Wayne Parham Messages: 18748 Registered: January 2001
Illuminati (33rd Degree)
You can measure off-axis response to find its directivity. As a general rule, DI increases as frequency rises and it reaches 10 at the frequency where wavelength equals the diameter of the radiator. The moving surface of the cone (minus suspension) is all that should be considered to be the radiator and the geometry of the cone and any cap can also modify directivity. But as a general rule, DI = 10 when dia = λ.