Since IEEE 802.11af was standardized in 2013 as one of the standards for TVWS (TV white-spaces) communication, a variety of radio devices such as a high-power radio device al-lowing a transmission power of 1 W and a dongle-type com-pact radio device have been prototyped and demonstrated in field experiments. Meanwhile, since all the reported prototypes were limited to a single channel operation with a channel bandwidth of 6 MHz, achieved throughput was inferior to the commercialized WLAN (Wireless Local Area Network) systems with a channel bandwidth of 20 MHz or more. In this paper, to enhance the throughput of the IEEE 802.11af system, we de-sign and prototype a radio device based on IEEE 802.11af with a channel aggregation function. In addition, we evaluate fun-damental characteristics of the prototype radio device including radio performance and throughput.