The study and design of small internal antennas in mobile handsets for communications

Abstract

In the recent time, the industry of mobile handsets has been developed, from mobile devices having the simple operation of voice communications to them containing a large number of functions. Around the worldwide, both communications and broadcasting are fused into one, DVB-H (Digital Video Broadcast) which is the European terrestrial digital broadcasting is not only simple broadcasting technique but also various kinds of services such as anytime, anywhere, anynetwork, anydevice, anyservice, which are supported for customers. RF technique, antenna, and wireless communications technique are required to satisfy demands and qualifications of wideband mobile communications. Especially, antenna technique which is able to operate wideband frequency in mobile communications is the most important core skill to synthesize broadcasting, satellite communications, and mobile communications and to realize a super-highway and wideband wireless multimedia services. As the DVB-H broadcasting service which is a next generation of mobile industry comes into mobile devices, techniques of receiving performance improvement, wideband and multiband operation are needed. The antenna part of DVB-H handsets is the most critical factor in mobile devices because the main reason for a failure of analog TV handset is inferiority of receiving performance. The DVB-H antenna including high effectiveness is hard to miniaturize for a built-in type due to its low frequency operating bands. Fundamentally, the physical length of an antenna structure has to be longer than $\lambda/4$. In the DVB-H applications, an antenna physical length has to be approximately 300 mm. We need a novel concept of internal antenna with various analysis to solve this problem. In this paper, several types of the novel monopole antennas with wideband techniques for the DVB-H mobile broadcasting service in handsets are presented. We studied problems of the frequency shift, bad performance, and bad effectiveness in the s...