In this study, we consider a wireless communication system in a point-to-point fading channel with additive white Gaussian noise. The relationship between consumed energy on sampling and decoding processes at the receiver side is a known fact. Accordingly, a receiver model that has two antennas combined with maximal ratio combining technique is considered and energy consumptions of such a system on sampling and decoding processes are evaluated. Total energy consumptions of both systems are compared under various data rates. The results show that the receiver model with two antennas consumed less energy on high data rates; however, using the receiver model with single antenna when the data rate is significantly low is more efficient.