Tim Brant is fully aware of his image. He knows people perceive him as the local boy made good, the Mr. Nice Guy among local television sportscasters. But he also is enough of a realist to know that his job with WJLA-TV-7 is basically based on a numbers game -- those wretched ratings -- and he says, "I know I'm in a fight, and I'm fighting back."

He is fighting two big-timers -- Channel 9's wisecracking new rich kid, Glenn Brenner, and George Michael, the Incredible Tape Machine over at Channel 4 -- and he is also fighting that image. But make no mistake, Brant sort of snarls, "'m no naive kid anymore. I know this business is competitive as hell, and I'm prepared to do what I have to do."

Most of all, Tim Brant knows he's got to get better. He knows that he must cut the cliches, eliminate all those "heys" that clutter his copy. He is fully aware that he should use more videotape, that his on-air presence must be more forceful, more assertive, less "Gee whiz folks, did ya' see that?"

But hey, sports fans, he says, give the kid a chance. He has been working in television less than 18 months, and knew nothing about the business when WJLA enticed him away from WMAL radio in September 1979, after he had rejected their advances three times.

Dan Lovett, the man he replaced, says simply, "I think it was a mistake for them to put him in this market his first time in television. I know Tim works hard at it, and I think he does well enough for the kind of support he gets. But they put him in for the first time in the eight market in the country, and that's never done. Ii just hope they give him the time he needs."

Brant insists they are. The station is paying for a coach to help his delivery. He now has his own sports producer, and a new weekend anchor/reporter has been hired. His time on the air and his budget is improving and he says he has been given the go-ahead to search America for the tape he needs to keep up with his rivals around town. And it doesn't hurt at all to have Joe Theismann on the payroll, even if he is an air hog.

Brant's boss, news director Dow Smith, says that Brant has done everything asked of him, and that he is under no more pressure than anyone else at the station. "My feeling is that here's a guy who is new to TV, who knows this area, who wants to do a good job and has a great attitude," Smith says. "I couldn't ask for anything more.

"I think he's made tremendous improvement . . . We've never done a survey that's definitive in where he stands. But I think he's beginning to hit a spark out there. I think people are starting to notice."

Brant thinks so, too. He is convinced he offers a viable alternative to Brenner's one-liners and Michael's highlights. In addition to the usual run of results, he has been concentratingg on local stories, high school features and rankings, human interest pieces he hopes will attract more than the hard core sports fan.

He also has a bit of George Plimpton in him. He has put on pads to play goalie with the Capitals, tried to go one-on-one with a Harlem Globetrotter and, in the piece he's proudest of, gone down the bobsled run at Lake Placid.

Brant, who will be 32 in February, is eminently qualified for that role. He was a standout three-sport athlete at St. John's High, and a starter on defense at the University of Maryland. He had a very brief tryout as a linebacker with the Redskins, and the day he was cut "was the first time in my life somebody told me I wasn't good enough.

"I came home crying, and my wife said to me, 'Hey (it must run in the family), you've got your degree, there's a lot of things you can do.'" Brant, a journalism major in college, started right at the top, and headed for New York and an interview with ABC sports. He was told to about-face to the boondocks for experience.

Instead, he returned to Washington, worked for a pharmaceutical company, then had a successful tryout with WMAL radio. "Those were four of the greatest years of my life," Brant says. "Harden and Weaver taught me how to act, Ed Meyer taught me how to write copy, and they gave me a lot of experience in things I'd never done before."

The first few months at WJLA were not especially joyful.Brant was given the sports job and Mike Patrick, the popular weekend anchor, was the odd man out.

Brant's on-air relationship with anchorman David Schoumacher can hardly be described as warm or cordial either. While Brenner yuks it up with Gordon Peterson, and while Michael and Jim Vance seem like best of friends, Schoumacher's demeanor occasionally makes it appear as if he's telling the audience this would be a wonderful time to go have dessert.

Brant, positive thinker that he is, prefers not to talk about his relationship with the anchor man. He says only that he believes he offers viewers a clear alternative to the other sportscasters, and that he feels he has the resources -- not to mention the talent -- to compete head to head.

"Right now, I feel I'm as good as anyone in Washington," he says. "I think the other guys do a good job, yes, and they've been doing it a long time. They've been deejays, they've been hired and fired, and they're at a point where their routines aren't going to change much. How much better are they gonna get? I think I get better every day I do it, and that's in my favor."