[supersub007]

Hello Iam trying to find the gain in dBi , given the following relation;
For a
I)4.8m Dish the gain is 44dBi
ii) 2.4m dish it's 38dBi
iii) 1.2m the gain is 32dBi

What is the gain on a 3.7m and a 4.6 m dish? What mathematical relation can be deployed in this scenario?

Thanks in advance .

[Capuchin]

Okay, so you can see that when the dish size double, the dBi increases by 6.

This is a logarithmic relation, since the dBi goes up by a fixed amount when the dish size doubles, the base of the log is 2.

So, we divide each dish size by a constant, in this case 1.2, this makes the altered dish sized 1, 2 and 4.

Now we take of the dish size, which gives us 0, 1 and 2 (see, increasing by a fixed amount now).

Now, we transform this to the increase that we see, which is done by multiplying by 6. And we add a constant, which is our base dBi of 32.

This gives us

where g is the gain and d is the dish size.

You can check this by putting in your known ds and seeing if you get the right gs out.
Now you can use this to find the answers to the rest of your questions.
I suggest you try making up your own data, and try to come up with a formula for that, so that you know that you can derive the formula in the way that I have above.

Let me know if any of that didn't make sense.

[supersub007]

Hi Capuchin, please write a book...

[Capuchin]

Heh, when I've finished learning. :)