HIGH ZENITHAL DIRECTIVITY FROM A DIPOLE ANTENNA ON A PHOTONIC CRYSTAL

A strip dipole on a (111)-oriented face centered cubic photonic crysta l is found to have a copolarized directivity and radiative gain of 9.1 and 7.2+/-1.4, respectively, along the zenith and at a frequency in t he first stop band of 18.0 GHz. Under the same conditions, the maximum copolarized directivity and radiative gain were 10.0 and 8.1+/-1.6, r espectively, in the H-plane 5 degrees down from the zenith. The zenith al results correspond to a 5.5-times greater radiation intensity than displayed by the same dipole in free space. From power balance measure ments, only 10% of this enhancement is attributed to superior power tr ansfer between the generator and antenna. The remainder is associated with constructive interference between the primary antenna radiation a nd radiation reflected from the crystal. (C) 1996 American Institute o f Physics.