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International Journal of Antennas and Propagation
Volume 2015, Article ID 954562, 11 pages
Research Article

A Low-Profile and Compact Split-Ring Antenna with Horizontally Polarized Omnidirectional Radiation

1Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang, 1, Chalongkrung Road, Ladkrabang, Bangkok 10520, Thailand
2Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan

Received 25 August 2014; Accepted 22 October 2014

Academic Editor: Guo Qing Luo

Copyright © 2015 Kittima Lertsakwimarn 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.


This paper presents a low-profile and compact printed antenna having an omnidirectional radiation pattern with horizontal polarization to the ground. The proposed antenna consists of an inner small fed ring, an outer coupled split ring, and a ground plane. The overall dimension of the proposed antenna is 45 mm × 50.5 mm × 11.6 mm (0.138λ0 × 0.155λ0 × 0.036λ0). The −10-dB of the antenna covers the 920-MHz RFID band, and the gain is about 1.45 dBi in the parallel direction to the ground plane. The measured results show good agreements with the simulated results. Furthermore, the reasons for the low-profile structure and the omnidirectional radiation pattern are also discussed.