Why are two antennas typically required for an ILS system?

In an Instrument Landing System (ILS), two antennas are essential because they serve distinct but complementary functions – one antenna is responsible for the localizer signal, which provides lateral guidance to the aircraft, while the other antenna handles the glideslope signal, which offers vertical guidance. The localizer antenna is positioned at the far end of the runway, aligned with its centerline, to assist aircraft in maintaining the proper horizontal approach path. Simultaneously, the glideslope antenna is located near the runway and emits the vertical guidance signal to help the aircraft descend at the correct angle on approach. This dual antenna system ensures precise navigation and safe landings under various visibility conditions.