Miniature built-in multiband antennas for mobile handsets

In this paper, we propose a new design for built-in handset antennas in that metal strips as additional resonators are directly connected with a feed strip. With the new design scheme, a quad-band antenna for covering GSM900, DCS1800, PCS1900, and UMTS2000 bands and a five-band antenna for covering GSM900, DCS1800, PCS1900, UMTS2000, and ISM2450 bands for use in mobile built-in handsets are experimentally carried out. Compared with the parasitic form with a shorted strip placed away from the main radiator in the open literature, the size of the proposed antennas can be reduced by an order of 10∼20%, which is desirable since the size of mobile phones is becoming smaller according to consumer preferences. Moreover, the impedance matching for each band of the new antennas becomes easy. The new quad-band and five-band built-in handset antennas are developed within the limits of a 36×16×8 mm³ volume. The antennas are also analyzed using the finite-difference time-domain technique. A good agreement is achieved between measurement and simulation.