Plate-loaded folded monopole antenna on a ground-plane edge

A folded Monopole antenna loaded with a rectangular plate placed at the edge of the ground plane is proposed and its characteristics are evaluated by numerical analysis with the FDTD method and by experiments. This antenna is characterized by a structure in which one of the two conductors forming a folded monopole element is a rectangular plate. The structure is suitable for surface mounting on a printed circuit board. In this paper, mainly for an antenna using a dielectric chip with a permittivity of 2.6, the configurations of the feed line and the short-circuited line and the shape of the loading conductor plate affecting the antenna characteristics are investigated. It is made clear that the element height and the shape of the loading plate along the longer side mainly contribute to the determination of the resonant frequency. The changes in the characteristics due to the finite size of the ground plane are studied both from the input characteristics and from the radiation characteristics. It is shown that the present antenna has radiation characteristics essentially identical to those of the monopole antenna and that the disturbance in the radiation patterns is caused by the fact that the length, of one side of the ground plane is close to resonance. Also, the characteristics of the antenna with a helical loading plate and the effect of the permittivity of the core materials used for size reduction of the antenna are evaluated. It is shown that an antenna with the electrical dimensions of the element reduced to one-half can be realized by a combination of the helical loading plate and a material with a permittivity of 10.2. (C) 2004 Wiley Periodicals, Inc.