Design of quad-band microstrip-fed stubs-loaded frequency reconfigurable antenna for multiband operation

A quad-band microstrip-fed stubs-loaded frequency reconfigurable printed antenna for multiband operation is presented and designed on RO 3003 substrate. The quad-band modes are excited due to integrating three asymmetrical inverted L-stubs in series with vertical rectangular strip above ground plane and circular patch. The predicated impedance bandwidths of 130 MHz (2.35–2.48 GHz), 200 MHz (3.49–3.69 GHz), 900 MHz (5.15–6.07 GHz), and 940 MHz (7.33–8.27 GHz) are achieved for 2.4/5.2/5.5 GHz WLAN, 3.5/5.5 GHz WiMAX and C-band applications. By employing three switches at different locations of stubs and changing the states of switches, antenna exhibits narrowband and wideband functionality with dual-, triple-, and quad-band behaviour while keeping antenna size 20 × 30 mm
²
. The designed antenna realized gain for different states of switches and 3D radiation pattern are analysed and presented.