UWB loop antenna with stable broadside radiation characteristics

摘要

In this article, a circular loop antenna with stable broadside radiation characteristics for ultrawideband (UWB) applications is proposed. It consists of a circular loop and circular sectors, and the circular sectors are used to directly match a 50- feed line over a UWB frequency band. The geometry of the proposed antenna is optimized to cover the 3.1-10.6 GHz UWB frequency band with stable broadside radiation patterns. The input impedance and voltage standing wave ratio (VSWR) characteristics of three different structures (a center-fed circular loop with thin strips, a structure with circular sectors as an end-truncated semicircular dipole, and the proposed loop antenna with circular sectors) are compared. The optimized proposed antenna is fabricated on a Teflon substrate. It exhibits a measured impedance frequency band of 3.08-12.27 GHz (120%) for a VSWR<2, which ensures operation in the UWB band. Measured broadside gain is 3.0-7.0 dBi, and stable broadside radiation patterns are observed in the entire UWB band. Measured group delay remains almost constant with a variation of less than +/- 0.5 ns for the face-to-face orientation, and this indicates good time domain performance of the antenna. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2515-2519, 2015