Microstrip line and CPW fed ultra wideband slot antennas with U-shaped tuning stub and reflector

Abstract

Wideband printed rectangular slot antennas backed with reflectors for unidirectional radiation patterns are investigated. A U-shaped tuning stub is used to improve the matching. Two different feeding mechanisms are introduced. A rectangular slot excited by microstrip line feed with a U-shaped tuning stub gives an impedance bandwidth of 110% (|S11| < -10dB). When the rectangular slot is excited by a coplanar waveguide (CPW), it gives an impedance bandwidth of 120%. Both slot antennas radiate broadside across the matching band, with front-to-back ratios of 20dB.