In laymen’s terms, antenna gain refers to the ability of the antenna to focus scattered radio frequency (RF) waves into a narrower, useful plane, thereby increasing signal strength. Antenna gain is expressed in decibels (db), and an antenna with higher gain will be able to make use of weaker signals more efficiently than an antenna with lower gain, all else being equal. In more practical terms, a consumer living at the outer reaches of his or her local networks’ broadcast range, will get better reception using a high-gain antenna than a low-gain model.
Antenna design dictates how efficient an antenna is in gathering the wavelengths it is designed to receive. High gain antennas makes use of extra elements to pull in wayward RF waves, focusing the radiation into a stream along a “flattened” trajectory. In a rough analogy, consider a magnifying glass that focuses scattered sunlight into a beam, greatly strengthening the beam’s power. Elements play the same role, and the ability to focus scattered RF waves results in a gain in signal strength, or antenna gain.
People who have trouble receiving over-the-air (OTA) broadcasts can possibly benefit from a high gain antenna, though it can’t work miracles. Regional topography can reduce broadcast range by blocking or scattering RF waves. Online tools such as those found at TVFool help consumers conduct research that can be useful when it comes to choosing the right antenna. An interactive map displays regional broadcasts, distance, and signal strength. Adjusting antenna height causes results to recalculate, enabling one to see if raising the antenna would result in better reception. Tools also indicate whether or not antenna gain will make a difference.
You might wonder, If antenna gain provides better reception, why not just buy a high gain antenna no matter what? The answer is twofold. A high gain antenna will generally be more expensive than a low gain model, so if you don’t need it, you can save some money. Also, the higher-the-gain, the more important it is to point the antenna exactly towards the station you want to receive. If it is a few degrees off, it might not pick up the signal at all. Therefore, if antenna gain isn’t required, it’s better to buy an antenna that can accommodate a broader angle of reception so that pointing it to an exact spot isn't so crucial.
Aside from height, gain and range, some antennas are made to withstand extreme weather; a good investment for those in harsh climates. Mounting masts are not always included but can be purchased separately along with cabling.
The claim is often made that free-to-air, local HDTV broadcasts come in clearer over roof antennas than through cable or satellite boxes, but your experience could vary. A roof antenna does provide a backup solution for receiving local channels if cable or satellite services are interrupted. Antennas range in price, starting at about $20 US Dollars (USD) for a basic model, extending to over $100 USD.