The 21-GHz band, which has a 600-MHz 2007. However, since rain attenuation broadcasting from much larger than that in the 12-GHz band, powerful countermeasures to improve service availability are ardently desired. Consequently, we are studying broadcasting systems equipped with storage devices to overcome the effects of such heavy rain attenuation in the 21-GHz band. We compare the performances of two systems, i.e., the time diversity scheme and the so-called "long block length interleave transmission scheme" we show suitable applications for the two systems. Finally, we describe a prototype apparatus that was designed and fabricated to verify effectiveness of the long block-length interleave scheme. In the apparatus, we used HDDs (hard disk drives) as storage devices. Since HDDs are not suitable for random access, such as interleaving we inverted "a double-stage interleave method". The successful demonstration of the apparatus using the method is reported.