Since this antenna does not come with a preamplifier, you may need to purchase one separately if you have the following issues: - The length of your coaxial wire exceeds 50 feet. - To split the signal into many TVs, you'll need to use a splitter. Using a preamplifier is also recommended if: - The closest TV broadcast tower is more than 20 miles away. - You are installing the antenna on the rooftop. Sometimes, high walls disrupt the signals.