The U-slot micro-strip patch antennas were originally developed for bandwidth broadening applications. This study presents a transmission line feed to modify the U-slot stacked rectangular micro-strip patch antenna for Ultra-Wide Band (UWB) communications. The modified antenna has a U-cut loaded with parallel slits and corner slots and is printed on a dielectric substrate of FR4 with relative p...

Acoustic performance for an interior requires an accurate description of the boundary materials' surface acoustic impedance. Analytical methods may be applied to a small class of test geometries, but inverse numerical methods provide greater flexibility. The parameter estimation problem requires minimizing prediction vice observed acoustic field pressure. The Bayesian-network sampling approach ...

Theories of the acoustic impedance of micro perforated panels and membranes for normally incident waves have been well developed for decades. These theories are mainly based on the assumption that the particle velocity at the boundary of the hole wall is equal to zero. This assumption is valid when the panel/membrane is massive and does not vibrate. This paper aims to investigate the effects of...

The acoustic attenuation performance of a single-pass, perforated concentric silencer filled with continuous strand fibers is investigated theoretically and experimentally. One-dimensional analytical and threedimensional boundary element methods are employed to predict the acoustic attenuation in the absence of mean flow. Measured complex characteristic impedance and wave number are used to acc...

This paper is concerned with the study of low-cost, low-power thermoacoustic electricity generators. Based on target electrical output power values of 50 and 100 W, three standing wave prototypes (of both one-stage and two-stage prototypes) integrating a commercial loudspeaker with different coupling arrangements are conceived. Each stage consists of a square-pore stack sandwiched between hot a...

Airborne capacitive micromachined ultrasonic transducers (CMUTs) have predominantly large input reactance with small series radiation resistance. To maximize the acoustic power at resonance we employ low cost LC matching networks between output impedance driving source and CMUT transducer. Conventional networks, including pi T-network topologies are employed to provide a high-Q match. An import...

Abstract Our previous study has revealed that acoustic resonances have non-negligible effects on photoacoustic signals for a liquid sample confined in thin tube. In this paper, we present numerical and experimental studies the of tube hardness directivity generated signal. A glass capillary silicone 1 mm diameter were tested using pulsed light 637 nm wavelength. Black ink was as material. capil...

A damping device, consisting of an annular tail-pipe, has been developed. It is applicable in situations wherein acoustic damping is required in combination with low flow resistance. Examples are ventilation systems, turboengines, intake and exhaust systems for internal combustion engines. The device consists of a central tube surrounded by a narrow slit. The central tube has an acoustic mass w...

Focusing beyond the acoustic diffraction limit has always been expected, especially in imaging and ultrasonic therapy. Manipulating waves offers an alternative application potential high-resolution medical ultrasound diagnosis treatment. Here, a two-dimensional circular meta-lens is presented, with sub-wavelength Helmholtz resonator array to implement super-diffraction focusing. The proposed co...

Acoustic measurements taken in a flow impedance tube are used to assess the relative accuracy of two waveguide methods for impedance eduction in the presence of grazing flow. The aeroacoustic environment is assumed to contain forward and backward-traveling acoustic waves, consisting of multiple modes, and uniform mean flow. Both methods require a measurement of the complex acoustic pressure pro...