a33
Specialised Contributor
- Joined
- Sep 24, 2009
- Messages
- 1,299
- Reaction score
- 745
- Points
- 113
- Age
- 64
- My Satellite Setup
-
XSAT410
Rebox RE-9000
- My Location
- The Netherlands
Yesterday I managed to adjust my excel satellite dish specs calculator, to calculate non-flat paraboloid dishes (such as the zone-1 and -2 dishes in the UK) as well.
Of course you could measure them with the water method (is that from John Legon?), but that measurement procedure is a bit of a hassle, to put it mildly.
I found a way to calculate from 4 measurements of the working area of the dish:
1) dish hight
2) depth of the dish in the middle: from dish surface to the line top-bottom of the dish
3) dish width (from left to right), measured exactly above the middle of the dish
4) depth of the dish in the middle, but now measured from dish surface to the line left-right of the dish.
I did program an algorythm, where in repeated identical steps the exact offset angle, focal distance and focal position are approached better each step.
The end-results fit the paraboloid shape perfectly.
Alas, I myself have no such paraboloid wider-than-high dish. So I did only have 'fictional' input data till now.
So, is there anybody that would like to do those four measurements on a zone-1 and/or a zone-2 dish?
Then I'll post the results of my calculator here.
The measuring should be done about this way:
1. Define the top and bottom of the working area of the dish, and also the left and right of the working area of the dish,
so that the (diamond-)distances top-right, right-bottom, bottom-left, left-top are exactly equal. Put dots (on some tape) on the dish.
(Take care: The left-right dots aren't necessarily on the highest point of the dish rim, I think!)
2. Find the middle of the dish, halfway between top-bottom, halfway between left-right. Put a dot there also.
3. Check that distance top to middle equals bottom to middle, and same for right to middle and left to middle.
4. Measure dish hight, and dish width.
5. Measure depth at the middle twice, as indicated above.
If you measure depth to dish rim, and the dish rim is higher than the dots on the working area of the dish: subtract the mean distance [dish rim to working area dot] from your measurement.
If possible, measure depths more accurately than 1 millimeter!
I'll look forward to the checking if the LNB feedhorn of the dishes is in fact placed at the calculated postion.
Greetz,
A33
Of course you could measure them with the water method (is that from John Legon?), but that measurement procedure is a bit of a hassle, to put it mildly.
I found a way to calculate from 4 measurements of the working area of the dish:
1) dish hight
2) depth of the dish in the middle: from dish surface to the line top-bottom of the dish
3) dish width (from left to right), measured exactly above the middle of the dish
4) depth of the dish in the middle, but now measured from dish surface to the line left-right of the dish.
I did program an algorythm, where in repeated identical steps the exact offset angle, focal distance and focal position are approached better each step.
The end-results fit the paraboloid shape perfectly.
Alas, I myself have no such paraboloid wider-than-high dish. So I did only have 'fictional' input data till now.
So, is there anybody that would like to do those four measurements on a zone-1 and/or a zone-2 dish?
Then I'll post the results of my calculator here.
The measuring should be done about this way:
1. Define the top and bottom of the working area of the dish, and also the left and right of the working area of the dish,
so that the (diamond-)distances top-right, right-bottom, bottom-left, left-top are exactly equal. Put dots (on some tape) on the dish.
(Take care: The left-right dots aren't necessarily on the highest point of the dish rim, I think!)
2. Find the middle of the dish, halfway between top-bottom, halfway between left-right. Put a dot there also.
3. Check that distance top to middle equals bottom to middle, and same for right to middle and left to middle.
4. Measure dish hight, and dish width.
5. Measure depth at the middle twice, as indicated above.
If you measure depth to dish rim, and the dish rim is higher than the dots on the working area of the dish: subtract the mean distance [dish rim to working area dot] from your measurement.
If possible, measure depths more accurately than 1 millimeter!
I'll look forward to the checking if the LNB feedhorn of the dishes is in fact placed at the calculated postion.
Greetz,
A33