Tiny Instruments Combine Power Meter And Sensor

These little measuring instruments pack a great deal of capability and accuracy into a package that saves space and money over conventional power meters and sensors.

Conventional microwave power measurements call for a power meter and the right power sensor for the frequency range and power level of interest. The LB4XX Series universal serial bus (USB) PowerSensor+ products from LadyBug Technologies LLC (Santa Rosa, CA) are hardly conventional, but they can make the same, highly accurate power measurements as the high-priced meter and sensor combinations, and in a fraction of the bench space. These compact measurement instruments work at frequencies from 10 MHz to 10 GHz and read power levels from -65 to +20 dBm with total error of 1 percent or less.

In the size of a traditional diode or thermocouple sensor, the LadyBug LB4XX PowerSensor+ instruments combine a sensor and detection electronics along with a USB interface for connection to an external computer. The LB4XX instruments feature USB plug & play connectivity for ease of use with a personal computer (PC) running Windows 2000 or Windows XP operating systems. The LB4XX instruments are supplied with a stand-alone Windows-compatible software program for controlling multiple sensors from a single PC, but they are also compatible with the LabVIEW graphical measurement development software from National Instruments (Austin, TX). The sensor-meters also feature support for other test development environments as well as standard software drivers, such as ActiveX and DLL drivers.

Three models are currently available, all of which are designed for power measurements from 10 MHz to 10 GHz (see table) . Model LB478A is designed for general-purpose power measurements from -30 to +20 dBm and will perform CW and pulse measurements. For power measurements over a wider dynamic range, the LB479A features a power-measurement range of -65 to +20 dBm and VSWR of 1.09:1. For pulsed measurement applications, model LB480A provides pulse profiling capabilities across a power-measurement-range of -65 to +20 dBm and a test match of 1.09:1. All three of the sensor-meter combination instruments boast root sum of squares (RSS) calibration factor uncertainty of 1 percent. All three are designed for maximum average power levels of +20 dBm and maximum pulse power of +23 dBm.

The basic model LB478A operates with VSWR of 1.15:1. It features a maximum peak-to-average ratio of -30 to +20 dBm from 10 MHz to 8 GHz and -20 to +20 dBm from 8 to 10 GHz. The higher-performance model LB479A and the pulse-profiling model LB480A operate with VSWR of 1.09:1 and have maximum peak-to-average ratio of -65 to +20 dBm from 10 MHz to 8 GHz and -50 to +20 dBm from 8 to 10 GHz. The pulse-profiling unit features a standard video bandwidth of 100 kHz with optional video bandwidths of 300 kHz, 1 MHz, and 2 MHz. It performs time-gated measurements to an integral trigger with 83-ns resolution.

All three of the instruments are only 2.25 in. long with a 1.5-in. diameter. They are available with a 0 to 1 V recorder out option to drive chart recorders, ALC loops, and voltmeters.

LadyBug Technologies LLC, 2017 Diego Ave., Santa Rosa, CA 95403; (707) 237-7074, Internet: www.ladybug-tech.com

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