Defense contractor Raytheon (RTN) said Monday it has agreed to buy Applied Signal Technology (APSG), which specializes in collecting and processing communication signals to support tactical and strategic intelligence missions, for an aggregate purchase price of approximately $490 million.

The $38 a share price represents an 8.5% premium over Applied Signal's stock closing price on Friday of $35.02, and a 37% premium to its closing price of $27.73 on Oct. 21, a day before it disclosed its intention to explore strategic alternatives. Year-to-date, APSG shares have risen nearly 82%. In fiscal 2009, Applied Signal reported revenue of $202.6 million.

The transaction is expected to close in the first quarter of 2011, and is not expected to have a "material effect" on the earnings of Waltham, Mass.-based Raytheon, the company said.

Applied Signal makes tactical signals and communications intelligence systems, data fusion and information operations/information assurance products with 90% of its sales to classified customers. Raytheon hopes to combine these systems with its own sensor technology, program management, mission support and system integration capabilities.

"Applied Signal brings world class technologies and talent that complement Raytheon's strong intelligence, surveillance and reconnaissance solutions," said Raytheon's Chairman and CEO William Swanson.