Reconfigurable Coplanar Inverted-F Antenna With Electronically Controlled Ground Slot

In this article, a coplanar inverted-F antenna with an electronically controlled ground slot enabling reconfigurability is proposed. Initially a quarter wavelength coplanar inverted-F radiator is designed to operate at 900 MHz. To minimize its size, the radiator is folded to occupy an area of about 10 × 40 mm2. Next, a ground slot is introduced to excite another resonance at around 1850 MHz without affecting the 900 MHz operation. The slot is loaded with three pairs of PIN diode switches with simple biasing circuits to vary its resonant frequency. The proposed reconfigurable antenna is fabricated and experimentally tested. A good agreement is achieved between the simulated and measured return loss of the antenna showing the experimental impedance bandwidth covering GSM900, PCS1900 and UMTS2100 services. In these frequency bands, the antenna offers nearly omni-directional radiation patterns with measured peak gain between 1.4 dBi to 3.45 dBi.