Design and analysis of internal antenna for mobile handsets

Abstract

In Webster``s Dictionary, an antenna is defined as ``a usually metallic device (as a rod or wire) form radiating or receiving radio waves.`` In other words the antenna is the transitional structure between free-space and n guiding device, and it is used to transport electromagnetic energy from the transmitting source to the antenna, or from the antenna to the receiver. Recently, in the competitive mobile phone market, there are several trends toward antennas: small, multi-function, multiband, broadband, low cost, and so on. The advent of these trends is a real challenge for antenna designers and accordingly mobile antennas integrated into the handsets or internal antennas have become a desirable candidate for them. Internal antennas offer many advantages over the conventional external antennas such as whip and helix ones. They are less prone to damage, compact in total size and aesthetic from the appearance point of view. In general, the antenna performances of mobile handsets are sensitive to the near components because internal antenna is placed on inside of handsets. Therefore, it is essential to obtain the data about material properties which are used to designing antennas, and the antenna design should be taken into account the effect of their surrounding components including shielding case, screws, case, and battery. In this thesis, the material measurement using the kit of Damaskos Inc. is proposed and two internal antennas for multi-band operation of mobile handsets are designed. First of all, the theory and method of measuring material characteristics are introduced. Also, the results which are obtained by using the kit of Damaskos Inc. is presented. Secondly, a triple-band built-in antenna operating at GSM, DCS, and IMT-2000 are proposed. The proposed antenna which is PIFA(Planar Inverted-F Antenna) type structure consists of the double shorting posts, feed post, and the dual crossed C-slot patch radiators. The bandwidth for covering GSM, DC...