Curl antennas over electromagnetic band-gap surface: a low profiled design for CP applications

The curl antenna was proposed as a simple radiator to generate circular polarized electromagnetic waves (see Nakano, H. et al., 1993). The design has been suggested for applications in wireless communications (see Colburn, J.S. and Rahmat-Samii, Y., 1996). However, it cannot work well when it is placed close to a finite PEC ground plane due to its reverse image. Recently, the electromagnetic band-gap (EBG) surface, also referred to as photonic band-gap (PBG) surface, has attracted researchers´ interest because it has a potential to build low profiled and high efficiency antennas (see Sievenpiper, D. et al., 1999; Zhan Li and Rahmat-Samii, Y., 2000). The square curl antenna over an EBG surface is investigated in depth. Compared to the conventional curl antenna, it has the attractive feature of low profile as well as circular polarization. The antenna height, ground plane size and band-gap effect are analyzed in detail by the finite difference time domain (FDTD) method. This low profiled CP antenna is suitable for GPS, LAN, satellite links and other wireless communication applications.