There is no cut and dry exact answer for this either as much of the requirement is dependent on the neighborhood and the area the antenna is mounted. As a general rule of thumb, the higher the antenna is mounted the better it is for signal strength and visual quality. However, it is neither practical nor sane to build a tower just for your antenna. 30 feet above the ground is usually the ideal height to receive most over the air signals. This means that you could mount the antenna on the roof of most single-storeyed buildings and have reasonably good signal strength. Signal strength is highly dependent on what structures surround the area that surrounds the signal receiver. A small house that is surrounded by large apartment complexes would need the antenna to be mounted much higher than normal in order to work as intended.