Spiral-shaped monopole antenna for quad-band operation of mobile handsets

This article presents the design and fabrication of a quad-band spiral-shaped monopole antenna for application ill a GPS (1575 +/- 10 MHz)/DCS (1710-1880 MHz)/PCS (18.50-1990 MHz) with a UMTS (1920-2170 MHz) band. To obtain sufficient bandwidth in VSWR < 2, an air layer is inserted between the ground plane and the substrate. A spiral-shaped monopole antenna that has a quad-band characteristic is used. Important design parameters are the spiral radiator gap's width and length, the air-gap's height, and the feed point's position. From these optimized parameters, a spiral-shaped monopole antenna is fabricated and measured. The measured results of the fabricated antenna are obtained from all bands at 940 MHz bandwidths in VSWR < 2 referenced to the center frequency, and the individual gain at 2.2 dBi, 2.5 dBi, 2.6 dBi, and 2.0 dBi. The experimental 3 dB beam width is shown to be broad across the pass band in the E-plane, and 74 degrees, 08 degrees, 64 degrees, and 60 degrees, respectively. (c) 2008 Wiley Periodicals, Inc.