geometry:

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

geometry:

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

dodos:

@ all

I am trying to figure everything out myself now. Anyway am not convinced of the above figure for the tripod. If it is pythagoras you used and did not approximate any value leading to your answer then i think the value for the tripod is wrong. Can you prove me wrong. My calculations which i have rechecked says it should be 175.0863 which i have now approximated to 175.1cm.

Can u prove otherwise.

My parameters were

Focal length : 123.1 cm
Radius : 160 cm

Now remember his depth was 52 cm so take that out of the 123.1 : (123.1 - 52) cm = 71.1 cm

Now using pythagoras: (71.1) squared + (160) squared = (the length of the tripod) squared

Now the length of the tripod = square root of {(71.1) squared + (160) squared}

= 175.0863 cm
approximately = 175.1 cm

Thanks

dodos:

@ all

I am trying to figure everything out myself now.  Anyway am not convinced of the above figure for the tripod.  If it is pythagoras you used and did not approximate any value leading to your answer then i think the value for the tripod is wrong.  Can you prove me wrong.  My calculations which i have rechecked says it should be 175.0863 which i have now approximated to 175.1cm.

Can u prove otherwise.

My parameters were

Focal length : 123.1 cm
Radius         : 160 cm

Now remember his depth was 52 cm so take that out of the 123.1 : (123.1 - 52) cm = 71.1 cm

Now using pythagoras: (71.1) squared + (160) squared = (the length of the tripod) squared

Now the length of the tripod = square root of {(71.1) squared + (160) squared}

                                             = 175.0863 cm
approximately                        = 175.1 cm

Thanks

geometry:

@ dodos,

you all have not taken to my warning about not going by the THEORY, i mean the diagram that i referred to as theory. I STATED that we should stick to the ACTUAL, the diagram referred to as actual. compare the two diagrams and you will see the reason you not arriving at my answer.
Even when i made a mistake of saying 'stick with the theory' which i latter corrected almost immediately , that we should go by 'actual'.
the values you have arrived at are from THEORY.
THE DIFFERENCE;
SIMPLY DEDUCT THE VALUE OF SCALAR RING FROM YOUR RADIUS BEFORE SQUARING IN YOUR PYTHAGORAS FORMULA.
LETS GO!  

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,
my question how do you come about 8.25cm for scalar ring?
is 8.25cm the standard size for all scalar rings?
ralph

geometry:

@ Newtonn, Newtonn, Newtonn.

i have called you three times now !
oya, take your tape and try to measure the diameter of a c-band scalar ring and tell me what value you get. since your calculation is based on the half of it , you divide what you get as diameter by two.
i am repeating this again, 'when i used my vernier calipers i got the diameter of c-band scalar ring to be 16.5cm.'
dividing this figure by two , what do you have ?
in my own case i got half of 16.5cm to be 8.25cm. let us know what you have.
now go to illustrated diagram again, stick with the 'actual', and that is what makes the difference.
i am very sure by now you are laughing.!!!
lol.
JUST TAKE YOUR TIME TO WORK ON THE 'ACTUAL' DIAGRAM, HAVE A CRITICAL LOOK AT IT AND YOU WILL SEE WHAT AND HOW DODOS HAS OVER COME THIS SAME PROBLEM.
CHEERS.
BY THE WAY, YOUR CALCULATION SEQUENCE LOOKS VERY GOOD, JUST BEAT THAT OBSTACLE, NOW!

geometry:

@ swordswifter,

f/D ratio is quite important in the designing of a satellite antenna, [dish].; it describes how deep or shallow your your dish is. there are values attach to different purposes for which an antenna is meant. it is the factor that describe the illumination method adopted in the antenna service life. there are different illumination methods for various reasons. i.e to guide against the interference from the ground [ground noise] or ground temperature.
i.e a too flat a dish would accept more ground noise than a deeper dish, while a dish that is too deep would not allow full illumination,,,and that is why we cut lnb especially for Out of-Foot- Print-Signals. because we are looking for a situation to fully bring larger percent of the converged signal to the lnb throat, apart from exposing the probes,.,,,here we are literally explaining 'beam angle'. some would call it apex angle and the rests. but then, the simplest way to understand this is to imaging your lnb to be a torch light placed at the focal point, facing downward,  the light from it now is expect to throw light upon the surface of the dish, remember your focal length is fixed, hence, the position of the torch is fixed, adjust the beam so as to cover the entire surface of the dish. this is the lay-man explanation of antenna ILLUMINATION, in visualization, one could reason it out that the further away the torch the easier it is to get the surface illuminated by the torch, and the more difficult it is for a touch too close to the surface to illuminate the dish surface.
From research results, it has being established that there is a critical value of f/D ratio for critical antenna illumination, ,,,and the value is 0.41  . I HAVE EXPERIMENTED THIS VALUE ,AND FOR REASONS, ADOPTED VALEUS LITTLE BIT BELOW AND ABOVE IT WITH VERY VERY GOOD RESULTS. i.e 0.39, 0.4, 0.42 and the extreem i have gone was 0.45. though i experimented 0.6 f/D before but not for TVRO, satellite tv.
i advice anybody in the house to choose 0.4 f/D ratio ,it worked for me.

geometry:

@ Newtonn,

to determine an equivalent half the diameter of scalar ring, you measure from the center of the hole on one of the three arms to hold the tripods, to the center of the ring for the lnb. the value should be somehow close to 8.25cm. try it .

Newtonn:

@geometry,
this the hole i wanted to mount the 3.2m dish,
i dig 1feet deep, is it OK or i should DIG more?
thks

swordswifter:

@Newtonn,
I can't answer the other questions for you but all i do know is any hole for mounting a big dish(specifically between 1.8m and 3.1m solid or mesh) should be 2ft to 3ft deep so that the weight or strong winds don't cause them to fall and get damaged.
@Geometry,
i've added some pictures to that particular album so you can take a look at it and tell me what you think.Thanks!

geometry:

@newtonn,

pls increase your hole depth to 1.5ft to 2ft.
do proper cement casting , concrete