The difference between a standard commercial EMC immunity test and a full military-grade radiated susceptibility test is measured in volts per metre. IEC 61000-4-3 requires 10 V/m for most commercial products. GJB151C RS103 (equivalent to MIL-STD-461) requires 200 V/m across the full test bandwidth for many defence categories — a factor of 400 in field strength, translating to 160,000× in radiated power for the same antenna and distance.
Why 200 V/m Is Demanding
Field strength from a transmitting antenna follows E (V/m) = √(30 × G × P) / d. For 200 V/m at 1m with a 10 dBi antenna, that's roughly 133W — manageable at first glance. But the requirement applies across the full 10 kHz to 18 GHz test range, and different frequency bands use very different antennas with very different gain: loop antennas at low frequency may have 0 dBi or lower gain, while microwave horns reach 20+ dBi. The result is that required power varies enormously by band.
The Required Power at Each Frequency Band
| Frequency Band | Typical Antenna | Antenna Gain | Required Power for 200 V/m at 1m |
|---|---|---|---|
| 10 kHz – 1 MHz | Loop antenna | -10 to 0 dBi | 1000–10,000W |
| 1 MHz – 30 MHz | Monopole/dipole | 0–2 dBi | 1000–4000W |
| 30 MHz – 1 GHz | Biconical/LPDA | 2–8 dBi | 200–1000W |
| 1 GHz – 6 GHz | LPDA/horn | 8–15 dBi | 50–200W |
| 6 GHz – 18 GHz | Horn antenna | 15–20 dBi | 20–50W |
Low-frequency bands (10 kHz to 30 MHz) are by far the most demanding, since low-gain antennas combined with large free-space path loss require enormous transmitter power. This is why a 200 V/m full-band system is built from multiple amplifier units, each optimised for its band.
The RFlight 200 V/m Solution Architecture
RFlight's solution uses a combination of amplifier series covering the full GJB151C/MIL-STD-461 band as a serialised shelf system, switched automatically by the EMC test software as frequency sweeps through the range.
Low Frequency (10 kHz–100 MHz): WPA-9k01 series delivers 1,500 to 15,000W, the most demanding segment.
VHF/UHF (80 MHz–1 GHz): WPA-00810 series delivers 2,000–3,000W.
L/S/C Band (0.7–6 GHz): WPA-0760 series delivers 800–1,000W.
X/Ku Band (6–18 GHz): WPA-6018/20180 series delivers 100–200W, sufficient given 20+ dBi horn antenna gain at this range.
The 200 V/m System as a Shelf Solution
RFlight's approach for full GJB151C compliance is a serialised shelf/rack system covering the full frequency range from a single integrated setup, with automated band switching, directional couplers for forward/reflected power monitoring, VSWR protection, and compatibility with major EMC test automation platforms (Keysight N6468A, DARE Emission Control, NSG STAR-System).
The 400 V/m Variant
For requirements exceeding 200 V/m — platform-level defence testing and HIRF simulation for large aircraft — RFlight provides a 400 V/m solution using parallel amplifier combining, which increases complexity and cost but scales directly from the 200 V/m architecture. Vehicle-mounted installation and polarisation switching are also available.
What the System Includes Beyond Amplifiers
A complete system includes signal sources, antennas (loop, biconical/LPDA, horn) matched and calibrated to each frequency range, directional couplers and power meters, isotropic field probes for calibration, and EMC test control software managing the full sweep sequence. Finch supplies all elements as a complete system.
Key Specification Checklist for a 200 V/m System
Confirm amplifier output power with margin at each band, P-1 compression point above rated operating power, gain flatness ≤±3 dB minimum, harmonic suppression ≤-15 dBc, output VSWR ≤2.0:1, automated band switching, protection circuits, and traceable calibration documentation.
Contact us about a 200 V/m test system | View EMC Amplifiers | RFlight