Short Course: Low-profile Natural and Metamaterial-Concept Antennas

Presented by

Hisamatsu Nakano
Hosei University, Koganei, Tokyo, Japan

Abstract

Low-profile antennas have been an ongoing topic of interest in the antenna field for over four decades. Their inherent characteristics of compactness, low aerodynamic resistance, and durability make them attractive for use in modern communication systems, particularly mobile systems and earth-satellite communication systems. As these systems advance, the need for smaller, more robust low-profile designs to meet ever-stricter system requirements has driven the field of low-profile antenna design forward. With this trend has come the need for new antenna design references; this short course is intended to help meet this need, covering recent progress in low-profile natural and metamaterial-concept antennas.

This course is composed of three chapters. Chapter 1 summarizes the analysis methods for low-profile natural and metamaterial-concept antennas. The method of moments and the explicit and implicit finite-difference time-domain methods are briefly described. In addition, an equivalent-circuit representation for metamaterial-concept antennas is presented and useful design equations are explained. Chapter 2 presents the following natural antennas: (N1) Inverted L-F card antenna, (N2) Fan- and elliptical-shaped card antennas, (N3) Fan-shaped base station antenna, (N4) Conducting body of revolution with a shorted parasitic ring (BOR-SPR) for a base station antenna, (N5) Linearly-polarized rhombic grid array for a beam scanning antenna, (N6) Circularly-polarized loop-based grid array for a beam scanning antenna, (N7) Tilted beam high-gain antenna system composed of a patch and an inhomogeneous plate, (N8) Curl antenna array for satellite communications, and (N9) Composite spiral and helical antenna for realizing a tilted beam. In addition, Chapter 3 discusses the following metamaterial-concept antennas: (M1) Line antenna for frequency beam-scanning, (M2) Loop antenna for linearly polarized broadside beam radiation, (M3) Loop antenna for counter circularly polarized dual-band radiation, (M4) Two-arm spiral antenna for counter circularly polarized dual-band radiation, and (M5) Helical antenna for counter circularly polarized dual-band radiation. Note that the antenna heights of the metamaterial-concept loop, and spiral antennas are approximately 1/100 of the wavelength at the lowest operating frequency.