An HDTV antenna is a piece of electronic equipment designed to receive television broadcasts in the form of electromagnetic signals that are being transmitted "over the air." When a television station broadcasts its programming, it is converted from audio and video information into these electromagnetic signals. The antenna receives the signals, which it then passes along to the HDTV tuner for converting it back into audio and video information.
The main purpose of having an HDTV antenna is to receive broadcasts from local television stations. Almost 90 percent of American households can receive at least five local television stations using only an HDTV antenna. This comes with no monthly cost, as opposed to cable or satellite television services which cost users a monthly fee for access to their programming.
Contrary to what many think, receiving channels from an HDTV antenna actually provides better picture quality than the same channels being received via a cable television provider. Data information is compressed so it can be sent directly into your home via a coaxial cable. The same data is sent out over the air uncompressed, which means it will look and sound better. Cable television obviously offers a far greater quantity and variety of channels than simply having an antenna does, but improved picture quality is a definite advantage of the HDTV antenna.