Internal Dual-band Patch Antenna for Mobile Phones

Development of small antennas for mobile phones has received a lot of attention during the last few years due to size reduction of the handsets, requirements to keep the amount of RF power absorbed by the user below standardized levels regardless of the handset size, and introduction of multimode phones. Single-band and dual-band phones in which the external whip or helix antenna has been replaced by an internal shorted patch antenna (or PIFA) are already in the market. It may be assumed that in the future there will also be a need for internal antennas which operate in several communication systems. In this paper, a multiresonant dual-band internal handset antenna is introduced. The antenna is based on the dual-resonant antenna structure reported in [1]. To our knowledge, this is the first internal handset antenna which covers the E-GSM900 (880 MHz 960 MHz), GSM1800 (1710 MHz 1880 MHz), DECT (1880 MHz 1900 MHz), PCS1900 (1850 MHz 1990 MHz), and UMTS (1900 MHz 2170 MHz) frequencies with a return loss Lretn ≥ 6 dB and high radiation efficiency. Previously shorted patch antennas (or PIFAs) with more than one band of operation have been reported e.g. in [2-4]. The dual-band PIFA was introduced in [2]. The idea was extended to multiband PIFAs in [3]. A compact dual-band PIFA with two capacitive feeds was reported in [4].