geometry:

@ newtoon,
remember pythagoras theorem ?
consider the two diagrams ; i.e theory and actual. stick to the theory. it gives you the actual tripod length with just little adjustment to actual focal length of your parabola [dish].
pytagoras states that; the square of the longest side (h^2 )  of a triangle is equal to the sum of the squares of the rest two sides 
( a^2 + b^2 ) . i.e h^ = a^2 + b^2
in the case of the represented diagram ,

h = t,
a = line CB,
c = line AB
FOR CLARITY SAKE, in the actual diagram, there is a value for  s , which is the radius of the scalar ring. the same value goes for ku- band lnb holder as indicated in the diagram.
by using my vernier calipers i got scalar ring diameter to be 16.5cm i.e the radius comes to 8.25cm which is (s)
hence; (a) = line CB = radius of the dish - s . i.e [DIAMETER/2] - 8.25CM.
            (C) = line AB = focal length - x.           i.e f -  DEPTH, = f - x,

don't forget x represents how deep your dish is.

Newtonn, do you see why u need to measure your dish depth ?

@ geometry and swordswifter
thks very much i will look into it,
plz i need your mail so that we can talk better.
here is my temporary mail.         5qAenHbblXIZ@meltmail.com

@ geometry

good work and good illustrations. I enjoyed recollecting my elementary math. Now concerning the depth of the dish, how can you measure in order to avoid errors. In other words one would have to measure from the center (in the middle) of the base of the dish to edge of the dish.

Am thinking of using a thing thread from one end of the tip of the dish to the other (as if measuring the diameter) and then putting a stick in the base of the dish up to the thread. Is this how to go about it. If yes how can one ensure that the stick is in the exact middle of the dish. What else can one do to eliminate or minimize errors as much as possible.

Hope my question is self explanatory

Thanks

dodos:

@ geometry

good work and good illustrations. I enjoyed recollecting my elementary math. Now concerning the depth of the dish, how can you measure in order to avoid errors. In other words one would have to measure from the center (in the middle) of the base of the dish to edge of the dish.

Am thinking of using a thing thread from one end of the tip of the dish to the other (as if measuring the diameter) and then putting a stick in the base of the dish up to the thread. Is this how to go about it. If yes how can one ensure that the stick is in the exact middle of the dish. What else can one do to eliminate or minimize errors as much as possible.

Hope my question is self explanatory

Thanks

@dodos,
yes you are right. just tie a rope from one edge to the other and measure it with a tape rule.
and get ur depth

@ geometry and swordswifter,
here is the parameters of ma 3.2m dish:
DIAMETER:320CM (3.2M)
RADIUS: 160CM (1.8M)
DEPTH: 52CM (5.2M)
LOOK INTO THE PARAMETERS AND TELL ME WHAT TRIPOD SIZE TO USE FOR MY 3.2M FIBER DISH
THKS @ geometry and swordswifter

@ Newtonn,
ur tripod = 167.6cm long.
ur focal lengh = 123.1cm.
Goodluck !

@ geometry and swordswifter,
here is the parameters of ma 3.2m dish:
DIAMETER:320CM (3.2M)
RADIUS: 160CM (1.8M)
DEPTH: 52CM (5.2M)
LOOK INTO THE PARAMETERS AND TELL ME WHAT TRIPOD SIZE TO USE FOR MY 3.2M FIBER DISH
THKS @ geometry and swordswifter

@Newtonn:
Your radius is 1.6m and depth 0.52m. Recheck!

@ lovala,,
you are right !
@ newtonn,
you wrote 160cm then bracketed 1.8m. But then, since you said your dish diameter is 320cm right from time, i assumed your your bracketed 1.8m is meant to be 1.6m. Plz, comfirm it.

geometry:

@ lovala,,
you are right !
@ newtonn,
you wrote 160cm then bracketed 1.8m. But then, since you said your dish diameter is 320cm right from time, i assumed your your bracketed 1.8m is meant to be 1.6m. Plz, comfirm it.

yes you are right, i did a mistake it's 1.6m and the depth it's .52m. thks

@ all,
Measuring Dish Depth:
the rope method is good, but you need the point on the rope to measure to. Thats the mid-point on the rope which is now the apertural center of your dish, i.e, the effective surface area. Invariably, the distance between the marked point on the rope and the center of your parabola (dish) is your depth. Now let's method another method.

'STIFF PIPE METHOD'

most tripods come in 1/2" light square pipe, before cutting measure out your diameter, mark out the two endsthen, the mid way which is your radius. Place the two ends on the rim (edge) of your dish such that it divides your dish into two equal halves. This is obtainable by making sure your two end marks coincide with the two opposite points on the edge of your parabola (dish). The simplest way to archive this is to, first of all, measure your diameter with a tape and then transfer over to your yet uncut square pipe.
Latter we will discuss TWO-TAPE-METHOD.

Plz, remember to mark the middle after transfering your measuement over to 'STIFF' square pipe.
Cheers.

@ geometry and swordswifter,
is it true that 3.2m dish cant show ABUDABI stations?
a friend told me so

geometry:

@ Newtonn,
your tripod = 167.6cm long.
your focal lengh = 123.1cm.
Goodluck !

@ geometry and sword

Can you please explain how you came by the above. Secondly are all c-band lnb holders the same size.

Thanks for your patience

dodos:

@ geometry and sword

Can you please explain how you came by the above.  Secondly are all c-band lnb holders the same size.

Thanks for your patience

http://mscir.tripod.com/parabola/
@dodos download the software from that site, use it to calculate ur focal point of any parabola dish,,,, and enjoy

dodos:

@ geometry and sword

Can you please explain how you came by the above. Secondly are all c-band lnb holders the same size.

Thanks for your patience

@dodos,
the formula of the focal point of a parabolic dish is
diameter squared divided by 16 xdept.

so if the diameter is 320 cm that is squares =102,400
depth is 52 cm so 52x16 =832

so 102,400 cm divided by 832= 123.07 cm
@ALL i just use my dish as an example, so if you are dealing with
bigger or smaller dish input ur parameters.
ralph

geometry:

@ newtoon,

remember pythagoras theorem ?
consider the two diagrams ; i.e theory and actual. stick to the theory. it gives you the actual tripod length with just little adjustment to actual focal length of your parabola [dish].
pytagoras states that; the square of the longest side (h^2 ) of a triangle is equal to the sum of the squares of the rest two sides
( a^2 + b^2 ) . i.e h^ = a^2 + b^2
in the case of the represented diagram ,

h = t,
a = line CB,
c = line AB
FOR CLARITY SAKE, in the actual diagram, there is a value for s , which is the radius of the scalar ring. the same value goes for ku- band lnb holder as indicated in the diagram.
by using my vernier calipers i got scalar ring diameter to be 16.5cm i.e the radius comes to 8.25cm which is (s)
hence; (a) = line CB = radius of the dish - s . i.e [DIAMETER/2] - 8.25CM.
(C) = line AB = focal length - x. i.e f - DEPTH, = f - x,

don't forget x represents how deep your dish is.

Newtonn, do you see why u need to measure your dish depth ?

@geometry, take a look @my formula.
the formula of the focal point of a parabolic dish is
diameter squared divided by 16 xdept.

so if the diameter is 320 cm that is squares =102,400
depth is 52 cm so 52x16 =832

so 102,400 cm divided by 832= 123.07 cm
check all the software use for calculating focal point
ralph

Hi all,
I'm announcing that The home made dish making adventure i embarked on which i nicknamed THE PROJECT with the help of a couple of friends since last year is now finally complete.Preliminary testing showed strong echoes arriving at the focal point.Actual testing will start tomorrow 8am local time at the Ghana Telecom University College campus-Tesano and as usual pictures will be posted afterwards.Dodos,Sathob,Salamander and other active nairalanders living in Accra are free to come and support.Thanks!
FTA-We will push the limits.

swordswifter:

Hi all,
I'm announcing that The home made dish making adventure i embarked on which i nicknamed THE PROJECT with the help of a couple of friends since last year is now finally complete.Preliminary testing showed strong echoes arriving at the focal point.Actual testing will start tomorrow 8am local time at the Ghana Telecom University College campus-Tesano and as usual pictures will be posted afterwards.Dodos,Sathob,Salamander and other active nairalanders living in Accra are free to come and support.Thanks!
FTA-We will push the limits.

am happy 4u,
keep da good work
ralph

@ Swordswifter,
that's what i'm talking about ! You are great ! Now that you are breaking the ice, let's go !
I strongly anticipate other members of this members to emulate this move of yours.
I'm waiting for your results. Goodluck. What size is THE PROJECT by the way ?

Members of the floor i meant.

geometry:

@ Swordswifter,
that's what i'm talking about ! You are great ! Now that you are breaking the ice, let's go !
I strongly anticipate other members of this members to emulate this move of yours.
I'm waiting for your results. Goodluck. What size is THE PROJECT by the way ?

@Geometry
It's 244cm in diameter but i know with time due to expansion and cooling it will reach 250cm.
If all things are to go as planned these are the parameters we are expecting:
Frequency 11296 MHz
Diameter 2440 mm.
Depth 150.00 mm.
f/D 1.01666666666667
-------------------------
f/D = 1.02
Focal Length = 2480.67 mm.
Illumination angle for feed = 55.3 degrees
Space attenuation = 0.51 dB
Desired taper = 9.49 db for 10 dB edge illumination
A simple feed horn would have a diameter of 2.12 wavelengths for a 3 dB beamwidth of 31.07 degrees
Gain at 50% efficiency = 46.20 dBi

^^^i still miss d size of 'The Project' dude plz put it in plain or simple english, nice work tho'!

@ dodos & all, There is a standard for lnb holder size, i.e, where holes are drilled, generally, this gives precise idea of what parameters to base your calculations of tripod length. That is why i stated in the previous post to go by 'actual' and not 'theory'. There is slight defence between the results from both instances. Check out the post with illustrated diagrams.

@ newtonn,
the post with illustrative diagram is sort of self explanatory. I distinguished the 'theory' from 'actual'.

swordswifter:

@Geometry
It's 244cm in diameter but i know with time due to expansion and cooling it will reach 250cm.
If all things are to go as planned these are the parameters we are expecting:
Frequency 11296 MHz
Diameter 2440 mm.
Depth 150.00 mm.
f/D 1.01666666666667
-------------------------
f/D = 1.02
Focal Length = 2480.67 mm.
Illumination angle for feed = 55.3 degrees
Space attenuation = 0.51 dB
Desired taper = 9.49 db for 10 dB edge illumination
A simple feed horn would have a diameter of 2.12 wavelengths for a 3 dB beamwidth of 31.07 degrees
Gain at 50% efficiency = 46.20 dBi

@swordswifter,
keep da spirit high,
we are waiting for your results including with the pictures and shot screen of quality
ralph

swordswifter:

Hi all,
I'm announcing that The home made dish making adventure i embarked on which i nicknamed THE PROJECT with the help of a couple of friends since last year is now finally complete.Preliminary testing showed strong echoes arriving at the focal point.Actual testing will start tomorrow 8am local time at the Ghana Telecom University College campus-Tesano and as usual pictures will be posted afterwards.Dodos,Sathob,Salamander and other active nairalanders living in Accra are free to come and support.Thanks!
FTA-We will push the limits.

@swordswifter,
kindly mail me on my temporary mail, its has only 5hrs to melt.
email: 9a1seUhoPX97@meltmail.com
thks

@ swordswifter,
i guess your dish is kinnda' too flat for acceptability. the acceptable range i know for f/D ratio range is 0.3 through 0.7 , for [TVRO] (Television Receive Only), yours might be a kind of push to the edge and i hope it works for you.
i 'l like to see your result for comparison, and maybe what you have supersedes the previous records. it could be a land mark, but then i'm afraid.
let's hope yours is a landmark success.
plz, feel free to let us have your results.
thank you.

@ swordswifter,
from your parameters and properties, your dish seems to be made of metal, i believe that answer the reason for the magnitude of your f/D ratio, 1.02.[ very high] 'fabrication convenience' !. then, if i may ask, how many sections, if you are working on a metal dish.
plz, let me know, it might help.
goodluck !

geometry:

@ swordswifter,
i guess your dish is kinnda' too flat for acceptability. the acceptable range i know for f/D ratio range is 0.3 through 0.7 , for [TVRO] (Television Receive Only), yours might be a kind of push to the edge and i hope it works for you.
i 'l like to see your result for comparison, and maybe what you have supersedes the previous records. it could be a land mark, but then i'm afraid.
let's hope yours is a landmark success.
plz, feel free to let us have your results.
thank you.

@geometry,
you are very right, coz when i checked it from my software, its very flat and d depth not deep
ralph

@Geometry, pls check my observation.
thks

@Geometry,
take a look at the program,
left side corner says linear diameter? what does it mean?
thks

@ newtonn,
your observation is accurate, that's the essence of designing, simulating and re-designing. All of these are important in science &engineering. (theory).
The linear diameter is what i call 'PARABOLIC ARC'. : You can say your curve length. You can verify this by real curve fittings on a piece of paper adopting an adequate scale. Then, use graduated french curve to measure out the curve and multiply by your scale. Compare your result with that from the software. They must be the same or with a neglegible variation.

@ swordswifter,
you care for a chat ?. I will be happy to talk to you. Personally.
Thank you.