Multi-Element GPS Antenna Array on an RF Bandgap Ground Plane

Antenna arrays on conventional ground planes present different deficiencies. For compact platforms, the propagation of RF surface currents results in lost power, radiation from the edges and other discontinuities. It also contributes to the strong coupling and causes blind angles and multipath interference. By building radio isolation into the ground plane of phased array antenna structures, it is possible to reduce these different disturbances. This isolation may be achieved by using corrugated surfaces. In this case, DC currents are conducted but not AC currents. Based on the previous work done on PBG structure, a new kind of surface called High Impedance Ground Plane can be used. This kind of ground plane presents the same characteristics are corrugated surfaces in all the directions. Moreover the thickness must no longer be one fourth of the wavelength and can be even much smaller. These ground planes have been applied antenna array in order to reduce the disturbances created on compact platforms. Phase measurements of two-dipole array clearly shows this reduction.