Characteristics of antennas with folded structure

For a long time, many types of antenna which have folded structure, have been introduced and investigated. In this paper, by investigating some kinds of antenna with folded structure through our previous researches, we discuss theoretically about folded structure and confirm its utility. Firstly, as a motive argument, we investigate the feeding method of folded dipole antenna (FDA) on a ground plane, and then signify its two-resonances and broadband characteristic. Next, by focusing on planar folded dipole antenna (PFDA) and bow-tie antenna (BTA), we show the effectiveness of folded structure in each case from two aspects of impedance adjustment and current pathway changing.