Design of a Dual-Band Loop-Type Ground Antenna Using Lumped Elements

Abstract

This thesis proposes a promotional antenna of loop-type ground antenna for dual-band characteristics. The existing loop-type ground antenna did not have dual-band characteristics. A dual band loop-type ground antenna is proposed, which is able to adjust the impedance bandwidth and resonant frequency by using lumped-element for wireless local area network (WLAN) applications. Consequently, the proposed antenna needs no additional matching network. The dual-band operation of the proposed antenna is realized by inserting an additional resonated loop feed structure into the existing loop-type ground antenna. As the proper value of the capacitor and the inductor are chosen, the impedance bandwidth of our antenna with voltage standing wave ratio (VSWR) equal to 3 is 85 MHz and 725 MHz at the 2.45 and 5.5 GHz frequency band, respectively. Its validity is demonstrated via both the computed and measured results. Good antenna patterns and efficiencies are achieved at the dual frequency band, as well as the physically small antenna element size of 10 � 5 mm2.