But WiMax has technological limitations of its own, including the need for line-of-sight connections between service towers in some circumstances and the lack of consistent spectrum available across national borders. A highly touted WiMax venture by SK Telecom in South Korea, where WiMax is known as "WiBro," has been a disappointment, with only about 150,000 Koreans having signed up for it so far, partly because other forms of wireless broadband are already available there.  

There's also the issue of cost: the Sprint-Clearwire deal was driven by the fact that neither company could really afford to build a national network on its own. Michael Rollins, an analyst at Citigroup, predicts that providing nationwide access could eventually cost Clearwire as much as $10 billion (aware of the escalating costs, Clearwire and Sprint had originally planned a looser partnership last year, but talks fell apart at the last minute).

So far, Wall Street's not impressed. Since May, when Sprint Nextel's stake was announced, Clearwire's shares have dropped more than 20 percent. And on May 12, the Kirkland, Washington-based company said its quarterly net loss had nearly doubled from a year ago, to $176.4 million, primarily due to the costs of building out its network and acquiring new customers (Clearwire added 48,000 subscribers in the quarter, bringing its total to 443,000, each of whom pay an average of $37 a month for wireless broadband access). Overall, the company's stock price has plunged by nearly half since its I.P.O. last year.

McCaw, however, remains unfazed, banking on what he sees as huge demand for mobile broadband and the sizable head start Clearwire has over its cellular competitors.

"Deploying the first nationwide mobile WiMax network, admittedly, is no easy task," says McCaw in an email. "But we believe we're well-positioned for success with the key building blocks that are necessary." Among those "building blocks," McCaw cites strong demand for high-speed mobile connections, a big time-to-market lead, plenty of spectrum resources ideally suited for wireless broadband services (with its ability to penetrate walls, WiMax is ideally suited for wireless broadband), substantial financing, and a favorable cost structure (WiMax's range is considerably longer than that of current cellular technology, meaning less towers need to be built).

While his recent record has not been good, when McCaw wins, he wins big. And, as usual, McCaw is confident to the point of arrogance and eager to get on with what may well be the most audacious communications network build-out since the birth of the cellular industry. In other words: Damn the skeptics, and lay on, McCaw.