Finite difference time domain analysis of microstrip antenna-circuit modules

Compact microstrip antenna-circuit modules, which could be used as front-ends for future wireless systems applications, require electromagnetic modelling due to the close interaction of the circuit with the antenna. Spectrum crowding and EMC/EMI issues call for modelling of the radiation of such modules. Coupling through fringing fields and the nonlinearities of active devices must be addressed. In this work, the FDTD method was used because it can provide the framework for inclusion of circuit elements in a full wave calculation. A software tool was developed and validated based on this method. The modules studied were chosen due to their compactness and their merit as system components. A module with simultaneous transmit-receive operation integrating an active circulator (using amplifiers in a ring-like arrangement) and a quarter wavelength antenna was analysed. Coupling effects were identified and their impact on the radiation patterns was shown. Electronically tuneable microstrip patch antennas using varactor diodes were also studied. Tuning range and harmonic radiation were demonstrated. Single and dual device Gunn oscillator antennas were analysed and their radiation patterns were calculated for the first time. All of our results were in agreement with experimental findings

The Regulatory Framework For Wireless Power Transfer Systems

A survey of the regulatory framework pertinent to Wireless Power Transfer systems is given. Both technical (power and frequency) considerations along with health safety radiation compliance are examined. A primer on regulatory processes is also included to facilitate the understanding of the developments. The current state is analysed and ongoing regulatory activities across the globe are discussed. Furthermore, a review of recent radiation safety studies of WPT systems is included

Correlation Effects on the MIMO Capacity for Conformal Antennas on a Paraboloid

The use of conformal antennas in a MIMO link scenario is investigated. Conformal slot antennas are considered both in the transmitter and the receiver. First, a new modified correlation coefficient is derived that goes beyond the Clarke coefficient and takes into account the element radiation pattern. Secondly, a hybrid formulation that accounts for the impact of the mutual coupling and the pattern dependent correlation on the capacity is presented. The mutual coupling for slots placed circumferentially on a paraboloid substrate is derived using a rigorous approach based on Uniform Theory of Diffraction (UTD). The capacity is evaluated for the case of Rayleigh fading channel considering the new pattern dependent correlation coefficient and the conformal antenna mutual coupling. The planar case is included as a limiting case. It is shown that for conformal antennas on a paraboloid the capacity degradation compared to the planar case is up to 0.5 bps/Hz due to coupling and correlation.Grant numbers : The authors acknowledge EU COST Action IC1301 Wireless Power Transmission for Sustainable Electronics

Performance analysis of a ultra-compact low-power rectenna in paper substrate for RF energy harvesting

In this paper the experimental results of a compact low-power rectenna in paper substrate, designed to operate in the Wi-Fi band, are presented. The complete prototype, based on an annular slot antenna and a single-diode rectifier, features a weight of 1.5 grams and shows an RF-to-dc conversion efficiency in the design band of about 40 % for a -10 dBm available input power, of about 28 % at -15 dBm, and in the range [10, 22] % at -20 dBm, corresponding to an output DC voltage in the order of 320, 240 and 60 mV respectively. Additionally, the rectenna features an efficiency higher then 7 % in the whole band 1.8-2.7 dBm for a power density estimated around 3 μW/cm2.Grant numbers : The work was supported by the EU COST Action IC1301 WiPE (Wireless Power Transmission for sustainable Electronics). © 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works

Evaluation of error vector magnitude due to combined IQ imbalances and phase noise

Novel closed form expressions for the Error Vector Magnitude (EVM) are presented. The expressions combine IQ amplitude and phase imbalances, DC offsets along with phase noise. Both the Gaussian and the Tikhonov probability density function are utilized for the oscillator phase noise distribution. The explicit conditions when EVM computations based on Tikhonov distribution converge to a Gaussian based are investigated. Furthermore, the application of the proposed EVM expressions is demonstrated by including phase noise masks, providing a direct means to Phase Locked Loop/Voltage Controlled Oscillator design parameters. Measurements are used to validate the proposed expressions.Grant number : The authors would like to acknowledge EU COST Action IC1301 Wireless Power Transmission for Sustainable Electronics (WIPE). The paper was supported by the Spanish Ministry of Economy and Competitiveness project TEC 2012-39143 (SOSRAD)

Regulations and standards for wireless power transfer systems

A survey of the regulatory framework pertinent to Wireless Power Transfer systems is given. Both technical (power and frequency) considerations along with health safety radiation compliance are examined. A primer on regulatory processes is also included to facilitate the understanding of the developments. The current state is analyzed and ongoing regulatory activities across the globe are discussed. Furthermore, a review of recent radiation safety studies of WPT systems is included

Evolutionary Algorithms applied to Antennas and Propagation: A Review of State-of-the-art

A review of evolutionary algorithms (EAs) with applications to antenna and propagation problems is presented. EAs have emerged as viable candidates for global optimization problems and have been attracting the attention of the research community interested in solving real-world engineering problems, as evidenced by the fact that very large number of antenna design problems have been addressed in the literature in recent years by using EAs. In this paper, our primary focus is on Genetic Algorithms (GAs), Particle Swarm Optimization (PSO), and Differential Evolution (DE), though we also briefly review other recently introduced nature-inspired algorithms. An overview of case examples optimized by each family of algorithms is included in the paper

Improved Propagation Modeling in Ultra-Wideband Indoor Communication Systems Utilizing Vector Fitting Technique of the Dielectric Properties of Building Materials

This paper demonstrates the application of the Finite-Difference Time-Domain method for dispersive media to indoor ultra-wideband channel modeling. A new description of the frequency dispersion of building materials, based on a partial-fraction approach, is proposed, utilizing experimentally measured data on complex permittivity values reported in the literature. The analytical dispersion model for a series of building materials is estimated through the Vector Fitting technique and the through-the-wall penetration is calculated for indicative cases. Finally, a small two-dimensional office environment is studied and several channel characteristics are calculated demonstrating the flexibility and robustness of the proposed formulation in communication modeling. The proposed FDTD implementation covers all the bandwidth in a single run instead of running simulations for every frequency or subband.Grant numbers : © 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works