Common RF and Microwave Measurements

The "Common RF and microwave Measurements" is a series of measurement tutorials and examples designed to help you understand the key components and methodology behind taking RF measurements as well as provide you a starting point in performing the measurements yourself.

For more information on RF concepts and related products visit ni.com/RF. Also, for more tutorials on concepts ranging from analog fundamentals to RF fundamentals visit the Measurement Fundamentals Series.

Frequency Response Measurement (Magnitude Response)

Frequency response is the measure of any system's response at the output to a signal of constant amplitude but varying frequency at its input. The frequency response is characterized by the magnitude (measured in dB) and the phase (measured in radians or degrees) of the system's response versus frequency.

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Noise Figure Measurement (NF)

All devices have inherent noise. When noise is quantified, it is usually referred to the device input. In other words, all noise power a UUT inherits is assumed to come from its input. The noise figure of a UUT is the ratio in dB of its noise power to the noise power that a matched resistive load would deliver at room temperature.

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1 dB Gain Compression Measurement (P1dB)

An amplifier maintains a constant gain for low-level input signals. However, at higher input levels, the amplifier goes into saturation and its gain decreases. The 1 dB compression point (P1dB) indicates the power level that causes the gain to drop by 1 dB from its small signal value.

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Harmonic Distortion Measurement (THD)

Harmonic distortion is a measure of the amount of power contained in the harmonics of a fundamental signal. Harmonic distortion is inherent to devices and systems that possess nonlinear characteristics—the more nonlinear the device, the greater its harmonic distortion.

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Intermodulation Distortion Measurement (IMD)

Two-tone third-order intermodulation distortion (IMD3) is the measure of the third-order distortion products produced by a nonlinear device when two tones closely spaced in frequency are fed into its input. This distortion product is usually so close to the carrier that it is almost impossible to filter out and can cause interference in multichannel communications equipment.

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Related Products

NI PXI-5660 2.7 GHz RF Vector Signal Analyzer The National Instruments PXI-5660 is a modular 2.7 GHz RF vector signal analyzer with 20 MHz of real-time bandwidth optimized for automated test. NI PXI-5671 2.7 GHz RF Vector Signal Generator The National Instruments PXI-5671 module is a 3-slot RF vector signal generator that delivers signal generation from 250 kHz to 2.7 GHz, 20 MHz of real-time bandwidth and up to 512 MB of memory. NI PXI-5652 6.6 GHz RF and Microwave Signal Generator The National Instruments PXI-5652 6.6 GHz RF and microwave signal generator is continuous-wave with modulation capability. It is excellent for setting up stimulus response applications with RF signal analyzers. NI RF Switches The National Instruments RF switch modules are ideal for expanding the channel count or increasing the flexibility of systems with signal bandwidths greater than 10 MHz to bandwidths as high as 26.5 GHz. NI LabVIEW The National Instruments PXI-5660 is a modular 2.7 GHz RF vector signal analyzer optimized for automated test. It provides high-throughput RF measurements in a compact, 3U PXI package. NI Modulation Toolkit The National Instruments Modulation Toolkit extends the built-in analysis capability of LabVIEW with functions and tools for signal generation, analysis, visualization, and processing of standard and custom digital and analog modulation formats. NI Spectral Measurements Toolkit The National Instruments Spectral Measurements Toolkit provides a set of flexible spectral measurements in LabVIEW and LabWindows/CVI, including power spectrum, peak power and frequency, in-band power, adjacent-channel power, and occupied bandwidth, as well as 3D spectrogram capabilities. NI Advanced Signal Processing Toolkit The National Instruments LabVIEW Signal Processing Toolkit is a suite of software tools, example programs, and utilities for time-frequency analysis, time-series analysis, and wavelets. It also includes a full version of the NI LabVIEW Digital Filter Design Toolkit. which is also available separately. NI Digital Filter Design Toolkit The National Instruments Digital Filter Design Toolkit extends LabVIEW with functions (LabVIEW VIs that install into the palette) and interactive tools for design, analysis, and implementation of digital filters.

Reader Comments | Submit a comment »

Extremely basic article, even after going through the content in the embedded links. This cannot be a tech article simply because the number of measurements profiled is less than the number of products listed!!!
- Santosh Reddy, Agni Instruments. santosh.reddyn@gmail.com - Sep 4, 2007