International Symposium on Antennas and Propagation
Compact Dual-Band Square-Ring Slot Antenna
Shien-Piao Pan, Chao-Shun Yang, Wei-Shan Chang, Jia-Yi Sze,
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Dual-band antennas have become very important in the applications of wireless local-area networks (WLANs) that employ multiple standards. Among these standards, IEEE 802.11b/g requires a band of 2.4-2.484 GHz; IEEE 802.11a, a band of 5.15-5.35 GHz and an additional band of 5.725-5.825 GHz; and HiperLAN2, a band of 5.47-5.725 GHz besides the band of 5.15-5.35 GHz . Since these standards may be simultaneously used in many systems, there is a need for designing a single antenna that can cover all these bands. In recent years, many microstripline-fed slot antennas have been developed for dual-frequency operations -. Although novel in structure and clever in feeding design, these antennas (inclusive of ground planes), if scaled to cover the 2.4 GHz WLAN frequency band, are relatively large. Hence, the objective of this paper is to design a compact antenna that can support the 2.4/5 GHz bands. The size of the proposed microstipline-fed square-ring slot antenna can be greatly reduced by implanting a pair of symmetric bent slots in the center square patch. In the frequency range of interest, the proposed antenna has three resonant modes, whereas the antenna without any embedded slots possesses only two resonant modes. Some structural parameters of the embedded slots can be adjusted to move the two frequency bands and improve their corresponding impedance-matching characteristics.