Search

A small antenna is critical in wireless communication and monitoring of vital signs using data collected by implantable devices. Numerous studies address antenna miniaturization and reliability challenges while maintaining performance efficiency in this field. A reliable small‐sized circularly polarized antenna of dimension (4.152 π × 1.28) mm3 developed for medical implants operating at the 1.4‐GHz Wireless Medical Telemetry Service (WMTS) narrow band is presented in this work. The shorting pin, variable arc slots, and substrate and superstrate of high dielectric constant techniques were used. The proposed antenna underwent testing in a three‐layer biological simulation environment that includes the skin, fat, and muscle. Subsequently, the antenna was fabricated, and measurements were performed by placing the antenna in beef biological tissues. The measurement results confirmed the simulated results. The antenna achieves an impedance bandwidth of 98 MHz (1.367~1.465 GHz, 7%). The effective axial ratio bandwidth (AR <3 dB) is 55.2 MHz (1.3668~1.422 GHz, 3.94%), which covers the CP operating frequency range. The simulation results attain a peak realized gain of −19.2 dBic. The communication link budget and the specific absorption rate (SAR) were analyzed. The results indicate that the radiation of the proposed antenna aligns with the safety limit of IEEE C95.1‐1999 standards. The antenna exhibits excellent performance and reliability compared to other works operating within the 1.4‐GHz WMTS band. [ABSTRACT FROM AUTHOR]

A wideband Magneto‐Electric Dipole (MED) antenna with high gain is proposed for the 700/800/850/900 MHz frequency bands for cellular network applications. The antenna comprises a half‐wavelength bow‐tie‐shaped dipole, an elongated magnetic loop and a ground reflector with four Elevated Ground Planes (EGPs) at reflector's corners. The EGPs enhance the antenna gain and Front‐to‐Back Ratio (FBR), which is a promising technique in the MED antenna design. The antenna is excited by a Γ ${\Gamma }$‐shaped coupling element. An analytical model of the proposed antenna is developed by employing Schelkunoff's model for dipole antennas and the transmission line theory complemented by radiation resistance corrections. The antenna design is validated with full‐wave numerical simulations. The antenna is fabricated using cut and bent metallic plates and tested in an anechoic chamber. The analytical, numerical and experimental results are in a good agreement. The experimental results confirm that the proposed MED antenna with dimensions of 1.44λ×1.44λ×0.27λ $1.44\lambda \times 1.44\lambda \times 0.27\lambda $ achieves a bandwidth of 61.53% (623.1–1176.8 MHz) for VSWR<1.5 $VSWR< 1.5$ and a stable gain of 9.8 ± $\pm $ 1.9 dBi. By employing the EGPs, the realized peak gain and FBR are enhanced by 0.52 dBi and 1.1 dB, respectively. Plain Language Summary: This study presents a novel Magneto‐Electric Dipole (MED) antenna design with improved bandwidth and gain characteristics tailored for the cellular network access across several frequency bands. As a distinctive feature, this MED antenna includes a ground reflector with Elevated Ground Planes (EGPs) at its corners to enhance its gain and Front‐to‐Back Ratio (FBR). Additionally, in this work we propose a new equivalent circuit for MED antennas based on the Schelkunoff's model for electric dipoles and the transmission line theory improved by radiation corrections. The performance of the MED antenna and the developed models are validated through numerical simulations and experimental testing. This research showcases advancements in MED antenna modeling and design aimed at increased performance and capacity of cellular networks. Key Points: Development of an analytical model for the proposed antenna using Schelkunoff's model for dipole antennas and transmission line theoryEGPs are utilized to enhance antenna gain and FBR, representing a promising technique in MED antenna design [ABSTRACT FROM AUTHOR]

In this paper, we proposed the distributed quantization and sparsity aware zero attracting least mean square (DQA‐ZA‐LMS) and its reweighted version (DQA‐RZA‐LMS) algorithms that can perform sparse spectrum sensing with the lowest power possible. The usage of the quantization aware diffusion adaptive networks has recently been proposed and they can be used in many possible mobile communicative applications. The sparsity aware feature of the proposed algorithm can help the network to track and estimate sparse random vectors that are shown to be the case with the spectrum of the new generation wireless communication systems such as 4G, 5G, 6G, and beyond. The spectrum sensing is considered in this paper to be performed by small cell eNode Bs (SC‐eNBs) for the 4th generation long term evolution (LTE) and the next generation eNB (ng‐eNB) networks for the 5th and 6th generation mobile communication systems that are scattered in an area collecting distributed quantized data from the environment and working collaboratively to estimate the sparse spectrum vectors. Our findings show that in comparison with the nonquantized version of the distributed ZA‐LMS (DZA‐LMS) and distributed regularized ZA‐LMS (DRZA‐LMS) algorithms, our proposed schemes perform considerably well using the quantized data and also reduce power consumption. [ABSTRACT FROM AUTHOR]

A wide-angle, dual-polarized frequency selective rasorber (FSR) with two absorption bands located at both sides of a passband is proposed. The structure comprises a lossy frequency selective surface (FSS), a bandpass FSS, and an air spacer located in between. A modified electric field coupled (ELC) resonator is used as a parallel resonance at the lossy layer to achieve a passband within the absorption band. The characteristic mode theory is utilized to investigate the absorption behavior of the lossy layer. Extensive simulations were carried out to assess the performance of the presented structure. Under the normal incidence, the proposed structure provides an operating bandwidth (|S11| < −10 dB) from 1.94 to 7.16 GHz, corresponding to a fractional bandwidth (FBW) of 114.7%. The achieved passband is around 4.3 GHz with a minimum insertion loss of 0.81 dB. The absorption bands with an absorption rate higher than 80% are 1.81–3.69 GHz (FBW of 68.4%) in the lower band and 4.95–7.43 GHz (FBW of 40%) in the upper band, respectively. It exhibits quite stable characteristics up to 50° angle of incidence. Furthermore, a prototype was fabricated and measured, which confirms that a good agreement exists between the experimental and simulation results. The proposed FSR is a suitable candidate for lowering the radar cross section (RCS) of the communication equipment or making them stealthy. [ABSTRACT FROM AUTHOR]