The study and design of small internal antenna for mobile communications

Abstract

The wireless communications have been dramatically developed with wireless devices in the last decades. In this competitive mobile phone market, the design of handset devices has been emphasized. In proportion to the importance of handset design, the antenna has been also spotlighted in handset design part. According to recent antenna trend, mobile antenna has been a internal type. Furthermore, the antenna must have small, high efficiency, multiband, broadband, and low cost characteristics. When it is integrated to commercial handset, the antenna should be considered with other handset components such as plastic case, battery, camera, and so on. Accordingly, this tendency of recent antenna design is a real challenge for antenna designer. In this thesis, several internal mobile antennas for wireless communications are proposed. Through analyzing the antenna characteristics, some motivations are explained such as ``why this antenna is developed``, ``how this antenna is designed``, ``what this antenna mechanism is``, ``how this antenna can be applied for commercial wireless devices``, ``which service area this antenna can be applied in``, and so on. And the reflectivity level test for anechoic chamber is accomplished for precision measurement. In this reflectivity level test, other motivations are also explained such as ``how the quiet zone can be decided``, ``what the proper reflectivity level is``, ``where the quiet zone is``, and so on. Firstly, an internal dual band printed antenna for mobile service bands is described. As a modified PIFA type, this antenna has small volume and leads to resonant frequencies with meandered ground line in CDMA and PCS. The proposed antenna dimension is 6$\times$40$mm^{2}$ and total size including PCB is 80$\times$40$mm^{2}$ with 1mm thickness in FR-4 substrate. The operating frequency ranges are 820-970MHz and 1750-1920MHz for VSWR$\lt$2.0 and radiation gains have maximally 0.94 and 1.89dBi for each frequency bands. S...