Compact dual-band quasi-self-complementary antenna for WLAN application

The concept of self-complementary (SC) antennas was first proposed and investigated by Y. Mushiake in 1948. An antenna with a self-complementary (SC) configuration has constant input impedance and can be designed in a compact manner for wideband operation. Due to these attractive features, SC antennas are highly suitable for wireless communication systems which need wideband operation but have limited room to mount the antenna. In practice, however, it may be more convenient for antenna engineers to design the SC antennas in an imperfect self-complementary manner. Such imperfect SC antennas are called quasi-self-complementary (QSC) antennas. Despite of the imperfectness, QSC antennas still show very good characteristics of broadband operation and nearly constant input impedance. SC and QSC antennas can be designed in a variety of geometries. In this paper, a uniplanar QSC antenna printed on a FR4 substrate with dual-band operation in the 2.4/5.2 GHz WLAN is proposed and investigated. The two operating modes result from the excitation of a monopole and its quasi-self-complementary structure. Because of the stand-alone nature, the designed QSC antenna does not need to connect to a ground plane of large area to obtain a stable performance, thus resulting in a very compact design and suitable for application in wireless devices having limited space to mount the antenna. The antenna design and the simulated and measured results are presented and discussed in the following sections.