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International Journal of Antennas and Propagation
Volume 2013, Article ID 232317, 5 pages
http://dx.doi.org/10.1155/2013/232317
Research Article

A Defected Ground Structure without Ground Contact Problem and Application to Branch Line Couplers

1Soonchunhyang University, Asan, Chungnam 336-745, Republic of Korea
2Chonbuk National University, Jeonju, Chonbuk 561-756, Republic of Korea
3East China of Jiaotong University, Nanchang 330013, China

Received 26 March 2013; Revised 11 June 2013; Accepted 23 June 2013

Academic Editor: Sha Luo

Copyright © 2013 Jongsik Lim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A new defected ground structure (DGS) microstrip line that is free from the ground contact problem is described together with its application example. The proposed DGS microstrip line adopts a double-layered substrate. The first layer contains the microstrip line and DGS patterns on the top and bottom planes as with the conventional DGS line. The second substrate, of which upper metal plane has already been removed, is attached to the bottom ground plane of the first layer. This structure prevents the ground plane of the first substrate with DGS patterns from making contact with the metal housing. The proposed DGS microstrip line has advantageous transmission and rejection characteristics, without the ground contact problem of DGS patterns, which has been a critical problem of previous DGS lines. A 10 dB branch line hybrid coupler is designed and measured, as an example of application of the proposed DGS microstrip line.