Real-time high-definition (HD) video transmission for long distances (.1 km) between an unmanned aerial vehicle (UAV) and a ground station is a challenging problem. The existing real-time solutions are limited to relatively low-quality video streaming, whereas an HD video, which is stored in the local memory, is accessible only when the UAV returns to the ground. In this study, a real-time HD video transmission system (VTS) with a multiple-input multiple-output (MIMO) antenna configuration and state-of-the-art coverage is proposed for security and inspection applications. The proposed VTS employs ultrathin, lightweight antennas that are suitable for seamless integration with a UAVfs body without any protrusion. A 3 × 3 MIMO configuration with large antenna bandwidths (3.9% at 2.4 GHz and 6.9% at 5.2 GHz ) enables the simultaneous transmission of multiple data streams with high data rates (>30 Mbps), and a high antenna gain ( 10 dBi) allows a relatively long communication range (>3 km). In field experiments, the UAV module (comprising thin conformal antennas, embedded electronics, an RF transceiver, and an HD camera) is attached to a commercial drone DJI Matrice 600 Pro. The HD videofs reception performance is investigated for operation in two frequency bands (2.4 and 5.2 GHz) for both horizontal and vertical antenna orientations. The maximum and average data rates for various distances are reported. Based on the conducted field experiments, it is found that the proposed VTS is capable of transmitting real-time HD video up to a 3.56-km distance with a receiver sensitivity of.76 dBm. The maximum achieved data rates at a 500-m distance are 10 and 43 Mbps for operation in the 2.4-and 5.2-GHz frequency bands, respectively.