# Electronics and Communication Engineering - Satellite Communication - Discussion

Discussion Forum : Satellite Communication - Section 1 (Q.No. 5)

5.

A 20 m antenna gives a certain uplink gain at frequencies of 4/6 GHz. For getting same gain in the 20/30 GHz band, antenna size required is metre.

Discussion:

12 comments Page 1 of 2.
Anurag Nande said:
9 years ago

Antenna diameter (d) is inversely proportional to the operating frequency (f).

So d = k*(1/f).

Note :- Here k is constant.

For up link f = 4GHz for down link f = 6GHz.

d = k*1/4 d = k*1/6.

d/5 = k*1/(4*5).

d/5 = k*1/(6*5).

d/5 = k/20 ---(1)

d/5 = k/30----(2).

So the resultant size of antenna from equation (1) and (2):

Size = d/5 = 20/5 = 4m.

Size = 4m.

So d = k*(1/f).

Note :- Here k is constant.

For up link f = 4GHz for down link f = 6GHz.

d = k*1/4 d = k*1/6.

d/5 = k*1/(4*5).

d/5 = k*1/(6*5).

d/5 = k/20 ---(1)

d/5 = k/30----(2).

So the resultant size of antenna from equation (1) and (2):

Size = d/5 = 20/5 = 4m.

Size = 4m.

(1)

Nirav Solanki said:
10 years ago

Here frequency is multiplied by 5 means the wavelength is divided by 5.

Now length of antenna is directly proportional to the half of the wavelength. So the ultimate length of antenna is divided by 5.

Now length of antenna is directly proportional to the half of the wavelength. So the ultimate length of antenna is divided by 5.

Zarana said:
9 years ago

How put 5?

We need height of 20/30 frequency. So do 4*5/6*5 & dived by 5 to 20 meter height?

So answer is 4?

We need height of 20/30 frequency. So do 4*5/6*5 & dived by 5 to 20 meter height?

So answer is 4?

(1)

Shreya said:
9 years ago

20m antenna-----4/6GHZ-----multiply by 5.

?---------------20/30GHZ.

4*5/6*5-----20/5=4m.

?---------------20/30GHZ.

4*5/6*5-----20/5=4m.

Shivanirajput said:
9 years ago

Antenna diameter is inversely proportional to frequency. So f*5 = d/5 = 4m.

Nisha said:
1 decade ago

Lambda = c/f.

If f' = 5f.

Then lambda' = lemda/5 = height of antenna = 4m.

If f' = 5f.

Then lambda' = lemda/5 = height of antenna = 4m.

Prakhar said:
1 decade ago

Antenna diameter is inversely proportional to the operating frequency.

Amul said:
8 years ago

Thanks for the explanation. It's very easy to understand.

Suresh said:
9 years ago

Thanks to explaining all of these.

THANAM SIVA said:
7 years ago

Thanks for explaining it.

(2)

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