In this paper, we study the feasibility of making intelligent antenna selection decision in IEEE 802.15.4 wireless sensor networks. This study provides us the basis to design and implement software defined intelligent antenna switching capability to wireless sensor nodes based on link quality metric, such as Received Signal Strength Indicator (RSSI). As a first step, we discuss in detail the results of our newly designed radio module (Inverted-F Antenna) for 2.4 GHz bandwidth wireless sensor networks. In the second step, we propose an intelligent antenna selection strategy to exploit antenna diversity. To evaluate, we consider TelosB motes and compare the performance of the built-in TelosB antenna with our proposed external antenna in both laboratory and realistic environments. Experimental results confirm the effectiveness of the proposed radio module over the built-in radio module of the TelosB motes.