For 'f' in GHz and 'D' in feet, I always use Gant, dB = 20 log( f x D ) + 7.5
But I think that's for 55% efficiency. If the eff is 60%, that's 20log(60/55) better = another 0.75 dB. So let's make it
Gant, dB = 20 log( f x D ) + 8.25
20 log( 6 D ) + 8.25 = 50
20 log( 6 D ) = 41.75
log ( 6 D ) = 2.0875
6 D = 102.0875
D = 102.0875 / 6 = 20.39 ft = 6.21 meters (rounded, but it looks reasonable; hope it's close)
use a dial indicator
To calculate the outer diameter (OD) of a cylindrical object when you have the inner diameter (ID) and the thickness of the material, you can use the formula: OD = ID + 2 × Thickness. This accounts for the thickness on both sides of the cylinder. Simply add twice the thickness to the inner diameter to get the outer diameter.
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My BIC turntable accomplishes this with a different sized belt pully. They have a U.S. diameter (60 HZ) and a U.K. diameter. Their parts department stock both. Joe
If the wire length is 100m and the Diameter is 1mm calculate the Resistance of wire?
My answer is: http://img854.imageshack.us/img854/4407/50198806.png how i wish i can link [img] [/img] here. sigh...
For any parabolic antenna used to focus radio waves, the following formula is pretty good. GdB = 20 log( F D ) + 7.5 G = the gain of the antenna in dB, compared to an isotropic antenna F = the frequency, in GHz, at which the gain is 'G' D = the diameter of the parabola, in feet The formula assumes that the antenna's efficiency is 50% . If this bothers you and you want to assume 100% efficiency, simply change the ' 7.5 ' to ' 10.5 '. The formula shows that if the diameter of the antenna is doubled, or if the frequency of interest is doubled, then the antenna has four times as much gain ( + 6 dB ).
Precisely measure the diameter (D) of the dish and depth (d) at the center of the dish. With these measurements, calculate the focal length (F) using the following formula: F=D2/16d
Calculate the area of the ball with a diameter of 12 metres
Calculate the sum
diameter = 2 * radius
Double the Radius to Calculate the Diameter.
Radius of a circle = diameter/2
You don't. You can calculate iits radius and cross-sectional area but its diameter has insufficient information to calculate its length
Divide the area by pi (= 3.14159 approx) to get diameter.
Circumference = diameter*pi
Divide the area by Pi to get the diameter.