Small Wideband Monopole Antenna With a Distributed Inductive Strip for LTE/GSM/UMTS

We present a small, planar, and dual-wideband antenna for handheld devices, which consists of a driven spiral monopole and a distributed inductive strip designed. A dual-wideband characteristic is realized by using a coupling feed, a distributed inductor, and a folded strip, which excite multiple resonant modes to achieve wide impedance matching. The antenna size is reduced by spiraling of the monopole and meandering and folding of the distributed inductive strip, which occupies 20 ×15 mm². The measured antenna gains and efficiencies are over 0.75 to 1.80 dBi and 60 to 82%, respectively. Radiation patterns are approximately omnidirectional in the x-y (H) planes for all bands: the LTE800, GSM850/900, GSM1800/1900, UMTS, and LTE2300/2500 bands.