A novel wideband (WB) 3D-printed elliptical double-ridged horn (EDRH) antenna filled with a high-dielectric material (i.e., a mixture of the paraffin and titanium oxide (TiO 2 )) is proposed for medical monitoring systems. The antenna has been designed and optimized to operate in the frequency range (2-6 GHz) to satisfy an optimal penetration level and to maintain a WB operation, which results in a high-resolution detection. The proposed antenna is embedded into a high-dielectric material to miniaturize its size and to further reduce the reflections due to mismatch with the body. The antenna was tested on tissue models consisting of two layers (i.e., skin and muscle). The reflection coefficients of the antenna, when it is on the modeled tissue, have been generated and compared with the reference of -6 dB. The obtained results show that the antenna benefits from the 4 GHz of bandwidth with a gain of 5-8 dB within the operating region.INDEX TERMS 3D printing, antenna, double-ridged horn, high-dielectric material, WB.

This paper presents a novel 3D-printed, pyramidal double-ridged horn antenna, filled with a high-dielectric material comprising a mixture of linseed oil and titanium oxide, for biomedical applications. In particular, this investigation explores the use of the antenna design to measure the abdominal fat layers of the human body. The antenna is designed to operate at the lowfrequency microwave bands and complemented with an absorber layer at the aperture to improve directivity. The proposed method aims to assess the fat layer thicknesses based on an analysis of the variations of the reflection coefficients. The system has been calibrated and validated based on a number of numerical timedomain simulations, as well as experimental analysis. Assessment of the first transition point in the reflection coefficient spectrum, has successfully predicted the rate of magnitude change caused by different layer thicknesses (e.g., oil and fat). Comparing coefficient spectra from various simulation experiments has allowed for eliminating the interferences arising from mismatches with the skin and muscle layers, resulting in the measurements of the fat layer thicknesses through the remaining power change rate.

In this paper, the basic physics of modulator are discussed and traditional silicon modulator in the early years is involved as a comparison. Fifty-seven research articles about graphene modulators are reviewed in detail. All the figure of merits including modulation depth, modulation speed, footprint, modulation bandwidth, operation bandwidth, and insertion loss of these modulators are well studied. The challenges and problems for graphene modulators are addressed by analyzing the first twenty-five references while the last thirty-five references of graphene modulators are reviewed to address the higher figure of merits that are still developing. Physics of other 2D materials are also mentioned as a comparison, especially a modulator by black phosphorus. We believe this review will give a good roadmap to develop better graphene modulators that solves the challenges and problems in this field.

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