The electrodynamical properties of a volume resonator formed by a perodic structure built from the metallic threads inside a rectangular waveguide (”grid” volume resonator) is considered for travelling wave tube and backward wave oscillator operation. Peculiarities of passing of electromagnetic waves with different polarizations through such volume resonator are discussed.

Wireless power transfer (WPT) using a metallic tube with axial slits was attempted to demonstrate WPT using magnetic resonance coupling to the diagnostics infrastructure. The transmission efficiency was measured at various distances using the transmission and receiver resonator in the tube. Furthermore, the transmission and receiver resonator were set respectively outside and inside of the tube...

A novel cavity perturbation technique using coaxial cavity ruonators for the measurement of complex permittivity of liquids is presented. The method employs two types of resonators (Resonator I and Resonator ll). Resonator l operates in the fre­ quency range 600 MHZ-7 CH2 and resonator ll operates in the frequency range 4 Gliz-14 CH2. The introduction of the capillary tube filled wit? the sampl...

A novel and practical acoustic energy harvesting mechanism to harvest traveling sound at low audible frequency is introduced and studied both experimentally and numerically. The acoustic energy harvester in this study contains a quarter-wavelength straight tube resonator with lead zirconate titanate (PZT) piezoelectric cantilever plates placed inside the tube. When the tube resonator is excited...

An adaptive-passive quarter-wave tube resonator silencer was experimentally tested using recorded in-duct reciprocating engine exhaust noise. The exhaust noise was re-played through a loudspeaker attached to one end of a duct, and the adaptive passive system was able to track changes in engine speed and provide attenuation of the noise at the fundamental firing frequency of the engine and the t...

Previous research of the authors pointed out that side-resonators can be applied to reduce fan noise. However, the noise reduction capabilities of most resonator geometries, e.g. tube resonators, cylindrical resonators (cylindrical air layers) and circular resonators (disc shaped air layers), are relatively narrow banded. This is disadvantageous in case resonators are used in combination with a...

In this paper, a theoretical study is conducted in order to establish the feasibility of a liquid metal acoustic resonator ͑liquid gallium or liquid aluminum͒ for high-amplitude acoustic oscillations. The fundamental resonant frequency typically lies between 5 and 40 kHz. The oscillations are induced by an alternating Lorentz force density applied directly to the liquid metal volume. Depending on...

Abstract A new configuration for a gas sensor is demonstrated. The configuration consists of an electroacoustic element coupled to an acoustic resonator, such as Kundt’s tube, exhibiting a resonance frequency that is related to the velocity of sound, which, in turn, is a function of the molecular mass of the gas within the resonator. Electrical impedance measurements were performed, whereby a r...

Resonator techniques can be successfully used to extract effective medium properties from dispersive materials. However, in some cases the dispersion can cause modes to repeat. If repeated modes are not taken into account, the useful range of the resonator technique is limited. A resonance tube containing tethered balloons is used to create a dispersive effective medium. Resonator measurements ...

The resonator impedance model of surface roughness in a cylindrical beam tube, derived in Ref. 1, is compared to the inductive impedance model of Ref. 2. It is shown that for long, smooth bunches the two models both give an inductive response, that the e ective inductance per length is proportional to the corrugation depth over the beam pipe radius, and that the absolute results also are compar...