Design of USB dongle antenna for WLAN applications using theory of characteristic modes

A compact universal serial bus (USB) antenna design for wireless USB dongle application is presented. The use of the theory of characteristic modes (CMs) to design such an antenna is novel and leads to a systematic antenna design scheme. The physical insight that the CM offers is of great importance for designing such an antenna. The systematic placing of reactive loads on the antenna body plays a key role in matching the antenna at the desired frequency bands. The proposed antenna´s overall size is (48 × 10 mm) and it can serve the WLAN IEEE 802.11 a/b/g/n bands (2.4/5.5 GHz). It could also be used for the Bluetooth and LTE applications.