In this communication, a practically realisable artificial planar magneto‐dielectric (MD) meta‐substrate is proposed and investigated for microstrip patch antenna miniaturisation. The meta‐substrate employs cross‐coupled twisted metallic split‐ring resonator ring pairs to achieve effective permeability (μeff) and permittivity (ɛeff) greater than that of the host dielectric which leads to antenna miniaturisation. Electromagnetic simulation and analysis of effective material parameters are performed to characterise it, which shows nearly equal enhanced effective permeability and permittivity (μeff ≃ ɛeff) at 2.35 GHz with low loss‐factor level not achievable from natural materials. An inset fed microstrip patch antenna is designed on the proposed MD meta‐substrate to test and validate its performance. The performances of the miniaturised patch antenna loaded with proposed dispersive MD meta‐substrate, non‐dispersive homogenous MD substrate, and high‐permittivity substrates (lossy and loss‐free) are compared with the conventional patch antenna on host dielectric. It is found that dispersive nature of the meta‐substrate plays a critical role in the antenna performance. The antenna on proposed meta‐substrate occupying an overall volume of 0.250λ0 × 0.344λ0 × 0.009λ0 at 2.35 GHz is 74.83% miniaturised as compared with the conventional antenna on host dielectric. To ensure the practicability, the designed antenna is fabricated and measured.
In this study, the magnitude and spatial distribution of frequency spectrum in the resting electroencephalogram (EEG) were examined to address the problem of detecting alcoholism in the cerebral motor cortex. The EEG signals were recorded from chronic alcoholic conditions (n = 20) and the control group (n = 20). Data were taken from motor cortex region and divided into five sub-bands (delta, theta, alpha, beta-1 and beta-2). Three methodologies were adopted for feature extraction: (1) absolute power, (2) relative power and (3) peak power frequency. The dimension of the extracted features is reduced by linear discrimination analysis and classified by support vector machine (SVM) and fuzzy C-mean clustering. The maximum classification accuracy (88 %) with SVM clustering was achieved with the EEG spectral features with absolute power frequency on F4 channel. Among the bands, relatively higher classification accuracy was found over theta band and beta-2 band in most of the channels when computed with the EEG features of relative power. Electrodes wise CZ, C3 and P4 were having more alteration. Considering the good classification accuracy obtained by SVM with relative band power features in most of the EEG channels of motor cortex, it can be suggested that the noninvasive automated online diagnostic system for the chronic alcoholic condition can be developed with the help of EEG signals.
A reactive impedance surface (RIS) based miniaturized bent slotted patch antenna is proposed and investigated for S-band applications around 2.39 GHz. Bent slots in the patch reduce the patch antenna size by increasing current path on the patch. Further a RIS substrate with cross-shaped patch elements printed over a grounded dielectric is optimized and investigated for antenna miniaturization. The proposed bent slotted patch antenna over RIS substrate is 38.75% miniaturized with respect to traditional patch antenna at a fixed operating frequency. The proposed antenna reveals an overall volume of 0.280λ0 × 0.280λ0 × 0.036λ0on a low-cost FR4 substrate at 2.39 GHz for S-band applications. The proposed antenna is fabricated and measured for its return loss. The measured results are in good agreement with simulated one.
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