HP / Agilent 85021B Microwave Directional Bridge 10MHz to 26.5GHz

The HP/Agilent 85021B is a precision microwave directional bridge for reflection and transmission measurements spanning 10 MHz to 26.5 GHz. Operating at 50 ohms nominal impedance, this instrument delivers directivity exceeding 35 dB across its frequency range with insertion loss below 1.5 dB typical. It integrates a zero-bias Schottky diode detector for return loss measurement and accepts RF input up to +23 dBm.

The 85021B connects via APC-3.5 Female connectors and pairs with HP/Agilent Scalar Network Analyzers to characterize microwave components, verify system performance, and execute ratio measurements when combined with external power splitting and detection circuits. Its compact form factor - 15 mm H × 110 mm W × 96 mm D, weighing 0.5 kg - suits laboratory, research, and field measurement environments where precise reflection and transmission data are critical to design validation and troubleshooting workflows.

Technical Specifications

• Frequency Range: 10 MHz to 26.5 GHz


• Nominal Impedance: 50 ohms


• Directivity: 36 dB (0.01–0.04 GHz and 20–26.5 GHz); 40 dB (0.04–20 GHz); typical >35 dB


• Insertion Loss: <1.5 dB (typical)


• Maximum Input Power: +23 dBm


• Internal Detector: One zero-bias Schottky diode


• Connectors: APC-3.5 Female (input, output, test port)


• Dimensions: 15 H × 110 W × 96 mm


• Weight: 0.5 kg (net)

Key Features

• Return loss measurement via integrated Schottky detector


• Transmission measurements with optional external detector


• Ratio measurement capability using power splitter and detector


• High directivity maintained across three frequency bands


• Compact, rugged construction

Typical Applications

• Reflection and transmission characterization of microwave components


• Return loss verification and system diagnostics


• Scalar network analysis and impedance measurement

Compatibility & Integration Designed for use with HP/Agilent Scalar Network Analyzers including the 8757A, 8756A, and 8755C.