Rohde & Schwarz FSU3 20Hz – 3.6GHz Spectrum Analyzer

The Rohde & Schwarz FSU3 is a spectrum analyzer covering 20 Hz to 3.6 GHz, engineered for demanding RF analysis in aerospace, defense, and microwave applications. This instrument delivers exceptional dynamic range, sensitivity, and resolution bandwidth for signal analysis, EMI measurements, and component testing. Advanced ASIC technology and RF circuit design enable superior measurement accuracy across the full frequency range.

Technical Specifications

• DC coupled: 20 Hz to 3.6 GHz


• AC coupled: 1 MHz to 3.6 GHz


• Frequency resolution: 0.01 Hz


• Counter resolution: Selectable 0.1 Hz to 10 kHz Reference Frequency


• Internal OCXO (standard): Aging 1 × 10⁻⁷ per year


• Internal OCXO with R&S FSU-B4 option: Aging 3 × 10⁻⁸ per year


• External reference: 1 MHz to 20 MHz in 1 Hz steps Sensitivity & Linearity


• DANL: Typically −152 dBm at 2 GHz (1 Hz bandwidth); −155 dBm (1 Hz bandwidth)


• With R&S FSU-B24 preamplifier: Typically −168 dBm (1 Hz) at 20 GHz


• Third order intercept: Typically +25 dBm; >20 dBm


• 1 dB compression point: +13 dBm at 0 dB RF attenuation Phase Noise & Selectivity


• Phase noise: Typically −160 dBc (1 Hz) at 10 MHz carrier offset; <−128 dBc


• Resolution bandwidth: 10 Hz to 50 MHz (standard filters); 1 Hz to 30 kHz (FFT filters); 200 Hz, 9 kHz, 120 kHz, 1 MHz (EMI filters)


• Video bandwidth: 1 Hz to 10 MHz Measurement Performance


• Adjacent channel leakage ratio: Typically 77 dB (3GPP); 84 dB with noise correction


• Sweep time: Minimum 2.5 ms; minimum 1 µs (zero span)


• Measurement speed: 80 measurements/s in manual mode


• RF attenuation: Up to 70 dB (with R&S FSU-B12 option)

Key Features

• Integrated preamplifier (R&S FSU-B25)


• Optional internal tracking generator 100 kHz to 3.6 GHz (R&S FSU-B9) for scalar network analysis


• Noise figure measurement via R&S FS-K30 application firmware


• Phase noise measurement via R&S FS-K40 application firmware


• USB interface and data storage to USB memory stick, hard drive, or floppy disk

Typical Applications

• Base station development and testing


• Signal characterization and EMI compliance measurements


• Microwave component validation


• Aerospace and defense RF analysis

Compatibility & Integration External generator control via R&S FSP-B10 enables integration into automated test systems. USB connectivity supports remote control and data logging.