alternatives to a fan in the bath
Water vapor rises, and hotter air rises, so the vent may be doing an adequate job all by itself. Are you unhappy with the rate at which steam disappears? Is your bathroom musty and moldy? Does steamy air get into the other rooms? What are you hoping to solve, fix or improve?
When air leaves the room through this vent, make up air has to come from somewhere. When steamy air leaves, "new" air comes from some other room. This would be through the crack under the door and through other openings.
If you want to get rid of the steam sooner, and not let part of it flow into other rooms after you open the door, think of how you can arrange for more make up air to come into the bathroom, somewhere low. Improving that flow will displace more steamy air more quickly. Bringing in the make up air at a low height helps keep the hot air moving upwards more smoothly as a separate layer, instead of diluting it.