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This paper presents the design, simulation, and fabrication of a 50 Ohm miniaturized rectenna for wireless energy harvesting for leadless pacemakers. The paper evaluates the performance of each section separately and also while cascaded. The system is designed to work at ultra-low RF input power. When the rectenna is placed 5 cm away from the body surface in simulations, the amount of received power is approximately −20 dBm. The proposed antenna is a miniature spiral PIFA with circular polarization at 673 MHz. The measured results, in and outside sheep’s fat tissue, show that about 15 MHz bandwidth can be realized with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\vert S 11\vert $ \end{document} below −10 dB and an axial ratio below 3 dB. Two types of rectifiers are fabricated and compared to choose the best one for such a system. Then, unlike most other researches which selected the doubler rectifier structure, this paper uses a single-diode rectifier structure at this power level. The rectenna can be encapsulated in a cylinder with a radius of 5 mm and a height of 3.2 mm. The efficiency of the rectenna reaches 40% at −20 dBm input power.

In this paper, a miniaturized implantable circularly polarized spiral Planar Inverted-F Antenna (SPIFA) in the UHF (600-800 MHz) band is presented. This antenna is intended for deep implantable devices such as leadless pacemakers and deep brain stimulation (DBS), which facilitates the reception of RF power from an external transmitter. The antenna is electrically small, with a volume of π× 5 mm × 5 mm × 3.2 mm and a diameter of 0.022λ. The performance of the proposed antenna in terms of reflection coefficient, realized gain and axial ratio are assessed when accounting for the effects of operating in different types of human body tissues, different biocompatible materials and different thicknesses and depths of the implanted antenna. Finally, the antenna is prototyped and measured in free space, a phantom model, in a cow's fat and muscle tissues to validate the simulation results, indicating good agreements. A realized gain around -20 dBm is achieved when operating in 50 mm depth in cow's muscle tissue while having electrically very small dimensions compared to implantable antennas reported in the literature.

A novel ring-opening reaction of donor-acceptor cyclopropanes through a one-pot three-component nucleophilic addition of amines, CS2, and D-A cyclopropanes has been described. New γ-dithiocarbamate dialkyl malonate skeletons were obtained in up to 97% yield.

This study presents a new method for measuring the propagation constant of transmission lines using a single line standard and without prior calibration of a two-port vector network analyzer (VNA). The method provides accurate results by emulating multiple line standards of the multiline calibration method. Each line standard was realized by sweeping an unknown network along a transmission line. The network need not be symmetric or reciprocal, but must exhibit both transmission and reflection. We performed measurements using a slab coaxial airline and repeated the measurements on three different VNAs. The measured propagation constant of the slab coaxial airline from all VNAs was nearly identical. By avoiding disconnecting or moving the cables, the proposed method eliminates errors related to the repeatability of connectors, resulting in improved broadband traceability to SI units.