cardinal radial
Eight imaginary straight lines extending radially on the ground from an antenna location in the following azimuths with respect to true North: 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°. [47CFR]
Note: The four radials at 0°, 90°, 180°, and 270° of azimuth with respect to true North are referred to as the cardinal points. The cardinal points are equivalent to true north, east, south, and west.