A baseband signal of 3.5 MHz frequency is modulated with a carrier signal of 3.5 GHz frequency using amplitude modulation method. What should be the minimum size of antenna required to transmit the modulated signal ?

Question

A baseband signal of 3.5 MHz frequency is modulated with a carrier signal of 3.5 GHz frequency using amplitude modulation method. What should be the minimum size of antenna required to transmit the modulated signal ? (A) 42.8 m (B) 42.8 mm (C) 21.4 mm (D) 21.4 m

Tardigrade Admin · Accepted Answer

fc=3.5 GHz fm=3.5 MHz Side band frequencies are fc-fm fc+fm. which are almost fc λ=( c / f c ) Minimum length of antenna = ( c / f c 4)=(λ/4)=(3 × 108/3.5 × 109 × 4) =21.4 mm

Q. A baseband signal of $3.5 M Hz$ frequency is modulated with a carrier signal of $3.5 G Hz$ frequency using amplitude modulation method. What should be the minimum size of antenna required to transmit the modulated signal ?

$42.8 m$

$42.8 mm$

$21.4 mm$

$21.4 m$

$f_{c} = 3.5 G Hz$
$f_{m} = 3.5 M Hz$
Side band frequencies are $f_{c} - f_{m} & f_{c} + f_{m}$ .
which are almost $f_{c}$
$λ = \frac{c}{f _{c}}$
Minimum length of antenna $=$
$\frac{c}{f _{c} 4} = \frac{λ}{4} = \frac{3 \times 1 0 ^{8}}{3.5 \times 1 0 ^{9} \times 4}$
$= 21.4 mm$

Q. A baseband signal of 3.5MHz frequency is modulated with a carrier signal of 3.5GHz frequency using amplitude modulation method. What should be the minimum size of antenna required to transmit the modulated signal ?

42.8m

42.8mm

21.4mm

21.4m