Reflections And Rf Sources

When an rf oscillator feeds a load directly, reflections from the load on arriving back at the source can influence the source output power and frequency. When the frequency of operation and the load conditions are fixed, the reflections, unless they are very large, do not usually affect the stability of the source output.

When changes are made in the load conditions, as for instance, when the load is an adjustable attenuator in an attenuation-measuring system, or when various loads or a sliding short circuit is connected to an impedance-measuring system, the change in load reflections can cause changes in the amplitude and frequency of the source. Similarly, when the source frequency is varied with fixed load conditions, the reflections (as observed from the source) change in amplitude and phase and affect the amplitude

Figure 2. Average isolation and insertion-loss characteristics of several isolators.

FREQUENCY-Gc

FREQUENCY-Gc

REFLECTION COEFFICIENT 0 2 04 0.6 OS

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