An electrically small low-profile and ultra-wideband antenna with monopole-like radiation characteristics

Abstract

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 λminis the free-space wavelength at the lowest frequency. The antenna has a kmina = 0.59, where kminis the wavenumber at the lowest frequency of operation. The frequency band covers LTE (0.7GHz), BDS (1.268 GHz), GPS (1.575 GHz), WIFI (2.5GHz) and WIMAX (3.5GHz).