Aperture-coupled patch antenna on UC-PBG substrate

The recently developed uniplanar compact photonic bandgap (UC-PBG) substrat e is successfully used to reduce surface-wave losses for an aperture couple d fed patch antenna on a thick high dielectric-constant substrate. The surf ace-wave dispersion diagram of the UC-PBG substrate has been numerically co mputed for two different substrate thickness (25 and 50 mil) and found to h ave a complete stopband in the frequency range of 10.9-13.5 and 11.4-12.8 G Hz, respectively. The thicker substrate is then used to enhance broadside g ain of a patch antenna working in the stopband at 12 GHz. Computed results and measured data show that, due to effective surface-wave suppression, the antenna mounted on the UC-PBG substrate has over 3-dB higher gain in the b roadside direction than the same antenna etched on a grounded dielectric sl ab with same thickness and dielectric constant. Cross-polarization level re mains 13 dB down the co-polar component level for both E- and H-planes.