While arched doorways add height and elegance to your home, they can also make an area feel too open. If you are trying to put an office or similar work area into a room that is accessed through an arched doorway, you need to cover it up in some way. There are a number of methods that you can use to cover your arched doorway that will give you both privacy and style.
Hang large blinds directly over the doorway. Blinds create a solid rectangular panel that runs from ceiling to floor. They provide a solid look, and they are suited to a space in which long, horizontal lines add to the existing architectural elements.
Mount a curved curtain rod over the top of the door, and thread curtains over it. You may need to trim the curtains as they hang on the rod, and then hem them.
Mount a long curtain rod across the wall where the arched doorway is located, and hang a curtain over it. This allows the curtains to hang straight without a need for trimming. Use a brightly colored curtain to give the wall some visual variety. This essentially allows you to add an accent wall without using any paint at all.
Stretch a folding screen across the arched doorway. While this leaves the top exposed unless you purchase a tall screen, it provides you with a rigid barrier between the room and the rest of the house.