Precision power measurements at RF/microwave frequencies once required a standalone power meter and the proper diode or thermistor sensor. But with a personal computer (PC) equipped with a Universal Serial Bus (USB) and the model PWR-6G+ USB power sensor from Mini-Circuits (minicircuits.com), power measurements can be made quickly and accurately over a level range of -30 to +20 dBm and across continuous-wave (CW) frequencies from 1 to 6000 MHz.

The PWR-6G+ USB power sensor (see figure) is ideal for use in laboratory testing, remote testing, and for portable measurements. Its simple USB connection and supplied software turns any PC or laptop computer into a fullfeatured power meter. It does not need an external power supply, but draws all required power (about 40 mA at +5 VDC) from the computer's USB port. The PWR-6G+ USB power sensor is considerably simpler to use than a conventional stand-alone power meter and sensor, and does not require any reference signal calibration prior to a measurement as does a conventional power meter.

Even without the calibration, the PWR-6G+ USB power sensor and a PC or laptop computer deliver 0.01-dB measurement resolution with typical linearity at room temperature of 0.1 dB. The power sensor is designed for use at operating temperatures from 0 to +50C. The typical power measurement uncertainty at room temperature (+25C) is 0.15 dB or better for measurements from -30 to +12 dBm across the full frequency range and 0.20 dB or better for measurements from +12 to +20 dBm across the full frequency range. Across the full operating temperature range, the power measurement uncertainty is 0.25 dB or better for measurements from -30 to +12 dBm across the full frequency range, and 0.35 dB or better for measurements from +12 to +20 dBm across the full frequency range. The USB power sensor features low VSWR of typically 1.1:1.

The PWR-6G+ USB power sensor is supplied with application software compatible with Windows 98, Windows XP, and Windows Vista operating systems. The software allows operators to apply as many as 100 averages to make accurate measurements even on fluctuating source signals, to show results in watts (W) or dBm, and to even enter the measurement temperature for correction purposes. The software requires a computer with USB 1.1/2.0 interface, at least 512 kB random-access memory (RAM), and a Pentium III or newer microprocessor. For improved versatility, the PWR- 6G+ is also supplied with a Type-Nto- SMA-male adapter for increased connectivity to different devices under test (DUTs). The PWR-6G+ USB power sensor supports production testing with measurement speed of 200 ms/measurement. Mini-Circuits, P. O. Box 350166, Brooklyn, NY 11235-0003; (718) 934-4500, Fax: (718) 332-4661, Internet: www.minicircuits.com.