What is the difference between CW power and peak power in circulator selection?

In RF circulator selection, CW power refers to the continuous power level that a circulator can handle over time, while peak power refers to the maximum short-duration power level that the circulator can withstand during a pulse or transient condition.

The key difference is simple: CW power is mainly a thermal problem; peak power is mainly a voltage, breakdown, and pulse-stress problem.

For a CW signal, the RF power is applied continuously. This means the circulator must dissipate heat steadily through its ferrite material, housing, connectors, and mounting surface. If the CW power is too high, the circulator may overheat, causing insertion loss increase, isolation drop, frequency shift, or long-term reliability issues. Industry guidance also notes that average power capability depends on factors such as output mismatch, connector type, and cooling conditions.

For a peak power signal, especially in pulsed radar or high-power communication systems, the signal may only appear for a very short time. The peak value can be much higher than the average power, but the circulator must still withstand the instantaneous RF stress. For pulsed RF signals, pulse power is closely related to average power and duty cycle; Mini-Circuits explains that pulse power can be calculated from average power divided by duty cycle.

For example, a radar system may have very high peak power but a relatively low average power because the pulse is active only for a small percentage of time. This is why engineers must provide not only “power,” but also:

• CW or pulsed operation
• Average power
• Peak power
• Pulse width
• Duty cycle
• Pulse repetition frequency
• Load VSWR
• Expected reflected power
• Cooling condition
• Operating temperature

For RF circulators and isolators, both peak power and average power need to be considered during selection. M2 Global also emphasizes that stringent peak and average power requirements must be evaluated together with worst-case load VSWR and cooling conditions.

HzBeat supports RF circulator selection and customization based on both CW power and peak power requirements. For applications such as radar systems, 5G base stations, satellite communication terminals, RF power amplifiers, and test equipment, HzBeat can evaluate frequency range, bandwidth, insertion loss, isolation, VSWR, power level, package size, connector type, and thermal conditions together.

Thanks to HzBeat’s strengths in wideband coverage, miniaturized design, and customized RF circulator solutions, engineers can select circulators not only by “how many watts,” but by the real working condition behind those watts.

In short, CW power tells you how much continuous heat the circulator must survive; peak power tells you how much instant RF stress it must withstand. A reliable circulator selection should always define both.