The Agilent/Keysight 8721A Directional Bridge is a passive RF test instrument for signal separation and return-loss measurement across 100 kHz to 100 MHz. It enables precise characterization of reflection and transmission in RF and microwave components by separating incident and reflected signals with exceptional directivity, making it essential for filter testing, impedance matching, and component validation.
Technical Specifications
• Frequency Range: 100 kHz to 100 MHz
• Impedance: 50 Ω (75 Ω option available)
• Insertion Loss: 6 dB nominal
• Coupling: 6 dB coupled to auxiliary arm
• Frequency Response: ±0.5 dB (0.1 to 110 MHz)
• Directivity: >40 dB (1 to 110 MHz)
• Load-Port Return Loss: >30 dB
• Maximum Input Power: +20 dBm
– Key Features
The bridge architecture provides >40 dB directivity across the measurement band, enabling separation of incident and reflected signals with high fidelity. The 6 dB coupling to the auxiliary arm supports power monitoring applications while maintaining 6 dB insertion loss in the main transmission path. Frequency response remains flat to ±0.5 dB across 0.1 to 110 MHz, accommodating swept measurements without gain correction. Load-port return loss exceeding 30 dB ensures minimal mismatch-induced errors when connected to high-impedance measurement instruments.
– Typical Applications
• Return loss and VSWR characterization of filters, attenuators, and connectors
• Complex reflection coefficient and impedance measurement
• Power monitoring and closed-loop leveling in automated test setups
• Transmission measurements in conjunction with swept signal sources
• Load power measurement via 6 dB attenuation in both arms
– Compatibility & Integration
Designed for integration with swept signal sources such as tracking generators and spectrum analyzers. Functions as a core component within transmission/reflection measurement kits and compatible with legacy network analyzers. Accepts 50 Ω RF coaxial connectors typical of instruments from this era.
