A polarization-insensitive dual-band artificial magnetic conductor (AMC) structure is designed and experimentally verified. It consists of a planar array of annular ring-slot loaded rectangular patches. Details of the proposed structure and origin of the two bands is discussed. Through simulations and measurements, it is shown that the structure is insensitive to polarization of the incident wave. The tuning of the higher AMC band is demonstrated by varying the capacitance of the annular slot through its width variation. The designed AMC is used as a reflector for a wideband monopole patch antenna. It is shown experimentally at the antenna frequencies in the AMC band that the gain of the antenna improves by almost 10 dB and front-to-back ratio is improved by 15 dB.Index Terms-Dual-band artificial magnetic conductor (AMC), gain enhancement, monopole antenna.
The purpose of this study is to apply and evaluate performance of wavelets and select an appropriate wavelet to detect the peaks and dicrotic notch from the waveform captured from infrared finger-tip Photoplethesmography (PPG) and detect the significant peaks and valleys from the signal captured from the radial artery. Accurate detection of dicrotic notch is important as it finds its usage in various medical applications viz. pulse oximeters, vascular diagnostics, digital beat-to-beat blood pressure measurement systems and autonomic function analyzers. The method was extended to detect points of interest in pressure signal from radial artery. Radial artery signals were captured from a robust system called 'Nadi Yantra' [1] developed for the validation of ancient method of non-invasive pulse diagnosis of ailments. The system uses piezoelectric based pressure system to capture the palpations from the radial artery. To characterize the signals, wavelets were applied and the percussion wave, tidal wave and dicrotic notch were detected. The techniques developed were executed on a set of 120 data samples from healthy subjects. Daubechies wavelet was found to be suitable for PPG and radial artery pulse analysis. Overall efficiency of 98.45% for PPG signal and 97.89% for radial artery signal was achieved.
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