Analysis of radiation from active microstrip antennas

The current interest in active microstrip antennas has highlighted the need for analysis of the radiation characteristics of such antennas. The paper describes the extension of the small magnetic dipole source analysis of microstrip line discontinuities to active devices. The analysis is then combined with the patch cavity model to form a flexible, approximate analysis suitable for implementation in active antenna computer-aided design packages. Computed results agree well with measurements and show that radiation from the active device and associated matching circuits can be significant. The analysis indicates that reduced radiation pattern perturbation will result from the active device being integrated within the periphery of the patch