Analysis and Design of a Cylindrical EBG-Based Directive Antenna

Abstract

Abstract-In this paper, a cylindrical electromagnetic bandgap (CEBG) structure composed of infinite metallic wires is analyzed, designed and used as a model to develop a new reconfigurable directive antenna. This structure is circularly and radially periodic, and it is excited at its center using an omnidirectional source. The analysis is based on calculating the transmission and reflection coefficients of a single cylindrical frequency selective surface (FSS) and then, considering only the fundamental mode interaction, deducing the frequency response of the CEBG structure composed of multiple cylindrical FSSs. For this structure, new analytical formulas are derived, and their accuracy is assessed compared to those obtained by the finite-difference time-domain method. As in rectangularly periodic structure case, the frequency response of the CEBG structure exhibits pass-bands and bandgaps, and it is possible to obtain directive beams by introducing defects in the periodic structure. Using this concept, a new antenna was developed to obtain a controllable directive beam. An antenna prototype, without control, was designed, fabricated, and tested. An excellent agreement was obtained between theory and experiment for both return loss and radiation patterns.

Comparison of Scattering Characteristics between Cylindrical Infinite and Finite Periodic Structure

“…Wire에 유기되는 전류를 표현하기 위해 아래와 같은 triangular sub-domain 기저 함수를 이용하였다. 의 공진 특성이 일어날 때, 바깥으로 공급되는 전원이 더 크게 되기 때문이다 [8]～ [10] . …”

Focusing Characteristics of a Metallic Cylindrical Electromagnetic Band Gap Structure With Defects

“…This coefficient is plotted in Fig. 2 by using the semi-analytical method proposed in [10]. From Fig.…”

“…8 and 9, respectively. The coefficient |T 3 | is the response of the structure considering the multiple reflection with the center, whereas the coefficient |t 3 | is the response of the structure if the multiple reflections with the center are not considered [10]. From Figs.…”

“…Recently, new periodic structures, Cylindrical Electromagnetic Band Gap (CEBG) structures, have been introduced and used as models to develop new directive antennas or new beam switching antennas [8][9][10]. To obtain the beam switching, the proposed technique consists of creating defects with discontinuous wires in an initial continuous wires structure, in order to obtain a directive beam turning on 360 • .…”

Analysis of different defect configurations in CEBG structures for directive patterns

“…Cylindrical Electromagnetic Band Gap (CEBG) structures are radially and circularly periodic, and they present pass-band and stop-band to cylindrical electromagnetic waves [3]. By applying a horn-shaped defect in these structures, it has been shown that a reconfigurable directive pattern can be obtained [4][5][6]. In [4], experimental results for a reconfigurable CEBG-based antenna have been presented, whereas in [5], an analysis of the transmission coefficient of CEBG structures and experimental results for a CEBG directive antenna have been proposed.…”