Experimental studies of a miniaturized CPW-fed slot antenna with the dual-frequency operation

Several practical techniques have been employed to modify the operating frequency, enhance the bandwidth and miniaturize the antenna size for a small coplanar waveguide (CPW)-fed slot antenna at 2.4 and 5.2 GHz, the industrial-scientific-medical (ISM) bands. These techniques include: utilizing an E-like feeding structure instead of the conventional T-shaped one; adding a matching stub at the slot edge; adding four floating patches on the bottom plane of the substrate. In experiments, the -10 dB bandwidths achieved were 220 and 600 MHz at 2.4 and 5.2 GHz, respectively. The proposed CPW-fed slot antenna not only creates the dual resonant frequency bands, but the antenna size is also reduced to approximately 60% of the traditional slot antenna. The E- and H-plane radiation patterns of the proposed CPW-fed slot antenna were measured at 2.45 and 5.2 GHz.