P. Jearapraditkul's research while affiliated with King Mongkut's Institute of Technology Ladkrabang and other places

This paper presents a coplanar waveguide (CPW) fed rectangular slot antenna with tuning stub and pi-strip for WLAN and WiMAX (2-6 GHz) applications. Simulation results show that the impedance matching for the proposed antenna depends on the location of the tuning stub and pi-strip, and the impedance bandwidth is mainly determined by the width and length of tuning stub. The bandwidth of slot antenna can achieve 116% (1.8-6.75 GHz). The radiation patterns are bi-directional and maximum gain is 4.8 dBi at 5.8 GHz.

The coplanar waveguide fed slot antenna with inset tuning stub is proposed for WLAN and WiMAX applications. This antenna consists of a rectangular patch element embedded with a tuning stub fed by CPW feed line. The antenna is designed for match impedance with 50 ohm of characteristic impedance of transmission line by using inset tuning stub for wideband matching. The simulation and measurement results show good agreement operation, which range of bandwidth can be achieved from 1.65 GHz - 6.35 GHz or 117%, suitable for applications to cover 2.4/5.2/5.8 GHz of WLAN bands and 2.5/3.5/5.5 GHz of WiMAX bands. The characteristics of antenna are proposed and analyzed for return loss, bandwidth, current distribution, voltage standing wave ratio and far field radiation patterns.

The coplanar waveguide fed slot antenna with inset L-stripe tuning stub is proposed for UWB applications. The antenna consists of two rectangular slots separated by center strip with CPW feed line. This antenna is design for match impedance with 50 ohm of characteristic impedance of transmission line by using inset L-stripe tuning stub for wideband matching. By adjusting dimension of inset L-strip tuning stub, the range of bandwidth can be achieved 144.6% (1.80 GHz - 11.2 GHz) of the center band coverage standard of IEEE 802.15a for ultra wideband operation. The characteristics of antenna are proposed and analyzed for instance input impedance, return loss, bandwidth, VSWR, and far field radiation patterns.

This paper presents the technique for reducing size of double rectangular slot loop antenna fed by microstrip line for dual frequency. The two difference configurations of double rectangular slot loop antenna are proposed for comparison on bandwidth and size of antenna. These antennas are designed for dual frequency support WLAN system coverage IEEE 802.11b/g (2.4-2.4835 GHz), IEEE 802.11j (4.90-5.091), IEEE 802.11a (5.15-5.35 GHz), and IEEE 802.16d (5.7-5.9 GHz). The PCB-FR4 substrate with dielectric constant (epsivr) 4.5 of thickness 1.6 mm is chose for low cost. The simulation results of these slot antennas are analyzed by using method of moment (MoM) from IE3D software. In this case, the result of bandwidth for low frequency and high frequency of one antenna are 11.29% and 62%, and other are 6.1% and 75.5%, respectively. The size with ground plane of double slot loop antenna can be reduced 12.9% or can be reduced size of double slot loop antenna about 21.5% when set the new inner conductor.