Google has agreed to acquire privately held radio ad firm dMarc Broadcasting for $102 million in cash and additional payments worth up to $1.14 billion if performance targets are met over the next three years.

The plan is for Google to integrate dMarc’s automated technology into its AdWords platform, which would create a new radio ad distribution channel for Google advertisers, perhaps auctioning or discounting unfilled ad spots in the same way as LastMinute.Com does for hotel rooms.

dMarc’s automated ad platform connects advertisers directly to radio stations while simplifying the sales process, scheduling, delivery and tracking of their campaigns.

Google VP/Advertising Sales Tim Armstrong said: “Google is committed to exploring new ways to extend targeted, measurable advertising to other forms of media. We anticipate that this acquisition will bring new ad dollars and accountability to radio by combining Google’s expansive network of advertisers with dMarc’s talented team. We look forward to working together to continue to grow and improve the ecosystem of the radio industry.”

He pointed out that the similarity between the dMarc and Google advertising philosophies had motivated Google to buy the company rather than try to build its own radio advertising network.

dMarc was formed in 2004 and is run by Chad and Ryan Steelberg, who serve as CEO and president, respectively. The brothers previously founded Adforce, an online advertising firm acquired by CMGI Inc. in 1999 for $500 million in stock, and Broadband Digital Group, a now defunct provider of free broadband access.

Google already has bought ads in print publications such as tech magazines and resold chunks of the space to its online advertisers.