Long Term Evolution (LTE) system adapts advanced Multiple Input Multiple Output (MIMO) antenna techniques on both uplink and downlink to achieve high peak data rates and higher system throughput. This enables LTE to support multimedia applications beyond web browsing and voice, which demands higher bandwidth configurations. LTE employs Orthogonal Frequency Division Multiple Access (OFDMA) in downlink to support spectrum flexibility in order to use upto 20MHz system bandwidth to improve the system throughput and robustness. Therefore the combined study of multi-antenna techniques and spectrum flexibility usage on the performance of LTE system becomes vital. Hence in this paper, an attempt has been made to evaluate the performance of different multi-antenna techniques with various system bandwidth configurations from 1.4MHz to 20MHz using QualNet 5.2 network simulator. The multi-antenna techniques considered for performance evaluation are Single Input Single Output (SISO), Multiple Input Single Output (MISO) and Multiple Input Multiple Output (MIMO). The performance metrics such as aggregate bytes received, average throughput, average delay and average jitter are considered for simulation study