2.4kW 4:1 Unun for multiband monopole rod and wire verticals

If you're looking for high-quality random wire antennas to pair with your 4:1 UNUN, check out our selection here.

Function

Trap- or coilless wire or rod antennas with a length varying from 6 to 14 meters are popular because of their simplicity. With some compromise, and a good antenna tuner, they can be deployed on multiple frequency bands.

The feedpoint impedance of such non-resonant vertical antennas is relatively random, causing high VSWR values. To bring the impedance within the range of a good external or built-in asymmetric antenna tuner, a 4:1 UNUN (Unbalanced to Unbalanced) impedance transformer is used as a pre-match unit.

The UNUN ensures reasonably low VSWR values on the coaxial feedline, minimizing excessive losses. As with any vertical antenna, the efficiency and radiation pattern largely depend on the radial field beneath the antenna. This can range from a simple grounding rod in temporary or emergency setups to an extensive radial plane in more permanent installations.

The UNUN can, with a conservative margin, withstand 1200 Watts PeP, even under mismatched conditions.

Mechanical Characteristics

• Optimized 61 mm diameter toroidal ferrite core.
• High-temperature-resistant Teflon coaxial cable with excellent dielectric strength.
• Professional-grade 50-ohm N-connector or SO-239 connector (IP66 rating when sealed with self-vulcanizing tape).
• Stainless steel M6 antenna terminals, made from corrosion-resistant 316 stainless steel.
• Durable, waterproof (IP64), and shock-resistant polycarbonate enclosure with UV protection. More info.
• Approximate weight: 500 g.

Electrical Properties

• Impedance transformation ratio: 4:1
• Maximum Power Ratings:
• 2400 W PEP @ VSWR < 2.0:1 (ICAS)
• 1200 W PEP @ VSWR < 2.0:1 (CCS)
• 850 W FT8/FT4 @ VSWR < 2.0:1
• For ICAS and CCS power definitions, refer to this guide.
• Important Note: For VSWR > 2:1, power de-rating is recommended:
  • VSWR > 3:1 → Limit power to < 600 W PEP.
  • VSWR > 5:1 → Limit power to < 300 W PEP.
• Operational frequency range: 1.5 to 30 MHz.
• Insertion loss: < 0.1 dB.
• Intrinsic VSWR: < 1.3:1 across the frequency range.

For additional documentation, visit our technical resources.