Radiation-Enhancement Properties of an X-Band Woodpile EBG and Its Application to a Planar Antenna

A woodpile Electromagnetic Bandgap (EBG) material has been designed, by using an in-house code that implements the Fourier Modal Method (FMM). A couple of alumina-woodpile samples have been fabricated. Several results have been collected for the transmission behaviour of the woodpile and of resonators with woodpile mirrors, in a shielded anechoic chamber, by using a vector network analyzer, in the 8-12GHz range. These new experimental data highlight interesting properties of 3D EBG resonators and suggest possible innovative applications. Comparisons of the collected results with FMM show a satisfactory agreement. An application of the EBG resonator has been considered, for gain enhancement of a microstrip antenna: an increase of about 10 dB in the broadside gain has been measured; experimental data and numerical results obtained with the commercial software HFSS show a good agreement. A comparison is presented between EBG resonator antennas and two-dimensional uniform arrays. Finally, HFSS results are provided for EBG resonator antennas working at higher frequencies or with a more selective superstrate: a gain enhancement of more than 18 dB is achieved by such antennas.