Clearwire, enriched with new pledges of WiMax spectrum and financing, released improved subscriber and revenue figures for its first quarter and said it planned to begin rolling out mobile WiMax before the end of the year.

Reporting a 72% subscriber growth to 443,000 and a 76% revenue growth to $51.5 million, Clearwire said it expects its new partnership with Sprint Nextel and others will close during the fourth quarter. The company's loss in the quarter jumped to $176 million from $96 million in the same quarter in 2007.

"We believe that the accelerated deployment of our mobile WiMax nationwide network will create a compelling opportunity to deliver the products and services that consumers want -- combining mobility and speed, with access anytime and anywhere, at home or away," said Benjamin Wolff, Clearwire's chief executive officer, in a statement. He added that 27 of its 46 U.S. markets have reached accounting EBITDA-positive status

Created by wireless pioneer Craig McCaw, Clearwire is working to deploy a nationwide WiMax network and last week picked up important support from Sprint Nextel, which donated a wide swath of spectrum to the joint venture and will own 51% of the new Clearwire. Other major investors include Intel and Google.

In a telephone session after the financial results were released, Wolff said its flagship 147-square-mile deployment in Portland, Oregon, is being prepared for a soft launch later this year. "The deployment of our mobile WiMax network in Portland continues to make excellent progress and we are pleased with the success that our vendor partners are having with the development of mobile WiMax enabled devices," said Wolff.

The company is offering PC cards, residential modems, and USB dongles for its service. Clearwire said it expects to sign up more than 500,000 subscribers by the end of the year and reach between 60 and 80 million persons by the end of 2009.

Subscribers, most of them receiving residential broadband services, currently are getting fixed WiMax. Clearwire plans to begin to switch over to mobile WiMax later this year.