The bunched beam is injected into a planar wiggler (B, =(More)
Design of a multi-stage depressed collector for efficient operation of a Free Electron Laser (FEL) oscillator requires knowledge of the electron beam energy distribution. This knowledge is necessary to determine the voltages of the depressed collector electrodes that optimize the collection efficiency and overall energy conversion efficiency of the FEL. The(More)
An electron beam, prebunched at the synchronous free-electron laser frequency and passing through a magnetic undulator, emits coherent (superradiant) synchrotron undulator radiation at the bunching frequency. If an external electromagnetic wave is introduced into the interaction region, at the same frequency and at a proper phase, the radiation process will(More)