Cloverleaf filtenna with reconfigurable quintuple rejection bands using defected microstrip structure

Abstract

This paper presents a quintuple-notched Filtenna based on a cloverleaf ultra-wideband (UWB) antenna and an inverted L-shaped bandstop filter (BSF). This filtenna rejects frequencies of Bluetooth (2.4 GHz), Wi-Max (3.5 GHz), Wi-Fi (5.2 GHz), ISM (5.8 GHz), and satellite communications (7.8 GHz). Using the defected microstrip structure (DMS) technique, all notches are obtained. The UWB antenna resonates over a frequency range from 2.1 to 13.6 GHz with double notches at 2.4 and 5.8 GHz, generated by etching two C-shaped DMSs on the patch. Two switches are connected to these two C- shaped slits. Controlling the ON/OFF states of these switches enables notch reconfiguration. The inverted L-shaped BSF suppresses triple notch rejections at 3.5, 5.2, and 7.8 GHz using three DMSs. Similarly, by controlling the ON/OFF states of three switches, frequency reconfiguration is observed. Simulation and measurement confirm that the UWB antenna, the BSF and the filtenna can operate in four states, eight states, and 20 states, respectively. The filtenna has good efficiency (79–95 %) and presents low radiation efficiency at rejection bands. It obtains stable gain (2–5.5 dBi) except at notches where the gain registers negative values. Additionally, this filtenna can freely switch between ultra-wideband mode and any notch-band mode.