HP / Agilent 85027A Directional Bridge, 10 MHz to 18 GHz

The HP/Agilent 85027A Directional Bridge is a precision reflection measurement instrument engineered for scalar network analyzer systems operating from 10 MHz to 18 GHz. The device delivers 40 dB directivity and exceptional test port match, enabling accurate S-parameter characterization of microwave components across the full frequency band. Dual detection modes

AC (modulated RF at 27.8 kHz) and DC (unmodulated RF) - accommodate both interference-rich environments and modulation-sensitive devices such as gain-controlled amplifiers.

Technical Specifications

• Frequency Range: 10 MHz to 18 GHz


• Impedance: 50 ohms


• Directivity: Typically 40 dB


• Test Port Match (SWR): 8.4 to 18 GHz specified for excellent match


• Maximum Input Power: +23 dBm or +10 Volts


• Input Connector: Type-N (female)


• Test Port Connector: APC-7


• Weight: 5 lb (shipping)

Key Features

• AC detection mode: Modulated RF signal (27.8 kHz) for EMI-resistant measurements


• DC detection mode: Unmodulated RF signal for modulation-sensitive component testing


• High directivity ensures precise reflection measurements across the full bandwidth


• Coaxial measurement capability to 18 GHz

Typical Applications

• Return loss and reflection coefficient measurement


• Microwave component and system characterization


• S-parameter acquisition in scalar network analyzer setups


• Testing of amplifiers and other gain-controlled circuits in DC mode


• High-interference environment measurements in AC mode

Compatibility & Integration Designed for operation with HP/Agilent scalar network analyzers:

HP 8757: Supports AC and DC detection modes

HP 8756: AC detection mode

HP 8755: AC detection mode For SMA device measurements, use with 7 mm to 3.5 mm adapter (typical) across the 10 MHz to 18 GHz range.