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225 to 400 MHz

SKU: 21-30-31

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UHF Satcom

The 21-30-31 is a combined Hi-Lo angle UHF Satcom Antenna designed for installation on military helicopters & aircraft operating up to 350 knots. The 21-30-31 has the coaxial connectors mounted on the bottom of the antenna base which has an 8 hole mounting plate.

The antenna consists of two co-located elements; a circularly polarized cross-dipole and a linearly polarized broadband monopole. The two elements have separate RF feeds, and by manual selection of either, full hemispheric pattern coverage is provided. The Lo angle mode is intended for elevation angles up to about 45° and the Hi angle for approximately 45° to zenith.

Construction is from rugged fiberglass, foam-filled for structural integrity and prevention of moisture ingress and has aluminum alloy dipole elements and base mounting flange.

The antenna footprint compatible with, and a lightweight replacement for various types of “mushroom” and “batwing” designs. 

  • Suitable for helicopters and aircraft operating up to 350 knots
  • Robust Construction
  • Lightweight
  • Hemispherical radiation pattern coverage with separate Hi and Lo angle elements
  • 200 Watts CW Power handling
  • Designed to MIL-STD-810 environmental requirements
  • 8 hole mounting plate to replace heavier “batwing” types  
Model # 21-30-31
Brand Cooper Antennas

Lo Angle : 225 - 400 MHz

Hi Angle : 225 - 400 MHz 


Lo Angle: +3 dBiL

Hi Angle: +8 dBiC 


Lo Angle: ≤ 3.0:1

Hi Angle: ≤ 1.5:1 

Impedance (nominal) 50 Ohms
Power 200 Watts CW

Lo Angle: Linear

Hi Angle: Right Hand Circular (maximum at zenith) 

Antenna RF Connector  Lo Angle: TNC Female Hi Angle: N Female 
Operational Temperature - 66°F (- 54 °C) to + 160°F (+71°C) 
Dipole span  19.9 inches (505mm) 
Overall Height 10 inches (254mm) 
Weight 3.5 lbs (1.6kg)
Fixing Holes 8 x Ø 0.218/0.229 inch (5.5/5.8mm) holes, counter sunk Ø 0.394/0.413 inches (10.0/10.49mm)


  • Urethane Lusterless Black
  • Other finish options are available.
  • Please specify finish required when ordering.

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