Every modern Electromagnetic Compatibility (EMC) testing laboratory starts with a high-quality signal source. A precision RF signal generator provides a stable foundation for any test bench. However, when it comes to Radiated Immunity testing, the base power of a generator (typically around +10 dBm) is drastically insufficient to create the required field strength (V/m).
This is where a high-quality broadband RF amplifier comes into play. But during the integration of the generator and the amplifier, engineers often make fatal mistakes that lead to distorted data, delayed certification timelines, and even burned-out components.
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2 Main Mistakes When Integrating an RF Generator
When building an RF path, you cannot simply connect two devices with a cable and hope for perfect results. Here are the two main traps in EMC testing:
1. Power Mismatch and Ignoring the P1dB Point If the output power supplied by the RF signal generator exceeds the amplifier’s compression point (P1dB), the perfect sine wave turns into a harmonic generator. The amplifier enters a non-linear state. As a result, you will irradiate the Device Under Test (DUT) not only with the fundamental frequency but also with powerful spurious harmonics. This invalidates your test results.
2. Lack of Protection Against High VSWR During tests in anechoic chambers, the impedance of the transmitting antenna can change drastically depending on the frequency and reflections. If the load is mismatched, all the unused power will reflect directly back into the amplifier. Without proper internal protection against high VSWR, the output transistors will burn out in milliseconds.
A Reliable Solution for the RF Path
To ensure a costly measurement setup operates stably, the signal source must work in tandem with reliable equipment.
Professional solid-state microwave amplifiers are designed specifically for harsh testing conditions. Thanks to built-in isolators and automatic mismatch protection, they amplify the clean signal from your RF signal generator without distortion. A properly matched equipment setup guarantees that the spectrum remains clean even under maximum loads, ensuring accuracy and repeatability in the laboratory.
FAQ
Q: Can I connect an RF signal generator directly to a transmitting antenna?
A: No. To generate the required field strength (e.g., 10 V/m or 30 V/m according to IEC standards), the power of a standard generator is insufficient. You will absolutely need an intermediate broadband RF power amplifier.
Q: How can I avoid damaging the amplifier when using a high-power generator?
A: Always verify the maximum allowable input signal level of the amplifier. Use attenuators between the generator and the amplifier if there is a risk of overload, and always choose amplifiers with built-in high VSWR protection.