Terminology » RF Components » Spectrum Analyzer vs. Network Analyzer: Key Differences

Spectrum Analyzer vs. Network Analyzer: Key Differences

spectrum analyzer network analyzer rf measurement signal analysis s parameter

Spectrum analyzers excel at analyzing signal strength and frequency, while network analyzers provide comprehensive testing of RF networks using S-parameter measurements. Both use tuned receivers operating over similar frequency ranges. The primary difference lies in their measurement applications.

This page will outline the key differences between spectrum analyzers and network analyzers.

Spectrum Analyzer basics

Figure 1: Spectrum analyzer using super-heterodyne architecture. (Refer to Spectrum Analyzer basics for more details.)

A network analyzer measures reflection coefficients, transmission coefficients, insertion loss, return loss, S-parameters, and more, primarily testing components, devices, and sub-modules.
A spectrum analyzer measures carrier power levels, harmonics, spurious signals, sidebands, phase noise, and more.
Network analyzers are designed to measure phase-related characteristics, like group delay, which isn’t possible with a spectrum analyzer.
Spectrum Analyzers helps discover unwanted signals and network analyzer helps measure known signals.

network analyzer inside

Figure 2: Network analyzer internal modules. (Refer to Network Analyzer basics and types for more details.)

A spectrum analyzer is essentially a receiver displaying the signal fed to its RF input port from any RF transmitting device via cable or antenna. Modern real-time spectrum analyzers can even decode and display complex broadband RF signals from wireless devices like WLAN, WiMAX, GSM, Zigbee, and LTE. This requires additional baseband circuitry. Spectrum analyzers do not have an incorporated source.
Network analyzers consist of a source and multiple receivers and measure broadband frequency signals using techniques like power and frequency sweeps.
Spectrum analyzers generally have wider IF bandwidths compared to most network analyzers. However, network analyzers offer higher measurement accuracy due to vector error correction.
With a spectrum analyzer, placing a marker on the display is easy, but interpreting the results can be challenging. Conversely, with a network analyzer, placing a marker might be harder, but interpreting the results is usually straightforward.

Spectrum Analyzer vs. Network Analyzer: A Feature Comparison

The following table provides a comparison between spectrum and network analyzers based on various features:

Feature	Spectrum analyzer	Network analyzer
Primary Function	Measures the magnitude of signals over a frequency range	Measures both the amplitude and phase of signals (S-parameters) in a network
Purpose	Frequency domain analysis (spectrum of signals)	Analyzes the characteristics of RF networks (scattering parameters)
Type of Signals	Analyzes a single input signal (passive measurement)	Analyzes the relationship between input and output signals (active measurement)
Key Measurements	Power spectral density, frequency, noise, harmonics	S-parameters (S11, S21, etc.), reflection coefficient, return loss
Ports	Typically single input port for signal measurement	Usually has two or more ports for input and output network connections
Frequency Range	Broad frequency range, typically from kHz to GHz	Specific to the design, also in kHz to GHz range but used for network elements
Applications	Signal strength, modulation analysis, EMC testing	Device characterization (antennas, filters, amplifiers, etc.)
Complexity	Relatively simpler to operate	More complex due to phase and impedance measurement
Display	Frequency vs. amplitude (power or voltage)	Plots amplitude and phase (Smith chart, polar plot, etc.)
Example Instruments	Keysight N9320B, R&S FSV	Keysight PNA-X, R&S ZNB Network Analyzer

Conclusion

Understanding the difference between spectrum and network analyzers is crucial for RF and microwave engineering. A spectrum analyzer focuses on the magnitude of signals across frequencies, ideal for signal strength and interference analysis. In contrast, a network analyzer measures both amplitude and phase, making it essential for evaluating RF components’ transmission and reflection properties.