Shares of Andrew Corp. ( ANDW) plunged Monday as investors ignored the company's doubling of third-quarter profit and focused on disappointing guidance for the fourth quarter.The company's shares were lately down $3.77, or 25.5%, to $11. The Orlando Park, Ill.-based wireless infrastructure designer said third-quarter earnings rose to $17.7 million, or 11 cents a share, up from $7.6 million, or 8 cents a share. Excluding an amortization charge of 3 cents a share in the latest quarter, the company earned 14 cents a share, beating analysts' estimates by a penny. Sales more than doubled to $493 million from $213.7 million, led by high demand in the broadband satellite market and wireless infrastructure, as well as the acquisition of Allen Telecom in the fourth quarter of 2003. For the fourth quarter, the company said it expects earnings of 4 cents to 7 cents a share, which includes about 6 cents a share on restructuring and amortization costs. The company also anticipates revenue of $460 million to $490 million. Analysts had been expecting earnings of 16 cents a share, excluding the charge, on revenue of $489 million. Andrew anticipates that gross margins will decline in the fourth quarter because of an adverse product and geographic mix shift. Research and development and selling and administrative expenses are expected to be relatively flat to modestly down on an absolute basis compared with the third quarter.