Bird - The RF Experts
4421A Multifunction RF Power Meter

Multifunction Power Meters

Dual Sensor Inputs

The Model 4421A is a Multifunction Power Meter to be used in combination with Bird’s Precision Power Sensors to display RF power readings with up to 1% accuracy. This intuitive display unit clearly identifies the Forward and Reflected power measurements within the RF path. In addition, return loss readings can also shown to provide additional insight into the RF system being monitored.

The 4421A is the next generation replacement for the industry standard Model 4421. Building upon the original model’s high level of accuracy and its ease of use, the new 4421A enhances the meter’s functionality by utilizing a smaller/lighter design, and by providing the ability to have dual sensor inputs.

  • Compatible with the full line of Bird's 402x-series power sensors.
  • Automatic sensor detection for seamless integration.
  • Large 9.7" full color LCD touchscreen display for easy readability.
  • Dual sensor option expands measurement capabilities.
  • Compact, lightweight and portable design enhances funtionality.
  • Forward Power in W or dBm
  • Reflected Power in W or dBm
  • Return Loss in VSWR, RL, or Reflection Coefficient
Product Selection Guide
Model Number # of Sensors Communication Port
4421A-10-00-0 Single 402x Sensor No
4421A-20-00-0 Dual 402x Sensors No
4421A-10-11-0 Single 402x Sensor RS-232
4421A-20-11-0 Dual 402x Sensors RS-232
4421A Multifunction RF Power Meter
product specifications:
Item No
Item Name
Multifunction Power Meter
Compatible Bird Power Sensors
4021, 4022, 4023, 4024, 4025, 4027 Series and 4028 Series
Power Range
Sensor dependent
Frequency Range
Sensor dependent
Sensor Channels
Model dependent: 1 or 2
VSWR Display
1.0 to 199.9
Return Loss Display
0 to 40 dB
9.7" TFT full color LCD with touch screen
AC Power
100-240 VAC, 50-60Hz, 30 W
Fuse Rating: 1A, IEC (5 x 20mm), Time-Delay
Type: Internal, rechargeable
Life: Up to 7 hours
Changer: Built-in. Approximately 4 hours to fully recharge.
Model dependent: RS-232, RJ-45
95% max (noncondensing)
4,600 m (max)
Operating: 0 to 40 °C

-10 to 50 °C, < 1 month
-10 to 35 °C, < 6 months
-10 to 25 °C, > 6 months

1 - Storage temperature limited by battery specification. Storage outside this range may degrade battery performance. For best performance, a full recharge is recommended every 6 months or if stored below 0 °C.
10.6" x 9.7" x 3.6"
(269 x 246 x 91 mm)
Less than 5 lb
CE Compliant
Shock and Vibration: MIL-PRF-28800F Class 4
compatible devices:
SMK-3000 Series
RF Calibration Kit
4020 Series
Directional Power Sensors
4027A Series
Precision Directional Power Sensors
4027F Series
Filtered Precision Directional Power Sensors
4028 Series
High Power Precision Directional Power Sensors
Coiled Latch-N-Lok Interface Cable