Two design parameters, SNR and correlation, are key factors for enhancing channel capacity in MIMO systems. Achieving high SNR and low correlation is desirable in antenna design. This paper discusses the relation between channel capacity and these two parameters, and presents simple formulas of this relation for propagation channels and antenna coupling of mobile terminals. According to these guidelines, indoor base station antennas are designed and examined using propagation measurements. We also present a suitable antenna design for mobile terminal antennas and based on a realistic propagation model, predicted the channel capacity of the antenna.