Question

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.

• A. 100
• B. 4
• C. 10
• D. 1

Answer 1

The correct option is B 4

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

So d = K x (1/f)

Note :- Here K is a constant

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

d = k x 1/4 d = k x 1/6

d/5 = k x 1/( 4 x 5)

d/5 = k x 1/( 6 x 5)

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

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

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

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

Hence, Size = 4 m