Keysight (Agilent) 778D

The Keysight (Agilent) 778D is a broadband dual-directional coupler engineered for RF power measurement and reflectometer applications. Operating across 100 MHz to 2 GHz, this device delivers 20 dB nominal coupling with directivity exceeding 36 dB below 1 GHz and 32 dB at 2 GHz. The coupler combines high directivity with accurate coupling characteristics, enabling precise measurement of reflection and transmission coefficients across multi-octave bandwidths.

– Technical Specifications

• Frequency Range: 100 MHz to 2 GHz
• Nominal Coupling: 20 dB
• Coupling Variation: ±1.0 dB or ±1.5 dB
• Mean Coupling Accuracy: ±0.5 dB
• Directivity: >36 dB to 1 GHz; 32 dB to 2 GHz; >30 dB overall
• Maximum Primary Line SWR: 1.1
• Insertion Loss: <0.60 dB
• Average Power Rating: 50 W
• Peak Power Rating: 500 W
• Connector Options: Type N or APC-7 on test port

– Key Features

• Multi-octave frequency coverage from VHF through S-band
• High directivity across operating band minimizes measurement errors
• Low insertion loss preserves signal integrity on primary transmission line
• Excellent primary line matching with SWR of 1.1 maximum
• Tight coupling accuracy of ±0.5 dB mean ensures consistent test results
• High power handling accommodates both average (50 W) and peak (500 W) RF signals

– Typical Applications

• Impedance and reflection coefficient measurements
• Device characterization via reflectometer configuration
• Frequency response testing and calibration
• Transmission and reflection characteristic verification

– Compatibility & Integration

The 778D connects to test equipment via designated TEST PORT. Integration with frequency response test sets such as the Keysight 8350B or Agilent 8755, and vector voltmeters including the Agilent 8508A or 8405A enables comprehensive impedance measurement campaigns.