The DM N4-4 navigation antenna is a true center-fed antenna which minimizes bearing errors when receiving VOR and ILS signals. The N4-4  provides considerably more gain at the horizon than fuselage mounted ""deer horn"" or ""vee"" antennas. Improved signal to noise ratio and reduced errors is due to the N4-4 greater discrimination against vertically polarized signals, and when properly installed on helicopters greater rotor modulation rejection is also provided. To obtain maximum performance, the installation location must be carefully considered. This N4-4 navigation antenna (EDMO# DM N4-4.1) is a single radiating element only.