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Guest Editor's Comments:Special Issue on SpiralAntennasHisamatsu Nakanoa College of Engineering Hosei University Koganei,Tokyo, JapanPublished online: 29 Oct 2010.

To cite this article: Hisamatsu Nakano (2000) Guest Editor's Comments:Special Issue on Spiral Antennas, Electromagnetics, 20:4, 269-270, DOI:10.1080/02726340050082119

To link to this article: http://dx.doi.org/10.1080/02726340050082119

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Electromagnetics, 20–2000Copyright © 2000 Taylor & Francis

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Guest Editor’s Comments:Special Issue on Spiral Antennas

HISAMATSU NAKANOCollege of EngineeringHosei UniversityKoganei, Tokyo, Japan

Recent growth in the demand for wireless communications has stimulated research in the spi-ral antenna field. This special issue of Electromagnetics reflects the latest development in thisfield. It includes seven papers that encompass the following topics:

� Su et al. present a simplified integral equation that can handle an arbitrarily shaped wirecovered with a thin dielectric material. They apply this equation to a two-arm spiralantenna coated with a thin dielectric material and solve it by using the method ofmoments. The effects of the dielectric material on the antenna characteristics arerevealed.

� A curl antenna is a single turn spiral fed by a vertical wire. Shafai presents a modifiedcurl antenna that radiates a tilted beam. The investigation covers array antennas com-posed of tilted-beam curls for mobile communications.

� Hirose, Wada, and Nakano also present an application of the curl antenna to the gen-eration of a circularly polarized conical beam. The axial ratio is improved by using par-asitic elements near the feed wire of a curl array antenna.

� Nakayama and Nakano investigate arrays composed of several rectangular spiralsabove a cylinder to obtain an omnidirectional pattern in the horizontal plane perpen-dicular to the cylinder axis. The mutual coupling effects among the spirals are revealedby comparing radiation patterns obtained using the method of moments and the patternmultiplication method.

� Spiral structures have inherent broadband radiation characteristics. Wang refers to aspiral-mode microstrip antenna, showing experimental results over a bandwidth of 9:1.The Voltage Standing Wave Ratio (VSWR) and the radiation pattern over this band-width are discussed.

� Nurnberger and Volakis also refer to the broadband characteristics of a spiral antennaconsisting of slot radiating elements. The antenna is backed by a shallow cavity. Theradiation characteristics of 6.25:1 and 15:1 bandwidth slot spirals are discussed.

� Conventionally,printed antennas are analyzed based on the assumption that the dielec-tric substrate on which the radiation elements are printed is of infinite extent. Kawano,Tago, and Nakano analyze a spiral antenna printed on a finite-size dielectric substrate.The current distribution is obtained by using the finite-difference time-domain method.A method for reducing the cross-polarization component is presented and a circularlypolarized conical beam is realized.

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270 H. Nakano

Circularly polarized antennas are gaining greater acceptance in wireless communica-tions, particularly, for mobile systems. Correspondingly, both theoretical and experimentalresearch on spiral antennas will continue, contributing to the better understanding and designof circularly polarized radiation elements. I hope that the topics in this special issue willbecome the basis of future work on spiral antennas.

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