What is an advantage of downward sloping radials on a ground plane antenna?

A standard quarter-wavelength ground plane antenna with perfectly horizontal radials typically has a feed point impedance of about 35 to 36 ohms. While this is usable, it represents a slight mismatch for standard 50-ohm coaxial cable and transmitters. By bending or sloping the ground radials downward (usually at about a 45-degree angle), the feed point impedance is raised to approximately 50 ohms. This provides a near-perfect match for standard 50-ohm coax, eliminating the need for external matching networks. Although changing the angle of the radials can have a very minor effect on the radiation angle, the primary, practical reason amateur radio operators slope them is to achieve this 50-ohm impedance match. 300 ohms is incorrect, as that impedance is typically associated with folded dipoles or twin-lead feedlines.