Sirio Thunder Base CB & 10m Ham Antenna 300W Peak, No Tuning, 25-29MHz, 1/4λ Helical

The Sirio Thunder is a compact, 1/4λ helical-loaded base station antenna engineered in Italy for CB 27MHz and 10-metre amateur radio use. With an exceptional bandwidth of ≥5 MHz at SWR ≤2 covering 25–29 MHz with no tuning required, it's one of the most plug-and-play base antennas in the Sirio range — perfect for operators who want reliable, hassle-free performance straight out of the box. With 100W continuous power handling (300W short time CW) and a gain of 0 dBd (2.15 dBi), it stands at just 960mm (3.15ft) tall, making it ideal for space-restricted installations. Designed for on-mast mounting and constructed from aluminium, copper, galvanised steel, and nylon.

Key Features

• 100W continuous power handling (CW)
• 300W short time power handling (CW)
• 25–29 MHz coverage — no tuning required
• Exceptional bandwidth: ≥5 MHz @ SWR ≤2
• Compatible with CB 27MHz & 10-metre amateur radio
• Gain: 0 dBd / 2.15 dBi
• Omnidirectional radiation pattern
• Linear vertical polarisation
• Compact 1/4λ helical loaded design
• On-mast mounting
• SO-239 (UHF-Female) connector
• Height: 960mm / 3.15ft — ideal for space-restricted installations
• Durable materials: aluminium, copper, galvanised steel & nylon
• Made in Italy by Sirio

Technical Specifications

• Type: 1/4λ helical loaded base antenna
• Radiation: Omnidirectional
• Polarisation: Linear vertical
• Frequency range: 25–29 MHz (no tuning required)
• Systems: CB 27MHz / 10m amateur (HAM)
• Gain: 0 dBd / 2.15 dBi
• Bandwidth: ≥5 MHz @ SWR ≤2
• Max power: 300W peak (CW short time) | 100W continuous (CW)
• Connector: SO-239 (UHF-Female)
• Height: 960mm / 3.15ft
• Mounting: On-mast
• Materials: Aluminium, copper, galvanised steel, nylon
• Country of origin: Italy