The focus of this thesis is to design a dielectric covered discone WLAN antenna working under the protocols of IEEE802.11 a/b/g/n. It has the wideband operation of discone antennas and the compact dimensions of dielectric resonator antennas which is compatible with the latest main protocol WLAN applications. This antenna has an ultra-wide bandwidth (2.25 GHz-6.0 GHz), which is sufficient for the data communication protocols of IEEE802.11 a/b/g/n (2401 MHz-2484 MHz and 5150 MHz-5825 MHz). Its directivity is 3.1 dBi at the lower frequency band and 5.3 dBi at the higher frequency band, which is enough to cover conventional indoor usages. In order to use similar radiation patterns at both operational bands the quad slot is added to the disk. The antenna is quite competitive compared to other commercially used antennas because of its wideband potential: it can be is used not only in WLAN applications, but also for other ultra-wideband applications.