Analyzers Spectrum
8 subcategories
This category guide provides practicing engineers and technical buyers with a fundamental overview of spectrum analyzers. These instruments measure the magnitude of input signals versus frequency over the instrument's full frequency range. Differentiating spectrum analyzers requires a close evaluation of core parameters, such as frequency range, resolution bandwidth (RBW), phase noise, Displayed Average Noise Level (DANL), and third-order intercept (TOI). Depending on whether your task involves field maintenance, laboratory design, or compliance testing, the optimal choice will shift between highly portable handheld instruments and high-performance benchtop platforms. This guide covers the key performance specifications to analyze when selecting a spectrum analyzer from our catalog.
- Frequency Range Coverages
- From 3 Hz up to 50 GHz (extendable to 325 GHz via external mixing)
- Available Form Factors
- Benchtop, Portable, and Handheld
- Key Performance Metrics
- Resolution Bandwidth, Phase Noise, DANL, and TOI
- Standard Input Impedance
- 50 Ω (75 Ω available for CATV-specific models)
Subcategories
Frequency Range and Bandwidth Capabilities
The frequency range of a spectrum analyzer dictates the boundary of signals it can resolve. Base-level and general-purpose RF spectrum analyzers typically cover ranges starting around 9 kHz or 100 Hz up to several gigahertz, such as the Keysight Technologies E4411B-BAS (9 kHz to 1.5 GHz) and the Keysight Technologies E4402B (100 Hz to 3.0 GHz). High-performance models extend lower boundaries down to 3 Hz, as seen in the Keysight Technologies E4440A, E4448A, and E4445A, or 10 Hz, as in the Rohde & Schwarz FSV7 and FSV30. Upper bounds can reach millimeter-wave frequencies, such as 40 GHz in the Keysight Technologies 8564E and 50 GHz in the Keysight Technologies 8565E. Select models support optional external mixing to push frequency coverage up to 325 GHz, including the Keysight Technologies E4440A and E4448A.
Resolution Bandwidth (RBW) is another critical metric that defines the instrument's selectivity. A narrow RBW enables the distinction of closely spaced signal components. High-performance models typically provide a minimum RBW down to 1 Hz, as found on the Keysight Technologies E4440A, Keysight Technologies 8563E, and Rohde & Schwarz FSEA30. For broader sweeps and fast signal capture, maximum RBW configurations can reach 8 MHz or 10 MHz, as seen in the Keysight Technologies E4448A and the Rohde & Schwarz FSV30.
Signal Integrity: Phase Noise, DANL, and Distortion
To detect weak signals and analyze modulation accurately, technical buyers must examine the instrument's internal noise contribution and distortion limits. Sensitivity is primarily determined by the Displayed Average Noise Level (DANL). High sensitivity is exemplified by the Anritsu MS2721B with a typical DANL of < -163 dBm (in a 1 Hz RBW at 1 GHz) and the Keysight Technologies E4440A with a typical DANL of -155 dBm at 1 GHz.
For close-in signal analysis, single sideband (SSB) phase noise is a key differentiator. High-performance instruments like the Keysight Technologies 8561E, 8563EC, and 8564E deliver phase noise values of ≤ -113 dBc/Hz at a 10 kHz offset (1 GHz carrier), compared to general-purpose portable units like the Keysight Technologies E4407B or E4404B, which specify phase noise at ≤ -90 dBc/Hz at the same offset.
Third-Order Intercept (TOI) measures the analyzer's ability to handle high-level signals without generating internal intermodulation distortion. High-performance analyzers achieve a TOI of +19 dBm (Keysight Technologies E4440A and Keysight Technologies E4443A) or +20 dBm (Rohde & Schwarz FSEA30 and Rohde & Schwarz FSEB30), whereas entry-level analyzers like the Keysight Technologies E4403B-BAS offer a lower TOI threshold of +7.5 dBm.
Form Factor and Environmental Adaptability
Identifying the right mechanical configuration depends on the operating environment. Handheld spectrum analyzers are optimized for field use, offering a lightweight profile and internal battery power. Key models include the Rohde & Schwarz FSH series (such as the FSH3 at 2.5 kg, and the FSH4 or FSH8 at 3 kg), the Keysight Technologies N9912A (2.7 kg), and the Keysight Technologies N9340B (3.2 kg). These instruments often feature integrated options like preamplifiers and tracking generators to facilitate antenna and transmission line testing in remote locations.
Conversely, benchtop units like the Keysight Technologies E4440A (24 kg) and the Rohde & Schwarz FSEB30 trade portability for superior laboratory specifications, larger displays, broader analysis bandwidths, and comprehensive connection interfaces including GPIB, LAN, and VGA outputs.
Frequently asked questions
- What is the practical impact of a 1 Hz resolution bandwidth?
- A 1 Hz RBW, available in high-performance models like the Keysight Technologies E4440A or 8563E, allows engineers to resolve extremely closely spaced signals and significantly lowers the displayed noise floor. This is essential for detecting low-level signals adjacent to high-power carriers, though it requires a longer sweep time.
- When is a 75 Ω RF input impedance required instead of the standard 50 Ω?
- While the majority of RF and microwave systems utilize 50 Ω impedance, 75 Ω is standard in the cable television (CATV) and broadcasting industries. Using a 50 Ω analyzer on a 75 Ω system causes measurement errors due to signal reflections. Models like the Keysight Technologies E4411B-BAS (which features a 75 Ω RF input) and the dedicated CATV Keysight Technologies 8591C are specifically configured for these applications.