A spiral‐shaped monopole antenna for quad‐band operation of mobile handsets

ABSTRACT: This article presents the design and fabrication of a quad‐band spiral‐shaped monopole antenna for application in a GPS (1575 ± 10 MHz)/DCS (1710–1880 MHz)/PCS (1850–1990 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 2.6 dBi. The experimental 3 dB beam width is shown to be broad across the pass band in the E‐plane, and 74°, 68°, 64°, and 60°, respectively.