Keysight (Agilent) 8471D Planar-Doped Barrier Diode Detector

The Keysight 8471D is a planar-doped barrier diode detector engineered for RF and low microwave signal detection, power measurement, and wideband video applications. Operating from 100 kHz to 2 GHz, this zero-bias detector delivers ±0.2 dB frequency response to 1 GHz and handles continuous input power up to 100 mW with short-term peaks of 0.7 W. The 8471D combines low-level sensitivity of 0.5 mV/µW with noise performance below 50 µV peak-to-peak, making it suitable for precision leveling loops and power monitoring circuits.

Technical Specifications

• Detector Type: Planar-Doped Barrier (PDB) diode


• Frequency Range: 100 kHz to 2 GHz


• Frequency Response: ±0.2 dB (100 kHz to 1 GHz); ±0.4 dB (1 GHz to 2 GHz)


• Input Impedance (SWR): <1.23 (DC to 1 GHz); <1.46 (1 GHz to 2 GHz)


• Maximum Continuous Input Power: 100 mW


• Maximum Short-Term Input Power: 0.7 W (<1 minute)


• Low-Level Sensitivity: 0.5 mV/µW


• Noise Floor: <50 µV peak-to-peak (CW, 100 mV output, 400 kHz bandwidth)


• Output Polarity: Negative (standard); positive (Option 103)


• Input Connector: BNC male


• Output Connector: BNC female

Key Features

• Zero-bias operation eliminates external power supply requirements


• Square-law region extends to –10 dBm with Option 102


• Compact form factor: 63.4 mm × 15.64 mm × 13.72 mm; 38.8 grams


• Environmental specifications comply with MIL-STD 883 standards


• Operating temperature range: –20°C to +85°C


• Rated for 50,000 ft altitude operation


• Vibration and shock hardened (MIL-STD 883 Method 2007 and 2002.1)

Typical Applications

• Leveling loop detection elements


• Power monitoring and measurement


• Wideband video detection in RF/microwave instrumentation


• Signal detection circuits

Compatibility & Integration BNC connectors on both input and output enable direct integration into standard RF test equipment and systems. Optional positive polarity output and extended square-law load option support varied circuit topologies and measurement requirements.