HHFW experiments on TST‐2 and UTST were performed. In the TST‐2 HHFW experiment, the pickup probe mounted on the inboard wall detected the same PDI lower sideband peak as probes on the outboard side. Since the frequency difference from the pump wave corresponds to the ion cyclotron frequency on the low field side, the lower sideband wave is believed to be generated at the plasma edge on the low field side, and propagated to the high field side. This component may be the FW. In the UTST HHFW experiment, direct measurements of the RF fields in the plasma were made successfully.