60-GHz LTCC Antenna Arrays - Ultra-Wideband and 60 GHz Communications for Biomedical Applications - page 226

Fig. 27 Simulated S
parameters of the proposed
low-loss cross-over structure
with higher dielectric constant and thicker thickness, the strong surface waves will
propagate along the substrate to weaken the radiation performance of the antenna.
For Port H exciting, as Fig. 29 a shows, there is strong electric field from the surface
waves in the area between the antenna elements, in particular along the y -axis.
Due to the surface wave, the original phase of each element has been changed.
Therefore, the radiation performance of antenna array is deteriorated. The proposed
open-ended SICs structure like an electric wall around the antenna element blocks
the surface wave propagating. As Fig. 29 b shows, because of the surface wave
substantially suppressed, the field distribution of the radiation patch elements is
improved obviously. On the other hand, the loss of the surface wave is reduced by
the open-ended SICs structure, more power as the effective radiation to enhance the
gain of the antenna array.
Fig. 28 Geometry of two GCPW-SL transitions. a Port H, b Port V