Measuring and calculating zone-1 and zone-2 dish

a33

Specialised Contributor
Joined
Sep 24, 2009
Messages
1,237
Reaction score
710
Points
113
Age
63
My Satellite Setup
XSAT410
Rebox RE-9000
My Location
NL
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
 

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Joined
Jan 1, 2000
Messages
35,533
Reaction score
8,554
Points
113
Age
59
Website
www.sat-elite.uk
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK
The easiest way of calculating the exact area would be to
1) weigh the material of the mesh that forms the reflector ( cut off the reinforcing perimeter beforehand), then
2) cut out a square section of known area (eg. 10 square cms),
3) use the weight of both items as a fraction, multiplying the 10cm sample into the full reflector size.
 

a33

Specialised Contributor
Joined
Sep 24, 2009
Messages
1,237
Reaction score
710
Points
113
Age
63
My Satellite Setup
XSAT410
Rebox RE-9000
My Location
NL
The easiest way of calculating the exact area would be to
1) weigh the material of the mesh that forms the reflector ( cut off the reinforcing perimeter beforehand), then
2) cut out a square section of known area (eg. 10 square cms),
3) use the weight of both items as a fraction, multiplying the 10cm sample into the full reflector size.

Ha ha.
I fail to see the humor in that.

I don't see that is has any relevance to my post, so I think it is totally off-topic.
Why don't you split off your post, and start your own thread with it?

Maybe here we can continue with people that have interest in what possibilities there are to calculate dish specs.
Or people who are willing to do the measurements, and are curious to the outcomes.
Or people who want to check and tweak their LNB-position in relation to the dish, or just check if their LNB-arm is sagging, for instance.


Greetz,
A33
 

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Joined
Jan 1, 2000
Messages
35,533
Reaction score
8,554
Points
113
Age
59
Website
www.sat-elite.uk
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK
The only other thread I could see on the forum from you, that provides a formula for feed optimising, relates to a multi feed system, with detail translated from a Russian forum in 2010. I could not find another you had started but that is not to say there isn't one.


I do have experience of good and bad dish design of this nature which might be on here ( Lenson Heath /Revox /Prodelin) though from memory they resulted, in the main a corporate exercise in damage limitation and the fixes were quietly rolled out without fanfare. I will have a look back through the files.

Moving forward though, I have two Zone 1 dish designs here, one is much more elliptical than the other, a second complete zone 2, and an Orbital dish of approximately 52cm diameter. They might serve as a Guinea pig for calculating the true focal point and if it deviates from one the manufacturer has settled on.
 

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Joined
Jan 1, 2000
Messages
35,533
Reaction score
8,554
Points
113
Age
59
Website
www.sat-elite.uk
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK

 

a33

Specialised Contributor
Joined
Sep 24, 2009
Messages
1,237
Reaction score
710
Points
113
Age
63
My Satellite Setup
XSAT410
Rebox RE-9000
My Location
NL
Funny that you link a topic about Triax TD110.
I did find an identical LNB-misplacement at my Triax TD 115:

Greetz,
A33
 

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Joined
Jan 1, 2000
Messages
35,533
Reaction score
8,554
Points
113
Age
59
Website
www.sat-elite.uk
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK
Triax took over the Lenson Heath name, some of their design and possibly a design 'engineer' or two.

Must have been almost 25 years ago though (Micromatic ?)
 
Top