Design of a novel dual-polarized microwave sensor for human bone fracture detection using reactive impedance surfaces

Abstract This paper presents a novel miniaturized dual-polarized transceiver sensor system for detecting fractures in human bone tissues. The system features a patch antenna and a Reactive Impedance Surface (RIS) layer that reduces its size by 30% compared to conventional designs, resulting in enhanced fracture detection accuracy. Additionally, the system includes a dielectric plano-concave lens that adapts to the human body and improves impedance matching for optimal performance. The lens contains via holes filled with a lossy dielectric material similar to human fat tissue, which concentrates electromagnetic (EM) power and increases penetration depth for more effective crack detection. To detect fractures, two identical sensors are placed opposite each other on the tissue and moved simultaneously. The amount of EM power collected by the receiver sensor is measured using S-parameters; the transmission coefficient (S21) phases and contrast between the crack and surrounding tissue are used to construct images of fractured bones. Full-wave simulations and experimental measurements on a semi-solid human arm mimicking phantom demonstrate the proposed dual-polarized sensor's ability to detect the location and orientation of narrow cracks in the millimeter range. The system exhibits reliable performance across different human bodies

Development of a metasurface-based slot antenna for 5G MIMO applications with minimized cross-polarization and stable radiation patterns through mode manipulation

Abstract This paper presents an approach for designing metasurface antennas using the characteristic mode analysis method for 5G mm-wave multiple input–multiple output (MIMO) systems. The proposed metasurface antenna consists of a 3 × 3 array of modified patches with additional slits and stubs, which are fed by a coupling slot. This configuration reshapes surface currents and improves the radiation performance across a broad frequency range. The design offers significant advantages such as reduced antenna size, minimized influence of higher-order modes, and maintained low cross-polarization (XP) level. Experimental results demonstrate that the proposed metasurface-based slot antenna provides a bandwidth of 29.6% (23–31 GHz) with a return loss better than 10 dB. It achieves a peak gain of 9.43 dB and exhibits an XP level below − 26 dB and − 48 dB at $$\varphi = 0^{ \circ }$$ φ = 0 ∘ and $$\varphi = 90^{ \circ }$$ φ = 90 ∘ planes, respectively. The physical dimensions of the antenna are 0.9λ0 × 0.9λ0 × 0.08λ0, where λ0 is the free space wavelength at 27 GHz, resulting in an approximately 41% reduction compared to the conventional metasurface patch antenna. Moreover, the design proves to be well-suited for MIMO systems, enabling close placement of antenna elements without degrading their radiation patterns. The experimental results in 1 × 2 and 2 × 2 MIMO configurations represent that the isolation between antenna elements are better than 18 dB and 21 dB, respectively. The performance of the antennas remains stable in both configurations, effectively addressing concerns such as beam squint and eliminating the common issue of beam splitting observed in conventional metasurface MIMO antennas. Moreover, the envelope correlation coefficient value in both MIMO configurations is lower than 0.003. This significant advancement offers a promising solution for compact 5G mm-wave massive MIMO applications

Mean length of utterance (MLU) in typically-developing 2.5-5.5 year-old Persian-speaking children in Iran

Introduction: Mean length of utterance in morphemes (MLU) is widely used as a general index of language development in pre-school children. Because of insufficient data on Persian language development in Iran, this study examined the MLU of Persian-speaking children and its relation to their in an attempt to help improving clinical decision making. Materials and Methods: This cross-sectional study was conducted on 171 typically-developing children 2.5-5.5 years of age who were recruited from nursery settings of Isfahan, Iran. The sample was selected using a mixed method of sampling and divided into six age groups. After an informal conversation with each child to gauge whether the child appeared to be typically developing in terms of language and cognitive levels, speech therapists played with and tape-recorded them. Each child's MLU was calculated for 75 complete and intelligible utterances longer than one word. The mean and standard deviation of MLU were computed for each age group within six-month intervals. The correlation between age and MLU was also investigated. Results: The children’s mean MLU increased between 37-42 and 43-48 months and also between 43-48 and 49-54 months of age. The increase in MLU from the first age group onward was statistically significant. The correlation between age in months and MLU in morphemes was significant, r(171) = 0.47, P < 0.005. Conclusion: The average MLU of the children in this study-and similar studies of Persian-speaking children is much higher than that reported for English-speaking children, and the correlation with age lower; mainly because of morpho-syntactic differences between languages. Age sensitivity of MLU in Persian, however, indicates its capability as a developmental scale for monitoring syntax development in Persian-speaking children which needs to be deeply investigated in relation to Persian language-specific features, either. Keywords: Mean length of utterance, Syntax development, Language development, Pre-school children, Speech therap