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.