Compact Folded Triband Monopole Antenna for USB Dongle Applications

This letter presents a compact monopole antenna for universal serial bus (USB) dongle applications. A simple folded monopole is selected in order to obtain a triple-band antenna that can be used in the 2.4/3.5/5.2/5.8-GHz bands, utilizing a limited space of 10 × 15 mm
²
. This structure is easily manufactured by connecting the metal pattern implemented in the upper and lower sides of a substrate through vias. Various parameter studies display that f
₁
and f
₂
are adjusted by the overall length of the antenna and coupling between the metal pattern in the upper side and the metal pattern in the lower side, respectively. Also, the studies show that /3 can be adjusted by the metal pattern implemented in the upper side of the substrate and matching stub. The measurement results show that 10-dB bandwidths are 8.4% (2364~2572 MHz), 17.62% (3054~3622 MHz), and 10.81% (5262~5859 MHz) at the three resonance frequencies.