Powerwave Technologies Inc. agreed to buy Hewlett-Packard Co.'s radio-frequency power-amplifier business and manufacturing facilities for $59 million, the companies said. Irvine-based Powerwave supplies power amplifiers used in wireless phone networks. It had 1997 sales of about $129 million. Hewlett-Packard, the world's No. 3 computer maker, had 1997 revenue of $42.9 billion. The business, part of HP's Wireless Infrastructure division, makes amplifiers for cellular and wireless communications. The companies announced the transaction after the close of U.S. trading. Powerwave's shares fell $1.88 to close at $6.56 on Nasdaq; shares of Palo Alto-based HP fell $2.95 to $48.56 on the New York Stock Exchange.