This paper presents a study of a novel monopole antenna for ultrawide-band (UWB) applications. Printed on a dielectric substrate and fed by a 50 /spl Omega/ microstrip line, a planar circular disc monopole has been demonstrated to provide an ultra wide 10 dB return loss bandwidth with satisfactory radiation properties. The parameters which affect the performance of the antenna in terms of its frequency domain characteristics are investigated. A good agreement is achieved between the simulation and the experiment. In addition, the time domain performance of the proposed antenna is also evaluated in simulations.

Study of a printed circular disc monopole antenna for UWB systems

Science and technologies based on terahertz frequency electromagnetic radiation (100 GHz–30 THz) have developed rapidly over the last 30 years. For most of the 20th Century, terahertz radiation, then referred to as sub-millimeter wave or far-infrared radiation, was mainly utilized by astronomers and some spectroscopists. Following the development of laser based terahertz time-domain spectroscopy in the 1980s and 1990s the field of THz science and technology expanded rapidly, to the extent that it now touches many areas from fundamental science to 'real world' applications. For example THz radiation is being used to optimize materials for new solar cells, and may also be a key technology for the next generation of airport security scanners. While the field was emerging it was possible to keep track of all new developments, however now the field has grown so much that it is increasingly difficult to follow the diverse range of new discoveries and applications that are appearing. At this point in time, when the field of THz science and technology is moving from an emerging to a more established and interdisciplinary field, it is apt to present a roadmap to help identify the breadth and future directions of the field. The aim of this roadmap is to present a snapshot of the present state of THz science and technology in 2017, and provide an opinion on the challenges and opportunities that the future holds. To be able to achieve this aim, we have invited a group of international experts to write 18 sections that cover most of the key areas of THz science and technology. We hope that The 2017 Roadmap on THz science and technology will prove to be a useful resource by providing a wide ranging introduction to the capabilities of THz radiation for those outside or just entering the field as well as providing perspective and breadth for those who are well established. We also feel that this review should serve as a useful guide for government and funding agencies.

The 2016 terahertz science and technology roadmap

The objective of this paper is to summarize the work that has been developed by the authors for the last several years, in order to demonstrate that the Theory of Characteristic Modes can be used to perform a systematic design of different types of antennas. Characteristic modes are real current modes that can be computed numerically for conducting bodies of arbitrary shape. Since characteristic modes form a set of orthogonal functions, they can be used to expand the total current on the surface of the body. However, this paper shows that what makes characteristic modes really attractive for antenna design is the physical insight they bring into the radiating phenomena taking place in the antenna. The resonance frequency of modes, as well as their radiating behavior, can be determined from the information provided by the eigenvalues associated with the characteristic modes. Moreover, by studying the current distribution of modes, an optimum feeding arrangement can be found in order to obtain the desired radiating behavior.

The Theory of Characteristic Modes Revisited: A Contribution to the Design of Antennas for Modern Applications

The planar monopole antenna is shown to provide extremely wideband impedance characteristics. Recently, many techniques to tailor and optimize the impedance bandwidth of these antennas have been investigated. These include the use of bevels, slots and shorting posts. These antennas are becoming popular, and have been proposed for modern and future wideband wireless applications. The radiation performance is also shown to be acceptable over a wide frequency range.

Wideband monopole antennas for multi-band wireless systems

Disclosed herein is an antenna apparatus for use in harvesting ambient radio frequency, RF, energy. The apparatus comprises one or more RF antenna components arranged to receive RF energy for producing electricity. The one or more RF antenna components comprise a plurality of frequency filtering components, each frequency filtering component being arranged to filter a respective frequency band of the received RF energy. Also disclosed herein is an apparatus comprising a rectifying circuit arranged to convert a variable electrical signal received at an input from an associated antenna into a direct current electrical signal for supplying to an electrical energy storage unit, the antenna for use in harvesting ambient radio frequency, RF, energy. The apparatus also comprises a power management module having an input arranged to receive the direct current and control supply of the direct current to the electrical energy storage unit. The rectifying circuit comprises a plurality of transmission lines, wherein the input of the rectifying circuit and the input of the power management module are connected via the plurality of transmission lines. The power management module is arranged at least partially within a boundary defined by the plurality of transmission lines.

Rf energy harvester

Look to this new, cutting-edge microstrip antenna book for the first exhaustive coverage of broadband techniques, including the most up-to-date information to help you choose and design the optimum broadband microstrip antenna configurations for your applications, without sacrificing other antenna parameters. The book shows you how to take advantage of the lightweight, low volume benefits of these antennas, by providing clear explanations of the various configurations and simple design equations that help you analyze and design microstrip antennas with speed and confidence. This practical resource offers you a comprehensive understanding of the radiation mechanism and characteristic of microstrip antennas, and provides guidance in designing new types of planar monopole antennas with multi-octave bandwidth. You learn how to select and design proper broadband microstrip antenna configurations for compact, tunable, dual-band and circular polarization applications. Moreover, the book compares all the broadband techniques and suggests the most attractive configuration. Extensively referenced with over 300 illustrations and 140 equations.

Broadband Microstrip Antennas

The circular disc monopole (CDM) antenna has been reported to yield wide-impedance bandwidth. Experiments have been carried out on a CDM that has twice the diameter of the reported disc with similar results. New configurations are proposed such as elliptical (with different ellipticity ratios), square, rectangular, and hexagonal disc monopole antennas. A simple formula is proposed to predict the frequency corresponding to the lower edge of the bandwidth for each of these configurations. The elliptical disc monopole (EDM) with ellipticity ratio of 1.1 yields the maximum bandwidth from 1.21 GHz to more than 13 GHz for voltage standing wave ratio (VSWR)<2.

Wide-band planar monopole antennas

This paper presents the design equations for lower band-edge frequency for all the regular shapes of printed monopole antennas with various feed positions. The length of the feed transmission line is a critical design parameter of these monopole antennas. Design curves for the length of the feed transmission line for various lower band-edge frequencies for all these regular shaped monopoles have been generated. A systematic study has been presented to explain the ultra-wide bandwidth obtained from these antennas with an example of elliptical monopole antenna.

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Design Aspects of Printed Monopole Antennas for Ultra-Wide Band Applications

Parametric study of ultrawideband printed elliptical monopole antennas have been presented. Design curve for the length of the feed transmission line for various lower band edge frequencies has been generated. Variation of bandwidth with ellipticity ratio of these configurations has also been studied. Experiments have been performed to measure bandwidth and radiation patterns of these configurations, which tally well with simulated results. The elliptical configuration with ellipticity ratio of 1.1 gives ultrawide impedance bandwidth ratio of 12.4:1 as compared to 10.2:1 of the circular monopole antenna. This antenna introduces minimum ringing and distortion/dispersion of the pulse in time domain

Ultrawideband Printed Elliptical Monopole Antennas

Aperture shape and size are the crucial parameters for the aperture coupled microstrip antennas (ACMSA). A systematic comparision of various aperture shapes for the aperture coupled rectangular microstrip antenna has been carried out. An optimum "hour glass"-shaped aperture configuration has been proposed for maximum coupling.

Kamla Prasan Ray

Papers

Broadband Microstrip Antennas

Wide-band planar monopole antennas

Design Aspects of Printed Monopole Antennas for Ultra-Wide Band Applications

Ultrawideband Printed Elliptical Monopole Antennas

Improved coupling for aperture coupled microstrip antennas