Radiation Efficiency and Gain Bounds for Microstrip Patch Antennas

This paper presents radiation efficiency and gain bounds for microstrip patch antennas. The presented bounds are shown to be good predictors of antenna performance. Using the bounds, patch miniaturization techniques based on high permittivity substrates and geometrical shaping are compared. Further, a semi-analytic model is developed to approximate the bounds. Measurements are used to validate the bounds. Finally, maximum bandwidth of a microstrip patch antenna is linked to its maximum radiation efficiency.