Traditional wattmeters are designed for constant amplitude RF signals like CW and FM, using diode detectors operated in their linear region to measure signal peaks and compute average power. Digitally modulated signals have time-varying amplitudes that linear-region diode detectors and traditional wattmeter electronics cannot accurately measure. The Bird 4480A overcomes this limitation by using a Schottky diode operated in its square law region, where output is directly proportional to power (V²), enabling accurate true average power measurements for both constant amplitude and variable amplitude digitally modulated signals.

The Bird 4480A uses a Schottky diode detector operated in its square-law region, where detector output is proportional to RF power rather than voltage peaks. This square-law operation enables accurate true average power measurements on time-varying, digitally modulated signals with peak-to-average ratios up to 10 dB.

Unlike traditional wattmeters, the 4480A does not rely on external, frequency- and power-specific elements, which can introduce additional uncertainty. The result is consistent ±4% accuracy for average power measurements across CW and digitally modulated signals throughout its 2 MHz to 1000 MHz frequency range.

Element-free design eliminates the need to carry, swap, and manage multiple frequency-specific and power-specific elements, reducing measurement errors caused by wrong element selection or damaged elements. The Bird 4480A covers 2 MHz to 1000 MHz in two bands without any elements, streamlining field operations and eliminating element-related errors. This results in faster measurements, reduced downtime, and consistent accuracy for improved reliability.

The Bird 4480A Digital Wattmeter uses directional coupling technology with approximately 30 dB of directivity to independently sample forward and reflected RF power flowing through the transmission line. Internal circuitry converts these RF signals into digital values for processing and display.

The LCD simultaneously displays forward power, reflected power, VSWR, and return loss in real time, providing immediate insight into transmission line performance. This allows technicians to quickly identify impedance mismatches and evaluate system performance without requiring additional measurements or reconfiguration.