ABSTRACT

In an ordinary electronic equipment, a resonant (or tuned) circuit consists of an inductive coil and a capacitor, which are connected either in series or in parallel. These circuits comprising lumped parameters L and C are not without some resistance in the lower frequency range. The presence of resistance in circuits results in losses and lowers their Q. Besides, in view of the resonance frequency relation {f0 = 1/2π√(LC)}, the requirement of L and C becomes too small at high frequencies. This may include requirement of lumped or distributed parameters. However, at higher frequencies, stray inductance and capacitance (Figure 4.1) attain greater significance in case of lumped parameters. Thus, at microwave range, conventional tank circuit is generally replaced by a cavity resonator.