This paper presents the effect of an EBG, Electromagnetic Band-Gap structure under a PIFA, Planar Inverted-F Antenna, and its antenna array. The EBG structures have special electromagnetic properties such as high surface impedance and suppression of propagating surface currents within a frequency band, which are very useful for wireless applications. The EBG presented is the AMC, Arti cial Magnetic Conductor, also called mushroom-like EBG structure. The AMC is used as the antenna array ground plane to observe the improvement on characteristics as bandwidth, gain and directivity. The PIFA is a type of antenna which has been used in many communication applications. It is a medium bandwidth radiator with reduced dimensions. A typical PIFA antenna is designed and it is used as element for the antenna array. The antenna array presented achieved a wide bandwidth and has a steerable radiation pattern.2 12681271Chen, Z.N., Hirasawa, K., Leung, K.-W., Luk, K.-M., A new inverted f antenna with a ring dielectric resonator (1999) IEEE Transactions on Vehicular Technology, 48 (4), pp. 1029-1032. , JulyKretly, L.C., Sodrejr, A.C., Tavora, A.A.S., Triangle PIFA antenna array prototype for wireless system applications (2002) IEEE ITS 2002 International Telecommunications Symposium, (CD), , SeptemberD. Jr., C.B., (2000) Adaptative Arrays and Diversity Antenna Configuration for Handheld Wireless Communication Terminals, , Ph.D. dissertation, Faculty of the Virginia Polytechnic Institute and State University, FebruarySievenpiper, D., Broas, R., Yablonovitch, E., Antennas on high-impedance ground planes (1999) IEEE MTT-S International Microwave Symposium Digest, 3, pp. 1245-1248Rahmat-Samii, Y., (2003) The Marvels of Electromagnetic Band Gap (Ebg) Structures: Novel Microwave and Opticap Applications, 1, pp. 265-275. , SeptemberSievenpiper, D.F., (1999) High-impedance Eletromagnetic Surfaces, , Ph.D. dissertation, UCLA electrical department, JanuaryEllis, G., Liw, S., Active planar inverted-f antennas for wireless applications (2003) IEEE Transactions on Antennas and Propagation, 51 (10), pp. 2899-2906. , OctoberClavijo, S., Diaz, R., McKinzie, W., Design methodology for sievenpiper high-impedance surfaces: An artificial magnetic conductor for positive gain electrically small antennas (2003) IEEE Transactions on Antennas and Propagation, 51 (10), pp. 2678-2690. , OctoberMcKinzie, W.E., Fahr, R.R., A low profile polarization diversity antenna built on an artificial magnetic conductor (2002) IEEE Antennas and Propagation Society International Symposium, 1, pp. 762-765Kretly, L.C., Silva, A.M.P.A., The influence of the height variation on the frequency bandgap in an amc, artificial magnetic conductor, for wireless applications: An em experimental design approach (2003) Proceedings of the 2003 SBMO/IEEE MTT-S International, 1, pp. 219-223. , SeptemberGarg, R., Bhartia, P., Bahl, I., Ittipiboon, A., (2001) Microstrip Antenna Design Handbook, , Artech HouseMuscat, A., Parini, C., Novel compact handset antenna (2001) International Conference on Antennas and Propagation, (480), pp. 336-339. , AprilPetrus, P., (1997) Novel Adaptive Array Algorithms and Their Impact on Cellular System Capacity, , Doctor of Philosophy in Electrical Engineering, Faculty of the Virginia Polytechnic Institute, March