Winfrey has the highest-rated TV talk show in the US

It features a show presented by Winfrey and her best friend, Gayle King, on where they discuss news and gossip.

Poet and civil rights activist Maya Angelou also hosts a show, along with several personalities from Winfrey's TV talk show and magazine O.

Broadcaster XM Satellite Radio will be hoping Winfrey can bring some of her 30 million TV viewers to its service.

The Oprah Winfrey Show has been America's highest-rated talk show for 18 consecutive series.

Female appeal

But financial analysts say the star's radio channel might not have the same impact.

"Oprah is not a radio personality, she's a TV personality," Kit Spring of investment bankers Stifel Nicolaus told Reuters.

"She mainly appeals to women and probably won't compel that many potential subscribers to go out and buy a radio."

Shares in XM Satellite Radio have halved in value this year over concerns about aggressive spending and a federal investigation into the broadcaster's marketing practices.

However, it is the largest satellite radio service in the US, with more than seven million subscribers.

Winfrey signed a three-year $55m (�31m) deal with the broadcaster in February.

Her channel will largely focus on lifestyle and advice programmes, and regular hosts include personal trainer Bob Greene, financial expert Jean Chatzky and design guru Nate Berkus - who all feature on Winfrey's TV show.