TV aerial amplifiers and signal boosters do work. They can help overcome signal losses because of cable resistance and because of the splitting of signals to multiple TV's. They won't however miraculously convert a poor or weak TV signal, into a good reliable signal. But when used right they can fix your signal issues.

Signal amplifiers—most commonly masthead and distribution amplifiers—are sometimes used in television systems to increase the level (strength) of signals received at a television set. They should only be used in areas that receive weaker signals from distant broadcast sites or to provide signals to several television receivers.

A distribution amplifier is installed just before the splitter and is used to amplify the signal for splitting to multiple TVs. ... Some situations may even require both if you are installing multiple TVs with a very long run of coaxial cable between the antenna and splitter.