Abstract

In-service degradation of a pipe section is monitored in real time with torsional guided waves which can resolve 5% damage to the internal wall. We use a single permanently installed source–receiver pair as opposed to the current state-of-the-art sensor rings. There is no baseline subtraction requirement as a single reflection coefficient is derived by internal referencing of the time trace. Even with continuously operating pump vibration, there is enough acoustic signal for confident damage localization. Since pipelines wear out gradually in industrial installations, the acoustic footprint is similar to that previously determined in periodically damaged pipes. The reflective method can thus be applied successfully to monitor structural health in industrial pipelines during operation as opposed to the current state-of-the-art guided wave inspection approaches using near-weld reflection techniques along with disassembled and re-assembled sensor rings.

Abstract

In this paper, a simple microstrip patch antenna and a two-element E-plane coupled microstrip antenna array employing a defected ground structure are investigated. Without defected ground structure, the antenna has an impedance bandwidth of 675 MHz (6.78% at the center frequency of 9.955 GHz) and a gain of around 4.38 dB. The performance of the microstrip antenna in terms of impedance bandwidth, matching performance, gain and return loss can be improved by introducing a defect in the ground plane. As a result of which, bandwidth of 1.652 GHz (16.42% at the center frequency of 10.06 GHz) and a gain of 8.96 dB along with 5 different other operating bands are achieved. After integrating the microstrip antenna with the proposed defected ground structure, effective footprint of the antenna is reduced up to 66.95%. When integrated with proposed DGS array, the same antenna array structure shows miniaturization up to 78.97%. The proposed defected ground structure when compared to other techniques shows an exceptionally lower mutual coupling between two E-plane coupled microstrip antenna elements.