Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
IEC 60235-5: Microwave Tube Measurements — Precision Testing of Radar Pulsed Magnetrons
Testing the “Heart” of Radar: How to Measure Pulsed Magnetron Output Power and Spectral Purity
IEC 60235-5 specifies microwave tube (pulsed magnetron, TWT, klystron) electrical measurement methods. Radar detection range is determined by transmitter output power and spectral purity — both derived from microwave tube testing.
| Parameter | Method | Typical (X-band magnetron) | Significance |
|---|---|---|---|
| Peak Power | Calorimetry or directional coupler + peak power meter | 200 kW–1 MW | Determines detection range (R⁴∝P) |
| Frequency Pushing | Measure Δf while varying anode current | 0.1–0.5 MHz/A | Affects MTI improvement factor and clutter rejection |
| Spectral Width | Spectrum analyzer (3 dB bandwidth) | 0.1–1% of center frequency | Affects range resolution and anti-jamming |
| Pulse Width | Detector + oscilloscope (half-power width) | 0.1–10 μs | Determines minimum detection range and range resolution |
Frequency Pushing — a magnetron-unique parameter: Anode current variation causes frequency shift due to electronic tuning effects of the electron beam with the resonant cavity. For coherent radar systems (pulse-Doppler), inter-pulse frequency consistency is critical — excessive frequency pushing (>0.3 MHz/A) degrades the MTI cancellation ratio and clutter rejection capability.
Calorimetric power measurement — the most accurate microwave power method: Absorb all microwave power into a water load; measure temperature rise ΔT and flow rate Q. P = 4.18 × Q × ΔT (kW). Calorimetric uncertainty can be as low as ±1.5% — the reference method for calibrating other power meters.
TN Lab — Radar detection range and resolution directly depend on microwave tube measurement accuracy.
