An antenna is placed in a dielectric medium of dielectric constant 6 . 25 . If the maximum size of that antenna is 5 . 0 mm , it can radiate a signal of minimum frequency of _____ GHz . (Given μ r = 1 for dielectric medium)

Step-by-step solution

We know that, refractive index is related to velocity as n = c v . Here, n = ε r μ r = 6 . 25 1 = 2 . 5 Since, effective length of antenna l > λ 4 ⇒ l > v 4 f So, f > v 4 l = c 4 l 2 . 5 = 3 × 10 8 2 . 5 × 4 × 5 × 10 - 3 = 6 × 10 9   Hz = 6   GHz .