Printed lambda/4 folded monopole with printed circuit board slot for penta-band

Abstract

In this paper, a printed /4 folded monopole with a printed circuit board slot is proposed for penta-band mobile terminals. The proposed antenna consists of a folded monopole fed by a coupling feed to reduce the length of the antenna and a printed circuit board slot to obtain an additional resonance in low band. The coupling feed can be represented by a series capacitance which reduces the large input impedance seen at the /4 mode for a conventional folded monopole and leads to a successful excitation of the /4 mode for the proposed antenna. In addition, the open-ended slot with a length of /4 on the printed circuit board is implemented to make an additional resonance. By designing the slot near the feeding point and flowing a surface current on the printed circuit board by itself, the proposed open-ended slot does not require a feed line across the slot. To verify the feasibility, we have simulated and measured the characteristics of the proposed antenna such as reflection coefficient, total efficiency, and far-field radiation pattern. The overall dimension of the antenna is 37.5mm (length) x8mm (width) x0.8mm (height), and the total efficiencies are measured more than 60% in the penta-band.