A circular sector-shaped dipole antenna with meandered arms based on an artificial magnetic conductor (AMC) is proposed in this study. compact unit cell of the AMC operating within 19–485 MHz designed using a ferrite material, which exhibits high-permeability characteristics high-frequency (HF), very-high-frequency (VHF), and ultra-high-frequency (UHF) bands. The configuration optimally binary ...

We use vector Hamiltonian formalism (VHF) to study theoretically three-magnon parametric interaction (or three-wave splitting) in a magnetic disk existing vortex ground state. The splitting is found obey two selection rules: (i) conservation of the total azimuthal number resultant spin-wave modes, and (ii) inequality for radial numbers interacting if mode directly excited by driving field radia...

We have developed a three dimensional (3D) interferometric beamforming technique for imaging lightning flashes using Very-High Frequency (VHF) radio data recorded from several hundreds antennas with baselines up to 100~km as offered by the Low Array (LOFAR). The long allow us distinguish fine structures on scale of meters while large number observe processes that radiate at same intensity backg...

This paper reports an observational study of lightning initial breakdown pulses (IBPs) using the low-frequency array radio telescope and a broadband magnetic field sensor. The data show that overall spatiotemporal evolution electrical causing IBP is rather complex. During IBP, spatially temporally separated bursts very high frequency (VHF) electromagnetic radiation occur in volume on order 1003...

In November 1999 the EISCAT high-power, high-frequency (HF) facility located near Tromsø, Norway, was used to create artificial plasma turbulence in the ionosphere. During the experiment the EISCAT 224 MHz radar and sometimes the 931 MHz radar were used to obtain measurements of incoherent scatter ion and plasma lines, and artificially enhanced spectra of E-region plasma waves were measured for...

This work presents the first simultaneous X-ray measurements from natural lightning in coincidence with a very high frequency (VHF) broadband interferometer. During an observational campaign north-central Colombia, five intense bursts were detected negative stepped leaders and two emissions dart leader. Thanks to angular time resolution of interferometer, it was possible locate origin high-ener...

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We present a physically-based clutter model for low frequency synthetic aperture radar that includes both distributed scatterers and large-amplitude discrete clutter. The model is used to generate a synthetic forest clutter scene comprised of two components, a background component and a heavy-tailed discrete component. Model parameters are based on characteristics of the scene, such as the rada...

a new output structure for class e power amplifier (pa) is proposed in this paper. a series lc resonator circuit, tuned near the second harmonic of the operating frequency is added to the output circuit. this resonator causes low impedance at the second harmonic. the output circuit is designed to shape the switch voltage of the class e amplifier and lower the voltage stress of the transistor. t...