A Low-profile Electrically Small Antenna with a Circular Slot for Global Positioning System Applications

A flexible, planar electrically small antenna (ESA) with omnidirectional radiation pattern is designed and fabricated for GPS and WLAN applications resonating at 1.5 GHz and 3.7 GHz.The design consists of a circular loop attached with 3 rectangular bars, and it is fed by a 50 Ω feed line.The circular loop in the antenna provides impedance matching.Generally, these electrically small antennas have narrow bandwidth.Here the antenna is fabricated on a polyimide substrate having a thickness of 0.1 mm, ε r of 3.4 mm, and it occupies a size of 38 mm × 34 mm.Electrically small antenna is designed at 1.5 GHz, 3.7 GHz, and the parameters that are measured are S 11 , VSWR, Ka values, quality factor, and radiation patterns.