The Keysight 8481B (formerly Agilent / HP) is a high-power coaxial thermocouple RF power sensor designed for measuring average power from 10 MHz to 18 GHz. Equipped with an integrated 30 dB attenuator, the 8481B reliably measures power levels from 0 dBm to +44 dBm (1 mW to 25 W). It delivers low SWR to minimize mismatch uncertainty and is compatible with Keysight EPM, EPM-P, and P-series power meters, as well as legacy 43X and VXI power meters.
Specifications
General
| Parameter | Value |
|---|---|
| Interfaces | None (analog connection to host power meter via standard 11730A cable) |
| Display | None (uses host power meter display) |
Physical
| Parameter | Value |
|---|---|
| Power Supply | Powered directly by the host power meter |
| Operating Temperature | 0 to 55 °C |
| Weight | 0.8 |
RF Performance Specifications
| Parameter | Value |
|---|---|
| Frequency Range | 10 MHz to 18 GHz |
| Power Measurement Range (dBm) | 0 to +44 dBm |
| Power Measurement Range (Watts) | 1 mW to 25 W |
| Maximum Continuous Input Power (CW) | 30 W average to 35 °C, derated linearly to 25 W average at 55 °C |
| Maximum Peak Input Power | 500 W |
| Nominal Impedance | 50 Ω |
| Sensor Technology Type | Thermocouple with integrated 30 dB attenuator |
Measurement Accuracy and Sensitivity
| Parameter | Value |
|---|---|
| Zero Set (Noise) | ±50 µW |
| Zero Drift | ±10 µW (within 1 hour at constant temperature) |
Calibration and Reference Standards
| Parameter | Value |
|---|---|
| Internal EEPROM Calibration Table Support | No (calibration factors printed on label for manual entry) |
Mechanical & Connector Specifications
| Parameter | Value |
|---|---|
| RF Input Connector Type | N-type (male) |
| Integral Cable Length | None (requires separate 11730A-series cable) |
Physical Characteristics
| Parameter | Value |
|---|---|
| Weight (Net) | 0.8 kg |
Environmental and Compliance Specifications
| Parameter | Value |
|---|---|
| Operating Temperature Range | 0 to 55 °C |
| Storage Temperature Range | -40 to +75 °C |
System Compatibility & Options
| Parameter | Value |
|---|---|
| Compatible Power Meters | Keysight EPM, EPM-P, P-series, E1416A VXI, discontinued 70100A, and discontinued 43X series |
| Required Sensor Cable | Keysight 11730A (or other 11730 series cables) |
RF Attenuator
| Parameter | Value |
|---|---|
| Attenuator Value | 30 dB |
| Attenuator Power Rating | 25 W average |
Performance
| Parameter | Value |
|---|---|
| Measurement Noise | < 110 µW |
Calibration
| Parameter | Value |
|---|---|
| Calibration Reference Frequency | 50 MHz |
Technology
Thermocouple
Applications
RF Power Measurement