Ultrawideband (UWB) communication systems require compact, inexpensive antennas. Because the enhanced impedance bandwidth of UWB antennas is an important aspect, several different methods have been investigated. Filtering is also required in UWB systems to avoid interference with other communication systems. This interference can occur with wireless local-area-networking (WLAN) systems operating at 5-GHz frequencies. It is therefore desirable to design UWB antennas that incorporate notch filtering to avoid potential interference. A group of researchers from Iran have proposed a compact rectangular slot antenna that incorporates dual-band notch filtering. It can also achieve an enhanced impedance bandwidth.
The proposed antenna was fabricated on a 1.6-mm-thick FR4 substrate. A 50-ohm coplanar-waveguide (CPW) transmission line serves as the feedline for the slot antenna. By cutting the corners of the structure’s rectangular patch while inserting semi-circular slots into the ground plane, the team significantly improved the antenna’s bandwidth. An elliptical-ring-slot (ERS) was etched into the rectangular patch to achieve notch filtering in the 5-GHz WLAN frequency range. To implement notch filtering in the 3-GHz range, two S-shaped slits were incorporated into the ground plane.
See “Very Small Dual Band-Notched Rectangular Slot Antenna With Enhanced Impedance Bandwidth,” IEEE Transactions on Antennas and Propagation, Oct. 2015, p. 4,529.