Page 389 - Basic Electrical Engineering
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curve and better is the ability of the network to accept current or power
signals.
Bandwidth
Bandwidth is the range of frequencies for which the power delivered to the
resistor is equal to half the power delivered to the resistor at resonance. As
can be seen from Fig. 3.68 (b), the range of frequencies is (f – f ) and the
1
2
corresponding current is i.e., 0.707 I 0
Power delivered at resonance
Half the power delivered at resonance =
Therefore, the range of frequencies within which current does not drop below
0.707 times the maximum value of current, i.e., I is called the bandwidth.
0
See Fig. 3.68 (b). The frequencies f and f are often called the lower and
1
2
upper cut-off frequencies. Bandwidth, BW = f − f .
2
1
From Fig. 3.68 (b) it is seen that at both f and f , the power delivered to R
1
2
is equal to half the power delivered to R at resonance.
Using equation (3.18) we can write
