AN ELECTRICALLY SMALL LOW-PROFILE AND ULTRA-WIDEBAND ANTENNA WITH MONOPOLE-LIKE RADIATION CHARACTERISTICS

This paper presents an electrically small, low-profile and ultra-wideband antenna with monopole-like radiation type. The antenna is composed of a top-loading hat and two tapered radiation patches on the crossed substrates shorted to the ground. Introducing two tapered radiation patches with the meander loop traces allows for achieving ultra-wideband operation and very low profile simultaneously. In addition, two columns of metal via-holes nested in the crossed substrates can broaden the bandwidth further. The proposed antenna is simulated, fabricated and measured. The measured and simulated results show good agreement and indicate that a measured VSWR lower than 2.0 over 632–3907 MHz (a 144% relative bandwidth) can be accomplished. The antenna has a low profile (0.053λmin) in height and occupies a small circle of radius 0.078λmin, where λmin is the free-space wavelength at the lowest frequency. The antenna has a kmina = 0.59, where kmin is the wavenumber at the lowest frequency of operation. The frequency band covers LTE (0.7 GHz), BDS (1.268 GHz), GPS (1.575 GHz), WIFI (2.5 GHz) and WIMAX (3.5 GHz).