Design and analysis of defected ground structure transformer for dual-band antenna

• Main Authors: Wai-Wa Choi, Ka Fai Chang, Chon Chio Leong, Pedro Cheong, Kam Weng Tam
• Format: Article
• Language: English
• Published: Wiley 2014-12-01
• Series: The Journal of Engineering
• Subjects: monopole antennas; planar antennas; multifrequency antennas; impedance convertors; defected ground structures; antenna radiation patterns; UHF antennas; defected ground structure transformer; dual-frequency DGS impedance transformer; dual-band antenna design; planar antenna structures; monopole antenna; monopole radiation patterns; frequency 2.4 GHz; frequency 900 MHz; loss 900 dB; bandwidth 34.4 MHz
• Online Access: http://digital-library.theiet.org/content/journals/10.1049/joe.2014.0275

This study presents a novel dual-band antenna design methodology utilising a dual-frequency impedance transformer with defected ground structure (DGS). The proposed dual-frequency DGS impedance transformer generates a second resonant frequency from a conventional single-band antenna, resulting dual-band operation. Simulation studies illustrate that the adopted design achieves versatile configurations for arbitrary operating frequencies and diverse input impedance ranges in planar antenna structures. To experimentally verify the proposed design methodology, a dual-frequency DGS impedance transformer was implemented for a 2.4 GHz monopole antenna to obtain a 900/2400 MHz dual-band antenna. Measurement shows that the 10 dB return loss bandwidth in 900 MHz band is 34.4 MHz, whereas that in 2400 MHz band is wider than 530 MHz. Typical monopole radiation patterns are observed at both operating bands.