A wideband cavity-backed patch antenna is presented for operating at PCS (Personal Communications Service), IMT200 and 2.4GHz WLAN (Wireless Local Area Network) bands. A parasitic patch and a probe with a capacitor patch are used to enhance the bandwidth. The cavity-backed and without cavity-backed antenna has been compared. It has been found that the cavity backed antenna has wide impedance bandwidth of 43% and high gain level. It can simultaneously serve most of the modern wireless communication applications that operate at 1.7GHz-2.5GHz.